package repository

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

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)
	programsMap := make(map[int64]*domain.TreeProgram)
	levelsMap := make(map[int64]*domain.TreeLevel)

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

		// PROGRAM
		program, ok := programsMap[row.ProgramID]
		if !ok {
			program = &domain.TreeProgram{
				ID:     row.ProgramID,
				Title:  row.ProgramTitle,
				Levels: []domain.TreeLevel{},
			}
			programsMap[row.ProgramID] = program
			course.Programs = append(course.Programs, *program)
		}

		// LEVEL
		level, ok := levelsMap[row.LevelID]
		if !ok {
			level = &domain.TreeLevel{
				ID:      row.LevelID,
				Title:   row.LevelTitle,
				Modules: []domain.TreeModule{},
			}
			levelsMap[row.LevelID] = level

			// Append level to its program
			for i := range course.Programs {
				if course.Programs[i].ID == row.ProgramID {
					course.Programs[i].Levels = append(course.Programs[i].Levels, *level)
					break
				}
			}
		}

		// MODULE (may be nil)
		if row.ModuleID.Valid {
			module := domain.TreeModule{
				ID:    row.ModuleID.Int64,
				Title: row.ModuleTitle.String,
			}

			// Append module to its level
			for i := range course.Programs {
				if course.Programs[i].ID == row.ProgramID {
					for j := range course.Programs[i].Levels {
						if course.Programs[i].Levels[j].ID == row.LevelID {
							course.Programs[i].Levels[j].Modules = append(course.Programs[i].Levels[j].Modules, module)
							break
						}
					}
					break
				}
			}
		}
	}

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

	return courses, nil
}