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 courseToDomain(c dbgen.Course) domain.Course {
	out := domain.Course{
		ID:        c.ID,
		ProgramID: c.ProgramID,
		Name:      c.Name,
	}
	out.Description = fromPgText(c.Description)
	out.Thumbnail = fromPgText(c.Thumbnail)
	out.CreatedAt = c.CreatedAt.Time
	if c.UpdatedAt.Valid {
		t := c.UpdatedAt.Time
		out.UpdatedAt = &t
	}
	out.SortOrder = int(c.SortOrder)
	return out
}

func (s *Store) CreateCourse(ctx context.Context, programID int64, input domain.CreateCourseInput) (domain.Course, error) {
	c, err := s.queries.CreateCourse(ctx, dbgen.CreateCourseParams{
		ProgramID:   programID,
		Name:        input.Name,
		Description: toPgText(input.Description),
		Thumbnail:   toPgText(input.Thumbnail),
	})
	if err != nil {
		return domain.Course{}, err
	}
	return courseToDomain(c), nil
}

func (s *Store) ListCourseIDsByProgram(ctx context.Context, programID int64) ([]int64, error) {
	return s.queries.ListCourseIDsByProgram(ctx, programID)
}

func (s *Store) GetCourseByID(ctx context.Context, id int64) (domain.Course, error) {
	c, err := s.queries.GetCourseByID(ctx, id)
	if err != nil {
		if errors.Is(err, pgx.ErrNoRows) {
			return domain.Course{}, pgx.ErrNoRows
		}
		return domain.Course{}, err
	}
	return courseToDomain(c), nil
}

func (s *Store) ListCoursesByProgramID(ctx context.Context, programID int64, limit, offset int32) ([]domain.Course, int64, error) {
	rows, err := s.queries.ListCoursesByProgramID(ctx, dbgen.ListCoursesByProgramIDParams{
		ProgramID: programID,
		Limit:     limit,
		Offset:    offset,
	})
	if err != nil {
		return nil, 0, err
	}
	if len(rows) == 0 {
		return []domain.Course{}, 0, nil
	}
	var total int64
	out := make([]domain.Course, 0, len(rows))
	for i, r := range rows {
		if i == 0 {
			total = r.TotalCount
		}
		out = append(out, courseToDomain(dbgen.Course{
			ID:          r.ID,
			ProgramID:   r.ProgramID,
			Name:        r.Name,
			Description: r.Description,
			Thumbnail:   r.Thumbnail,
			CreatedAt:   r.CreatedAt,
			UpdatedAt:   r.UpdatedAt,
			SortOrder:   r.SortOrder,
		}))
	}
	return out, total, nil
}

func (s *Store) UpdateCourse(ctx context.Context, id int64, input domain.UpdateCourseInput) (domain.Course, error) {
	var nameText pgtype.Text
	if input.Name != nil {
		nameText = pgtype.Text{String: *input.Name, Valid: true}
	} else {
		nameText = pgtype.Text{Valid: false}
	}
	c, err := s.queries.UpdateCourse(ctx, dbgen.UpdateCourseParams{
		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.Course{}, pgx.ErrNoRows
		}
		return domain.Course{}, err
	}
	return courseToDomain(c), nil
}

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