package handlers

import (
	"context"
	dbgen "Yimaru-Backend/gen/db"
	"Yimaru-Backend/internal/domain"
	"errors"
	"strconv"
	"strings"
	"unicode/utf8"

	"github.com/gofiber/fiber/v2"
	"github.com/jackc/pgx/v5"
	"github.com/jackc/pgx/v5/pgtype"
)

type createCourseSubCategoryReq struct {
	CategoryID   int64   `json:"category_id"`
	Name         string  `json:"name"`
	Description  *string `json:"description"`
	DisplayOrder *int32  `json:"display_order"`
	IsActive     *bool   `json:"is_active"`
}

type createCourseCategoryReq struct {
	Name     string `json:"name"`
	IsActive *bool  `json:"is_active"`
}

type createCourseReq struct {
	CategoryID    int64   `json:"category_id"`
	SubCategoryID *int64  `json:"sub_category_id"`
	Title         string  `json:"title"`
	Description   *string `json:"description"`
	Thumbnail     *string `json:"thumbnail"`
	IntroVideoURL *string `json:"intro_video_url"`
	IsActive      *bool   `json:"is_active"`
}

type updateCourseReq struct {
	Title         *string `json:"title"`
	Description   *string `json:"description"`
	Thumbnail     *string `json:"thumbnail"`
	IntroVideoURL *string `json:"intro_video_url"`
	IsActive      *bool   `json:"is_active"`
}

type updateCourseThumbnailReq struct {
	ThumbnailURL string `json:"thumbnail_url"`
}

type createLevelReq struct {
	CourseID     int64   `json:"course_id"`
	CEFRLevel    string  `json:"cefr_level"`
	Title        *string `json:"title"`
	Description  *string `json:"description"`
	Thumbnail    *string `json:"thumbnail"`
	DisplayOrder *int32  `json:"display_order"`
	IsActive     *bool   `json:"is_active"`
}

type updateLevelReq struct {
	Title        *string `json:"title"`
	Description  *string `json:"description"`
	Thumbnail    *string `json:"thumbnail"`
	DisplayOrder *int32  `json:"display_order"`
	IsActive     *bool   `json:"is_active"`
}

type createModuleReq struct {
	LevelID      int64   `json:"level_id"`
	Title        string  `json:"title"`
	Description  *string `json:"description"`
	IconURL      *string `json:"icon_url"`
	DisplayOrder *int32  `json:"display_order"`
	IsActive     *bool   `json:"is_active"`
}

type updateModuleReq struct {
	Title        *string `json:"title"`
	Description  *string `json:"description"`
	IconURL      *string `json:"icon_url"`
	DisplayOrder *int32  `json:"display_order"`
	IsActive     *bool   `json:"is_active"`
}

type createSubModuleReq struct {
	ModuleID     int64   `json:"module_id"`
	Title        string  `json:"title"`
	Description  *string `json:"description"`
	Thumbnail    *string `json:"thumbnail"`
	Tips         *string `json:"tips"`
	DisplayOrder *int32  `json:"display_order"`
	IsActive     *bool   `json:"is_active"`
}

type createSubModuleVideoReq struct {
	SubModuleID  int64   `json:"sub_module_id"`
	Title        string  `json:"title"`
	Description  *string `json:"description"`
	VideoURL     string  `json:"video_url"`
	Duration     *int32  `json:"duration"`
	Resolution   *string `json:"resolution"`
	Visibility   *string `json:"visibility"`
	InstructorID *string `json:"instructor_id"`
	Thumbnail    *string `json:"thumbnail"`
	DisplayOrder *int32  `json:"display_order"`
	Status       *string `json:"status"`
}

type updateSubModuleReq struct {
	Title        *string `json:"title"`
	Description  *string `json:"description"`
	Thumbnail    *string `json:"thumbnail"`
	Tips         *string `json:"tips"`
	DisplayOrder *int32  `json:"display_order"`
	IsActive     *bool   `json:"is_active"`
}

type updateSubModuleVideoReq struct {
	Title       *string `json:"title"`
	Description *string `json:"description"`
	VideoURL    *string `json:"video_url"`
}

type updatePracticeReq struct {
	Title       *string `json:"title"`
	Description *string `json:"description"`
	Persona     *string `json:"persona"`
	IsActive    *bool   `json:"is_active"`
}

type createSubModuleLessonReq struct {
	SubModuleID      int64   `json:"sub_module_id"`
	Title            string  `json:"title"`
	Description      *string `json:"description"`
	Thumbnail        *string `json:"thumbnail"`
	TeachingText     *string `json:"teaching_text"`
	TeachingImageURL *string `json:"teaching_image_url"`
	TeachingAudioURL *string `json:"teaching_audio_url"`
	TeachingVideoURL *string `json:"teaching_video_url"`
	DisplayOrder     *int32  `json:"display_order"`
	IsActive         *bool   `json:"is_active"`
}

type updateSubModuleLessonReq struct {
	SubModuleID      *int64  `json:"sub_module_id"`
	Title            *string `json:"title"`
	Description      *string `json:"description"`
	Thumbnail        *string `json:"thumbnail"`
	TeachingText     *string `json:"teaching_text"`
	TeachingImageURL *string `json:"teaching_image_url"`
	TeachingAudioURL *string `json:"teaching_audio_url"`
	TeachingVideoURL *string `json:"teaching_video_url"`
	DisplayOrder     *int32  `json:"display_order"`
	IsActive         *bool   `json:"is_active"`
}

type createSubModulePracticeReq struct {
	SubModuleID   int64   `json:"sub_module_id"`
	Title         string  `json:"title"`
	Description   *string `json:"description"`
	Thumbnail     *string `json:"thumbnail"`
	IntroVideoURL *string `json:"intro_video_url"`
	QuestionSetID int64   `json:"question_set_id"`
	DisplayOrder  *int32  `json:"display_order"`
	IsActive      *bool   `json:"is_active"`
}

type capstoneQuestionItem struct {
	QuestionID   int64  `json:"question_id"`
	DisplayOrder *int32 `json:"display_order"`
}

type createSubModuleCapstoneReq struct {
	SubModuleID      int64                  `json:"sub_module_id"`
	Title            string                 `json:"title"`
	Description      *string                `json:"description"`
	Tips             *string                `json:"tips"`
	Thumbnail        *string                `json:"thumbnail"`
	TimeLimitMinutes *int32                 `json:"time_limit_minutes"`
	PassingScore     *int32                 `json:"passing_score"`
	ShuffleQuestions *bool                  `json:"shuffle_questions"`
	Status           *string                `json:"status"`
	DisplayOrder     *int32                 `json:"display_order"`
	IsActive         *bool                  `json:"is_active"`
	Questions        []capstoneQuestionItem `json:"questions"`
}

type updateSubModuleCapstoneReq struct {
	Title            *string                `json:"title"`
	Description      *string                `json:"description"`
	Tips             *string                `json:"tips"`
	Thumbnail        *string                `json:"thumbnail"`
	TimeLimitMinutes *int32                 `json:"time_limit_minutes"`
	PassingScore     *int32                 `json:"passing_score"`
	ShuffleQuestions *bool                  `json:"shuffle_questions"`
	Status           *string                `json:"status"`
	DisplayOrder     *int32                 `json:"display_order"`
	IsActive         *bool                  `json:"is_active"`
	Questions        []capstoneQuestionItem `json:"questions"`
}

type createModuleCapstoneReq struct {
	ModuleID         int64                  `json:"module_id"`
	Title            string                 `json:"title"`
	Description      *string                `json:"description"`
	Tips             *string                `json:"tips"`
	Thumbnail        *string                `json:"thumbnail"`
	TimeLimitMinutes *int32                 `json:"time_limit_minutes"`
	PassingScore     *int32                 `json:"passing_score"`
	ShuffleQuestions *bool                  `json:"shuffle_questions"`
	Status           *string                `json:"status"`
	DisplayOrder     *int32                 `json:"display_order"`
	IsActive         *bool                  `json:"is_active"`
	Questions        []capstoneQuestionItem `json:"questions"`
}

type updateModuleCapstoneReq struct {
	Title            *string                `json:"title"`
	Description      *string                `json:"description"`
	Tips             *string                `json:"tips"`
	Thumbnail        *string                `json:"thumbnail"`
	TimeLimitMinutes *int32                 `json:"time_limit_minutes"`
	PassingScore     *int32                 `json:"passing_score"`
	ShuffleQuestions *bool                  `json:"shuffle_questions"`
	Status           *string                `json:"status"`
	DisplayOrder     *int32                 `json:"display_order"`
	IsActive         *bool                  `json:"is_active"`
	Questions        []capstoneQuestionItem `json:"questions"`
}

type legacyHierarchyRow struct {
	CategoryID      int64   `json:"category_id"`
	CategoryName    string  `json:"category_name"`
	SubCategoryID   *int64  `json:"sub_category_id"`
	SubCategoryName *string `json:"sub_category_name"`
	CourseID        *int64  `json:"course_id"`
	CourseTitle     *string `json:"course_title"`
}

func toText(v *string) pgtype.Text {
	if v == nil {
		return pgtype.Text{Valid: false}
	}
	return pgtype.Text{String: *v, Valid: true}
}

func mergeTextField(current pgtype.Text, req *string) pgtype.Text {
	if req == nil {
		return current
	}
	if *req == "" {
		return pgtype.Text{Valid: false}
	}
	return pgtype.Text{String: *req, Valid: true}
}

func stringPtrFromPgText(t pgtype.Text) *string {
	if !t.Valid {
		return nil
	}
	s := t.String
	return &s
}

func toInt4(v *int32) pgtype.Int4 {
	if v == nil {
		return pgtype.Int4{Valid: false}
	}
	return pgtype.Int4{Int32: *v, Valid: true}
}

func boolOrNil(v *bool) interface{} {
	if v == nil {
		return nil
	}
	return *v
}

func intOrNil(v *int32) interface{} {
	if v == nil {
		return nil
	}
	return *v
}

func textPtr(v pgtype.Text) *string {
	if !v.Valid {
		return nil
	}
	s := v.String
	return &s
}

// ListCourseCategories godoc
// @Summary List course categories
// @Description Legacy-compatible endpoint for listing course categories
// @Tags course-management
// @Produce json
// @Success 200 {object} domain.Response
// @Failure 500 {object} domain.ErrorResponse
// @Router /api/v1/course-management/categories [get]
func (h *Handler) ListCourseCategories(c *fiber.Ctx) error {
	rows, err := h.analyticsDB.GetAllCourseCategories(c.Context(), dbgen.GetAllCourseCategoriesParams{
		Offset: pgtype.Int4{Int32: 0, Valid: true},
		Limit:  pgtype.Int4{Int32: 10000, Valid: true},
	})
	if err != nil {
		return c.Status(fiber.StatusInternalServerError).JSON(domain.ErrorResponse{Message: "Failed to load categories", Error: err.Error()})
	}

	total := 0
	if len(rows) > 0 {
		total = int(rows[0].TotalCount)
	}

	return c.JSON(domain.Response{
		Message: "Categories retrieved successfully",
		Data: map[string]interface{}{
			"categories":  rows,
			"total_count": total,
		},
	})
}

// ListCoursesByCategory godoc
// @Summary List courses by category
// @Description Legacy-compatible endpoint that returns courses for one category
// @Tags course-management
// @Produce json
// @Param categoryId path int true "Category ID"
// @Param offset query int false "Offset"
// @Param limit query int false "Limit"
// @Success 200 {object} domain.Response
// @Failure 400 {object} domain.ErrorResponse
// @Failure 500 {object} domain.ErrorResponse
// @Router /api/v1/course-management/categories/{categoryId}/courses [get]
func (h *Handler) ListCoursesByCategory(c *fiber.Ctx) error {
	categoryID, err := strconv.ParseInt(c.Params("categoryId"), 10, 64)
	if err != nil || categoryID <= 0 {
		return c.Status(fiber.StatusBadRequest).JSON(domain.ErrorResponse{Message: "Invalid category ID", Error: "categoryId must be a positive integer"})
	}

	offset := int32(c.QueryInt("offset", 0))
	if offset < 0 {
		offset = 0
	}
	limit := int32(c.QueryInt("limit", 10000))
	if limit <= 0 {
		limit = 10000
	}

	rows, err := h.analyticsDB.GetCoursesByCategory(c.Context(), dbgen.GetCoursesByCategoryParams{
		CategoryID: categoryID,
		Offset:     pgtype.Int4{Int32: offset, Valid: true},
		Limit:      pgtype.Int4{Int32: limit, Valid: true},
	})
	if err != nil {
		return c.Status(fiber.StatusInternalServerError).JSON(domain.ErrorResponse{Message: "Failed to load courses", Error: err.Error()})
	}

	total := 0
	if len(rows) > 0 {
		total = int(rows[0].TotalCount)
	}

	return c.JSON(domain.Response{
		Message: "Courses retrieved successfully",
		Data: map[string]interface{}{
			"courses":     rows,
			"total_count": total,
		},
	})
}

// ListAllCourses godoc
// @Summary List all courses
// @Description Returns all courses with pagination
// @Tags course-management
// @Produce json
// @Param offset query int false "Offset"
// @Param limit query int false "Limit"
// @Success 200 {object} domain.Response
// @Failure 500 {object} domain.ErrorResponse
// @Router /api/v1/course-management/courses [get]
func (h *Handler) ListAllCourses(c *fiber.Ctx) error {
	offset := int32(c.QueryInt("offset", 0))
	if offset < 0 {
		offset = 0
	}
	limit := int32(c.QueryInt("limit", 10000))
	if limit <= 0 {
		limit = 10000
	}

	rows, err := h.analyticsDB.GetAllCourses(c.Context(), dbgen.GetAllCoursesParams{
		Offset: pgtype.Int4{Int32: offset, Valid: true},
		Limit:  pgtype.Int4{Int32: limit, Valid: true},
	})
	if err != nil {
		return c.Status(fiber.StatusInternalServerError).JSON(domain.ErrorResponse{Message: "Failed to load courses", Error: err.Error()})
	}

	total := 0
	if len(rows) > 0 {
		total = int(rows[0].TotalCount)
	}

	return c.JSON(domain.Response{
		Message: "Courses retrieved successfully",
		Data: map[string]interface{}{
			"courses":     rows,
			"total_count": total,
		},
	})
}

// ListHumanLanguageCourses godoc
// @Summary List Human Language courses
// @Description Returns all courses under Human Language category
// @Tags course-management
// @Produce json
// @Param offset query int false "Offset"
// @Param limit query int false "Limit"
// @Success 200 {object} domain.Response
// @Failure 500 {object} domain.ErrorResponse
// @Router /api/v1/course-management/human-language/courses [get]
func (h *Handler) ListHumanLanguageCourses(c *fiber.Ctx) error {
	offset := int32(c.QueryInt("offset", 0))
	if offset < 0 {
		offset = 0
	}
	limit := int32(c.QueryInt("limit", 10000))
	if limit <= 0 {
		limit = 10000
	}

	rows, err := h.analyticsDB.GetHumanLanguageCourses(c.Context(), dbgen.GetHumanLanguageCoursesParams{
		Offset: pgtype.Int4{Int32: offset, Valid: true},
		Limit:  pgtype.Int4{Int32: limit, Valid: true},
	})
	if err != nil {
		return c.Status(fiber.StatusInternalServerError).JSON(domain.ErrorResponse{Message: "Failed to load Human Language courses", Error: err.Error()})
	}

	total := 0
	if len(rows) > 0 {
		total = int(rows[0].TotalCount)
	}

	return c.JSON(domain.Response{
		Message: "Human Language courses retrieved successfully",
		Data: map[string]interface{}{
			"courses":     rows,
			"total_count": total,
		},
	})
}

// ListCoursesBySubCategory godoc
// @Summary List courses by sub-category
// @Description Returns courses for one sub-category
// @Tags course-management
// @Produce json
// @Param subCategoryId path int true "Sub-category ID"
// @Param offset query int false "Offset"
// @Param limit query int false "Limit"
// @Success 200 {object} domain.Response
// @Failure 400 {object} domain.ErrorResponse
// @Failure 500 {object} domain.ErrorResponse
// @Router /api/v1/course-management/sub-categories/{subCategoryId}/courses [get]
func (h *Handler) ListCoursesBySubCategory(c *fiber.Ctx) error {
	subCategoryID, err := strconv.ParseInt(c.Params("subCategoryId"), 10, 64)
	if err != nil || subCategoryID <= 0 {
		return c.Status(fiber.StatusBadRequest).JSON(domain.ErrorResponse{Message: "Invalid sub-category ID", Error: "subCategoryId must be a positive integer"})
	}

	offset := int32(c.QueryInt("offset", 0))
	if offset < 0 {
		offset = 0
	}
	limit := int32(c.QueryInt("limit", 10000))
	if limit <= 0 {
		limit = 10000
	}

	rows, err := h.analyticsDB.GetCoursesBySubCategory(c.Context(), dbgen.GetCoursesBySubCategoryParams{
		SubCategoryID: pgtype.Int8{Int64: subCategoryID, Valid: true},
		Offset:        pgtype.Int4{Int32: offset, Valid: true},
		Limit:         pgtype.Int4{Int32: limit, Valid: true},
	})
	if err != nil {
		return c.Status(fiber.StatusInternalServerError).JSON(domain.ErrorResponse{Message: "Failed to load courses", Error: err.Error()})
	}

	total := 0
	if len(rows) > 0 {
		total = int(rows[0].TotalCount)
	}

	return c.JSON(domain.Response{
		Message: "Courses retrieved successfully",
		Data: map[string]interface{}{
			"courses":     rows,
			"total_count": total,
		},
	})
}

// GetCourseByID godoc
// @Summary Get course detail
// @Description Returns one course by ID
// @Tags course-management
// @Produce json
// @Param courseId path int true "Course ID"
// @Success 200 {object} domain.Response
// @Failure 400 {object} domain.ErrorResponse
// @Failure 404 {object} domain.ErrorResponse
// @Failure 500 {object} domain.ErrorResponse
// @Router /api/v1/course-management/courses/{courseId} [get]
func (h *Handler) GetCourseByID(c *fiber.Ctx) error {
	courseID, err := strconv.ParseInt(c.Params("courseId"), 10, 64)
	if err != nil || courseID <= 0 {
		return c.Status(fiber.StatusBadRequest).JSON(domain.ErrorResponse{
			Message: "Invalid course ID",
			Error:   "courseId must be a positive integer",
		})
	}

	course, err := h.analyticsDB.GetCourseByID(c.Context(), courseID)
	if err != nil {
		return c.Status(fiber.StatusNotFound).JSON(domain.ErrorResponse{
			Message: "Course not found",
			Error:   err.Error(),
		})
	}

	return c.JSON(domain.Response{
		Message: "Course retrieved successfully",
		Data:    course,
	})
}

// ListAllLevels godoc
// @Summary List all levels
// @Description Returns all levels with pagination
// @Tags course-management
// @Produce json
// @Param offset query int false "Offset"
// @Param limit query int false "Limit"
// @Success 200 {object} domain.Response
// @Failure 500 {object} domain.ErrorResponse
// @Router /api/v1/course-management/levels [get]
func (h *Handler) ListAllLevels(c *fiber.Ctx) error {
	offset := int32(c.QueryInt("offset", 0))
	if offset < 0 {
		offset = 0
	}
	limit := int32(c.QueryInt("limit", 10000))
	if limit <= 0 {
		limit = 10000
	}

	rows, err := h.analyticsDB.GetAllLevels(c.Context(), dbgen.GetAllLevelsParams{
		Offset: pgtype.Int4{Int32: offset, Valid: true},
		Limit:  pgtype.Int4{Int32: limit, Valid: true},
	})
	if err != nil {
		return c.Status(fiber.StatusInternalServerError).JSON(domain.ErrorResponse{Message: "Failed to load levels", Error: err.Error()})
	}

	total := 0
	if len(rows) > 0 {
		total = int(rows[0].TotalCount)
	}

	return c.JSON(domain.Response{
		Message: "Levels retrieved successfully",
		Data: map[string]interface{}{
			"levels":      rows,
			"total_count": total,
		},
	})
}

// ListLevelsByCourse godoc
// @Summary List levels by course
// @Description Returns all active levels for one course
// @Tags course-management
// @Produce json
// @Param courseId path int true "Course ID"
// @Success 200 {object} domain.Response
// @Failure 400 {object} domain.ErrorResponse
// @Failure 500 {object} domain.ErrorResponse
// @Router /api/v1/course-management/courses/{courseId}/levels [get]
func (h *Handler) ListLevelsByCourse(c *fiber.Ctx) error {
	courseID, err := strconv.ParseInt(c.Params("courseId"), 10, 64)
	if err != nil || courseID <= 0 {
		return c.Status(fiber.StatusBadRequest).JSON(domain.ErrorResponse{
			Message: "Invalid course ID",
			Error:   "courseId must be a positive integer",
		})
	}

	rows, err := h.analyticsDB.GetLevelsByCourseID(c.Context(), courseID)
	if err != nil {
		return c.Status(fiber.StatusInternalServerError).JSON(domain.ErrorResponse{Message: "Failed to load levels", Error: err.Error()})
	}

	return c.JSON(domain.Response{
		Message: "Levels retrieved successfully",
		Data: map[string]interface{}{
			"levels":      rows,
			"total_count": len(rows),
		},
	})
}

// GetLevelByID godoc
// @Summary Get level detail
// @Description Returns one level by ID
// @Tags course-management
// @Produce json
// @Param levelId path int true "Level ID"
// @Success 200 {object} domain.Response
// @Failure 400 {object} domain.ErrorResponse
// @Failure 404 {object} domain.ErrorResponse
// @Failure 500 {object} domain.ErrorResponse
// @Router /api/v1/course-management/levels/{levelId} [get]
func (h *Handler) GetLevelByID(c *fiber.Ctx) error {
	levelID, err := strconv.ParseInt(c.Params("levelId"), 10, 64)
	if err != nil || levelID <= 0 {
		return c.Status(fiber.StatusBadRequest).JSON(domain.ErrorResponse{
			Message: "Invalid level ID",
			Error:   "levelId must be a positive integer",
		})
	}

	level, err := h.analyticsDB.GetLevelByID(c.Context(), levelID)
	if err != nil {
		return c.Status(fiber.StatusNotFound).JSON(domain.ErrorResponse{
			Message: "Level not found",
			Error:   err.Error(),
		})
	}

	return c.JSON(domain.Response{
		Message: "Level retrieved successfully",
		Data:    level,
	})
}

// ListAllModules godoc
// @Summary List all modules
// @Description Returns all modules with pagination
// @Tags course-management
// @Produce json
// @Param offset query int false "Offset"
// @Param limit query int false "Limit"
// @Success 200 {object} domain.Response
// @Failure 500 {object} domain.ErrorResponse
// @Router /api/v1/course-management/modules [get]
func (h *Handler) ListAllModules(c *fiber.Ctx) error {
	offset := int32(c.QueryInt("offset", 0))
	if offset < 0 {
		offset = 0
	}
	limit := int32(c.QueryInt("limit", 10000))
	if limit <= 0 {
		limit = 10000
	}

	rows, err := h.analyticsDB.GetAllModules(c.Context(), dbgen.GetAllModulesParams{
		Offset: pgtype.Int4{Int32: offset, Valid: true},
		Limit:  pgtype.Int4{Int32: limit, Valid: true},
	})
	if err != nil {
		return c.Status(fiber.StatusInternalServerError).JSON(domain.ErrorResponse{Message: "Failed to load modules", Error: err.Error()})
	}

	total := 0
	if len(rows) > 0 {
		total = int(rows[0].TotalCount)
	}

	return c.JSON(domain.Response{
		Message: "Modules retrieved successfully",
		Data: map[string]interface{}{
			"modules":     rows,
			"total_count": total,
		},
	})
}

// ListModulesByLevel godoc
// @Summary List modules by level
// @Description Returns all active modules for one level
// @Tags course-management
// @Produce json
// @Param levelId path int true "Level ID"
// @Success 200 {object} domain.Response
// @Failure 400 {object} domain.ErrorResponse
// @Failure 500 {object} domain.ErrorResponse
// @Router /api/v1/course-management/levels/{levelId}/modules [get]
func (h *Handler) ListModulesByLevel(c *fiber.Ctx) error {
	levelID, err := strconv.ParseInt(c.Params("levelId"), 10, 64)
	if err != nil || levelID <= 0 {
		return c.Status(fiber.StatusBadRequest).JSON(domain.ErrorResponse{
			Message: "Invalid level ID",
			Error:   "levelId must be a positive integer",
		})
	}

	rows, err := h.analyticsDB.GetModulesByLevelID(c.Context(), levelID)
	if err != nil {
		return c.Status(fiber.StatusInternalServerError).JSON(domain.ErrorResponse{Message: "Failed to load modules", Error: err.Error()})
	}

	return c.JSON(domain.Response{
		Message: "Modules retrieved successfully",
		Data: map[string]interface{}{
			"modules":     rows,
			"total_count": len(rows),
		},
	})
}

// GetModuleByID godoc
// @Summary Get module detail
// @Description Returns one module by ID
// @Tags course-management
// @Produce json
// @Param moduleId path int true "Module ID"
// @Success 200 {object} domain.Response
// @Failure 400 {object} domain.ErrorResponse
// @Failure 404 {object} domain.ErrorResponse
// @Failure 500 {object} domain.ErrorResponse
// @Router /api/v1/course-management/modules/{moduleId} [get]
func (h *Handler) GetModuleByID(c *fiber.Ctx) error {
	moduleID, err := strconv.ParseInt(c.Params("moduleId"), 10, 64)
	if err != nil || moduleID <= 0 {
		return c.Status(fiber.StatusBadRequest).JSON(domain.ErrorResponse{
			Message: "Invalid module ID",
			Error:   "moduleId must be a positive integer",
		})
	}

	mod, err := h.analyticsDB.GetModuleByID(c.Context(), moduleID)
	if err != nil {
		return c.Status(fiber.StatusNotFound).JSON(domain.ErrorResponse{
			Message: "Module not found",
			Error:   err.Error(),
		})
	}

	return c.JSON(domain.Response{
		Message: "Module retrieved successfully",
		Data:    mod,
	})
}

// ListAllSubModules godoc
// @Summary List all sub-modules
// @Description Returns all sub-modules with pagination
// @Tags course-management
// @Produce json
// @Param offset query int false "Offset"
// @Param limit query int false "Limit"
// @Success 200 {object} domain.Response
// @Failure 500 {object} domain.ErrorResponse
// @Router /api/v1/course-management/sub-modules [get]
func (h *Handler) ListAllSubModules(c *fiber.Ctx) error {
	offset := int32(c.QueryInt("offset", 0))
	if offset < 0 {
		offset = 0
	}
	limit := int32(c.QueryInt("limit", 10000))
	if limit <= 0 {
		limit = 10000
	}

	rows, err := h.analyticsDB.GetAllSubModules(c.Context(), dbgen.GetAllSubModulesParams{
		Offset: pgtype.Int4{Int32: offset, Valid: true},
		Limit:  pgtype.Int4{Int32: limit, Valid: true},
	})
	if err != nil {
		return c.Status(fiber.StatusInternalServerError).JSON(domain.ErrorResponse{Message: "Failed to load sub-modules", Error: err.Error()})
	}

	total := 0
	if len(rows) > 0 {
		total = int(rows[0].TotalCount)
	}

	return c.JSON(domain.Response{
		Message: "Sub-modules retrieved successfully",
		Data: map[string]interface{}{
			"sub_modules": rows,
			"total_count": total,
		},
	})
}

// ListSubModulesByModule godoc
// @Summary List sub-modules by module
// @Description Returns all active sub-modules for one module
// @Tags course-management
// @Produce json
// @Param moduleId path int true "Module ID"
// @Success 200 {object} domain.Response
// @Failure 400 {object} domain.ErrorResponse
// @Failure 500 {object} domain.ErrorResponse
// @Router /api/v1/course-management/modules/{moduleId}/sub-modules [get]
func (h *Handler) ListSubModulesByModule(c *fiber.Ctx) error {
	moduleID, err := strconv.ParseInt(c.Params("moduleId"), 10, 64)
	if err != nil || moduleID <= 0 {
		return c.Status(fiber.StatusBadRequest).JSON(domain.ErrorResponse{
			Message: "Invalid module ID",
			Error:   "moduleId must be a positive integer",
		})
	}

	rows, err := h.analyticsDB.GetSubModulesByModuleID(c.Context(), moduleID)
	if err != nil {
		return c.Status(fiber.StatusInternalServerError).JSON(domain.ErrorResponse{Message: "Failed to load sub-modules", Error: err.Error()})
	}

	return c.JSON(domain.Response{
		Message: "Sub-modules retrieved successfully",
		Data: map[string]interface{}{
			"sub_modules": rows,
			"total_count": len(rows),
		},
	})
}

// GetSubModuleByID godoc
// @Summary Get sub-module detail
// @Description Returns one sub-module by ID
// @Tags course-management
// @Produce json
// @Param subModuleId path int true "Sub-module ID"
// @Success 200 {object} domain.Response
// @Failure 400 {object} domain.ErrorResponse
// @Failure 404 {object} domain.ErrorResponse
// @Failure 500 {object} domain.ErrorResponse
// @Router /api/v1/course-management/sub-modules/{subModuleId} [get]
func (h *Handler) GetSubModuleByID(c *fiber.Ctx) error {
	subModuleID, err := strconv.ParseInt(c.Params("subModuleId"), 10, 64)
	if err != nil || subModuleID <= 0 {
		return c.Status(fiber.StatusBadRequest).JSON(domain.ErrorResponse{
			Message: "Invalid sub-module ID",
			Error:   "subModuleId must be a positive integer",
		})
	}

	subModule, err := h.analyticsDB.GetSubModuleByID(c.Context(), subModuleID)
	if err != nil {
		return c.Status(fiber.StatusNotFound).JSON(domain.ErrorResponse{
			Message: "Sub-module not found",
			Error:   err.Error(),
		})
	}

	return c.JSON(domain.Response{
		Message: "Sub-module retrieved successfully",
		Data:    subModule,
	})
}

// ListCourseSubCategories godoc
// @Summary List course sub-categories
// @Description Returns all active course sub-categories
// @Tags course-management
// @Produce json
// @Param offset query int false "Offset"
// @Param limit query int false "Limit"
// @Success 200 {object} domain.Response
// @Failure 500 {object} domain.ErrorResponse
// @Router /api/v1/course-management/sub-categories [get]
func (h *Handler) ListCourseSubCategories(c *fiber.Ctx) error {
	offset := int32(c.QueryInt("offset", 0))
	if offset < 0 {
		offset = 0
	}
	limit := int32(c.QueryInt("limit", 10000))
	if limit <= 0 {
		limit = 10000
	}

	rows, err := h.analyticsDB.GetCourseSubCategories(c.Context(), dbgen.GetCourseSubCategoriesParams{
		Offset: pgtype.Int4{Int32: offset, Valid: true},
		Limit:  pgtype.Int4{Int32: limit, Valid: true},
	})
	if err != nil {
		return c.Status(fiber.StatusInternalServerError).JSON(domain.ErrorResponse{Message: "Failed to load sub-categories", Error: err.Error()})
	}

	total := 0
	if len(rows) > 0 {
		total = int(rows[0].TotalCount)
	}

	return c.JSON(domain.Response{
		Message: "Sub-categories retrieved successfully",
		Data: map[string]interface{}{
			"sub_categories": rows,
			"total_count":    total,
		},
	})
}

// ListCourseSubCategoriesByCategory godoc
// @Summary List sub-categories for a course category
// @Description Returns active sub-categories for the given category ID
// @Tags course-management
// @Produce json
// @Param categoryId path int true "Category ID"
// @Param offset query int false "Offset"
// @Param limit query int false "Limit"
// @Success 200 {object} domain.Response
// @Failure 400 {object} domain.ErrorResponse
// @Failure 404 {object} domain.ErrorResponse
// @Failure 500 {object} domain.ErrorResponse
// @Router /api/v1/course-management/categories/{categoryId}/sub-categories [get]
func (h *Handler) ListCourseSubCategoriesByCategory(c *fiber.Ctx) error {
	categoryID, err := strconv.ParseInt(c.Params("categoryId"), 10, 64)
	if err != nil || categoryID <= 0 {
		return c.Status(fiber.StatusBadRequest).JSON(domain.ErrorResponse{
			Message: "Invalid category ID",
			Error:   "categoryId must be a positive integer",
		})
	}
	if _, err := h.analyticsDB.GetCourseCategoryByID(c.Context(), categoryID); err != nil {
		if errors.Is(err, pgx.ErrNoRows) {
			return c.Status(fiber.StatusNotFound).JSON(domain.ErrorResponse{
				Message: "Category not found",
				Error:   err.Error(),
			})
		}
		return c.Status(fiber.StatusInternalServerError).JSON(domain.ErrorResponse{
			Message: "Failed to load category",
			Error:   err.Error(),
		})
	}

	offset := int32(c.QueryInt("offset", 0))
	if offset < 0 {
		offset = 0
	}
	limit := int32(c.QueryInt("limit", 10000))
	if limit <= 0 {
		limit = 10000
	}

	rows, err := h.analyticsDB.GetCourseSubCategoriesByCategoryID(c.Context(), dbgen.GetCourseSubCategoriesByCategoryIDParams{
		CategoryID: categoryID,
		Offset:     pgtype.Int4{Int32: offset, Valid: true},
		Limit:      pgtype.Int4{Int32: limit, Valid: true},
	})
	if err != nil {
		return c.Status(fiber.StatusInternalServerError).JSON(domain.ErrorResponse{
			Message: "Failed to load sub-categories",
			Error:   err.Error(),
		})
	}

	total := 0
	if len(rows) > 0 {
		total = int(rows[0].TotalCount)
	}

	return c.JSON(domain.Response{
		Message: "Sub-categories retrieved successfully",
		Data: map[string]interface{}{
			"sub_categories": rows,
			"total_count":    total,
		},
	})
}

// ListHumanLanguageCourseSubCategories godoc
// @Summary List Human Language sub-categories
// @Description Returns active sub-categories under Human Language category
// @Tags course-management
// @Produce json
// @Param offset query int false "Offset"
// @Param limit query int false "Limit"
// @Success 200 {object} domain.Response
// @Failure 500 {object} domain.ErrorResponse
// @Router /api/v1/course-management/human-language/sub-categories [get]
func (h *Handler) ListHumanLanguageCourseSubCategories(c *fiber.Ctx) error {
	offset := int32(c.QueryInt("offset", 0))
	if offset < 0 {
		offset = 0
	}
	limit := int32(c.QueryInt("limit", 10000))
	if limit <= 0 {
		limit = 10000
	}

	rows, err := h.analyticsDB.GetHumanLanguageCourseSubCategories(c.Context(), dbgen.GetHumanLanguageCourseSubCategoriesParams{
		Offset: pgtype.Int4{Int32: offset, Valid: true},
		Limit:  pgtype.Int4{Int32: limit, Valid: true},
	})
	if err != nil {
		return c.Status(fiber.StatusInternalServerError).JSON(domain.ErrorResponse{Message: "Failed to load Human Language sub-categories", Error: err.Error()})
	}

	total := 0
	if len(rows) > 0 {
		total = int(rows[0].TotalCount)
	}

	return c.JSON(domain.Response{
		Message: "Human Language sub-categories retrieved successfully",
		Data: map[string]interface{}{
			"sub_categories": rows,
			"total_count":    total,
		},
	})
}

// CreateCourseCategory godoc
// @Summary Create course category
// @Description Legacy-compatible endpoint for creating a course category
// @Tags course-management
// @Accept json
// @Produce json
// @Param body body createCourseCategoryReq true "Create category payload"
// @Success 201 {object} domain.Response
// @Failure 400 {object} domain.ErrorResponse
// @Failure 500 {object} domain.ErrorResponse
// @Router /api/v1/course-management/categories [post]
func (h *Handler) CreateCourseCategory(c *fiber.Ctx) error {
	var req createCourseCategoryReq
	if err := c.BodyParser(&req); err != nil {
		return c.Status(fiber.StatusBadRequest).JSON(domain.ErrorResponse{Message: "Invalid request body", Error: err.Error()})
	}
	if strings.TrimSpace(req.Name) == "" {
		return c.Status(fiber.StatusBadRequest).JSON(domain.ErrorResponse{Message: "name is required"})
	}

	created, err := h.analyticsDB.CreateCourseCategory(c.Context(), dbgen.CreateCourseCategoryParams{
		Name:    req.Name,
		Column2: boolOrNil(req.IsActive),
	})
	if err != nil {
		return c.Status(fiber.StatusInternalServerError).JSON(domain.ErrorResponse{Message: "Failed to create category", Error: err.Error()})
	}

	return c.Status(fiber.StatusCreated).JSON(domain.Response{Message: "Course category created", Data: created})
}

func (h *Handler) DeleteCourseCategory(c *fiber.Ctx) error {
	categoryID, err := strconv.ParseInt(c.Params("categoryId"), 10, 64)
	if err != nil || categoryID <= 0 {
		return c.Status(fiber.StatusBadRequest).JSON(domain.ErrorResponse{Message: "Invalid category ID", Error: "categoryId must be a positive integer"})
	}

	if err := h.analyticsDB.DeleteCourseCategoryCompat(c.Context(), categoryID); err != nil {
		return c.Status(fiber.StatusInternalServerError).JSON(domain.ErrorResponse{Message: "Failed to delete category", Error: err.Error()})
	}

	return c.JSON(domain.Response{Message: "Course category deleted"})
}

// CreateCourse godoc
// @Summary Create course
// @Description Legacy-compatible endpoint for creating a course
// @Tags course-management
// @Accept json
// @Produce json
// @Param body body createCourseReq true "Create course payload"
// @Success 201 {object} domain.Response
// @Failure 400 {object} domain.ErrorResponse
// @Failure 500 {object} domain.ErrorResponse
// @Router /api/v1/course-management/courses [post]
func (h *Handler) CreateCourse(c *fiber.Ctx) error {
	var req createCourseReq
	if err := c.BodyParser(&req); err != nil {
		return c.Status(fiber.StatusBadRequest).JSON(domain.ErrorResponse{Message: "Invalid request body", Error: err.Error()})
	}
	if req.CategoryID <= 0 || strings.TrimSpace(req.Title) == "" {
		return c.Status(fiber.StatusBadRequest).JSON(domain.ErrorResponse{Message: "category_id and title are required"})
	}

	isActive := true
	if req.IsActive != nil {
		isActive = *req.IsActive
	}
	description := ""
	if req.Description != nil {
		description = *req.Description
	}
	thumbnail := ""
	if req.Thumbnail != nil {
		thumbnail = *req.Thumbnail
	}
	introVideoURL := ""
	if req.IntroVideoURL != nil {
		introVideoURL = *req.IntroVideoURL
	}

	created, err := h.analyticsDB.CreateCourseCompat(
		c.Context(),
		req.CategoryID,
		req.SubCategoryID,
		req.Title,
		description,
		thumbnail,
		introVideoURL,
		isActive,
	)
	if err != nil {
		return c.Status(fiber.StatusInternalServerError).JSON(domain.ErrorResponse{Message: "Failed to create course", Error: err.Error()})
	}

	return c.Status(fiber.StatusCreated).JSON(domain.Response{Message: "Course created", Data: created})
}

// UpdateCourse godoc
// @Summary Update course
// @Description Legacy-compatible endpoint for updating a course
// @Tags course-management
// @Accept json
// @Produce json
// @Param courseId path int true "Course ID"
// @Param body body updateCourseReq true "Update course payload"
// @Success 200 {object} domain.Response
// @Failure 400 {object} domain.ErrorResponse
// @Failure 500 {object} domain.ErrorResponse
// @Router /api/v1/course-management/courses/{courseId} [put]
func (h *Handler) UpdateCourse(c *fiber.Ctx) error {
	courseID, err := strconv.ParseInt(c.Params("courseId"), 10, 64)
	if err != nil || courseID <= 0 {
		return c.Status(fiber.StatusBadRequest).JSON(domain.ErrorResponse{Message: "Invalid course ID", Error: "courseId must be a positive integer"})
	}

	var req updateCourseReq
	if err := c.BodyParser(&req); err != nil {
		return c.Status(fiber.StatusBadRequest).JSON(domain.ErrorResponse{Message: "Invalid request body", Error: err.Error()})
	}

	existing, err := h.analyticsDB.GetCourseByID(c.Context(), courseID)
	if err != nil {
		return c.Status(fiber.StatusInternalServerError).JSON(domain.ErrorResponse{Message: "Failed to load course", Error: err.Error()})
	}

	title := existing.Title
	if req.Title != nil {
		title = *req.Title
	}
	description := existing.Description
	if req.Description != nil {
		description = toText(req.Description)
	}
	thumbnail := existing.Thumbnail
	if req.Thumbnail != nil {
		thumbnail = toText(req.Thumbnail)
	}
	introVideo := existing.IntroVideoUrl
	if req.IntroVideoURL != nil {
		introVideo = toText(req.IntroVideoURL)
	}
	isActive := existing.IsActive
	if req.IsActive != nil {
		isActive = *req.IsActive
	}

	if err := h.analyticsDB.UpdateCourse(c.Context(), dbgen.UpdateCourseParams{
		Title:         title,
		Description:   description,
		Thumbnail:     thumbnail,
		IntroVideoUrl: introVideo,
		IsActive:      isActive,
		ID:            courseID,
	}); err != nil {
		return c.Status(fiber.StatusInternalServerError).JSON(domain.ErrorResponse{Message: "Failed to update course", Error: err.Error()})
	}

	updated, err := h.analyticsDB.GetCourseByID(c.Context(), courseID)
	if err != nil {
		return c.Status(fiber.StatusInternalServerError).JSON(domain.ErrorResponse{Message: "Course updated but failed to fetch latest record", Error: err.Error()})
	}

	return c.JSON(domain.Response{Message: "Course updated", Data: updated})
}

// DeleteCourse godoc
// @Summary Delete course
// @Description Legacy-compatible endpoint for deleting a course
// @Tags course-management
// @Produce json
// @Param courseId path int true "Course ID"
// @Success 200 {object} domain.Response
// @Failure 400 {object} domain.ErrorResponse
// @Failure 500 {object} domain.ErrorResponse
// @Router /api/v1/course-management/courses/{courseId} [delete]
func (h *Handler) DeleteCourse(c *fiber.Ctx) error {
	courseID, err := strconv.ParseInt(c.Params("courseId"), 10, 64)
	if err != nil || courseID <= 0 {
		return c.Status(fiber.StatusBadRequest).JSON(domain.ErrorResponse{Message: "Invalid course ID", Error: "courseId must be a positive integer"})
	}

	if err := h.analyticsDB.DeleteCourse(c.Context(), courseID); err != nil {
		return c.Status(fiber.StatusInternalServerError).JSON(domain.ErrorResponse{Message: "Failed to delete course", Error: err.Error()})
	}

	return c.JSON(domain.Response{Message: "Course deleted"})
}

// UpdateCourseThumbnail godoc
// @Summary Update course thumbnail
// @Description Legacy-compatible endpoint for updating course thumbnail
// @Tags course-management
// @Accept json
// @Produce json
// @Param courseId path int true "Course ID"
// @Param body body updateCourseThumbnailReq true "Update course thumbnail payload"
// @Success 200 {object} domain.Response
// @Failure 400 {object} domain.ErrorResponse
// @Failure 500 {object} domain.ErrorResponse
// @Router /api/v1/course-management/courses/{courseId}/thumbnail [post]
func (h *Handler) UpdateCourseThumbnail(c *fiber.Ctx) error {
	courseID, err := strconv.ParseInt(c.Params("courseId"), 10, 64)
	if err != nil || courseID <= 0 {
		return c.Status(fiber.StatusBadRequest).JSON(domain.ErrorResponse{Message: "Invalid course ID", Error: "courseId must be a positive integer"})
	}

	var req updateCourseThumbnailReq
	if err := c.BodyParser(&req); err != nil {
		return c.Status(fiber.StatusBadRequest).JSON(domain.ErrorResponse{Message: "Invalid request body", Error: err.Error()})
	}

	existing, err := h.analyticsDB.GetCourseByID(c.Context(), courseID)
	if err != nil {
		return c.Status(fiber.StatusInternalServerError).JSON(domain.ErrorResponse{Message: "Failed to load course", Error: err.Error()})
	}
	thumb := req.ThumbnailURL
	if strings.TrimSpace(thumb) == "" {
		return c.Status(fiber.StatusBadRequest).JSON(domain.ErrorResponse{Message: "thumbnail_url is required"})
	}

	if err := h.analyticsDB.UpdateCourse(c.Context(), dbgen.UpdateCourseParams{
		Title:         existing.Title,
		Description:   existing.Description,
		Thumbnail:     pgtype.Text{String: thumb, Valid: true},
		IntroVideoUrl: existing.IntroVideoUrl,
		IsActive:      existing.IsActive,
		ID:            courseID,
	}); err != nil {
		return c.Status(fiber.StatusInternalServerError).JSON(domain.ErrorResponse{Message: "Failed to update course thumbnail", Error: err.Error()})
	}

	updated, err := h.analyticsDB.GetCourseByID(c.Context(), courseID)
	if err != nil {
		return c.Status(fiber.StatusInternalServerError).JSON(domain.ErrorResponse{Message: "Thumbnail updated but failed to fetch latest record", Error: err.Error()})
	}

	return c.JSON(domain.Response{Message: "Course thumbnail updated", Data: updated})
}

// UnifiedHierarchy godoc
// @Summary Get unified course hierarchy
// @Description Returns full hierarchy: category -> sub-category -> course
// @Tags course-management
// @Produce json
// @Success 200 {object} domain.Response
// @Failure 500 {object} domain.ErrorResponse
// @Router /api/v1/course-management/hierarchy [get]
func (h *Handler) UnifiedHierarchy(c *fiber.Ctx) error {
	rows, err := h.analyticsDB.GetCoursesWithHierarchy(c.Context())
	if err != nil {
		if isMissingCourseSubCategoryTableErr(err) {
			legacyRows, legacyErr := h.buildLegacyHierarchyRows(c)
			if legacyErr != nil {
				return c.Status(fiber.StatusInternalServerError).JSON(domain.ErrorResponse{Message: "Failed to load hierarchy", Error: legacyErr.Error()})
			}
			return c.JSON(domain.Response{Message: "Unified hierarchy retrieved successfully", Data: legacyRows})
		}
		return c.Status(fiber.StatusInternalServerError).JSON(domain.ErrorResponse{Message: "Failed to load hierarchy", Error: err.Error()})
	}
	return c.JSON(domain.Response{Message: "Unified hierarchy retrieved successfully", Data: rows})
}

// UnifiedHierarchyByCourse godoc
// @Summary Get hierarchy for a course
// @Description Returns hierarchy nodes for one course including levels/modules/sub-modules
// @Tags course-management
// @Produce json
// @Param courseId path int true "Course ID"
// @Success 200 {object} domain.Response
// @Failure 400 {object} domain.ErrorResponse
// @Failure 500 {object} domain.ErrorResponse
// @Router /api/v1/course-management/courses/{courseId}/hierarchy [get]
func (h *Handler) UnifiedHierarchyByCourse(c *fiber.Ctx) error {
	courseID, err := strconv.ParseInt(c.Params("courseId"), 10, 64)
	if err != nil {
		return c.Status(fiber.StatusBadRequest).JSON(domain.ErrorResponse{Message: "Invalid course ID", Error: err.Error()})
	}
	rows, err := h.analyticsDB.GetFullHierarchyByCourseID(c.Context(), courseID)
	if err != nil {
		if isMissingCourseSubCategoryTableErr(err) {
			course, getCourseErr := h.analyticsDB.GetCourseByID(c.Context(), courseID)
			if getCourseErr != nil {
				return c.Status(fiber.StatusInternalServerError).JSON(domain.ErrorResponse{Message: "Failed to load course hierarchy", Error: getCourseErr.Error()})
			}
			return c.JSON(domain.Response{
				Message: "Course hierarchy retrieved successfully",
				Data: []map[string]interface{}{
					{
						"course_id":                course.ID,
						"course_title":             course.Title,
						"level_id":                 nil,
						"cefr_level":               nil,
						"level_title":              nil,
						"level_description":        nil,
						"level_thumbnail":          nil,
						"module_id":                nil,
						"module_title":             nil,
						"module_icon_url":          nil,
						"sub_module_id":            nil,
						"sub_module_title":         nil,
						"sub_module_description":   nil,
						"sub_module_thumbnail":     nil,
						"sub_module_tips":          nil,
						"sub_module_display_order": nil,
					},
				},
			})
		}
		return c.Status(fiber.StatusInternalServerError).JSON(domain.ErrorResponse{Message: "Failed to load course hierarchy", Error: err.Error()})
	}
	return c.JSON(domain.Response{Message: "Course hierarchy retrieved successfully", Data: rows})
}

// CourseLearningPath godoc
// @Summary Get course learning path
// @Description Legacy-compatible endpoint for course learning path
// @Tags course-management
// @Produce json
// @Param courseId path int true "Course ID"
// @Success 200 {object} domain.Response
// @Failure 400 {object} domain.ErrorResponse
// @Failure 500 {object} domain.ErrorResponse
// @Router /api/v1/course-management/courses/{courseId}/learning-path [get]
func (h *Handler) CourseLearningPath(c *fiber.Ctx) error {
	courseID, err := strconv.ParseInt(c.Params("courseId"), 10, 64)
	if err != nil || courseID <= 0 {
		return c.Status(fiber.StatusBadRequest).JSON(domain.ErrorResponse{Message: "Invalid course ID", Error: "courseId must be a positive integer"})
	}

	course, err := h.analyticsDB.GetCourseByID(c.Context(), courseID)
	if err != nil {
		return c.Status(fiber.StatusInternalServerError).JSON(domain.ErrorResponse{Message: "Failed to load course", Error: err.Error()})
	}
	category, err := h.analyticsDB.GetCourseCategoryByID(c.Context(), course.CategoryID)
	if err != nil {
		return c.Status(fiber.StatusInternalServerError).JSON(domain.ErrorResponse{Message: "Failed to load course category", Error: err.Error()})
	}
	rows, err := h.analyticsDB.GetFullHierarchyByCourseID(c.Context(), courseID)
	if err != nil {
		return c.Status(fiber.StatusInternalServerError).JSON(domain.ErrorResponse{Message: "Failed to load course learning path", Error: err.Error()})
	}

	subCourseByID := map[int64]*domain.LearningPathSubCourse{}
	subCourseOrder := make([]int64, 0)
	for _, row := range rows {
		if !row.SubModuleID.Valid {
			continue
		}
		subModuleID := row.SubModuleID.Int64
		if _, exists := subCourseByID[subModuleID]; exists {
			continue
		}
		title := ""
		if row.SubModuleTitle.Valid {
			title = row.SubModuleTitle.String
		}
		level := ""
		if row.LevelTitle.Valid && strings.TrimSpace(row.LevelTitle.String) != "" {
			level = strings.TrimSpace(row.LevelTitle.String)
		} else if row.CefrLevel.Valid {
			level = row.CefrLevel.String
		}
		displayOrder := int32(len(subCourseOrder))
		if row.SubModuleDisplayOrder.Valid {
			displayOrder = row.SubModuleDisplayOrder.Int32
		}
		subCourseByID[subModuleID] = &domain.LearningPathSubCourse{
			ID:                subModuleID,
			Title:             title,
			Description:       textPtr(row.SubModuleDescription),
			Thumbnail:         textPtr(row.SubModuleThumbnail),
			Tips:              textPtr(row.SubModuleTips),
			DisplayOrder:      displayOrder,
			Level:             level,
			SubLevel:          level,
			PrerequisiteCount: 0,
			Prerequisites:     []domain.LearningPathPrerequisite{},
			Videos:            []domain.LearningPathVideo{},
			Practices:         []domain.LearningPathPractice{},
		}
		subCourseOrder = append(subCourseOrder, subModuleID)
	}

	for _, subModuleID := range subCourseOrder {
		node := subCourseByID[subModuleID]
		videos, videoErr := h.analyticsDB.GetSubModuleVideos(c.Context(), subModuleID)
		if videoErr != nil {
			return c.Status(fiber.StatusInternalServerError).JSON(domain.ErrorResponse{Message: "Failed to load sub-module videos", Error: videoErr.Error()})
		}
		for _, v := range videos {
			node.Videos = append(node.Videos, domain.LearningPathVideo{
				ID:                v.ID,
				Title:             v.Title,
				Description:       textPtr(v.Description),
				VideoURL:          v.VideoUrl,
				Duration:          int32(v.Duration.Int32),
				Resolution:        textPtr(v.Resolution),
				DisplayOrder:      v.DisplayOrder,
				VimeoID:           textPtr(v.VimeoID),
				VimeoEmbedURL:     textPtr(v.VimeoEmbedUrl),
				VideoHostProvider: textPtr(v.VideoHostProvider),
			})
		}
		node.VideoCount = int64(len(node.Videos))

		practices, practiceErr := h.analyticsDB.GetSubModulePractices(c.Context(), subModuleID)
		if practiceErr != nil {
			return c.Status(fiber.StatusInternalServerError).JSON(domain.ErrorResponse{Message: "Failed to load sub-module practices", Error: practiceErr.Error()})
		}
		for _, p := range practices {
			node.Practices = append(node.Practices, domain.LearningPathPractice{
				ID:            p.ID,
				Title:         p.Title,
				Description:   textPtr(p.Description),
				Status:        p.Status,
				IntroVideoURL: textPtr(p.IntroVideoUrl),
				QuestionCount: p.QuestionCount,
			})
		}
		node.PracticeCount = int64(len(node.Practices))
	}

	subCourses := make([]domain.LearningPathSubCourse, 0, len(subCourseOrder))
	for _, id := range subCourseOrder {
		subCourses = append(subCourses, *subCourseByID[id])
	}

	path := domain.LearningPath{
		CourseID:      course.ID,
		CourseTitle:   course.Title,
		Description:   textPtr(course.Description),
		Thumbnail:     textPtr(course.Thumbnail),
		IntroVideoURL: textPtr(course.IntroVideoUrl),
		CategoryID:    category.ID,
		CategoryName:  category.Name,
		SubCourses:    subCourses,
	}

	return c.JSON(domain.Response{Message: "Course learning path retrieved successfully", Data: path})
}

func isMissingCourseSubCategoryTableErr(err error) bool {
	if err == nil {
		return false
	}
	return strings.Contains(strings.ToLower(err.Error()), "relation \"course_sub_categories\" does not exist")
}

func (h *Handler) buildLegacyHierarchyRows(c *fiber.Ctx) ([]legacyHierarchyRow, error) {
	categories, err := h.analyticsDB.GetAllCourseCategories(c.Context(), dbgen.GetAllCourseCategoriesParams{
		Offset: pgtype.Int4{Int32: 0, Valid: true},
		Limit:  pgtype.Int4{Int32: 10000, Valid: true},
	})
	if err != nil {
		return nil, err
	}

	out := make([]legacyHierarchyRow, 0, len(categories))
	for _, cat := range categories {
		courses, courseErr := h.analyticsDB.GetCoursesByCategory(c.Context(), dbgen.GetCoursesByCategoryParams{
			CategoryID: cat.ID,
			Offset:     pgtype.Int4{Int32: 0, Valid: true},
			Limit:      pgtype.Int4{Int32: 10000, Valid: true},
		})
		if courseErr != nil {
			return nil, courseErr
		}

		if len(courses) == 0 {
			out = append(out, legacyHierarchyRow{
				CategoryID:      cat.ID,
				CategoryName:    cat.Name,
				SubCategoryID:   nil,
				SubCategoryName: nil,
				CourseID:        nil,
				CourseTitle:     nil,
			})
			continue
		}

		for _, course := range courses {
			courseID := course.ID
			courseTitle := course.Title
			out = append(out, legacyHierarchyRow{
				CategoryID:      cat.ID,
				CategoryName:    cat.Name,
				SubCategoryID:   nil,
				SubCategoryName: nil,
				CourseID:        &courseID,
				CourseTitle:     &courseTitle,
			})
		}
	}

	return out, nil
}

// CreateCourseSubCategory godoc
// @Summary Create course sub-category
// @Description Creates a sub-category under a course category
// @Tags course-management
// @Accept json
// @Produce json
// @Param body body createCourseSubCategoryReq true "Create sub-category payload"
// @Success 201 {object} domain.Response
// @Failure 400 {object} domain.ErrorResponse
// @Failure 500 {object} domain.ErrorResponse
// @Router /api/v1/course-management/sub-categories [post]
func (h *Handler) CreateCourseSubCategory(c *fiber.Ctx) error {
	var req createCourseSubCategoryReq
	if err := c.BodyParser(&req); err != nil {
		return c.Status(fiber.StatusBadRequest).JSON(domain.ErrorResponse{Message: "Invalid request body", Error: err.Error()})
	}
	if req.CategoryID <= 0 || strings.TrimSpace(req.Name) == "" {
		return c.Status(fiber.StatusBadRequest).JSON(domain.ErrorResponse{Message: "category_id and name are required"})
	}
	created, err := h.analyticsDB.CreateCourseSubCategory(c.Context(), dbgen.CreateCourseSubCategoryParams{
		CategoryID:  req.CategoryID,
		Name:        req.Name,
		Description: toText(req.Description),
		Column4:     intOrNil(req.DisplayOrder),
		Column5:     boolOrNil(req.IsActive),
	})
	if err != nil {
		return c.Status(fiber.StatusInternalServerError).JSON(domain.ErrorResponse{Message: "Failed to create sub-category", Error: err.Error()})
	}
	return c.Status(fiber.StatusCreated).JSON(domain.Response{Message: "Course sub-category created", Data: created})
}

func (h *Handler) DeleteCourseSubCategory(c *fiber.Ctx) error {
	subCategoryID, err := strconv.ParseInt(c.Params("subCategoryId"), 10, 64)
	if err != nil || subCategoryID <= 0 {
		return c.Status(fiber.StatusBadRequest).JSON(domain.ErrorResponse{Message: "Invalid sub-category ID", Error: "subCategoryId must be a positive integer"})
	}

	if err := h.analyticsDB.DeleteCourseSubCategoryCompat(c.Context(), subCategoryID); err != nil {
		return c.Status(fiber.StatusInternalServerError).JSON(domain.ErrorResponse{Message: "Failed to delete sub-category", Error: err.Error()})
	}

	return c.JSON(domain.Response{Message: "Course sub-category deleted"})
}

// CreateLevel godoc
// @Summary Create level
// @Description Creates a level under a course. cefr_level is a short level code or label (1–64 characters), unique per course; optional title defaults to that value; optional description and thumbnail
// @Tags course-management
// @Accept json
// @Produce json
// @Param body body createLevelReq true "Create level payload"
// @Success 201 {object} domain.Response
// @Failure 400 {object} domain.ErrorResponse
// @Failure 500 {object} domain.ErrorResponse
// @Router /api/v1/course-management/levels [post]
func (h *Handler) CreateLevel(c *fiber.Ctx) error {
	var req createLevelReq
	if err := c.BodyParser(&req); err != nil {
		return c.Status(fiber.StatusBadRequest).JSON(domain.ErrorResponse{Message: "Invalid request body", Error: err.Error()})
	}
	cefr := strings.TrimSpace(req.CEFRLevel)
	if req.CourseID <= 0 || cefr == "" {
		return c.Status(fiber.StatusBadRequest).JSON(domain.ErrorResponse{Message: "course_id and cefr_level are required"})
	}
	if strings.Contains(cefr, "\x00") {
		return c.Status(fiber.StatusBadRequest).JSON(domain.ErrorResponse{Message: "cefr_level must not contain NUL characters"})
	}
	const maxCefrLevelRunes = 64
	if utf8.RuneCountInString(cefr) > maxCefrLevelRunes {
		return c.Status(fiber.StatusBadRequest).JSON(domain.ErrorResponse{Message: "cefr_level must be at most 64 characters"})
	}
	title := cefr
	if req.Title != nil {
		if t := strings.TrimSpace(*req.Title); t != "" {
			title = t
		}
	}
	created, err := h.analyticsDB.CreateLevel(c.Context(), dbgen.CreateLevelParams{
		CourseID:    req.CourseID,
		CefrLevel:   cefr,
		Title:       title,
		Description: toText(req.Description),
		Thumbnail:   toText(req.Thumbnail),
		Column6:     intOrNil(req.DisplayOrder),
		Column7:     boolOrNil(req.IsActive),
	})
	if err != nil {
		return c.Status(fiber.StatusInternalServerError).JSON(domain.ErrorResponse{Message: "Failed to create level", Error: err.Error()})
	}
	return c.Status(fiber.StatusCreated).JSON(domain.Response{Message: "Level created", Data: created})
}

// UpdateLevel godoc
// @Summary Update level
// @Description Updates level title, description, thumbnail, display order, and active flag
// @Tags course-management
// @Accept json
// @Produce json
// @Param levelId path int true "Level ID"
// @Param body body updateLevelReq true "Update level payload"
// @Success 200 {object} domain.Response
// @Failure 400 {object} domain.ErrorResponse
// @Failure 404 {object} domain.ErrorResponse
// @Failure 500 {object} domain.ErrorResponse
// @Router /api/v1/course-management/levels/{levelId} [put]
func (h *Handler) UpdateLevel(c *fiber.Ctx) error {
	levelID, err := strconv.ParseInt(c.Params("levelId"), 10, 64)
	if err != nil || levelID <= 0 {
		return c.Status(fiber.StatusBadRequest).JSON(domain.ErrorResponse{Message: "Invalid level ID", Error: "levelId must be a positive integer"})
	}
	var req updateLevelReq
	if err := c.BodyParser(&req); err != nil {
		return c.Status(fiber.StatusBadRequest).JSON(domain.ErrorResponse{Message: "Invalid request body", Error: err.Error()})
	}

	current, err := h.analyticsDB.GetLevelByID(c.Context(), levelID)
	if err != nil {
		return c.Status(fiber.StatusNotFound).JSON(domain.ErrorResponse{Message: "Level not found", Error: err.Error()})
	}

	targetTitle := current.Title
	if req.Title != nil {
		t := strings.TrimSpace(*req.Title)
		if t == "" {
			return c.Status(fiber.StatusBadRequest).JSON(domain.ErrorResponse{Message: "title cannot be empty"})
		}
		targetTitle = t
	}

	targetDescription := mergeTextField(current.Description, req.Description)
	targetThumbnail := mergeTextField(current.Thumbnail, req.Thumbnail)

	targetDisplayOrder := current.DisplayOrder
	if req.DisplayOrder != nil {
		targetDisplayOrder = *req.DisplayOrder
	}

	targetIsActive := current.IsActive
	if req.IsActive != nil {
		targetIsActive = *req.IsActive
	}

	updated, err := h.analyticsDB.UpdateLevel(c.Context(), dbgen.UpdateLevelParams{
		Title:        targetTitle,
		Description:  targetDescription,
		Thumbnail:    targetThumbnail,
		DisplayOrder: targetDisplayOrder,
		IsActive:     targetIsActive,
		ID:           levelID,
	})
	if err != nil {
		return c.Status(fiber.StatusInternalServerError).JSON(domain.ErrorResponse{Message: "Failed to update level", Error: err.Error()})
	}

	return c.JSON(domain.Response{Message: "Level updated", Data: updated})
}

// CreateModule godoc
// @Summary Create module
// @Description Creates a module under a level; optional icon_url stores a module icon image URL
// @Tags course-management
// @Accept json
// @Produce json
// @Param body body createModuleReq true "Create module payload"
// @Success 201 {object} domain.Response
// @Failure 400 {object} domain.ErrorResponse
// @Failure 500 {object} domain.ErrorResponse
// @Router /api/v1/course-management/modules [post]
func (h *Handler) CreateModule(c *fiber.Ctx) error {
	var req createModuleReq
	if err := c.BodyParser(&req); err != nil {
		return c.Status(fiber.StatusBadRequest).JSON(domain.ErrorResponse{Message: "Invalid request body", Error: err.Error()})
	}
	if req.LevelID <= 0 || strings.TrimSpace(req.Title) == "" {
		return c.Status(fiber.StatusBadRequest).JSON(domain.ErrorResponse{Message: "level_id and title are required"})
	}
	created, err := h.analyticsDB.CreateModule(c.Context(), dbgen.CreateModuleParams{
		LevelID:     req.LevelID,
		Title:       req.Title,
		Description: toText(req.Description),
		IconUrl:     toText(req.IconURL),
		Column5:     intOrNil(req.DisplayOrder),
		Column6:     boolOrNil(req.IsActive),
	})
	if err != nil {
		return c.Status(fiber.StatusInternalServerError).JSON(domain.ErrorResponse{Message: "Failed to create module", Error: err.Error()})
	}
	return c.Status(fiber.StatusCreated).JSON(domain.Response{Message: "Module created", Data: created})
}

// UpdateModule godoc
// @Summary Update module
// @Description Updates module title, description, icon URL, display order, and active flag
// @Tags course-management
// @Accept json
// @Produce json
// @Param moduleId path int true "Module ID"
// @Param body body updateModuleReq true "Update module payload"
// @Success 200 {object} domain.Response
// @Failure 400 {object} domain.ErrorResponse
// @Failure 404 {object} domain.ErrorResponse
// @Failure 500 {object} domain.ErrorResponse
// @Router /api/v1/course-management/modules/{moduleId} [put]
func (h *Handler) UpdateModule(c *fiber.Ctx) error {
	moduleID, err := strconv.ParseInt(c.Params("moduleId"), 10, 64)
	if err != nil || moduleID <= 0 {
		return c.Status(fiber.StatusBadRequest).JSON(domain.ErrorResponse{Message: "Invalid module ID", Error: "moduleId must be a positive integer"})
	}
	var req updateModuleReq
	if err := c.BodyParser(&req); err != nil {
		return c.Status(fiber.StatusBadRequest).JSON(domain.ErrorResponse{Message: "Invalid request body", Error: err.Error()})
	}

	current, err := h.analyticsDB.GetModuleByID(c.Context(), moduleID)
	if err != nil {
		return c.Status(fiber.StatusNotFound).JSON(domain.ErrorResponse{Message: "Module not found", Error: err.Error()})
	}

	targetTitle := current.Title
	if req.Title != nil {
		t := strings.TrimSpace(*req.Title)
		if t == "" {
			return c.Status(fiber.StatusBadRequest).JSON(domain.ErrorResponse{Message: "title cannot be empty"})
		}
		targetTitle = t
	}
	targetDesc := mergeTextField(current.Description, req.Description)
	targetIcon := mergeTextField(current.IconUrl, req.IconURL)
	targetOrder := current.DisplayOrder
	if req.DisplayOrder != nil {
		targetOrder = *req.DisplayOrder
	}
	targetActive := current.IsActive
	if req.IsActive != nil {
		targetActive = *req.IsActive
	}

	updated, err := h.analyticsDB.UpdateModule(c.Context(), dbgen.UpdateModuleParams{
		Title:        targetTitle,
		Description:  targetDesc,
		IconUrl:      targetIcon,
		DisplayOrder: targetOrder,
		IsActive:     targetActive,
		ID:           moduleID,
	})
	if err != nil {
		return c.Status(fiber.StatusInternalServerError).JSON(domain.ErrorResponse{Message: "Failed to update module", Error: err.Error()})
	}
	return c.JSON(domain.Response{Message: "Module updated", Data: updated})
}

// CreateSubModule godoc
// @Summary Create sub-module
// @Description Creates a sub-module under a module; optional thumbnail (image URL) and tips text
// @Tags course-management
// @Accept json
// @Produce json
// @Param body body createSubModuleReq true "Create sub-module payload"
// @Success 201 {object} domain.Response
// @Failure 400 {object} domain.ErrorResponse
// @Failure 500 {object} domain.ErrorResponse
// @Router /api/v1/course-management/sub-modules [post]
func (h *Handler) CreateSubModule(c *fiber.Ctx) error {
	var req createSubModuleReq
	if err := c.BodyParser(&req); err != nil {
		return c.Status(fiber.StatusBadRequest).JSON(domain.ErrorResponse{Message: "Invalid request body", Error: err.Error()})
	}
	if req.ModuleID <= 0 || strings.TrimSpace(req.Title) == "" {
		return c.Status(fiber.StatusBadRequest).JSON(domain.ErrorResponse{Message: "module_id and title are required"})
	}
	created, err := h.analyticsDB.CreateSubModule(c.Context(), dbgen.CreateSubModuleParams{
		ModuleID:    req.ModuleID,
		Title:       req.Title,
		Description: toText(req.Description),
		Thumbnail:   toText(req.Thumbnail),
		Tips:        toText(req.Tips),
		Column6:     intOrNil(req.DisplayOrder),
		Column7:     boolOrNil(req.IsActive),
	})
	if err != nil {
		return c.Status(fiber.StatusInternalServerError).JSON(domain.ErrorResponse{Message: "Failed to create sub-module", Error: err.Error()})
	}
	return c.Status(fiber.StatusCreated).JSON(domain.Response{Message: "Sub-module created", Data: created})
}

// CreateSubModuleVideo godoc
// @Summary Create sub-module video
// @Description Creates a video under a sub-module
// @Tags course-management
// @Accept json
// @Produce json
// @Param body body createSubModuleVideoReq true "Create sub-module video payload"
// @Success 201 {object} domain.Response
// @Failure 400 {object} domain.ErrorResponse
// @Failure 500 {object} domain.ErrorResponse
// @Router /api/v1/course-management/sub-module-videos [post]
func (h *Handler) CreateSubModuleVideo(c *fiber.Ctx) error {
	var req createSubModuleVideoReq
	if err := c.BodyParser(&req); err != nil {
		return c.Status(fiber.StatusBadRequest).JSON(domain.ErrorResponse{Message: "Invalid request body", Error: err.Error()})
	}
	if req.SubModuleID <= 0 || strings.TrimSpace(req.Title) == "" || strings.TrimSpace(req.VideoURL) == "" {
		return c.Status(fiber.StatusBadRequest).JSON(domain.ErrorResponse{Message: "sub_module_id, title and video_url are required"})
	}
	created, err := h.analyticsDB.CreateSubModuleVideo(c.Context(), dbgen.CreateSubModuleVideoParams{
		SubModuleID:     req.SubModuleID,
		Title:           req.Title,
		Description:     toText(req.Description),
		VideoUrl:        req.VideoURL,
		Duration:        toInt4(req.Duration),
		Resolution:      toText(req.Resolution),
		Column7:         nil,
		Visibility:      toText(req.Visibility),
		InstructorID:    toText(req.InstructorID),
		Thumbnail:       toText(req.Thumbnail),
		Column12:        intOrNil(req.DisplayOrder),
		Column13:        req.Status,
		VimeoID:         pgtype.Text{Valid: false},
		VimeoEmbedUrl:   pgtype.Text{Valid: false},
		VimeoPlayerHtml: pgtype.Text{Valid: false},
		VimeoStatus:     pgtype.Text{Valid: false},
		Column18:        nil,
	})
	if err != nil {
		return c.Status(fiber.StatusInternalServerError).JSON(domain.ErrorResponse{Message: "Failed to create sub-module video", Error: err.Error()})
	}
	return c.Status(fiber.StatusCreated).JSON(domain.Response{Message: "Sub-module video created", Data: created})
}

// CreateSubModuleLesson godoc
// @Summary Create lesson under sub-module
// @Description Creates a sub-module lesson with teaching content (text, image, audio, video URLs) and optional thumbnail
// @Tags course-management
// @Accept json
// @Produce json
// @Param body body createSubModuleLessonReq true "Create lesson payload"
// @Success 201 {object} domain.Response
// @Failure 400 {object} domain.ErrorResponse
// @Failure 500 {object} domain.ErrorResponse
// @Router /api/v1/course-management/sub-module-lessons [post]
func (h *Handler) CreateSubModuleLesson(c *fiber.Ctx) error {
	var req createSubModuleLessonReq
	if err := c.BodyParser(&req); err != nil {
		return c.Status(fiber.StatusBadRequest).JSON(domain.ErrorResponse{Message: "Invalid request body", Error: err.Error()})
	}
	if req.SubModuleID <= 0 || strings.TrimSpace(req.Title) == "" {
		return c.Status(fiber.StatusBadRequest).JSON(domain.ErrorResponse{Message: "sub_module_id and title are required"})
	}
	created, err := h.analyticsDB.CreateSubModuleLesson(c.Context(), dbgen.CreateSubModuleLessonParams{
		SubModuleID:      req.SubModuleID,
		Title:            strings.TrimSpace(req.Title),
		Description:      toText(req.Description),
		Thumbnail:        toText(req.Thumbnail),
		TeachingText:     toText(req.TeachingText),
		TeachingImageUrl: toText(req.TeachingImageURL),
		TeachingAudioUrl: toText(req.TeachingAudioURL),
		TeachingVideoUrl: toText(req.TeachingVideoURL),
		Column9:          intOrNil(req.DisplayOrder),
		Column10:         boolOrNil(req.IsActive),
	})
	if err != nil {
		return c.Status(fiber.StatusInternalServerError).JSON(domain.ErrorResponse{Message: "Failed to create lesson", Error: err.Error()})
	}
	return c.Status(fiber.StatusCreated).JSON(domain.Response{Message: "Lesson created", Data: created})
}

// GetSubModuleLessons godoc
// @Summary Get lessons under sub-module
// @Description Returns lessons for a sub-module. By default only active lessons; pass include_inactive=true to include inactive rows (e.g. admin / CMS).
// @Tags course-management
// @Accept json
// @Produce json
// @Param subModuleId path int true "Sub-module ID"
// @Param include_inactive query bool false "Include inactive lessons"
// @Success 200 {object} domain.Response
// @Failure 400 {object} domain.ErrorResponse
// @Failure 500 {object} domain.ErrorResponse
// @Router /api/v1/course-management/sub-modules/{subModuleId}/lessons [get]
func (h *Handler) GetSubModuleLessons(c *fiber.Ctx) error {
	subModuleID, err := strconv.ParseInt(c.Params("subModuleId"), 10, 64)
	if err != nil || subModuleID <= 0 {
		return c.Status(fiber.StatusBadRequest).JSON(domain.ErrorResponse{
			Message: "Invalid sub-module ID",
			Error:   "subModuleId must be a valid positive integer",
		})
	}

	var lessons []dbgen.SubModuleLesson
	if c.QueryBool("include_inactive", false) {
		lessons, err = h.analyticsDB.GetSubModuleLessonsAll(c.Context(), subModuleID)
	} else {
		lessons, err = h.analyticsDB.GetSubModuleLessons(c.Context(), subModuleID)
	}
	if err != nil {
		return c.Status(fiber.StatusInternalServerError).JSON(domain.ErrorResponse{
			Message: "Failed to get sub-module lessons",
			Error:   err.Error(),
		})
	}

	return c.Status(fiber.StatusOK).JSON(domain.Response{
		Message: "Sub-module lessons retrieved successfully",
		Data:    lessons,
	})
}

// GetSubModuleLessonByID godoc
// @Summary Get lesson detail
// @Description Returns one lesson detail by lesson ID (active or inactive)
// @Tags course-management
// @Accept json
// @Produce json
// @Param lessonId path int true "Lesson ID"
// @Success 200 {object} domain.Response
// @Failure 400 {object} domain.ErrorResponse
// @Failure 404 {object} domain.ErrorResponse
// @Failure 500 {object} domain.ErrorResponse
// @Router /api/v1/course-management/sub-module-lessons/{lessonId} [get]
func (h *Handler) GetSubModuleLessonByID(c *fiber.Ctx) error {
	lessonID, err := strconv.ParseInt(c.Params("lessonId"), 10, 64)
	if err != nil || lessonID <= 0 {
		return c.Status(fiber.StatusBadRequest).JSON(domain.ErrorResponse{
			Message: "Invalid lesson ID",
			Error:   "lessonId must be a valid positive integer",
		})
	}

	lesson, err := h.analyticsDB.GetSubModuleLessonByID(c.Context(), lessonID)
	if err != nil {
		return c.Status(fiber.StatusNotFound).JSON(domain.ErrorResponse{
			Message: "Lesson not found",
			Error:   err.Error(),
		})
	}

	return c.Status(fiber.StatusOK).JSON(domain.Response{
		Message: "Lesson detail retrieved successfully",
		Data:    lesson,
	})
}

// UpdateSubModuleLesson godoc
// @Summary Update lesson detail
// @Description Updates lesson teaching content, thumbnail, ordering, and active flag
// @Tags course-management
// @Accept json
// @Produce json
// @Param lessonId path int true "Lesson ID"
// @Param body body updateSubModuleLessonReq true "Update lesson payload"
// @Success 200 {object} domain.Response
// @Failure 400 {object} domain.ErrorResponse
// @Failure 404 {object} domain.ErrorResponse
// @Failure 500 {object} domain.ErrorResponse
// @Router /api/v1/course-management/sub-module-lessons/{lessonId} [put]
func (h *Handler) UpdateSubModuleLesson(c *fiber.Ctx) error {
	lessonID, err := strconv.ParseInt(c.Params("lessonId"), 10, 64)
	if err != nil || lessonID <= 0 {
		return c.Status(fiber.StatusBadRequest).JSON(domain.ErrorResponse{
			Message: "Invalid lesson ID",
			Error:   "lessonId must be a valid positive integer",
		})
	}

	var req updateSubModuleLessonReq
	if err := c.BodyParser(&req); err != nil {
		return c.Status(fiber.StatusBadRequest).JSON(domain.ErrorResponse{
			Message: "Invalid request body",
			Error:   err.Error(),
		})
	}

	currentLesson, err := h.analyticsDB.GetSubModuleLessonByID(c.Context(), lessonID)
	if err != nil {
		return c.Status(fiber.StatusNotFound).JSON(domain.ErrorResponse{
			Message: "Lesson not found",
			Error:   err.Error(),
		})
	}

	targetSubModuleID := currentLesson.SubModuleID
	if req.SubModuleID != nil {
		if *req.SubModuleID <= 0 {
			return c.Status(fiber.StatusBadRequest).JSON(domain.ErrorResponse{Message: "sub_module_id must be a positive integer"})
		}
		targetSubModuleID = *req.SubModuleID
	}

	targetTitle := currentLesson.Title
	if req.Title != nil {
		t := strings.TrimSpace(*req.Title)
		if t == "" {
			return c.Status(fiber.StatusBadRequest).JSON(domain.ErrorResponse{Message: "title cannot be empty"})
		}
		targetTitle = t
	}

	targetDescription := mergeTextField(currentLesson.Description, req.Description)
	targetThumbnail := mergeTextField(currentLesson.Thumbnail, req.Thumbnail)
	targetTeachingText := mergeTextField(currentLesson.TeachingText, req.TeachingText)
	targetTeachingImage := mergeTextField(currentLesson.TeachingImageUrl, req.TeachingImageURL)
	targetTeachingAudio := mergeTextField(currentLesson.TeachingAudioUrl, req.TeachingAudioURL)
	targetTeachingVideo := mergeTextField(currentLesson.TeachingVideoUrl, req.TeachingVideoURL)

	targetDisplayOrder := currentLesson.DisplayOrder
	if req.DisplayOrder != nil {
		targetDisplayOrder = *req.DisplayOrder
	}

	targetIsActive := currentLesson.IsActive
	if req.IsActive != nil {
		targetIsActive = *req.IsActive
	}

	updatedLesson, err := h.analyticsDB.UpdateSubModuleLesson(c.Context(), dbgen.UpdateSubModuleLessonParams{
		SubModuleID:      targetSubModuleID,
		Title:            targetTitle,
		Description:      targetDescription,
		Thumbnail:        targetThumbnail,
		TeachingText:     targetTeachingText,
		TeachingImageUrl: targetTeachingImage,
		TeachingAudioUrl: targetTeachingAudio,
		TeachingVideoUrl: targetTeachingVideo,
		DisplayOrder:     targetDisplayOrder,
		IsActive:         targetIsActive,
		ID:               lessonID,
	})
	if err != nil {
		return c.Status(fiber.StatusInternalServerError).JSON(domain.ErrorResponse{
			Message: "Failed to update lesson",
			Error:   err.Error(),
		})
	}

	return c.Status(fiber.StatusOK).JSON(domain.Response{
		Message: "Lesson updated successfully",
		Data:    updatedLesson,
	})
}

// CreateSubModulePractice godoc
// @Summary Create practice under sub-module
// @Description Creates a sub-module practice with metadata and linked question set
// @Tags course-management
// @Accept json
// @Produce json
// @Param body body createSubModulePracticeReq true "Create practice payload"
// @Success 201 {object} domain.Response
// @Failure 400 {object} domain.ErrorResponse
// @Failure 500 {object} domain.ErrorResponse
// @Router /api/v1/course-management/sub-module-practices [post]
func (h *Handler) CreateSubModulePractice(c *fiber.Ctx) error {
	var req createSubModulePracticeReq
	if err := c.BodyParser(&req); err != nil {
		return c.Status(fiber.StatusBadRequest).JSON(domain.ErrorResponse{Message: "Invalid request body", Error: err.Error()})
	}
	if req.SubModuleID <= 0 || req.QuestionSetID <= 0 || strings.TrimSpace(req.Title) == "" {
		return c.Status(fiber.StatusBadRequest).JSON(domain.ErrorResponse{Message: "sub_module_id, title and question_set_id are required"})
	}
	created, err := h.analyticsDB.CreateSubModulePractice(c.Context(), dbgen.CreateSubModulePracticeParams{
		SubModuleID:   req.SubModuleID,
		Title:         req.Title,
		Description:   toText(req.Description),
		Thumbnail:     toText(req.Thumbnail),
		IntroVideoUrl: toText(req.IntroVideoURL),
		QuestionSetID: req.QuestionSetID,
		Column7:       intOrNil(req.DisplayOrder),
		Column8:       boolOrNil(req.IsActive),
	})
	if err != nil {
		return c.Status(fiber.StatusInternalServerError).JSON(domain.ErrorResponse{Message: "Failed to create practice", Error: err.Error()})
	}
	return c.Status(fiber.StatusCreated).JSON(domain.Response{Message: "Practice created", Data: created})
}

// CreateSubModuleCapstone godoc
// @Summary Create capstone under sub-module
// @Description Creates a capstone assessment with a new CAPSTONE question set, metadata, and ordered questions
// @Tags course-management
// @Accept json
// @Produce json
// @Param body body createSubModuleCapstoneReq true "Create capstone payload"
// @Success 201 {object} domain.Response
// @Failure 400 {object} domain.ErrorResponse
// @Failure 500 {object} domain.ErrorResponse
// @Router /api/v1/course-management/sub-module-capstones [post]
func (h *Handler) CreateSubModuleCapstone(c *fiber.Ctx) error {
	var req createSubModuleCapstoneReq
	if err := c.BodyParser(&req); err != nil {
		return c.Status(fiber.StatusBadRequest).JSON(domain.ErrorResponse{Message: "Invalid request body", Error: err.Error()})
	}
	if req.SubModuleID <= 0 || strings.TrimSpace(req.Title) == "" {
		return c.Status(fiber.StatusBadRequest).JSON(domain.ErrorResponse{Message: "sub_module_id and title are required"})
	}
	if len(req.Questions) == 0 {
		return c.Status(fiber.StatusBadRequest).JSON(domain.ErrorResponse{Message: "At least one question is required"})
	}
	seenQ := make(map[int64]struct{}, len(req.Questions))
	for _, q := range req.Questions {
		if q.QuestionID <= 0 {
			return c.Status(fiber.StatusBadRequest).JSON(domain.ErrorResponse{Message: "Each question_id must be a positive integer"})
		}
		if _, dup := seenQ[q.QuestionID]; dup {
			return c.Status(fiber.StatusBadRequest).JSON(domain.ErrorResponse{Message: "Duplicate question_id values are not allowed"})
		}
		seenQ[q.QuestionID] = struct{}{}
		if _, err := h.questionsSvc.GetQuestionByID(c.Context(), q.QuestionID); err != nil {
			return c.Status(fiber.StatusBadRequest).JSON(domain.ErrorResponse{Message: "Invalid question_id", Error: err.Error()})
		}
	}

	ownerType := "SUB_MODULE"
	shuffle := false
	if req.ShuffleQuestions != nil {
		shuffle = *req.ShuffleQuestions
	}
	status := "DRAFT"
	if req.Status != nil && strings.TrimSpace(*req.Status) != "" {
		status = strings.TrimSpace(*req.Status)
	}

	title := strings.TrimSpace(req.Title)
	createdSet, err := h.questionsSvc.CreateQuestionSet(c.Context(), domain.CreateQuestionSetInput{
		Title:            title,
		Description:      req.Description,
		SetType:          string(domain.QuestionSetTypeCapstone),
		OwnerType:        &ownerType,
		OwnerID:          &req.SubModuleID,
		BannerImage:      req.Thumbnail,
		TimeLimitMinutes: req.TimeLimitMinutes,
		PassingScore:     req.PassingScore,
		ShuffleQuestions: &shuffle,
		Status:           &status,
	})
	if err != nil {
		return c.Status(fiber.StatusInternalServerError).JSON(domain.ErrorResponse{Message: "Failed to create capstone question set", Error: err.Error()})
	}

	capRow, err := h.analyticsDB.CreateSubModuleCapstone(c.Context(), dbgen.CreateSubModuleCapstoneParams{
		SubModuleID:   req.SubModuleID,
		Title:         title,
		Description:   toText(req.Description),
		Tips:          toText(req.Tips),
		Thumbnail:     toText(req.Thumbnail),
		QuestionSetID: createdSet.ID,
		Column7:       intOrNil(req.DisplayOrder),
		Column8:       boolOrNil(req.IsActive),
	})
	if err != nil {
		_ = h.questionsSvc.DeleteQuestionSet(c.Context(), createdSet.ID)
		return c.Status(fiber.StatusInternalServerError).JSON(domain.ErrorResponse{Message: "Failed to create capstone", Error: err.Error()})
	}

	for idx, cq := range req.Questions {
		order := cq.DisplayOrder
		if order == nil {
			o := int32(idx)
			order = &o
		}
		if _, err := h.questionsSvc.AddQuestionToSet(c.Context(), createdSet.ID, cq.QuestionID, order); err != nil {
			_ = h.questionsSvc.DeleteQuestionSet(c.Context(), createdSet.ID)
			return c.Status(fiber.StatusInternalServerError).JSON(domain.ErrorResponse{Message: "Failed to attach capstone questions", Error: err.Error()})
		}
	}

	detail, err := h.analyticsDB.GetSubModuleCapstoneByID(c.Context(), capRow.ID)
	if err != nil {
		return c.Status(fiber.StatusInternalServerError).JSON(domain.ErrorResponse{Message: "Capstone created but failed to load detail", Error: err.Error()})
	}
	items, err := h.questionsSvc.GetQuestionSetItems(c.Context(), detail.QuestionSetID)
	if err != nil {
		return c.Status(fiber.StatusInternalServerError).JSON(domain.ErrorResponse{Message: "Capstone created but failed to load questions", Error: err.Error()})
	}

	return c.Status(fiber.StatusCreated).JSON(domain.Response{
		Message: "Capstone created",
		Data: map[string]interface{}{
			"capstone":  detail,
			"questions": items,
		},
	})
}

// GetSubModulePractices godoc
// @Summary Get practices under sub-module
// @Description Returns all active practices attached to a sub-module
// @Tags course-management
// @Accept json
// @Produce json
// @Param subModuleId path int true "Sub-module ID"
// @Success 200 {object} domain.Response
// @Failure 400 {object} domain.ErrorResponse
// @Failure 500 {object} domain.ErrorResponse
// @Router /api/v1/course-management/sub-modules/{subModuleId}/practices [get]
func (h *Handler) GetSubModulePractices(c *fiber.Ctx) error {
	subModuleID, err := strconv.ParseInt(c.Params("subModuleId"), 10, 64)
	if err != nil || subModuleID <= 0 {
		return c.Status(fiber.StatusBadRequest).JSON(domain.ErrorResponse{
			Message: "Invalid sub-module ID",
			Error:   "subModuleId must be a positive integer",
		})
	}

	practices, err := h.analyticsDB.GetSubModulePractices(c.Context(), subModuleID)
	if err != nil {
		return c.Status(fiber.StatusInternalServerError).JSON(domain.ErrorResponse{
			Message: "Failed to load sub-module practices",
			Error:   err.Error(),
		})
	}
	if practices == nil {
		practices = []dbgen.GetSubModulePracticesRow{}
	}

	return c.JSON(domain.Response{
		Message:    "Sub-module practices retrieved successfully",
		Success:    true,
		StatusCode: fiber.StatusOK,
		Data: map[string]interface{}{
			"practices":   practices,
			"total_count": len(practices),
		},
	})
}

func practiceRowFromSubModuleQuestionSet(qs domain.QuestionSet) dbgen.GetSubModulePracticeByIDRow {
	row := dbgen.GetSubModulePracticeByIDRow{
		ID:            0,
		Title:         qs.Title,
		QuestionSetID: qs.ID,
		DisplayOrder:  0,
		Status:        qs.Status,
		SetType:       qs.SetType,
		IsActive:      !strings.EqualFold(qs.Status, "ARCHIVED"),
	}
	if qs.OwnerID != nil {
		row.SubModuleID = *qs.OwnerID
	}
	if qs.Description != nil {
		row.Description = pgtype.Text{String: *qs.Description, Valid: true}
	}
	if qs.IntroVideoURL != nil {
		row.IntroVideoUrl = pgtype.Text{String: *qs.IntroVideoURL, Valid: true}
	}
	return row
}

// resolveCourseManagementPractice loads an active sub_module_practices row, or a SUB_MODULE-owned PRACTICE
// question_set with no bridge row (id is always question_sets.id in that case).
func (h *Handler) resolveCourseManagementPractice(ctx context.Context, id int64) (dbgen.GetSubModulePracticeByIDRow, error) {
	row, err := h.analyticsDB.GetSubModulePracticeByID(ctx, id)
	if err == nil {
		return row, nil
	}
	if !errors.Is(err, pgx.ErrNoRows) {
		return dbgen.GetSubModulePracticeByIDRow{}, err
	}
	qs, err := h.questionsSvc.GetQuestionSetByID(ctx, id)
	if err != nil {
		if errors.Is(err, pgx.ErrNoRows) {
			return dbgen.GetSubModulePracticeByIDRow{}, pgx.ErrNoRows
		}
		return dbgen.GetSubModulePracticeByIDRow{}, err
	}
	if !strings.EqualFold(qs.SetType, string(domain.QuestionSetTypePractice)) {
		return dbgen.GetSubModulePracticeByIDRow{}, pgx.ErrNoRows
	}
	if qs.OwnerType == nil || !strings.EqualFold(*qs.OwnerType, "SUB_MODULE") || qs.OwnerID == nil {
		return dbgen.GetSubModulePracticeByIDRow{}, pgx.ErrNoRows
	}
	out := practiceRowFromSubModuleQuestionSet(qs)
	_, total, err := h.questionsSvc.GetQuestionSetItemsPaginated(ctx, qs.ID, nil, 1, 0)
	if err == nil {
		out.QuestionCount = total
	}
	return out, nil
}

// GetSubModulePracticeByID godoc
// @Summary Get practice detail
// @Description Returns one practice. practiceId may be sub_module_practices.id, question_sets.id, or (if no bridge row) a SUB_MODULE PRACTICE question set id.
// @Tags course-management
// @Accept json
// @Produce json
// @Param practiceId path int true "Practice row id or question set id"
// @Success 200 {object} domain.Response
// @Failure 400 {object} domain.ErrorResponse
// @Failure 404 {object} domain.ErrorResponse
// @Failure 500 {object} domain.ErrorResponse
// @Router /api/v1/course-management/practices/{practiceId} [get]
func (h *Handler) GetSubModulePracticeByID(c *fiber.Ctx) error {
	practiceID, err := strconv.ParseInt(c.Params("practiceId"), 10, 64)
	if err != nil || practiceID <= 0 {
		return c.Status(fiber.StatusBadRequest).JSON(domain.ErrorResponse{
			Message: "Invalid practice ID",
			Error:   "practiceId must be a positive integer",
		})
	}

	practice, err := h.resolveCourseManagementPractice(c.Context(), practiceID)
	if err != nil {
		if errors.Is(err, pgx.ErrNoRows) {
			return c.Status(fiber.StatusNotFound).JSON(domain.ErrorResponse{
				Message: "Practice not found",
				Error:   err.Error(),
			})
		}
		return c.Status(fiber.StatusInternalServerError).JSON(domain.ErrorResponse{
			Message: "Failed to load practice",
			Error:   err.Error(),
		})
	}

	return c.JSON(domain.Response{
		Message:    "Practice retrieved successfully",
		Success:    true,
		StatusCode: fiber.StatusOK,
		Data:       practice,
	})
}

// GetSubModulePracticeDetail godoc
// @Summary Get practice with full question list
// @Description Returns practice metadata and ordered questions. practiceId may be sub_module_practices.id, linked question_sets.id, or a SUB_MODULE PRACTICE set id when no sub_module_practices row exists.
// @Tags course-management
// @Produce json
// @Param practiceId path int true "Practice row id or question set id"
// @Success 200 {object} domain.Response
// @Failure 400 {object} domain.ErrorResponse
// @Failure 404 {object} domain.ErrorResponse
// @Failure 500 {object} domain.ErrorResponse
// @Router /api/v1/course-management/practices/{practiceId}/detail [get]
func (h *Handler) GetSubModulePracticeDetail(c *fiber.Ctx) error {
	practiceID, err := strconv.ParseInt(c.Params("practiceId"), 10, 64)
	if err != nil || practiceID <= 0 {
		return c.Status(fiber.StatusBadRequest).JSON(domain.ErrorResponse{
			Message: "Invalid practice ID",
			Error:   "practiceId must be a positive integer",
		})
	}
	practice, err := h.resolveCourseManagementPractice(c.Context(), practiceID)
	if err != nil {
		if errors.Is(err, pgx.ErrNoRows) {
			return c.Status(fiber.StatusNotFound).JSON(domain.ErrorResponse{
				Message: "Practice not found",
				Error:   err.Error(),
			})
		}
		return c.Status(fiber.StatusInternalServerError).JSON(domain.ErrorResponse{
			Message: "Failed to load practice",
			Error:   err.Error(),
		})
	}
	const pageSize int32 = 500
	var allItems []domain.QuestionSetItemWithQuestion
	var offset int32
	var totalCount int64
	for {
		batch, total, err := h.questionsSvc.GetQuestionSetItemsPaginated(c.Context(), practice.QuestionSetID, nil, pageSize, offset)
		if err != nil {
			return c.Status(fiber.StatusInternalServerError).JSON(domain.ErrorResponse{
				Message: "Failed to load practice questions",
				Error:   err.Error(),
			})
		}
		totalCount = total
		allItems = append(allItems, batch...)
		if int64(len(allItems)) >= total || len(batch) == 0 {
			break
		}
		offset += pageSize
	}
	practice.QuestionCount = totalCount
	return c.JSON(domain.Response{
		Message:    "Practice retrieved successfully",
		Success:    true,
		StatusCode: fiber.StatusOK,
		Data: map[string]interface{}{
			"practice":  practice,
			"questions": questionSetItemsToRes(allItems),
		},
	})
}

// GetSubModuleCapstones godoc
// @Summary List capstones under sub-module
// @Description Returns active capstones for a sub-module with question-set settings and question counts
// @Tags course-management
// @Produce json
// @Param subModuleId path int true "Sub-module ID"
// @Success 200 {object} domain.Response
// @Failure 400 {object} domain.ErrorResponse
// @Failure 500 {object} domain.ErrorResponse
// @Router /api/v1/course-management/sub-modules/{subModuleId}/capstones [get]
func (h *Handler) GetSubModuleCapstones(c *fiber.Ctx) error {
	subModuleID, err := strconv.ParseInt(c.Params("subModuleId"), 10, 64)
	if err != nil || subModuleID <= 0 {
		return c.Status(fiber.StatusBadRequest).JSON(domain.ErrorResponse{
			Message: "Invalid sub-module ID",
			Error:   "subModuleId must be a valid positive integer",
		})
	}
	rows, err := h.analyticsDB.GetSubModuleCapstones(c.Context(), subModuleID)
	if err != nil {
		return c.Status(fiber.StatusInternalServerError).JSON(domain.ErrorResponse{
			Message: "Failed to load sub-module capstones",
			Error:   err.Error(),
		})
	}
	return c.JSON(domain.Response{
		Message: "Sub-module capstones retrieved successfully",
		Data: map[string]interface{}{
			"capstones":   rows,
			"total_count": len(rows),
		},
	})
}

// GetSubModuleCapstoneByID godoc
// @Summary Get capstone detail
// @Description Returns one capstone with question-set fields and the ordered question list
// @Tags course-management
// @Produce json
// @Param capstoneId path int true "Capstone ID"
// @Success 200 {object} domain.Response
// @Failure 400 {object} domain.ErrorResponse
// @Failure 404 {object} domain.ErrorResponse
// @Failure 500 {object} domain.ErrorResponse
// @Router /api/v1/course-management/capstones/{capstoneId} [get]
func (h *Handler) GetSubModuleCapstoneByID(c *fiber.Ctx) error {
	capstoneID, err := strconv.ParseInt(c.Params("capstoneId"), 10, 64)
	if err != nil || capstoneID <= 0 {
		return c.Status(fiber.StatusBadRequest).JSON(domain.ErrorResponse{
			Message: "Invalid capstone ID",
			Error:   "capstoneId must be a valid positive integer",
		})
	}
	detail, err := h.analyticsDB.GetSubModuleCapstoneByID(c.Context(), capstoneID)
	if err != nil {
		return c.Status(fiber.StatusNotFound).JSON(domain.ErrorResponse{
			Message: "Capstone not found",
			Error:   err.Error(),
		})
	}
	items, err := h.questionsSvc.GetQuestionSetItems(c.Context(), detail.QuestionSetID)
	if err != nil {
		return c.Status(fiber.StatusInternalServerError).JSON(domain.ErrorResponse{
			Message: "Failed to load capstone questions",
			Error:   err.Error(),
		})
	}
	return c.JSON(domain.Response{
		Message: "Capstone retrieved successfully",
		Data: map[string]interface{}{
			"capstone":  detail,
			"questions": items,
		},
	})
}

func (h *Handler) GetSubModuleVideos(c *fiber.Ctx) error {
	subModuleID, err := strconv.ParseInt(c.Params("subModuleId"), 10, 64)
	if err != nil || subModuleID <= 0 {
		return c.Status(fiber.StatusBadRequest).JSON(domain.ErrorResponse{Message: "Invalid sub-module ID", Error: "subModuleId must be a positive integer"})
	}

	videos, err := h.analyticsDB.GetSubModuleVideos(c.Context(), subModuleID)
	if err != nil {
		return c.Status(fiber.StatusInternalServerError).JSON(domain.ErrorResponse{Message: "Failed to load sub-module videos", Error: err.Error()})
	}

	return c.JSON(domain.Response{
		Message: "Sub-module videos retrieved successfully",
		Data: map[string]interface{}{
			"videos":      videos,
			"total_count": len(videos),
		},
	})
}

func (h *Handler) UpdateSubModule(c *fiber.Ctx) error {
	subModuleID, err := strconv.ParseInt(c.Params("subModuleId"), 10, 64)
	if err != nil || subModuleID <= 0 {
		return c.Status(fiber.StatusBadRequest).JSON(domain.ErrorResponse{Message: "Invalid sub-module ID", Error: "subModuleId must be a positive integer"})
	}

	current, err := h.analyticsDB.GetSubModuleByID(c.Context(), subModuleID)
	if err != nil {
		return c.Status(fiber.StatusNotFound).JSON(domain.ErrorResponse{Message: "Sub-module not found", Error: err.Error()})
	}

	var req updateSubModuleReq
	if err := c.BodyParser(&req); err != nil {
		return c.Status(fiber.StatusBadRequest).JSON(domain.ErrorResponse{Message: "Invalid request body", Error: err.Error()})
	}

	targetTitle := current.Title
	if req.Title != nil {
		t := strings.TrimSpace(*req.Title)
		if t == "" {
			return c.Status(fiber.StatusBadRequest).JSON(domain.ErrorResponse{Message: "title cannot be empty"})
		}
		targetTitle = t
	}
	targetDesc := mergeTextField(current.Description, req.Description)
	targetThumb := mergeTextField(current.Thumbnail, req.Thumbnail)
	targetTips := mergeTextField(current.Tips, req.Tips)
	targetOrder := current.DisplayOrder
	if req.DisplayOrder != nil {
		targetOrder = *req.DisplayOrder
	}
	targetActive := current.IsActive
	if req.IsActive != nil {
		targetActive = *req.IsActive
	}

	updated, err := h.analyticsDB.UpdateSubModule(c.Context(), dbgen.UpdateSubModuleParams{
		Title:        targetTitle,
		Description:  targetDesc,
		Thumbnail:    targetThumb,
		Tips:         targetTips,
		DisplayOrder: targetOrder,
		IsActive:     targetActive,
		ID:           subModuleID,
	})
	if err != nil {
		return c.Status(fiber.StatusInternalServerError).JSON(domain.ErrorResponse{Message: "Failed to update sub-module", Error: err.Error()})
	}
	return c.JSON(domain.Response{Message: "Sub-module updated", Data: updated})
}

func (h *Handler) DeleteSubModule(c *fiber.Ctx) error {
	subModuleID, err := strconv.ParseInt(c.Params("subModuleId"), 10, 64)
	if err != nil || subModuleID <= 0 {
		return c.Status(fiber.StatusBadRequest).JSON(domain.ErrorResponse{Message: "Invalid sub-module ID", Error: "subModuleId must be a positive integer"})
	}

	if err := h.analyticsDB.DeleteSubModuleCompat(c.Context(), subModuleID); err != nil {
		return c.Status(fiber.StatusInternalServerError).JSON(domain.ErrorResponse{Message: "Failed to delete sub-module", Error: err.Error()})
	}
	return c.JSON(domain.Response{Message: "Sub-module deleted"})
}

func (h *Handler) DeleteModule(c *fiber.Ctx) error {
	moduleID, err := strconv.ParseInt(c.Params("moduleId"), 10, 64)
	if err != nil || moduleID <= 0 {
		return c.Status(fiber.StatusBadRequest).JSON(domain.ErrorResponse{Message: "Invalid module ID", Error: "moduleId must be a positive integer"})
	}

	if err := h.analyticsDB.DeleteModuleCompat(c.Context(), moduleID); err != nil {
		return c.Status(fiber.StatusInternalServerError).JSON(domain.ErrorResponse{Message: "Failed to delete module", Error: err.Error()})
	}
	return c.JSON(domain.Response{Message: "Module deleted"})
}

func (h *Handler) UpdateSubModuleVideo(c *fiber.Ctx) error {
	videoID, err := strconv.ParseInt(c.Params("videoId"), 10, 64)
	if err != nil || videoID <= 0 {
		return c.Status(fiber.StatusBadRequest).JSON(domain.ErrorResponse{Message: "Invalid video ID", Error: "videoId must be a positive integer"})
	}

	var req updateSubModuleVideoReq
	if err := c.BodyParser(&req); err != nil {
		return c.Status(fiber.StatusBadRequest).JSON(domain.ErrorResponse{Message: "Invalid request body", Error: err.Error()})
	}
	if req.Title == nil || strings.TrimSpace(*req.Title) == "" || req.VideoURL == nil || strings.TrimSpace(*req.VideoURL) == "" {
		return c.Status(fiber.StatusBadRequest).JSON(domain.ErrorResponse{Message: "title and video_url are required"})
	}

	description := ""
	if req.Description != nil {
		description = *req.Description
	}

	if err := h.analyticsDB.UpdateSubModuleVideoCompat(c.Context(), videoID, *req.Title, description, *req.VideoURL); err != nil {
		return c.Status(fiber.StatusInternalServerError).JSON(domain.ErrorResponse{Message: "Failed to update sub-module video", Error: err.Error()})
	}
	return c.JSON(domain.Response{Message: "Sub-module video updated"})
}

func (h *Handler) DeleteSubModuleVideo(c *fiber.Ctx) error {
	videoID, err := strconv.ParseInt(c.Params("videoId"), 10, 64)
	if err != nil || videoID <= 0 {
		return c.Status(fiber.StatusBadRequest).JSON(domain.ErrorResponse{Message: "Invalid video ID", Error: "videoId must be a positive integer"})
	}

	if err := h.analyticsDB.DeleteSubModuleVideoCompat(c.Context(), videoID); err != nil {
		return c.Status(fiber.StatusInternalServerError).JSON(domain.ErrorResponse{Message: "Failed to delete sub-module video", Error: err.Error()})
	}
	return c.JSON(domain.Response{Message: "Sub-module video deleted"})
}

func (h *Handler) UpdatePractice(c *fiber.Ctx) error {
	practiceID, err := strconv.ParseInt(c.Params("practiceId"), 10, 64)
	if err != nil || practiceID <= 0 {
		return c.Status(fiber.StatusBadRequest).JSON(domain.ErrorResponse{Message: "Invalid practice ID", Error: "practiceId must be a positive integer"})
	}

	var req updatePracticeReq
	if err := c.BodyParser(&req); err != nil {
		return c.Status(fiber.StatusBadRequest).JSON(domain.ErrorResponse{Message: "Invalid request body", Error: err.Error()})
	}

	if req.IsActive != nil {
		if err := h.analyticsDB.UpdatePracticeStatusCompat(c.Context(), practiceID, *req.IsActive); err != nil {
			return c.Status(fiber.StatusInternalServerError).JSON(domain.ErrorResponse{Message: "Failed to update practice status", Error: err.Error()})
		}
		return c.JSON(domain.Response{Message: "Practice status updated"})
	}

	title := ""
	if req.Title != nil {
		title = *req.Title
	}
	description := ""
	if req.Description != nil {
		description = *req.Description
	}
	persona := ""
	if req.Persona != nil {
		persona = *req.Persona
	}
	if strings.TrimSpace(title) == "" {
		return c.Status(fiber.StatusBadRequest).JSON(domain.ErrorResponse{Message: "title is required"})
	}

	if err := h.analyticsDB.UpdatePracticeCompat(c.Context(), practiceID, title, description, persona); err != nil {
		return c.Status(fiber.StatusInternalServerError).JSON(domain.ErrorResponse{Message: "Failed to update practice", Error: err.Error()})
	}
	return c.JSON(domain.Response{Message: "Practice updated"})
}

func (h *Handler) DeletePractice(c *fiber.Ctx) error {
	practiceID, err := strconv.ParseInt(c.Params("practiceId"), 10, 64)
	if err != nil || practiceID <= 0 {
		return c.Status(fiber.StatusBadRequest).JSON(domain.ErrorResponse{Message: "Invalid practice ID", Error: "practiceId must be a positive integer"})
	}

	if err := h.analyticsDB.DeletePracticeCompat(c.Context(), practiceID); err != nil {
		return c.Status(fiber.StatusInternalServerError).JSON(domain.ErrorResponse{Message: "Failed to delete practice", Error: err.Error()})
	}
	return c.JSON(domain.Response{Message: "Practice deleted"})
}

// UpdateSubModuleCapstone godoc
// @Summary Update capstone
// @Description Updates capstone content, question-set assessment settings, and optionally replaces the question list
// @Tags course-management
// @Accept json
// @Produce json
// @Param capstoneId path int true "Capstone ID"
// @Param body body updateSubModuleCapstoneReq true "Update capstone payload"
// @Success 200 {object} domain.Response
// @Failure 400 {object} domain.ErrorResponse
// @Failure 404 {object} domain.ErrorResponse
// @Failure 500 {object} domain.ErrorResponse
// @Router /api/v1/course-management/capstones/{capstoneId} [put]
func (h *Handler) UpdateSubModuleCapstone(c *fiber.Ctx) error {
	capstoneID, err := strconv.ParseInt(c.Params("capstoneId"), 10, 64)
	if err != nil || capstoneID <= 0 {
		return c.Status(fiber.StatusBadRequest).JSON(domain.ErrorResponse{Message: "Invalid capstone ID", Error: "capstoneId must be a positive integer"})
	}
	var req updateSubModuleCapstoneReq
	if err := c.BodyParser(&req); err != nil {
		return c.Status(fiber.StatusBadRequest).JSON(domain.ErrorResponse{Message: "Invalid request body", Error: err.Error()})
	}

	cur, err := h.analyticsDB.GetSubModuleCapstoneByID(c.Context(), capstoneID)
	if err != nil {
		return c.Status(fiber.StatusNotFound).JSON(domain.ErrorResponse{Message: "Capstone not found", Error: err.Error()})
	}

	targetTitle := cur.Title
	if req.Title != nil {
		t := strings.TrimSpace(*req.Title)
		if t == "" {
			return c.Status(fiber.StatusBadRequest).JSON(domain.ErrorResponse{Message: "title cannot be empty"})
		}
		targetTitle = t
	}
	targetDesc := mergeTextField(cur.Description, req.Description)
	targetTips := mergeTextField(cur.Tips, req.Tips)
	targetThumb := mergeTextField(cur.Thumbnail, req.Thumbnail)
	targetOrder := cur.DisplayOrder
	if req.DisplayOrder != nil {
		targetOrder = *req.DisplayOrder
	}
	targetActive := cur.IsActive
	if req.IsActive != nil {
		targetActive = *req.IsActive
	}

	if _, err := h.analyticsDB.UpdateSubModuleCapstone(c.Context(), dbgen.UpdateSubModuleCapstoneParams{
		Title:        targetTitle,
		Description:  targetDesc,
		Tips:         targetTips,
		Thumbnail:    targetThumb,
		DisplayOrder: targetOrder,
		IsActive:     targetActive,
		ID:           capstoneID,
	}); err != nil {
		return c.Status(fiber.StatusInternalServerError).JSON(domain.ErrorResponse{Message: "Failed to update capstone", Error: err.Error()})
	}

	qs, err := h.questionsSvc.GetQuestionSetByID(c.Context(), cur.QuestionSetID)
	if err != nil {
		return c.Status(fiber.StatusInternalServerError).JSON(domain.ErrorResponse{Message: "Failed to load capstone question set", Error: err.Error()})
	}

	tlm := qs.TimeLimitMinutes
	if req.TimeLimitMinutes != nil {
		tlm = req.TimeLimitMinutes
	}
	ps := qs.PassingScore
	if req.PassingScore != nil {
		ps = req.PassingScore
	}
	sh := qs.ShuffleQuestions
	if req.ShuffleQuestions != nil {
		sh = *req.ShuffleQuestions
	}
	st := qs.Status
	if req.Status != nil && strings.TrimSpace(*req.Status) != "" {
		st = strings.TrimSpace(*req.Status)
	}

	if err := h.questionsSvc.UpdateQuestionSet(c.Context(), cur.QuestionSetID, domain.CreateQuestionSetInput{
		Title:            targetTitle,
		Description:      stringPtrFromPgText(targetDesc),
		BannerImage:      stringPtrFromPgText(targetThumb),
		Persona:          qs.Persona,
		TimeLimitMinutes: tlm,
		PassingScore:     ps,
		ShuffleQuestions: &sh,
		Status:           &st,
		SubCourseVideoID: qs.SubCourseVideoID,
		IntroVideoURL:    qs.IntroVideoURL,
	}); err != nil {
		return c.Status(fiber.StatusInternalServerError).JSON(domain.ErrorResponse{Message: "Failed to update capstone question set", Error: err.Error()})
	}

	if req.Questions != nil {
		seen := make(map[int64]struct{}, len(req.Questions))
		for idx, q := range req.Questions {
			if q.QuestionID <= 0 {
				return c.Status(fiber.StatusBadRequest).JSON(domain.ErrorResponse{Message: "Each question_id must be a positive integer"})
			}
			if _, exists := seen[q.QuestionID]; exists {
				return c.Status(fiber.StatusBadRequest).JSON(domain.ErrorResponse{Message: "Duplicate question_id values are not allowed"})
			}
			seen[q.QuestionID] = struct{}{}
			if _, err := h.questionsSvc.GetQuestionByID(c.Context(), q.QuestionID); err != nil {
				return c.Status(fiber.StatusBadRequest).JSON(domain.ErrorResponse{Message: "Invalid question_id in questions payload", Error: err.Error()})
			}
			order := q.DisplayOrder
			if order == nil {
				o := int32(idx)
				order = &o
			}
			if _, err := h.questionsSvc.AddQuestionToSet(c.Context(), cur.QuestionSetID, q.QuestionID, order); err != nil {
				return c.Status(fiber.StatusInternalServerError).JSON(domain.ErrorResponse{Message: "Failed to upsert capstone question", Error: err.Error()})
			}
		}
		existingItems, err := h.questionsSvc.GetQuestionSetItems(c.Context(), cur.QuestionSetID)
		if err != nil {
			return c.Status(fiber.StatusInternalServerError).JSON(domain.ErrorResponse{Message: "Failed to load existing capstone questions", Error: err.Error()})
		}
		for _, item := range existingItems {
			if _, keep := seen[item.QuestionID]; keep {
				continue
			}
			if err := h.questionsSvc.RemoveQuestionFromSet(c.Context(), cur.QuestionSetID, item.QuestionID); err != nil {
				return c.Status(fiber.StatusInternalServerError).JSON(domain.ErrorResponse{Message: "Failed to remove capstone question", Error: err.Error()})
			}
		}
	}

	detail, err := h.analyticsDB.GetSubModuleCapstoneByID(c.Context(), capstoneID)
	if err != nil {
		return c.Status(fiber.StatusInternalServerError).JSON(domain.ErrorResponse{Message: "Capstone updated but failed to load detail", Error: err.Error()})
	}
	items, err := h.questionsSvc.GetQuestionSetItems(c.Context(), detail.QuestionSetID)
	if err != nil {
		return c.Status(fiber.StatusInternalServerError).JSON(domain.ErrorResponse{Message: "Capstone updated but failed to load questions", Error: err.Error()})
	}
	return c.JSON(domain.Response{
		Message: "Capstone updated successfully",
		Data: map[string]interface{}{
			"capstone":  detail,
			"questions": items,
		},
	})
}

// DeleteCapstone godoc
// @Summary Delete capstone
// @Description Deletes the capstone and its backing question set (and question items)
// @Tags course-management
// @Produce json
// @Param capstoneId path int true "Capstone ID"
// @Success 200 {object} domain.Response
// @Failure 400 {object} domain.ErrorResponse
// @Failure 500 {object} domain.ErrorResponse
// @Router /api/v1/course-management/capstones/{capstoneId} [delete]
func (h *Handler) DeleteCapstone(c *fiber.Ctx) error {
	capstoneID, err := strconv.ParseInt(c.Params("capstoneId"), 10, 64)
	if err != nil || capstoneID <= 0 {
		return c.Status(fiber.StatusBadRequest).JSON(domain.ErrorResponse{Message: "Invalid capstone ID", Error: "capstoneId must be a positive integer"})
	}
	if err := h.analyticsDB.DeleteCapstoneCompat(c.Context(), capstoneID); err != nil {
		return c.Status(fiber.StatusInternalServerError).JSON(domain.ErrorResponse{Message: "Failed to delete capstone", Error: err.Error()})
	}
	return c.JSON(domain.Response{Message: "Capstone deleted"})
}

// CreateModuleCapstone godoc
// @Summary Create module capstone
// @Description Creates a module-level capstone with a new CAPSTONE question set and ordered questions
// @Tags course-management
// @Accept json
// @Produce json
// @Param body body createModuleCapstoneReq true "Create module capstone payload"
// @Success 201 {object} domain.Response
// @Failure 400 {object} domain.ErrorResponse
// @Failure 500 {object} domain.ErrorResponse
// @Router /api/v1/course-management/module-capstones [post]
func (h *Handler) CreateModuleCapstone(c *fiber.Ctx) error {
	var req createModuleCapstoneReq
	if err := c.BodyParser(&req); err != nil {
		return c.Status(fiber.StatusBadRequest).JSON(domain.ErrorResponse{Message: "Invalid request body", Error: err.Error()})
	}
	if req.ModuleID <= 0 || strings.TrimSpace(req.Title) == "" {
		return c.Status(fiber.StatusBadRequest).JSON(domain.ErrorResponse{Message: "module_id and title are required"})
	}
	if len(req.Questions) == 0 {
		return c.Status(fiber.StatusBadRequest).JSON(domain.ErrorResponse{Message: "At least one question is required"})
	}
	seenQ := make(map[int64]struct{}, len(req.Questions))
	for _, q := range req.Questions {
		if q.QuestionID <= 0 {
			return c.Status(fiber.StatusBadRequest).JSON(domain.ErrorResponse{Message: "Each question_id must be a positive integer"})
		}
		if _, dup := seenQ[q.QuestionID]; dup {
			return c.Status(fiber.StatusBadRequest).JSON(domain.ErrorResponse{Message: "Duplicate question_id values are not allowed"})
		}
		seenQ[q.QuestionID] = struct{}{}
		if _, err := h.questionsSvc.GetQuestionByID(c.Context(), q.QuestionID); err != nil {
			return c.Status(fiber.StatusBadRequest).JSON(domain.ErrorResponse{Message: "Invalid question_id", Error: err.Error()})
		}
	}

	ownerType := "MODULE"
	shuffle := false
	if req.ShuffleQuestions != nil {
		shuffle = *req.ShuffleQuestions
	}
	status := "DRAFT"
	if req.Status != nil && strings.TrimSpace(*req.Status) != "" {
		status = strings.TrimSpace(*req.Status)
	}

	title := strings.TrimSpace(req.Title)
	createdSet, err := h.questionsSvc.CreateQuestionSet(c.Context(), domain.CreateQuestionSetInput{
		Title:            title,
		Description:      req.Description,
		SetType:          string(domain.QuestionSetTypeCapstone),
		OwnerType:        &ownerType,
		OwnerID:          &req.ModuleID,
		BannerImage:      req.Thumbnail,
		TimeLimitMinutes: req.TimeLimitMinutes,
		PassingScore:     req.PassingScore,
		ShuffleQuestions: &shuffle,
		Status:           &status,
	})
	if err != nil {
		return c.Status(fiber.StatusInternalServerError).JSON(domain.ErrorResponse{Message: "Failed to create module capstone question set", Error: err.Error()})
	}

	capRow, err := h.analyticsDB.CreateModuleCapstone(c.Context(), dbgen.CreateModuleCapstoneParams{
		ModuleID:      req.ModuleID,
		Title:         title,
		Description:   toText(req.Description),
		Tips:          toText(req.Tips),
		Thumbnail:     toText(req.Thumbnail),
		QuestionSetID: createdSet.ID,
		Column7:       intOrNil(req.DisplayOrder),
		Column8:       boolOrNil(req.IsActive),
	})
	if err != nil {
		_ = h.questionsSvc.DeleteQuestionSet(c.Context(), createdSet.ID)
		return c.Status(fiber.StatusInternalServerError).JSON(domain.ErrorResponse{Message: "Failed to create module capstone", Error: err.Error()})
	}

	for idx, cq := range req.Questions {
		order := cq.DisplayOrder
		if order == nil {
			o := int32(idx)
			order = &o
		}
		if _, err := h.questionsSvc.AddQuestionToSet(c.Context(), createdSet.ID, cq.QuestionID, order); err != nil {
			_ = h.questionsSvc.DeleteQuestionSet(c.Context(), createdSet.ID)
			return c.Status(fiber.StatusInternalServerError).JSON(domain.ErrorResponse{Message: "Failed to attach module capstone questions", Error: err.Error()})
		}
	}

	detail, err := h.analyticsDB.GetModuleCapstoneByID(c.Context(), capRow.ID)
	if err != nil {
		return c.Status(fiber.StatusInternalServerError).JSON(domain.ErrorResponse{Message: "Module capstone created but failed to load detail", Error: err.Error()})
	}
	items, err := h.questionsSvc.GetQuestionSetItems(c.Context(), detail.QuestionSetID)
	if err != nil {
		return c.Status(fiber.StatusInternalServerError).JSON(domain.ErrorResponse{Message: "Module capstone created but failed to load questions", Error: err.Error()})
	}

	return c.Status(fiber.StatusCreated).JSON(domain.Response{
		Message: "Module capstone created",
		Data: map[string]interface{}{
			"capstone":  detail,
			"questions": items,
		},
	})
}

// GetModuleCapstones godoc
// @Summary List capstones under module
// @Description Returns active module capstones with question-set settings and question counts
// @Tags course-management
// @Produce json
// @Param moduleId path int true "Module ID"
// @Success 200 {object} domain.Response
// @Failure 400 {object} domain.ErrorResponse
// @Failure 500 {object} domain.ErrorResponse
// @Router /api/v1/course-management/modules/{moduleId}/capstones [get]
func (h *Handler) GetModuleCapstones(c *fiber.Ctx) error {
	moduleID, err := strconv.ParseInt(c.Params("moduleId"), 10, 64)
	if err != nil || moduleID <= 0 {
		return c.Status(fiber.StatusBadRequest).JSON(domain.ErrorResponse{
			Message: "Invalid module ID",
			Error:   "moduleId must be a valid positive integer",
		})
	}
	rows, err := h.analyticsDB.GetModuleCapstones(c.Context(), moduleID)
	if err != nil {
		return c.Status(fiber.StatusInternalServerError).JSON(domain.ErrorResponse{
			Message: "Failed to load module capstones",
			Error:   err.Error(),
		})
	}
	return c.JSON(domain.Response{
		Message: "Module capstones retrieved successfully",
		Data: map[string]interface{}{
			"capstones":   rows,
			"total_count": len(rows),
		},
	})
}

// GetModuleCapstoneByID godoc
// @Summary Get module capstone detail
// @Description Returns one module capstone with question-set fields and the ordered question list
// @Tags course-management
// @Produce json
// @Param moduleCapstoneId path int true "Module capstone ID"
// @Success 200 {object} domain.Response
// @Failure 400 {object} domain.ErrorResponse
// @Failure 404 {object} domain.ErrorResponse
// @Failure 500 {object} domain.ErrorResponse
// @Router /api/v1/course-management/module-capstones/{moduleCapstoneId} [get]
func (h *Handler) GetModuleCapstoneByID(c *fiber.Ctx) error {
	capstoneID, err := strconv.ParseInt(c.Params("moduleCapstoneId"), 10, 64)
	if err != nil || capstoneID <= 0 {
		return c.Status(fiber.StatusBadRequest).JSON(domain.ErrorResponse{
			Message: "Invalid module capstone ID",
			Error:   "moduleCapstoneId must be a valid positive integer",
		})
	}
	detail, err := h.analyticsDB.GetModuleCapstoneByID(c.Context(), capstoneID)
	if err != nil {
		return c.Status(fiber.StatusNotFound).JSON(domain.ErrorResponse{
			Message: "Module capstone not found",
			Error:   err.Error(),
		})
	}
	items, err := h.questionsSvc.GetQuestionSetItems(c.Context(), detail.QuestionSetID)
	if err != nil {
		return c.Status(fiber.StatusInternalServerError).JSON(domain.ErrorResponse{
			Message: "Failed to load module capstone questions",
			Error:   err.Error(),
		})
	}
	return c.JSON(domain.Response{
		Message: "Module capstone retrieved successfully",
		Data: map[string]interface{}{
			"capstone":  detail,
			"questions": items,
		},
	})
}

// UpdateModuleCapstone godoc
// @Summary Update module capstone
// @Description Updates module capstone content, question-set assessment settings, and optionally replaces the question list
// @Tags course-management
// @Accept json
// @Produce json
// @Param moduleCapstoneId path int true "Module capstone ID"
// @Param body body updateModuleCapstoneReq true "Update module capstone payload"
// @Success 200 {object} domain.Response
// @Failure 400 {object} domain.ErrorResponse
// @Failure 404 {object} domain.ErrorResponse
// @Failure 500 {object} domain.ErrorResponse
// @Router /api/v1/course-management/module-capstones/{moduleCapstoneId} [put]
func (h *Handler) UpdateModuleCapstone(c *fiber.Ctx) error {
	capstoneID, err := strconv.ParseInt(c.Params("moduleCapstoneId"), 10, 64)
	if err != nil || capstoneID <= 0 {
		return c.Status(fiber.StatusBadRequest).JSON(domain.ErrorResponse{Message: "Invalid module capstone ID", Error: "moduleCapstoneId must be a positive integer"})
	}
	var req updateModuleCapstoneReq
	if err := c.BodyParser(&req); err != nil {
		return c.Status(fiber.StatusBadRequest).JSON(domain.ErrorResponse{Message: "Invalid request body", Error: err.Error()})
	}

	cur, err := h.analyticsDB.GetModuleCapstoneByID(c.Context(), capstoneID)
	if err != nil {
		return c.Status(fiber.StatusNotFound).JSON(domain.ErrorResponse{Message: "Module capstone not found", Error: err.Error()})
	}

	targetTitle := cur.Title
	if req.Title != nil {
		t := strings.TrimSpace(*req.Title)
		if t == "" {
			return c.Status(fiber.StatusBadRequest).JSON(domain.ErrorResponse{Message: "title cannot be empty"})
		}
		targetTitle = t
	}
	targetDesc := mergeTextField(cur.Description, req.Description)
	targetTips := mergeTextField(cur.Tips, req.Tips)
	targetThumb := mergeTextField(cur.Thumbnail, req.Thumbnail)
	targetOrder := cur.DisplayOrder
	if req.DisplayOrder != nil {
		targetOrder = *req.DisplayOrder
	}
	targetActive := cur.IsActive
	if req.IsActive != nil {
		targetActive = *req.IsActive
	}

	if _, err := h.analyticsDB.UpdateModuleCapstone(c.Context(), dbgen.UpdateModuleCapstoneParams{
		Title:        targetTitle,
		Description:  targetDesc,
		Tips:         targetTips,
		Thumbnail:    targetThumb,
		DisplayOrder: targetOrder,
		IsActive:     targetActive,
		ID:           capstoneID,
	}); err != nil {
		return c.Status(fiber.StatusInternalServerError).JSON(domain.ErrorResponse{Message: "Failed to update module capstone", Error: err.Error()})
	}

	qs, err := h.questionsSvc.GetQuestionSetByID(c.Context(), cur.QuestionSetID)
	if err != nil {
		return c.Status(fiber.StatusInternalServerError).JSON(domain.ErrorResponse{Message: "Failed to load module capstone question set", Error: err.Error()})
	}

	tlm := qs.TimeLimitMinutes
	if req.TimeLimitMinutes != nil {
		tlm = req.TimeLimitMinutes
	}
	ps := qs.PassingScore
	if req.PassingScore != nil {
		ps = req.PassingScore
	}
	sh := qs.ShuffleQuestions
	if req.ShuffleQuestions != nil {
		sh = *req.ShuffleQuestions
	}
	st := qs.Status
	if req.Status != nil && strings.TrimSpace(*req.Status) != "" {
		st = strings.TrimSpace(*req.Status)
	}

	if err := h.questionsSvc.UpdateQuestionSet(c.Context(), cur.QuestionSetID, domain.CreateQuestionSetInput{
		Title:            targetTitle,
		Description:      stringPtrFromPgText(targetDesc),
		BannerImage:      stringPtrFromPgText(targetThumb),
		Persona:          qs.Persona,
		TimeLimitMinutes: tlm,
		PassingScore:     ps,
		ShuffleQuestions: &sh,
		Status:           &st,
		SubCourseVideoID: qs.SubCourseVideoID,
		IntroVideoURL:    qs.IntroVideoURL,
	}); err != nil {
		return c.Status(fiber.StatusInternalServerError).JSON(domain.ErrorResponse{Message: "Failed to update module capstone question set", Error: err.Error()})
	}

	if req.Questions != nil {
		seen := make(map[int64]struct{}, len(req.Questions))
		for idx, q := range req.Questions {
			if q.QuestionID <= 0 {
				return c.Status(fiber.StatusBadRequest).JSON(domain.ErrorResponse{Message: "Each question_id must be a positive integer"})
			}
			if _, exists := seen[q.QuestionID]; exists {
				return c.Status(fiber.StatusBadRequest).JSON(domain.ErrorResponse{Message: "Duplicate question_id values are not allowed"})
			}
			seen[q.QuestionID] = struct{}{}
			if _, err := h.questionsSvc.GetQuestionByID(c.Context(), q.QuestionID); err != nil {
				return c.Status(fiber.StatusBadRequest).JSON(domain.ErrorResponse{Message: "Invalid question_id in questions payload", Error: err.Error()})
			}
			order := q.DisplayOrder
			if order == nil {
				o := int32(idx)
				order = &o
			}
			if _, err := h.questionsSvc.AddQuestionToSet(c.Context(), cur.QuestionSetID, q.QuestionID, order); err != nil {
				return c.Status(fiber.StatusInternalServerError).JSON(domain.ErrorResponse{Message: "Failed to upsert module capstone question", Error: err.Error()})
			}
		}
		existingItems, err := h.questionsSvc.GetQuestionSetItems(c.Context(), cur.QuestionSetID)
		if err != nil {
			return c.Status(fiber.StatusInternalServerError).JSON(domain.ErrorResponse{Message: "Failed to load existing module capstone questions", Error: err.Error()})
		}
		for _, item := range existingItems {
			if _, keep := seen[item.QuestionID]; keep {
				continue
			}
			if err := h.questionsSvc.RemoveQuestionFromSet(c.Context(), cur.QuestionSetID, item.QuestionID); err != nil {
				return c.Status(fiber.StatusInternalServerError).JSON(domain.ErrorResponse{Message: "Failed to remove module capstone question", Error: err.Error()})
			}
		}
	}

	detail, err := h.analyticsDB.GetModuleCapstoneByID(c.Context(), capstoneID)
	if err != nil {
		return c.Status(fiber.StatusInternalServerError).JSON(domain.ErrorResponse{Message: "Module capstone updated but failed to load detail", Error: err.Error()})
	}
	items, err := h.questionsSvc.GetQuestionSetItems(c.Context(), detail.QuestionSetID)
	if err != nil {
		return c.Status(fiber.StatusInternalServerError).JSON(domain.ErrorResponse{Message: "Module capstone updated but failed to load questions", Error: err.Error()})
	}
	return c.JSON(domain.Response{
		Message: "Module capstone updated successfully",
		Data: map[string]interface{}{
			"capstone":  detail,
			"questions": items,
		},
	})
}

// DeleteModuleCapstone godoc
// @Summary Delete module capstone
// @Description Deletes the module capstone and its backing question set
// @Tags course-management
// @Produce json
// @Param moduleCapstoneId path int true "Module capstone ID"
// @Success 200 {object} domain.Response
// @Failure 400 {object} domain.ErrorResponse
// @Failure 500 {object} domain.ErrorResponse
// @Router /api/v1/course-management/module-capstones/{moduleCapstoneId} [delete]
func (h *Handler) DeleteModuleCapstone(c *fiber.Ctx) error {
	capstoneID, err := strconv.ParseInt(c.Params("moduleCapstoneId"), 10, 64)
	if err != nil || capstoneID <= 0 {
		return c.Status(fiber.StatusBadRequest).JSON(domain.ErrorResponse{Message: "Invalid module capstone ID", Error: "moduleCapstoneId must be a positive integer"})
	}
	if err := h.analyticsDB.DeleteModuleCapstoneCompat(c.Context(), capstoneID); err != nil {
		return c.Status(fiber.StatusInternalServerError).JSON(domain.ErrorResponse{Message: "Failed to delete module capstone", Error: err.Error()})
	}
	return c.JSON(domain.Response{Message: "Module capstone deleted"})
}