using MediaBrowser.Common.IO;
using MediaBrowser.Common.Net;
using MediaBrowser.Controller.Configuration;
using MediaBrowser.Controller.Entities;
using MediaBrowser.Controller.Entities.Audio;
using MediaBrowser.Controller.Library;
using MediaBrowser.Controller.Providers;
using MediaBrowser.Model.Entities;
using MediaBrowser.Model.Logging;
using System;
using System.IO;
using System.Text;
using System.Threading;
using System.Threading.Tasks;
using System.Xml;

namespace MediaBrowser.Providers.Music
{
    /// <summary>
    /// Class FanArtAlbumProvider
    /// </summary>
    public class FanArtAlbumProvider : FanartBaseProvider
    {
        /// <summary>
        /// The _provider manager
        /// </summary>
        private readonly IProviderManager _providerManager;

        /// <summary>
        /// The _music brainz resource pool
        /// </summary>
        private readonly SemaphoreSlim _musicBrainzResourcePool = new SemaphoreSlim(1, 1);

        /// <summary>
        /// Gets the HTTP client.
        /// </summary>
        /// <value>The HTTP client.</value>
        protected IHttpClient HttpClient { get; private set; }

        internal static FanArtAlbumProvider Current { get; private set; }
        private readonly IFileSystem _fileSystem;

        /// <summary>
        /// Initializes a new instance of the <see cref="FanArtAlbumProvider"/> class.
        /// </summary>
        /// <param name="httpClient">The HTTP client.</param>
        /// <param name="logManager">The log manager.</param>
        /// <param name="configurationManager">The configuration manager.</param>
        /// <param name="providerManager">The provider manager.</param>
        public FanArtAlbumProvider(IHttpClient httpClient, ILogManager logManager, IServerConfigurationManager configurationManager, IProviderManager providerManager, IFileSystem fileSystem)
            : base(logManager, configurationManager)
        {
            _providerManager = providerManager;
            _fileSystem = fileSystem;
            HttpClient = httpClient;

            Current = this;
        }

        /// <summary>
        /// Gets the priority.
        /// </summary>
        /// <value>The priority.</value>
        public override MetadataProviderPriority Priority
        {
            get { return MetadataProviderPriority.Fourth; }
        }

        /// <summary>
        /// Supportses the specified item.
        /// </summary>
        /// <param name="item">The item.</param>
        /// <returns><c>true</c> if XXXX, <c>false</c> otherwise</returns>
        public override bool Supports(BaseItem item)
        {
            return item is MusicAlbum;
        }

        public override ItemUpdateType ItemUpdateType
        {
            get
            {
                return ItemUpdateType.ImageUpdate;
            }
        }
        
        /// <summary>
        /// Gets a value indicating whether [refresh on version change].
        /// </summary>
        /// <value><c>true</c> if [refresh on version change]; otherwise, <c>false</c>.</value>
        protected override bool RefreshOnVersionChange
        {
            get
            {
                return true;
            }
        }

        /// <summary>
        /// Gets the provider version.
        /// </summary>
        /// <value>The provider version.</value>
        protected override string ProviderVersion
        {
            get
            {
                return "17";
            }
        }

        /// <summary>
        /// Needses the refresh internal.
        /// </summary>
        /// <param name="item">The item.</param>
        /// <param name="providerInfo">The provider info.</param>
        /// <returns><c>true</c> if XXXX, <c>false</c> otherwise</returns>
        protected override bool NeedsRefreshInternal(BaseItem item, BaseProviderInfo providerInfo)
        {
            if (string.IsNullOrEmpty(item.GetProviderId(MetadataProviders.Musicbrainz)))
            {
                return false;
            }

            if (!ConfigurationManager.Configuration.DownloadMusicAlbumImages.Disc &&
                !ConfigurationManager.Configuration.DownloadMusicAlbumImages.Primary)
            {
                return false;
            }

            return base.NeedsRefreshInternal(item, providerInfo);
        }

        protected override DateTime CompareDate(BaseItem item)
        {
            var artistMusicBrainzId = item.Parent.GetProviderId(MetadataProviders.Musicbrainz);

            if (!string.IsNullOrEmpty(artistMusicBrainzId))
            {
                var artistXmlPath = FanArtArtistProvider.GetArtistDataPath(ConfigurationManager.CommonApplicationPaths, artistMusicBrainzId);
                artistXmlPath = Path.Combine(artistXmlPath, "fanart.xml");

                var file = new FileInfo(artistXmlPath);

                if (file.Exists)
                {
                    return _fileSystem.GetLastWriteTimeUtc(file);
                }
            } 
            
            return base.CompareDate(item);
        }

        /// <summary>
        /// Fetches metadata and returns true or false indicating if any work that requires persistence was done
        /// </summary>
        /// <param name="item">The item.</param>
        /// <param name="force">if set to <c>true</c> [force].</param>
        /// <param name="cancellationToken">The cancellation token.</param>
        /// <returns>Task{System.Boolean}.</returns>
        public override async Task<bool> FetchAsync(BaseItem item, bool force, CancellationToken cancellationToken)
        {
            cancellationToken.ThrowIfCancellationRequested();

            var artistMusicBrainzId = item.Parent.GetProviderId(MetadataProviders.Musicbrainz);

            BaseProviderInfo data;

            if (!item.ProviderData.TryGetValue(Id, out data))
            {
                data = new BaseProviderInfo();
                item.ProviderData[Id] = data;
            }

            if (!string.IsNullOrEmpty(artistMusicBrainzId))
            {
                var artistXmlPath = FanArtArtistProvider.GetArtistDataPath(ConfigurationManager.CommonApplicationPaths, artistMusicBrainzId);
                artistXmlPath = Path.Combine(artistXmlPath, "fanart.xml");

                var artistXmlFileInfo = new FileInfo(artistXmlPath);

                if (artistXmlFileInfo.Exists)
                {
                    var album = (MusicAlbum)item;

                    var releaseEntryId = item.GetProviderId(MetadataProviders.Musicbrainz);

                    var musicBrainzReleaseGroupId = album.GetProviderId(MetadataProviders.MusicBrainzReleaseGroup);
                    // Fanart uses the release group id so we'll have to get that now using the release entry id
                    if (string.IsNullOrEmpty(musicBrainzReleaseGroupId))
                    {
                        musicBrainzReleaseGroupId = await GetReleaseGroupId(releaseEntryId, cancellationToken).ConfigureAwait(false);

                        album.SetProviderId(MetadataProviders.MusicBrainzReleaseGroup, musicBrainzReleaseGroupId);
                    }

                    var doc = new XmlDocument();

                    doc.Load(artistXmlPath);

                    cancellationToken.ThrowIfCancellationRequested();

                    if (ConfigurationManager.Configuration.DownloadMusicAlbumImages.Disc && !item.HasImage(ImageType.Disc))
                    {
                        // Try try with the release entry Id, if that doesn't produce anything try the release group id
                        var node = doc.SelectSingleNode("//fanart/music/albums/album[@id=\"" + releaseEntryId + "\"]/cdart/@url");

                        if (node == null && !string.IsNullOrEmpty(musicBrainzReleaseGroupId))
                        {
                            node = doc.SelectSingleNode("//fanart/music/albums/album[@id=\"" + musicBrainzReleaseGroupId + "\"]/cdart/@url");
                        }

                        var path = node != null ? node.Value : null;

                        if (!string.IsNullOrEmpty(path))
                        {
                            await _providerManager.SaveImage(item, path, FanArtResourcePool, ImageType.Disc, null, cancellationToken)
                                .ConfigureAwait(false);
                        }
                    }

                    if (ConfigurationManager.Configuration.DownloadMusicAlbumImages.Primary && !item.HasImage(ImageType.Primary))
                    {
                        // Try try with the release entry Id, if that doesn't produce anything try the release group id
                        var node = doc.SelectSingleNode("//fanart/music/albums/album[@id=\"" + releaseEntryId + "\"]/albumcover/@url");

                        if (node == null && !string.IsNullOrEmpty(musicBrainzReleaseGroupId))
                        {
                            node = doc.SelectSingleNode("//fanart/music/albums/album[@id=\"" + musicBrainzReleaseGroupId + "\"]/albumcover/@url");
                        }

                        var path = node != null ? node.Value : null;

                        if (!string.IsNullOrEmpty(path))
                        {
                            await _providerManager.SaveImage(item, path, FanArtResourcePool, ImageType.Primary, null, cancellationToken)
                                .ConfigureAwait(false);
                        }
                    }
                }

            }

            SetLastRefreshed(item, DateTime.UtcNow);

            return true;
        }

        /// <summary>
        /// The _last music brainz request
        /// </summary>
        private DateTime _lastRequestDate = DateTime.MinValue;

        /// <summary>
        /// Gets the music brainz response.
        /// </summary>
        /// <param name="url">The URL.</param>
        /// <param name="cancellationToken">The cancellation token.</param>
        /// <returns>Task{XmlDocument}.</returns>
        internal async Task<XmlDocument> GetMusicBrainzResponse(string url, CancellationToken cancellationToken)
        {
            await _musicBrainzResourcePool.WaitAsync(cancellationToken).ConfigureAwait(false);

            try
            {
                var diff = 1500 - (DateTime.Now - _lastRequestDate).TotalMilliseconds;

                // MusicBrainz is extremely adamant about limiting to one request per second

                if (diff > 0)
                {
                    await Task.Delay(Convert.ToInt32(diff), cancellationToken).ConfigureAwait(false);
                }

                _lastRequestDate = DateTime.Now;

                var doc = new XmlDocument();

                using (var xml = await HttpClient.Get(new HttpRequestOptions
                {
                    Url = url,
                    CancellationToken = cancellationToken,
                    UserAgent = Environment.MachineName

                }).ConfigureAwait(false))
                {
                    using (var oReader = new StreamReader(xml, Encoding.UTF8))
                    {
                        doc.Load(oReader);
                    }
                }

                return doc;
            }
            finally
            {
                _lastRequestDate = DateTime.Now;

                _musicBrainzResourcePool.Release();
            }
        }

        /// <summary>
        /// Gets the release group id internal.
        /// </summary>
        /// <param name="releaseEntryId">The release entry id.</param>
        /// <param name="cancellationToken">The cancellation token.</param>
        /// <returns>Task{System.String}.</returns>
        private async Task<string> GetReleaseGroupId(string releaseEntryId, CancellationToken cancellationToken)
        {
            var url = string.Format("http://www.musicbrainz.org/ws/2/release-group/?query=reid:{0}", releaseEntryId);

            var doc = await GetMusicBrainzResponse(url, cancellationToken).ConfigureAwait(false);

            var ns = new XmlNamespaceManager(doc.NameTable);
            ns.AddNamespace("mb", "http://musicbrainz.org/ns/mmd-2.0#");
            var node = doc.SelectSingleNode("//mb:release-group-list/mb:release-group/@id", ns);

            return node != null ? node.Value : null;
        }
    }
}