using System.Text.Json;

namespace Jellyfin.Plugin.SmartPlaylist {
    public interface IStore {
        Task<SmartPlaylistDto?> GetSmartPlaylistAsync(SmartPlaylistId smartPlaylistId);
        Task<SmartPlaylistDto[]> GetAllSmartPlaylistsAsync();
        Task SaveSmartPlaylistAsync(SmartPlaylistDto smartPlaylist);
        void DeleteSmartPlaylist(SmartPlaylistId smartPlaylistId);
    }

    public class Store : IStore {
        private readonly ISmartPlaylistFileSystem _fileSystem;
        public Store(ISmartPlaylistFileSystem fileSystem) {
            _fileSystem = fileSystem;
        }
        private async Task<SmartPlaylistDto?> LoadPlaylistAsync(string filename) {
            await using var r = File.OpenRead(filename);
            return await JsonSerializer.DeserializeAsync<SmartPlaylistDto>(r).ConfigureAwait(false);
        }
        public async Task<SmartPlaylistDto?> GetSmartPlaylistAsync(SmartPlaylistId smartPlaylistId) {
            string filename = _fileSystem.FindSmartPlaylistFilePath(smartPlaylistId);
            return await LoadPlaylistAsync(filename).ConfigureAwait(false);
        }
        public async Task<SmartPlaylistDto[]> GetAllSmartPlaylistsAsync() {
            var t = _fileSystem.FindAllSmartPlaylistFilePaths().Select(LoadPlaylistAsync).ToArray();
            await Task.WhenAll(t).ConfigureAwait(false);
            return t.Where(x => x != null).Select(x => x.Result).ToArray();
        }
        public async Task SaveSmartPlaylistAsync(SmartPlaylistDto smartPlaylist) {
            string filename = _fileSystem.GetSmartPlaylistFilePath(smartPlaylist.Id);
            await using var w = File.Create(filename);
            await JsonSerializer.SerializeAsync(w, smartPlaylist).ConfigureAwait(false);
        }
        public void DeleteSmartPlaylist(SmartPlaylistId smartPlaylistId) {
            string filename = _fileSystem.FindSmartPlaylistFilePath(smartPlaylistId);
            if (File.Exists(filename)) { File.Delete(filename); }
        }
    }
}