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(SmartPlaylistDto smartPlaylist);
    }

    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);
            var dto = (await JsonSerializer.DeserializeAsync<SmartPlaylistDto>(r).ConfigureAwait(false));
            if (dto == null) {
                throw new ApplicationException("");
            }
            dto.Filename = filename;
            return dto;
        }
        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);
        }
        private void DeleteSmartPlaylistById(SmartPlaylistId smartPlaylistId) {
            try {
                string filename = _fileSystem.FindSmartPlaylistFilePath(smartPlaylistId);
                if (File.Exists(filename)) { File.Delete(filename); }
            } catch (System.InvalidOperationException) {}
        }
        public void DeleteSmartPlaylist(SmartPlaylistDto smartPlaylist) {
            if (File.Exists(smartPlaylist.Filename)) { File.Delete(smartPlaylist.Filename); }
            DeleteSmartPlaylistById(smartPlaylist.Id);
        }
    }
}