using System;
using System.IO;
using System.Linq;
using System.Threading;
using System.Threading.Tasks;
using Microsoft.Extensions.Hosting;
using MediaBrowser.Controller.Library;
using MediaBrowser.Controller.Plugins;

namespace Jellyfin.Plugin.Webdav
{
    /// <summary>
    /// Hosted service that synchronizes WebDAV content into a local cache directory
    /// and registers it as a Jellyfin virtual folder.
    /// </summary>
    public class WebDavSyncService : IHostedService
    {
        private readonly WebDavClientService _client;
        private readonly PluginConfiguration _config;
        private readonly ILibraryManager _libraryManager;
        private readonly IServerApplicationHost _appHost;

        public WebDavSyncService(WebDavClientService client, PluginConfiguration config, ILibraryManager libraryManager, IServerApplicationHost appHost)
        {
            _client = client;
            _config = config;
            _libraryManager = libraryManager;
            _appHost = appHost;
        }

        public async Task StartAsync(CancellationToken cancellationToken)
        {
            // Compute local root under DefaultUserViewsPath
            var localRoot = Path.Combine(_appHost.ApplicationPaths.DefaultUserViewsPath, "WebDAV");
            Directory.CreateDirectory(localRoot);

            // Sync directories recursively
            await SyncDirectory(_config.RootPath, localRoot, cancellationToken).ConfigureAwait(false);

            // Register the virtual folder pointing to the synced cache
            var options = new LibraryOptions();
            await _libraryManager.AddVirtualFolder("WebDAV", null, options, true).ConfigureAwait(false);
        }

        private async Task SyncDirectory(string remotePath, string localPath, CancellationToken cancellationToken)
        {
            var resources = await _client.ListAsync(remotePath).ConfigureAwait(false);
            foreach (var res in resources.Where(r => r.DisplayName != null))
            {
                if (cancellationToken.IsCancellationRequested)
                {
                    break;
                }

                var name = res.DisplayName;
                var remoteSub = $"{remotePath.TrimEnd('/')}/{name}";
                var localSub = Path.Combine(localPath, name);

                if (res.IsCollection)
                {
                    Directory.CreateDirectory(localSub);
                    await SyncDirectory(remoteSub, localSub, cancellationToken).ConfigureAwait(false);
                }
                else
                {
                    using var stream = await _client.GetStreamAsync(remoteSub).ConfigureAwait(false);
                    using var fs = File.Create(localSub);
                    await stream.CopyToAsync(fs, cancellationToken).ConfigureAwait(false);
                }
            }
        }

        public Task StopAsync(CancellationToken cancellationToken) => Task.CompletedTask;
    }
}