package repository

import (
	"Yimaru-Backend/internal/domain"
	"context"
	"fmt"

	"github.com/jackc/pgx/v5/pgtype"
)

func (s *Store) GetFullLearningTree(ctx context.Context) ([]domain.TreeCourse, error) {
	rows, err := s.queries.GetFullLearningTree(ctx)
	if err != nil {
		return nil, err
	}

	coursesMap := make(map[int64]*domain.TreeCourse)

	for _, row := range rows {
		course, ok := coursesMap[row.CourseID]
		if !ok {
			course = &domain.TreeCourse{
				ID:         row.CourseID,
				Title:      row.CourseTitle,
				SubCourses: []domain.TreeSubCourse{},
			}
			coursesMap[row.CourseID] = course
		}

		if row.SubCourseID.Valid {
			subCourse := domain.TreeSubCourse{
				ID:    row.SubCourseID.Int64,
				Title: row.SubCourseTitle.String,
				Level: row.SubCourseLevel.String,
			}
			course.SubCourses = append(course.SubCourses, subCourse)
		}
	}

	courses := make([]domain.TreeCourse, 0, len(coursesMap))
	for _, course := range coursesMap {
		courses = append(courses, *course)
	}

	return courses, nil
}

func (s *Store) GetCourseLearningPath(ctx context.Context, courseID int64) (domain.LearningPath, error) {
	rows, err := s.queries.GetCourseLearningPath(ctx, courseID)
	if err != nil {
		return domain.LearningPath{}, err
	}
	if len(rows) == 0 {
		return domain.LearningPath{}, fmt.Errorf("course not found")
	}

	first := rows[0]
	path := domain.LearningPath{
		CourseID:      first.CourseID,
		CourseTitle:   first.CourseTitle,
		Description:   ptrString(first.CourseDescription),
		Thumbnail:     ptrString(first.CourseThumbnail),
		IntroVideoURL: ptrString(first.CourseIntroVideoUrl),
		CategoryID:    first.CategoryID,
		CategoryName:  first.CategoryName,
		SubCourses:    []domain.LearningPathSubCourse{},
	}

	for _, row := range rows {
		if !row.SubCourseID.Valid {
			continue
		}

		scID := row.SubCourseID.Int64

		// Fetch prerequisites, videos, practices for this sub-course
		prerequisites, _ := s.getSubCoursePrerequisitesForPath(ctx, scID)
		videos, _ := s.getSubCourseVideosForPath(ctx, scID)
		practices, _ := s.getSubCoursePracticesForPath(ctx, scID)

		sc := domain.LearningPathSubCourse{
			ID:                scID,
			Title:             row.SubCourseTitle.String,
			Description:       ptrString(row.SubCourseDescription),
			Thumbnail:         ptrString(row.SubCourseThumbnail),
			DisplayOrder:      row.SubCourseDisplayOrder.Int32,
			Level:             row.SubCourseLevel.String,
			PrerequisiteCount: row.PrerequisiteCount,
			VideoCount:        row.VideoCount,
			PracticeCount:     row.PracticeCount,
			Prerequisites:     prerequisites,
			Videos:            videos,
			Practices:         practices,
		}
		path.SubCourses = append(path.SubCourses, sc)
	}

	return path, nil
}

func (s *Store) getSubCoursePrerequisitesForPath(ctx context.Context, subCourseID int64) ([]domain.LearningPathPrerequisite, error) {
	rows, err := s.queries.GetSubCoursePrerequisitesForLearningPath(ctx, subCourseID)
	if err != nil {
		return nil, err
	}
	result := make([]domain.LearningPathPrerequisite, len(rows))
	for i, row := range rows {
		result[i] = domain.LearningPathPrerequisite{
			SubCourseID: row.PrerequisiteSubCourseID,
			Title:       row.Title,
			Level:       row.Level,
		}
	}
	return result, nil
}

func (s *Store) getSubCourseVideosForPath(ctx context.Context, subCourseID int64) ([]domain.LearningPathVideo, error) {
	rows, err := s.queries.GetSubCourseVideosForLearningPath(ctx, subCourseID)
	if err != nil {
		return nil, err
	}
	result := make([]domain.LearningPathVideo, len(rows))
	for i, row := range rows {
		result[i] = domain.LearningPathVideo{
			ID:                row.ID,
			Title:             row.Title,
			Description:       ptrString(row.Description),
			VideoURL:          row.VideoUrl,
			Duration:          row.Duration,
			Resolution:        ptrString(row.Resolution),
			DisplayOrder:      row.DisplayOrder,
			VimeoID:           ptrString(row.VimeoID),
			VimeoEmbedURL:     ptrString(row.VimeoEmbedUrl),
			VideoHostProvider: ptrString(row.VideoHostProvider),
		}
	}
	return result, nil
}

func (s *Store) getSubCoursePracticesForPath(ctx context.Context, subCourseID int64) ([]domain.LearningPathPractice, error) {
	ownerID := pgtype.Int8{Int64: subCourseID, Valid: true}
	rows, err := s.queries.GetSubCoursePracticesForLearningPath(ctx, ownerID)
	if err != nil {
		return nil, err
	}
	result := make([]domain.LearningPathPractice, len(rows))
	for i, row := range rows {
		result[i] = domain.LearningPathPractice{
			ID:            row.ID,
			Title:         row.Title,
			Description:   ptrString(row.Description),
			Persona:       ptrString(row.Persona),
			Status:        row.Status,
			QuestionCount: row.QuestionCount,
		}
	}
	return result, nil
}