// Package media serves generic item endpoints: detail, the raw file, cover
// art, and progress. It knows nothing about any specific media format; modules
// register cover extractors and expose their own metadata endpoints.
package media

import (
	"context"
	"database/sql"
	"errors"
	"fmt"
	"path/filepath"
)

// ErrItemNotFound means no item matched.
var ErrItemNotFound = errors.New("media: item not found")

// Item is one media item plus the root of its library.
type Item struct {
	ID        int64
	LibraryID int64
	Kind      string
	Path      string // path relative to the library root
	Title     string
	Year      int
	Missing   bool

	// RootPath is the absolute library root, so AbsPath can be computed.
	RootPath string
}

// AbsPath returns the absolute filesystem path of the item's file.
//
// item.path is stored relative to the library root and the root is stored
// resolved, so this join cannot escape the library.
func (i Item) AbsPath() string {
	return filepath.Join(i.RootPath, filepath.FromSlash(i.Path))
}

// LoadItem loads an item and its library root.
func LoadItem(ctx context.Context, db *sql.DB, id int64) (Item, error) {
	var it Item
	err := db.QueryRowContext(ctx, `
		SELECT i.id, i.library_id, i.kind, i.path, i.title, COALESCE(i.year, 0), i.missing, l.root_path
		FROM media_items i
		JOIN libraries l ON l.id = i.library_id
		WHERE i.id = ?`, id,
	).Scan(&it.ID, &it.LibraryID, &it.Kind, &it.Path, &it.Title, &it.Year, &it.Missing, &it.RootPath)
	if errors.Is(err, sql.ErrNoRows) {
		return Item{}, ErrItemNotFound
	}
	if err != nil {
		return Item{}, fmt.Errorf("media: load item: %w", err)
	}
	return it, nil
}

// FileEntry is one physical file backing an item.
type FileEntry struct {
	ID        int64  `json:"id"`
	Path      string `json:"path"`
	Size      int64  `json:"size"`
	Container string `json:"container"`
	Missing   bool   `json:"missing"`
}

// FileCount returns how many files back an item.
func FileCount(ctx context.Context, db *sql.DB, itemID int64) (int, error) {
	var n int
	err := db.QueryRowContext(ctx, `SELECT count(*) FROM media_files WHERE item_id = ?`, itemID).Scan(&n)
	return n, err
}