namespace Jellyfin.Plugin.Webdav
{
    using System.IO;
    using MediaBrowser.Controller;
    using System.Linq;
    using System.Threading;
    using System.Threading.Tasks;
    using Jellyfin.Plugin.Webdav.Configuration;
    using MediaBrowser.Controller.Library;
    using System.Collections.Generic;
    using Microsoft.Extensions.Hosting;
    using MediaBrowser.Model.Configuration;

    /// <summary>
    /// Hosted service that synchronizes WebDAV content into the local cache directory
    /// and registers it as a Jellyfin virtual folder.
    /// </summary>
    public sealed class WebDavSyncService : IHostedService
    {
        private readonly WebDavClientService client;
        private readonly PluginConfiguration config;
        private readonly IServerApplicationPaths appPaths;
        private readonly ILibraryManager libraryManager;

        /// <summary>
        /// Initializes a new instance of the <see cref="WebDavSyncService"/> class.
        /// </summary>
        /// <param name="client">The WebDAV client service.</param>
        /// <param name="config">The plugin configuration.</param>
        /// <param name="appPaths">Server application paths.</param>
        /// <param name="libraryManager">Library manager.</param>
        public WebDavSyncService(
            WebDavClientService client,
            PluginConfiguration config,
            IServerApplicationPaths appPaths,
            ILibraryManager libraryManager)
        {
            this.client = client;
            this.config = config;
            this.appPaths = appPaths;
            this.libraryManager = libraryManager;
        }

        /// <inheritdoc/>
        public async Task StartAsync(CancellationToken cancellationToken)
        {
            // Determine cache root: either configured directory or default user views path
            var baseCache = string.IsNullOrWhiteSpace(config.CacheDirectory)
                ? appPaths.DefaultUserViewsPath
                : config.CacheDirectory;
            var localRoot = Path.Combine(baseCache, "WebDAV");
            if (!Directory.Exists(localRoot))
            {
                Directory.CreateDirectory(localRoot);
            }

            await SyncDirectoryAsync(config.RootPath.Trim('/'), localRoot, cancellationToken)
                .ConfigureAwait(false);

            var options = new LibraryOptions();
            await libraryManager
                .AddVirtualFolder("WebDAV", null, options, true)
                .ConfigureAwait(false);
            libraryManager.AddMediaPath("WebDAV", new MediaPathInfo { Path = localRoot });
        }

        private async Task SyncDirectoryAsync(string remotePath, string localPath, CancellationToken token)
        {
            var resources = await client.ListAsync(remotePath).ConfigureAwait(false);
            foreach (var item in resources.Where(r => !string.IsNullOrEmpty(r.DisplayName)))
            {
                if (token.IsCancellationRequested)
                {
                    break;
                }

                var name = item.DisplayName!;
                var remoteItem = $"{remotePath}/{name}";
                var localItem = Path.Combine(localPath, name);

                if (item.IsCollection)
                {
                    if (!Directory.Exists(localItem))
                    {
                        Directory.CreateDirectory(localItem);
                    }
                    await SyncDirectoryAsync(remoteItem, localItem, token).ConfigureAwait(false);
                }
                else
                {
                    using var stream = await client.GetStreamAsync(remoteItem).ConfigureAwait(false);
                    using var fs = File.Create(localItem);
                    await stream.CopyToAsync(fs, token).ConfigureAwait(false);
                }
            }
        }

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