using System;
using System.Collections.Generic;
using System.Linq;
using NLog;
using NzbDrone.Common.Extensions;
using NzbDrone.Common.Instrumentation.Extensions;
using NzbDrone.Common.Serializer;
using NzbDrone.Core.IndexerSearch.Definitions;
using NzbDrone.Core.Parser;
using NzbDrone.Core.Parser.Model;

namespace NzbDrone.Core.DecisionEngine
{
    public interface IMakeDownloadDecision
    {
        List<DownloadDecision> GetRssDecision(List<ReleaseInfo> reports);
        List<DownloadDecision> GetSearchDecision(List<ReleaseInfo> reports, SearchCriteriaBase searchCriteriaBase);
    }

    public class DownloadDecisionMaker : IMakeDownloadDecision
    {
        private readonly IEnumerable<IDecisionEngineSpecification> _specifications;
        private readonly IParsingService _parsingService;
        private readonly Logger _logger;

        public DownloadDecisionMaker(IEnumerable<IDecisionEngineSpecification> specifications, IParsingService parsingService, Logger logger)
        {
            _specifications = specifications;
            _parsingService = parsingService;
            _logger = logger;
        }

        public List<DownloadDecision> GetRssDecision(List<ReleaseInfo> reports)
        {
            return GetAlbumDecisions(reports).ToList();
        }

        public List<DownloadDecision> GetSearchDecision(List<ReleaseInfo> reports, SearchCriteriaBase searchCriteriaBase)
        {
            return GetAlbumDecisions(reports, searchCriteriaBase).ToList();
        }

        private IEnumerable<DownloadDecision> GetAlbumDecisions(List<ReleaseInfo> reports, SearchCriteriaBase searchCriteria = null)
        {
            if (reports.Any())
            {
                _logger.ProgressInfo("Processing {0} releases", reports.Count);
            }
            else
            {
                _logger.ProgressInfo("No results found");
            }

            var reportNumber = 1;

            foreach (var report in reports)
            {
                DownloadDecision decision = null;
                _logger.ProgressTrace("Processing release {0}/{1}", reportNumber, reports.Count);

                try
                {
                    var parsedAlbumInfo = Parser.Parser.ParseAlbumTitle(report.Title);

                    if (!report.Artist.IsNullOrWhiteSpace())
                    {
                        parsedAlbumInfo.ArtistName = report.Artist;
                    }

                    if (!report.Album.IsNullOrWhiteSpace())
                    {
                        parsedAlbumInfo.AlbumTitle = report.Album;
                    }

                    if (parsedAlbumInfo != null && !parsedAlbumInfo.ArtistName.IsNullOrWhiteSpace())
                    {
                        var remoteAlbum = _parsingService.Map(parsedAlbumInfo, searchCriteria);
                        remoteAlbum.Release = report;

                        if (remoteAlbum.Artist == null)
                        {
                            decision = new DownloadDecision(remoteAlbum, new Rejection("Unknown Artist"));
                        }
                        else if (remoteAlbum.Albums.Empty())
                        {
                            decision = new DownloadDecision(remoteAlbum, new Rejection("Unable to parse albums from release name"));
                        }
                        else
                        {
                            remoteAlbum.DownloadAllowed = remoteAlbum.Albums.Any();
                            decision = GetDecisionForReport(remoteAlbum, searchCriteria);
                        }
                    }
                }
                catch (Exception e)
                {
                    _logger.Error(e, "Couldn't process release.");

                    var remoteAlbum = new RemoteAlbum { Release = report };
                    decision = new DownloadDecision(remoteAlbum, new Rejection("Unexpected error processing release"));
                }

                reportNumber++;

                if (decision != null)
                {
                    if (decision.Rejections.Any())
                    {
                        _logger.Debug("Release rejected for the following reasons: {0}", string.Join(", ", decision.Rejections));
                    }

                    else
                    {
                        _logger.Debug("Release accepted");
                    }

                    yield return decision;
                }
            }
        }

        private DownloadDecision GetDecisionForReport(RemoteAlbum remoteAlbum, SearchCriteriaBase searchCriteria = null)
        {
            var reasons = new Rejection[0];

            foreach (var specifications in _specifications.GroupBy(v => v.Priority).OrderBy(v => v.Key))
            {
                reasons = specifications.Select(c => EvaluateSpec(c, remoteAlbum, searchCriteria))
                                                        .Where(c => c != null)
                                                        .ToArray();

                if (reasons.Any()) break;
            }
            return new DownloadDecision(remoteAlbum, reasons.ToArray());
        }

        private Rejection EvaluateSpec(IDecisionEngineSpecification spec, RemoteAlbum remoteAlbum, SearchCriteriaBase searchCriteriaBase = null)
        {
            try
            {
                var result = spec.IsSatisfiedBy(remoteAlbum, searchCriteriaBase);

                if (!result.Accepted)
                {
                    return new Rejection(result.Reason, spec.Type);
                }
            }
            catch (NotImplementedException e)
            {
                _logger.Trace("Spec " + spec.GetType().Name + " not implemented.");
            }
            catch (Exception e)
            {
                e.Data.Add("report", remoteAlbum.Release.ToJson());
                e.Data.Add("parsed", remoteAlbum.ParsedAlbumInfo.ToJson());
                _logger.Error(e, "Couldn't evaluate decision on {0}", remoteAlbum.Release.Title);
                return new Rejection($"{spec.GetType().Name}: {e.Message}");
            }

            return null;
        }
    }
}
