package repository

import (
	"context"
	"errors"

	dbgen "Yimaru-Backend/gen/db"
	"Yimaru-Backend/internal/domain"

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

func examPrepUnitToDomain(u dbgen.ExamPrepUnit) domain.ExamPrepUnit {
	out := domain.ExamPrepUnit{
		ID:              u.ID,
		CatalogCourseID: u.CatalogCourseID,
		Name:            u.Name,
		SortOrder:       int(u.SortOrder),
	}
	out.Description = fromPgText(u.Description)
	out.Thumbnail = fromPgText(u.Thumbnail)
	out.CreatedAt = u.CreatedAt.Time
	if u.UpdatedAt.Valid {
		t := u.UpdatedAt.Time
		out.UpdatedAt = &t
	}
	return out
}

func (s *Store) CreateExamPrepUnit(ctx context.Context, catalogCourseID int64, input domain.CreateExamPrepUnitInput) (domain.ExamPrepUnit, error) {
	if input.SortOrder != nil {
		q, tx, err := s.BeginTx(ctx)
		if err != nil {
			return domain.ExamPrepUnit{}, err
		}
		defer func() { _ = tx.Rollback(ctx) }()
		target := int32(*input.SortOrder)
		if _, err := tx.Exec(ctx,
			`UPDATE exam_prep.units SET sort_order = sort_order + 1 WHERE catalog_course_id = $1 AND sort_order >= $2`,
			catalogCourseID, target,
		); err != nil {
			return domain.ExamPrepUnit{}, err
		}
		u, err := q.ExamPrepCreateUnit(ctx, dbgen.ExamPrepCreateUnitParams{
			CatalogCourseID: catalogCourseID,
			Name:            input.Name,
			Description:     toPgText(input.Description),
			Thumbnail:       toPgText(input.Thumbnail),
			SortOrder:       pgtype.Int4{Int32: target, Valid: true},
		})
		if err != nil {
			return domain.ExamPrepUnit{}, err
		}
		if err := tx.Commit(ctx); err != nil {
			return domain.ExamPrepUnit{}, err
		}
		return examPrepUnitToDomain(u), nil
	}

	u, err := s.queries.ExamPrepCreateUnit(ctx, dbgen.ExamPrepCreateUnitParams{
		CatalogCourseID: catalogCourseID,
		Name:            input.Name,
		Description:     toPgText(input.Description),
		Thumbnail:       toPgText(input.Thumbnail),
		SortOrder:       pgtype.Int4{Valid: false},
	})
	if err != nil {
		return domain.ExamPrepUnit{}, err
	}
	return examPrepUnitToDomain(u), nil
}

func (s *Store) GetExamPrepUnitByID(ctx context.Context, id int64) (domain.ExamPrepUnit, error) {
	u, err := s.queries.ExamPrepGetUnitByID(ctx, id)
	if err != nil {
		if errors.Is(err, pgx.ErrNoRows) {
			return domain.ExamPrepUnit{}, pgx.ErrNoRows
		}
		return domain.ExamPrepUnit{}, err
	}
	out := examPrepUnitToDomain(dbgen.ExamPrepUnit{
		ID:              u.ID,
		CatalogCourseID: u.CatalogCourseID,
		Name:            u.Name,
		Description:     u.Description,
		Thumbnail:       u.Thumbnail,
		SortOrder:       u.SortOrder,
		CreatedAt:       u.CreatedAt,
		UpdatedAt:       u.UpdatedAt,
	})
	out.HasPractice = u.HasPractice
	return out, nil
}

func (s *Store) ListExamPrepUnitsByCatalogCourse(ctx context.Context, catalogCourseID int64, limit, offset int32) ([]domain.ExamPrepUnit, int64, error) {
	rows, err := s.queries.ExamPrepListUnitsByCatalogCourse(ctx, dbgen.ExamPrepListUnitsByCatalogCourseParams{
		CatalogCourseID: catalogCourseID,
		Limit:           limit,
		Offset:          offset,
	})
	if err != nil {
		return nil, 0, err
	}
	if len(rows) == 0 {
		return []domain.ExamPrepUnit{}, 0, nil
	}
	var total int64
	out := make([]domain.ExamPrepUnit, 0, len(rows))
	for i, r := range rows {
		if i == 0 {
			total = r.TotalCount
		}
		item := examPrepUnitToDomain(dbgen.ExamPrepUnit{
			ID:              r.ID,
			CatalogCourseID: r.CatalogCourseID,
			Name:            r.Name,
			Description:     r.Description,
			Thumbnail:       r.Thumbnail,
			SortOrder:       r.SortOrder,
			CreatedAt:       r.CreatedAt,
			UpdatedAt:       r.UpdatedAt,
		})
		item.ModulesCount = &r.ModulesCount
		item.LessonsCount = &r.LessonsCount
		item.PracticesCount = &r.PracticesCount
		item.HasPractice = r.HasPractice
		out = append(out, item)
	}
	return out, total, nil
}

func (s *Store) ListExamPrepUnitIDsByCatalogCourse(ctx context.Context, catalogCourseID int64) ([]int64, error) {
	return s.queries.ExamPrepListUnitIDsByCatalogCourse(ctx, catalogCourseID)
}

func (s *Store) UpdateExamPrepUnit(ctx context.Context, id int64, input domain.UpdateExamPrepUnitInput) (domain.ExamPrepUnit, error) {
	var nameText pgtype.Text
	if input.Name != nil {
		nameText = pgtype.Text{String: *input.Name, Valid: true}
	} else {
		nameText = pgtype.Text{Valid: false}
	}
	u, err := s.queries.ExamPrepUpdateUnit(ctx, dbgen.ExamPrepUpdateUnitParams{
		ID:          id,
		Name:        nameText,
		Description: optionalTextUpdate(input.Description),
		Thumbnail:   optionalTextUpdate(input.Thumbnail),
		SortOrder:   optionalInt4Update(input.SortOrder),
	})
	if err != nil {
		if errors.Is(err, pgx.ErrNoRows) {
			return domain.ExamPrepUnit{}, pgx.ErrNoRows
		}
		return domain.ExamPrepUnit{}, err
	}
	return examPrepUnitToDomain(u), nil
}

func (s *Store) DeleteExamPrepUnit(ctx context.Context, id int64) error {
	return s.queries.ExamPrepDeleteUnit(ctx, id)
}