package repository

import (
	"context"
	"fmt"

	dbgen "Yimaru-Backend/gen/db"
)

// CompleteLessonForUser records lesson completion and cascades to module, course, and program when the user
// has fully completed the preceding scope. Runs in a single transaction.
func (s *Store) CompleteLessonForUser(ctx context.Context, userID, lessonID int64) error {
	q, tx, err := s.BeginTx(ctx)
	if err != nil {
		return fmt.Errorf("begin tx: %w", err)
	}
	defer func() { _ = tx.Rollback(ctx) }()

	if err := q.InsertUserLessonProgress(ctx, dbgen.InsertUserLessonProgressParams{UserID: userID, LessonID: lessonID}); err != nil {
		return err
	}
	lesson, err := q.GetLessonByID(ctx, lessonID)
	if err != nil {
		return err
	}
	mod, err := q.GetModuleByID(ctx, lesson.ModuleID)
	if err != nil {
		return err
	}
	crs, err := q.GetCourseByID(ctx, mod.CourseID)
	if err != nil {
		return err
	}
	nLess, err := q.CountLessonsInModule(ctx, lesson.ModuleID)
	if err != nil {
		return err
	}
	nDoneLess, err := q.CountUserCompletedLessonsInModule(ctx, dbgen.CountUserCompletedLessonsInModuleParams{
		ModuleID: lesson.ModuleID,
		UserID:   userID,
	})
	if err != nil {
		return err
	}
	if nLess > 0 && nDoneLess >= nLess {
		if err := q.InsertUserModuleProgress(ctx, dbgen.InsertUserModuleProgressParams{UserID: userID, ModuleID: mod.ID}); err != nil {
			return err
		}
		nMods, err := q.CountModulesInCourse(ctx, mod.CourseID)
		if err != nil {
			return err
		}
		nDoneMods, err := q.CountUserCompletedModulesInCourse(ctx, dbgen.CountUserCompletedModulesInCourseParams{
			CourseID: mod.CourseID,
			UserID:   userID,
		})
		if err != nil {
			return err
		}
		if nMods > 0 && nDoneMods >= nMods {
			if err := q.InsertUserCourseProgress(ctx, dbgen.InsertUserCourseProgressParams{UserID: userID, CourseID: crs.ID}); err != nil {
				return err
			}
			nCr, err := q.CountCoursesInProgram(ctx, crs.ProgramID)
			if err != nil {
				return err
			}
			nCrDone, err := q.CountUserCompletedCoursesInProgram(ctx, dbgen.CountUserCompletedCoursesInProgramParams{
				ProgramID: crs.ProgramID,
				UserID:    userID,
			})
			if err != nil {
				return err
			}
			if nCr > 0 && nCrDone >= nCr {
				if err := q.InsertUserProgramProgress(ctx, dbgen.InsertUserProgramProgressParams{UserID: userID, ProgramID: crs.ProgramID}); err != nil {
					return err
				}
			}
		}
	}
	if err := tx.Commit(ctx); err != nil {
		return fmt.Errorf("commit: %w", err)
	}
	return nil
}