package course_management

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

// --- Prerequisites (admin) ---

func (s *Service) AddSubCoursePrerequisite(ctx context.Context, subCourseID, prerequisiteSubCourseID int64) error {
	if subCourseID == prerequisiteSubCourseID {
		return domain.ErrSelfPrerequisite
	}
	return s.progressionStore.AddSubCoursePrerequisite(ctx, subCourseID, prerequisiteSubCourseID)
}

func (s *Service) RemoveSubCoursePrerequisite(ctx context.Context, subCourseID, prerequisiteSubCourseID int64) error {
	return s.progressionStore.RemoveSubCoursePrerequisite(ctx, subCourseID, prerequisiteSubCourseID)
}

func (s *Service) GetSubCoursePrerequisites(ctx context.Context, subCourseID int64) ([]domain.SubCoursePrerequisite, error) {
	return s.progressionStore.GetSubCoursePrerequisites(ctx, subCourseID)
}

func (s *Service) GetSubCourseDependents(ctx context.Context, prerequisiteSubCourseID int64) ([]domain.SubCourseDependent, error) {
	return s.progressionStore.GetSubCourseDependents(ctx, prerequisiteSubCourseID)
}

// --- User progress ---

func (s *Service) CheckSubCourseAccess(ctx context.Context, userID, subCourseID int64) (bool, error) {
	unmet, err := s.progressionStore.CountUnmetPrerequisites(ctx, subCourseID, userID)
	if err != nil {
		return false, err
	}
	return unmet == 0, nil
}

func (s *Service) StartSubCourse(ctx context.Context, userID, subCourseID int64) (domain.UserSubCourseProgress, error) {
	accessible, err := s.CheckSubCourseAccess(ctx, userID, subCourseID)
	if err != nil {
		return domain.UserSubCourseProgress{}, err
	}
	if !accessible {
		return domain.UserSubCourseProgress{}, domain.ErrPrerequisiteNotMet
	}

	return s.progressionStore.StartSubCourseProgress(ctx, userID, subCourseID)
}

func (s *Service) UpdateSubCourseProgress(ctx context.Context, userID, subCourseID int64, percentage int16) error {
	return s.progressionStore.UpdateSubCourseProgress(ctx, userID, subCourseID, percentage)
}

func (s *Service) CompleteSubCourse(ctx context.Context, userID, subCourseID int64) error {
	return s.progressionStore.CompleteSubCourse(ctx, userID, subCourseID)
}

func (s *Service) RecalculateSubCourseProgress(ctx context.Context, userID, subCourseID int64) error {
	return s.progressionStore.RecalculateSubCourseProgress(ctx, userID, subCourseID)
}

func (s *Service) GetUserSubCourseProgress(ctx context.Context, userID, subCourseID int64) (domain.UserSubCourseProgress, error) {
	return s.progressionStore.GetUserSubCourseProgress(ctx, userID, subCourseID)
}

func (s *Service) GetUserCourseProgress(ctx context.Context, userID, courseID int64) ([]domain.UserCourseProgressItem, error) {
	return s.progressionStore.GetUserCourseProgress(ctx, userID, courseID)
}

func (s *Service) GetSubCoursesWithProgress(ctx context.Context, userID, courseID int64) ([]domain.SubCourseWithProgress, error) {
	return s.progressionStore.GetSubCoursesWithProgressByCourse(ctx, userID, courseID)
}