package handlers

import (
	"Yimaru-Backend/internal/domain"
	"Yimaru-Backend/internal/services/courses"
	"Yimaru-Backend/internal/services/programs"
	"context"
	"errors"
	"strconv"

	"github.com/gofiber/fiber/v2"
)

// CreateCourse godoc
// @Summary Create course
// @Description Create a course under a program. Optional sort_order assigns position within that program (siblings shifted); omit to append after the current highest sort_order in the program.
// @Tags courses
// @Accept json
// @Produce json
// @Param id path int true "Program ID"
// @Param body body domain.CreateCourseInput true "Course"
// @Success 201 {object} domain.Response
// @Failure 400 {object} domain.ErrorResponse
// @Failure 404 {object} domain.ErrorResponse
// @Router /api/v1/programs/{id}/courses [post]
func (h *Handler) CreateCourse(c *fiber.Ctx) error {
	programID, err := strconv.ParseInt(c.Params("id"), 10, 64)
	if err != nil {
		return c.Status(fiber.StatusBadRequest).JSON(domain.ErrorResponse{
			Message: "Invalid program id",
			Error:   err.Error(),
		})
	}
	var req domain.CreateCourseInput
	if err := c.BodyParser(&req); err != nil {
		return c.Status(fiber.StatusBadRequest).JSON(domain.ErrorResponse{
			Message: "Invalid request body",
			Error:   err.Error(),
		})
	}
	if valErrs, ok := h.validator.Validate(c, req); !ok {
		return c.Status(fiber.StatusBadRequest).JSON(domain.ErrorResponse{
			Message: "Validation failed",
			Error:   firstValidationError(valErrs),
		})
	}
	course, err := h.courseSvc.Create(c.Context(), programID, req)
	if err != nil {
		if errors.Is(err, programs.ErrProgramNotFound) {
			return c.Status(fiber.StatusNotFound).JSON(domain.ErrorResponse{
				Message: "Program not found",
				Error:   err.Error(),
			})
		}
		return c.Status(fiber.StatusInternalServerError).JSON(domain.ErrorResponse{
			Message: "Failed to create course",
			Error:   err.Error(),
		})
	}
	actorID := c.Locals("user_id").(int64)
	actorRole := string(c.Locals("role").(domain.Role))
	ip := c.IP()
	ua := c.Get("User-Agent")
	rid := course.ID
	go h.activityLogSvc.RecordAction(context.Background(), &actorID, &actorRole, domain.ActionCourseCreated, domain.ResourceCourse, &rid, "Created course: "+course.Name, nil, &ip, &ua)

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

// ListCoursesByProgram godoc
// @Summary List courses by program
// @Tags courses
// @Produce json
// @Param id path int true "Program ID"
// @Param limit query int false "Page size" default(20)
// @Param offset query int false "Offset" default(0)
// @Success 200 {object} domain.Response
// @Failure 404 {object} domain.ErrorResponse
// @Router /api/v1/programs/{id}/courses [get]
func (h *Handler) ListCoursesByProgram(c *fiber.Ctx) error {
	programID, err := strconv.ParseInt(c.Params("id"), 10, 64)
	if err != nil {
		return c.Status(fiber.StatusBadRequest).JSON(domain.ErrorResponse{
			Message: "Invalid program id",
			Error:   err.Error(),
		})
	}
	limit, _ := strconv.Atoi(c.Query("limit", "20"))
	offset, _ := strconv.Atoi(c.Query("offset", "0"))
	items, total, err := h.courseSvc.ListByProgram(c.Context(), programID, int32(limit), int32(offset))
	if err != nil {
		if errors.Is(err, programs.ErrProgramNotFound) {
			return c.Status(fiber.StatusNotFound).JSON(domain.ErrorResponse{
				Message: "Program not found",
				Error:   err.Error(),
			})
		}
		return c.Status(fiber.StatusInternalServerError).JSON(domain.ErrorResponse{
			Message: "Failed to list courses",
			Error:   err.Error(),
		})
	}
	uid := c.Locals("user_id").(int64)
	role := c.Locals("role").(domain.Role)
	for i := range items {
		if err := h.lmsProgressSvc.ApplyAccessCourse(c.Context(), role, uid, &items[i]); err != nil {
			return c.Status(fiber.StatusInternalServerError).JSON(domain.ErrorResponse{
				Message: "Failed to build course list",
				Error:   err.Error(),
			})
		}
	}
	return c.JSON(domain.Response{
		Message: "Courses retrieved successfully",
		Data: fiber.Map{
			"courses":     items,
			"total_count": total,
			"limit":       limit,
			"offset":      offset,
		},
		Success:    true,
		StatusCode: fiber.StatusOK,
	})
}

// GetCourse godoc
// @Summary Get course by ID
// @Tags courses
// @Produce json
// @Param id path int true "Course ID"
// @Success 200 {object} domain.Response
// @Failure 404 {object} domain.ErrorResponse
// @Router /api/v1/courses/{id} [get]
func (h *Handler) GetCourse(c *fiber.Ctx) error {
	id, err := strconv.ParseInt(c.Params("id"), 10, 64)
	if err != nil {
		return c.Status(fiber.StatusBadRequest).JSON(domain.ErrorResponse{
			Message: "Invalid course id",
			Error:   err.Error(),
		})
	}
	course, err := h.courseSvc.GetByID(c.Context(), id)
	if err != nil {
		if errors.Is(err, courses.ErrCourseNotFound) {
			return c.Status(fiber.StatusNotFound).JSON(domain.ErrorResponse{
				Message: "Course not found",
				Error:   err.Error(),
			})
		}
		return c.Status(fiber.StatusInternalServerError).JSON(domain.ErrorResponse{
			Message: "Failed to load course",
			Error:   err.Error(),
		})
	}
	uid := c.Locals("user_id").(int64)
	role := c.Locals("role").(domain.Role)
	if err := h.lmsProgressSvc.ApplyAccessCourse(c.Context(), role, uid, &course); err != nil {
		return c.Status(fiber.StatusInternalServerError).JSON(domain.ErrorResponse{
			Message: "Failed to evaluate course access",
			Error:   err.Error(),
		})
	}
	if err := lmsBlockIfInaccessible(c, course.Access); err != nil {
		return err
	}
	return c.JSON(domain.Response{
		Message:    "Course retrieved successfully",
		Data:       course,
		Success:    true,
		StatusCode: fiber.StatusOK,
	})
}

// UpdateCourse godoc
// @Summary Update course
// @Tags courses
// @Accept json
// @Produce json
// @Param id path int true "Course ID"
// @Param body body domain.UpdateCourseInput true "Fields to update"
// @Success 200 {object} domain.Response
// @Failure 404 {object} domain.ErrorResponse
// @Router /api/v1/courses/{id} [put]
func (h *Handler) UpdateCourse(c *fiber.Ctx) error {
	id, err := strconv.ParseInt(c.Params("id"), 10, 64)
	if err != nil {
		return c.Status(fiber.StatusBadRequest).JSON(domain.ErrorResponse{
			Message: "Invalid course id",
			Error:   err.Error(),
		})
	}
	var req domain.UpdateCourseInput
	if err := c.BodyParser(&req); err != nil {
		return c.Status(fiber.StatusBadRequest).JSON(domain.ErrorResponse{
			Message: "Invalid request body",
			Error:   err.Error(),
		})
	}
	course, err := h.courseSvc.Update(c.Context(), id, req)
	if err != nil {
		if errors.Is(err, courses.ErrCourseNotFound) {
			return c.Status(fiber.StatusNotFound).JSON(domain.ErrorResponse{
				Message: "Course not found",
				Error:   err.Error(),
			})
		}
		return c.Status(fiber.StatusInternalServerError).JSON(domain.ErrorResponse{
			Message: "Failed to update course",
			Error:   err.Error(),
		})
	}
	actorID := c.Locals("user_id").(int64)
	actorRole := string(c.Locals("role").(domain.Role))
	ip := c.IP()
	ua := c.Get("User-Agent")
	rid := course.ID
	go h.activityLogSvc.RecordAction(context.Background(), &actorID, &actorRole, domain.ActionCourseUpdated, domain.ResourceCourse, &rid, "Updated course: "+course.Name, nil, &ip, &ua)

	return c.JSON(domain.Response{
		Message:    "Course updated successfully",
		Data:       course,
		Success:    true,
		StatusCode: fiber.StatusOK,
	})
}

// DeleteCourse godoc
// @Summary Delete course
// @Tags courses
// @Param id path int true "Course ID"
// @Success 200 {object} domain.Response
// @Failure 404 {object} domain.ErrorResponse
// @Router /api/v1/courses/{id} [delete]
func (h *Handler) DeleteCourse(c *fiber.Ctx) error {
	id, err := strconv.ParseInt(c.Params("id"), 10, 64)
	if err != nil {
		return c.Status(fiber.StatusBadRequest).JSON(domain.ErrorResponse{
			Message: "Invalid course id",
			Error:   err.Error(),
		})
	}
	if err := h.courseSvc.Delete(c.Context(), id); err != nil {
		if errors.Is(err, courses.ErrCourseNotFound) {
			return c.Status(fiber.StatusNotFound).JSON(domain.ErrorResponse{
				Message: "Course not found",
				Error:   err.Error(),
			})
		}
		return c.Status(fiber.StatusInternalServerError).JSON(domain.ErrorResponse{
			Message: "Failed to delete course",
			Error:   err.Error(),
		})
	}
	actorID := c.Locals("user_id").(int64)
	actorRole := string(c.Locals("role").(domain.Role))
	ip := c.IP()
	ua := c.Get("User-Agent")
	go h.activityLogSvc.RecordAction(context.Background(), &actorID, &actorRole, domain.ActionCourseDeleted, domain.ResourceCourse, &id, "Deleted course", nil, &ip, &ua)

	return c.JSON(domain.Response{
		Message:    "Course deleted successfully",
		Success:    true,
		StatusCode: fiber.StatusOK,
	})
}