using System;
using System.Collections.Generic;
using System.Linq;
using System.Xml.Linq;
using NzbDrone.Common.Extensions;
using NzbDrone.Core.Indexers.Exceptions;
using NzbDrone.Core.Parser.Model;
using NzbDrone.Core.ThingiProvider;

namespace NzbDrone.Core.Indexers.Newznab
{
    public class NewznabRssParser : RssParser
    {
        public const string ns = "{http://www.newznab.com/DTD/2010/feeds/attributes/}";

        private readonly NewznabSettings _settings;
        private readonly ProviderDefinition _definition;
        private readonly INewznabCapabilitiesProvider _capabilitiesProvider;

        public NewznabRssParser(NewznabSettings settings, ProviderDefinition definition, INewznabCapabilitiesProvider capabilitiesProvider)
        {
            PreferredEnclosureMimeTypes = UsenetEnclosureMimeTypes;
            UseEnclosureUrl = true;
            _settings = settings;
            _definition = definition;
            _capabilitiesProvider = capabilitiesProvider;
        }

        public static void CheckError(XDocument xdoc, IndexerResponse indexerResponse)
        {
            var error = xdoc.Descendants("error").FirstOrDefault();

            if (error == null)
            {
                return;
            }

            var code = Convert.ToInt32(error.Attribute("code").Value);
            var errorMessage = error.Attribute("description").Value;

            if (code >= 100 && code <= 199)
            {
                throw new IndexerAuthException(errorMessage);
            }

            if (!indexerResponse.Request.Url.FullUri.Contains("apikey=") && (errorMessage == "Missing parameter" || errorMessage.Contains("apikey")))
            {
                throw new IndexerAuthException("Indexer requires an API key");
            }

            if (errorMessage == "Request limit reached")
            {
                throw new RequestLimitReachedException(indexerResponse, "API limit reached");
            }

            throw new NewznabException(indexerResponse, errorMessage);
        }

        protected override bool PreProcess(IndexerResponse indexerResponse)
        {
            var xdoc = LoadXmlDocument(indexerResponse);

            CheckError(xdoc, indexerResponse);

            return true;
        }

        protected override bool PostProcess(IndexerResponse indexerResponse, List<XElement> items, List<ReleaseInfo> releases)
        {
            var enclosureTypes = items.SelectMany(GetEnclosures).Select(v => v.Type).Distinct().ToArray();
            if (enclosureTypes.Any() && enclosureTypes.Intersect(PreferredEnclosureMimeTypes).Empty())
            {
                if (enclosureTypes.Intersect(TorrentEnclosureMimeTypes).Any())
                {
                    _logger.Warn("Feed does not contain {0}, found {1}, did you intend to add a Torznab indexer?", NzbEnclosureMimeType, enclosureTypes[0]);
                }
                else
                {
                    _logger.Warn("Feed does not contain {0}, found {1}.", NzbEnclosureMimeType, enclosureTypes[0]);
                }
            }

            return true;
        }

        protected override ReleaseInfo ProcessItem(XElement item, ReleaseInfo releaseInfo)
        {
            if (!item.Elements("enclosure").Any(e =>
            {
                var type = e.Attribute("type");
                if (type == null)
                {
                    return true;
                }

                return type.Value == "application/x-nzb";
            }))
            {
                return null;
            }

            releaseInfo = base.ProcessItem(item, releaseInfo);
            releaseInfo.ImdbId = GetIntAttribute(item, "imdb");
            releaseInfo.TmdbId = GetIntAttribute(item, "tmdbid");
            releaseInfo.TvdbId = GetIntAttribute(item, "tvdbid");
            releaseInfo.TvRageId = GetIntAttribute(item, "rageid");
            releaseInfo.Grabs = GetIntAttribute(item, "grabs");
            releaseInfo.Files = GetIntAttribute(item, "files");
            releaseInfo.PosterUrl = GetPosterUrl(item);

            return releaseInfo;
        }

        protected override string GetInfoUrl(XElement item)
        {
            return ParseUrl(item.TryGetValue("comments").TrimEnd("#comments"));
        }

        protected override string GetCommentUrl(XElement item)
        {
            return ParseUrl(item.TryGetValue("comments"));
        }

        protected override ICollection<IndexerCategory> GetCategory(XElement item)
        {
            var capabilities = _capabilitiesProvider.GetCapabilities(_settings, _definition);
            var cats = TryGetMultipleNewznabAttributes(item, "category");
            var results = new List<IndexerCategory>();

            // Try to find <category> elements for some indexers that suck at following the rules.
            if (cats.Count == 0)
            {
                cats = item.Elements("category").Select(e => e.Value).ToList();
            }

            foreach (var cat in cats)
            {
                var indexerCat = capabilities.Categories.MapTrackerCatToNewznab(cat);

                if (indexerCat != null)
                {
                    results.AddRange(indexerCat);
                }
            }

            return results;
        }

        protected override long GetSize(XElement item)
        {
            long size;

            var sizeString = TryGetNewznabAttribute(item, "size");
            if (!sizeString.IsNullOrWhiteSpace() && long.TryParse(sizeString, out size))
            {
                return size;
            }

            size = GetEnclosureLength(item);

            return size;
        }

        protected override DateTime GetPublishDate(XElement item)
        {
            var dateString = TryGetNewznabAttribute(item, "usenetdate");
            if (!dateString.IsNullOrWhiteSpace())
            {
                return XElementExtensions.ParseDate(dateString);
            }

            return base.GetPublishDate(item);
        }

        protected override string GetDownloadUrl(XElement item)
        {
            var url = base.GetDownloadUrl(item);

            if (!Uri.IsWellFormedUriString(url, UriKind.Absolute))
            {
                var enclosure = item.Elements("enclosure");
                var filtered = enclosure.Where(e =>
                {
                    var type = e.Attribute("type");
                    if (type == null)
                    {
                        return true;
                    }

                    return type.Value == "application/x-nzb";
                });

                var xElements = filtered as XElement[] ?? filtered.ToArray();
                if (!xElements.Any())
                {
                    return url;
                }

                var attr = xElements.First().Attribute("url");
                if (attr != null)
                {
                    url = attr.Value;
                }
            }

            return url;
        }

        protected virtual int GetIntAttribute(XElement item, string attribute)
        {
            var idString = TryGetNewznabAttribute(item, attribute);
            int idInt;

            if (!idString.IsNullOrWhiteSpace() && int.TryParse(idString, out idInt))
            {
                return idInt;
            }

            return 0;
        }

        protected virtual string GetPosterUrl(XElement item)
        {
            return ParseUrl(TryGetNewznabAttribute(item, "coverurl"));
        }

        protected virtual int GetImdbYear(XElement item)
        {
            var imdbYearString = TryGetNewznabAttribute(item, "imdbyear");
            int imdbYear;

            if (!imdbYearString.IsNullOrWhiteSpace() && int.TryParse(imdbYearString, out imdbYear))
            {
                return imdbYear;
            }

            return 1900;
        }

        protected string TryGetNewznabAttribute(XElement item, string key, string defaultValue = "")
        {
            var attrElement = item.Elements(ns + "attr").FirstOrDefault(e => e.Attribute("name").Value.Equals(key, StringComparison.OrdinalIgnoreCase));
            if (attrElement != null)
            {
                var attrValue = attrElement.Attribute("value");
                if (attrValue != null)
                {
                    return attrValue.Value;
                }
            }

            return defaultValue;
        }

        protected List<string> TryGetMultipleNewznabAttributes(XElement item, string key)
        {
            var attrElements = item.Elements(ns + "attr").Where(e => e.Attribute("name").Value.Equals(key, StringComparison.OrdinalIgnoreCase));
            var results = new List<string>();

            foreach (var element in attrElements)
            {
                var attrValue = element.Attribute("value");
                if (attrValue != null)
                {
                    results.Add(attrValue.Value);
                }
            }

            return results;
        }
    }
}