package photos

import (
	"context"
	"errors"
	"time"

	"github.com/jackc/pgx/v5"
	"github.com/jackc/pgx/v5/pgxpool"

	"shared-album/internal/models"
)

var ErrNotFound = errors.New("photo not found")

type Store struct {
	pool *pgxpool.Pool
}

func NewStore(pool *pgxpool.Pool) *Store { return &Store{pool: pool} }

const photoColumns = `p.id, p.album_id, p.uploader_id, p.storage_key,
	COALESCE(p.thumb_key, ''), COALESCE(p.preview_key, ''),
	p.original_filename, p.size, p.width, p.height, p.mime_type,
	p.taken_at, p.latitude, p.longitude, COALESCE(p.caption, ''), p.created_at,
	u.id, u.name, COALESCE(u.avatar_url, ''),
	(SELECT count(*) FROM likes l WHERE l.photo_id = p.id),
	(SELECT count(*) FROM comments c WHERE c.photo_id = p.id),
	EXISTS(SELECT 1 FROM likes l WHERE l.photo_id = p.id AND l.user_id = $2)`

func scanPhoto(row pgx.Row) (*models.Photo, error) {
	var p models.Photo
	err := row.Scan(&p.ID, &p.AlbumID, &p.UploaderID, &p.StorageKey,
		&p.ThumbKey, &p.PreviewKey,
		&p.OriginalFilename, &p.Size, &p.Width, &p.Height, &p.MimeType,
		&p.TakenAt, &p.Latitude, &p.Longitude, &p.Caption, &p.CreatedAt,
		&p.Uploader.ID, &p.Uploader.Name, &p.Uploader.AvatarURL,
		&p.LikesCount, &p.CommentsCount, &p.LikedByMe)
	if err != nil {
		if errors.Is(err, pgx.ErrNoRows) {
			return nil, ErrNotFound
		}
		return nil, err
	}
	return &p, nil
}

func (s *Store) Create(ctx context.Context, p *models.Photo) error {
	return s.pool.QueryRow(ctx,
		`INSERT INTO photos (id, album_id, uploader_id, storage_key, original_filename,
			size, width, height, mime_type, taken_at, latitude, longitude, caption)
		 VALUES ($1,$2,$3,$4,$5,$6,$7,$8,$9,$10,$11,$12,$13)
		 RETURNING created_at`,
		p.ID, p.AlbumID, p.UploaderID, p.StorageKey, p.OriginalFilename,
		p.Size, p.Width, p.Height, p.MimeType, p.TakenAt, p.Latitude, p.Longitude, p.Caption,
	).Scan(&p.CreatedAt)
}

func (s *Store) SetVariants(ctx context.Context, id, thumbKey, previewKey string) error {
	_, err := s.pool.Exec(ctx,
		`UPDATE photos SET thumb_key = $2, preview_key = $3 WHERE id = $1`, id, thumbKey, previewKey)
	return err
}

func (s *Store) GetByID(ctx context.Context, id, viewerID string) (*models.Photo, error) {
	return scanPhoto(s.pool.QueryRow(ctx,
		`SELECT `+photoColumns+`
		 FROM photos p JOIN users u ON u.id = p.uploader_id
		 WHERE p.id = $1`, id, viewerID))
}

type ListParams struct {
	AlbumID string
	Viewer  string
	Cursor  string
	Since   *time.Time
	Limit   int
}

func (s *Store) List(ctx context.Context, in ListParams) ([]models.Photo, error) {
	if in.Limit <= 0 || in.Limit > 100 {
		in.Limit = 50
	}
	rows, err := s.pool.Query(ctx,
		`SELECT `+photoColumns+`
		 FROM photos p JOIN users u ON u.id = p.uploader_id
		 WHERE p.album_id = $1
		   AND ($3 = '' OR (p.created_at, p.id) < (SELECT created_at, id FROM photos WHERE id = $3))
		   AND ($4::timestamptz IS NULL OR p.created_at > $4)
		 ORDER BY p.created_at DESC, p.id DESC
		 LIMIT $5`,
		in.AlbumID, in.Viewer, in.Cursor, in.Since, in.Limit)
	if err != nil {
		return nil, err
	}
	defer rows.Close()

	out := []models.Photo{}
	for rows.Next() {
		var p models.Photo
		if err := rows.Scan(&p.ID, &p.AlbumID, &p.UploaderID, &p.StorageKey,
			&p.ThumbKey, &p.PreviewKey,
			&p.OriginalFilename, &p.Size, &p.Width, &p.Height, &p.MimeType,
			&p.TakenAt, &p.Latitude, &p.Longitude, &p.Caption, &p.CreatedAt,
			&p.Uploader.ID, &p.Uploader.Name, &p.Uploader.AvatarURL,
			&p.LikesCount, &p.CommentsCount, &p.LikedByMe); err != nil {
			return nil, err
		}
		out = append(out, p)
	}
	return out, rows.Err()
}

func (s *Store) Delete(ctx context.Context, id string) error {
	tag, err := s.pool.Exec(ctx, `DELETE FROM photos WHERE id = $1`, id)
	if err != nil {
		return err
	}
	if tag.RowsAffected() == 0 {
		return ErrNotFound
	}
	return nil
}

func (s *Store) SetCoverIfEmpty(ctx context.Context, albumID, photoID string) {
	_, _ = s.pool.Exec(ctx,
		`UPDATE albums SET cover_photo_id = $2 WHERE id = $1 AND cover_photo_id IS NULL`,
		albumID, photoID)
}

func (s *Store) UpdateFilename(ctx context.Context, id, filename string) error {
	tag, err := s.pool.Exec(ctx, `UPDATE photos SET original_filename = $2 WHERE id = $1`, id, filename)
	if err != nil {
		return err
	}
	if tag.RowsAffected() == 0 {
		return ErrNotFound
	}
	return nil
}