using System;
using System.Collections.Generic;
using System.Linq;
using NLog;
using NzbDrone.Common.Messaging;
using NzbDrone.Core.Lifecycle;


namespace NzbDrone.Core.Indexers
{

    public class Indexer
    {
        public int DefinitionId { get; set; }
        public string Name { get; set; }
        public bool Enable { get; set; }
        public IIndexerSetting Settings { get; set; }
        public IIndexer Instance { get; set; }
    }

    public interface IIndexerService
    {
        List<Indexer> All();
        List<IIndexer> GetAvailableIndexers();
        Indexer Get(string name);
    }

    public class IndexerService : IIndexerService, IHandle<ApplicationStartedEvent>
    {
        private readonly IIndexerRepository _indexerRepository;
        private readonly Logger _logger;

        private readonly IList<IIndexer> _indexers;

        public IndexerService(IIndexerRepository indexerRepository, IEnumerable<IIndexer> indexers, Logger logger)
        {
            _indexerRepository = indexerRepository;
            _logger = logger;
            _indexers = indexers.ToList();
        }


        public List<Indexer> All()
        {
            return _indexerRepository.All().Select(ToIndexer).ToList();
        }

        public List<IIndexer> GetAvailableIndexers()
        {
            return All().Where(c => c.Enable && c.Settings.IsValid).Select(c=>c.Instance).ToList();
        }


        public Indexer Get(string name)
        {
            return ToIndexer(_indexerRepository.Get(name));
        }


        private Indexer ToIndexer(IndexerDefinition definition)
        {
            var indexer = new Indexer();
            indexer.DefinitionId = definition.Id;
            indexer.Enable = definition.Enable;
            indexer.Instance = GetInstance(definition);
            indexer.Name = definition.Name;

            if (indexer.Instance.GetType().GetMethod("ImportSettingsFromJson") != null)
            {
                indexer.Settings = ((dynamic)indexer.Instance).ImportSettingsFromJson(definition.Settings);
            }
            else
            {
                indexer.Settings = NullSetting.Instance;
            }


            return indexer;
        }

        private IIndexer GetInstance(IndexerDefinition indexerDefinition)
        {
            var existingInstance = _indexers.Single(c => c.GetType().Name.Equals(indexerDefinition.Implementation, StringComparison.CurrentCultureIgnoreCase));
            var instance = (IIndexer)Activator.CreateInstance(existingInstance.GetType());
            instance.InstanceDefinition = indexerDefinition;

            return instance;
        }

        public void Handle(ApplicationStartedEvent message)
        {
            _logger.Debug("Initializing indexers. Count {0}", _indexers.Count);

            if (!All().Any())
            {
                var definitions = _indexers.SelectMany(delegate(IIndexer indexer)
                    {
                        return indexer.DefaultDefinitions;
                    });

                _indexerRepository.InsertMany(definitions.ToList());
            }
        }
    }
}