using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
using NLog;
using NzbDrone.Common.Extensions;
using NzbDrone.Common.Instrumentation.Extensions;
using NzbDrone.Common.TPL;
using NzbDrone.Core.Books;
using NzbDrone.Core.DecisionEngine;
using NzbDrone.Core.Indexers;
using NzbDrone.Core.IndexerSearch.Definitions;
using NzbDrone.Core.Parser.Model;

namespace NzbDrone.Core.IndexerSearch
{
    public interface ISearchForReleases
    {
        List<DownloadDecision> BookSearch(int bookId, bool missingOnly, bool userInvokedSearch, bool interactiveSearch);
        List<DownloadDecision> AuthorSearch(int authorId, bool missingOnly, bool userInvokedSearch, bool interactiveSearch);
    }

    public class ReleaseSearchService : ISearchForReleases
    {
        private readonly IIndexerFactory _indexerFactory;
        private readonly IBookService _bookService;
        private readonly IAuthorService _authorService;
        private readonly IMakeDownloadDecision _makeDownloadDecision;
        private readonly Logger _logger;

        public ReleaseSearchService(IIndexerFactory indexerFactory,
                                IBookService bookService,
                                IAuthorService authorService,
                                IMakeDownloadDecision makeDownloadDecision,
                                Logger logger)
        {
            _indexerFactory = indexerFactory;
            _bookService = bookService;
            _authorService = authorService;
            _makeDownloadDecision = makeDownloadDecision;
            _logger = logger;
        }

        public List<DownloadDecision> BookSearch(int bookId, bool missingOnly, bool userInvokedSearch, bool interactiveSearch)
        {
            var book = _bookService.GetBook(bookId);
            return BookSearch(book, missingOnly, userInvokedSearch, interactiveSearch);
        }

        public List<DownloadDecision> AuthorSearch(int authorId, bool missingOnly, bool userInvokedSearch, bool interactiveSearch)
        {
            var author = _authorService.GetAuthor(authorId);
            return AuthorSearch(author, missingOnly, userInvokedSearch, interactiveSearch);
        }

        public List<DownloadDecision> AuthorSearch(Author author, bool missingOnly, bool userInvokedSearch, bool interactiveSearch)
        {
            var searchSpec = Get<AuthorSearchCriteria>(author, userInvokedSearch, interactiveSearch);
            var books = _bookService.GetBooksByAuthor(author.Id);

            books = books.Where(a => a.Monitored).ToList();

            searchSpec.Books = books;

            return Dispatch(indexer => indexer.Fetch(searchSpec), searchSpec);
        }

        public List<DownloadDecision> BookSearch(Book book, bool missingOnly, bool userInvokedSearch, bool interactiveSearch)
        {
            var author = _authorService.GetAuthor(book.AuthorId);

            var searchSpec = Get<BookSearchCriteria>(author, new List<Book> { book }, userInvokedSearch, interactiveSearch);

            searchSpec.BookTitle = book.Editions.Value.SingleOrDefault(x => x.Monitored).Title;

            // searchSpec.BookIsbn = book.Isbn13;
            if (book.ReleaseDate.HasValue)
            {
                searchSpec.BookYear = book.ReleaseDate.Value.Year;
            }

            return Dispatch(indexer => indexer.Fetch(searchSpec), searchSpec);
        }

        private TSpec Get<TSpec>(Author author, List<Book> books, bool userInvokedSearch, bool interactiveSearch)
            where TSpec : SearchCriteriaBase, new()
        {
            var spec = new TSpec();

            spec.Books = books;
            spec.Author = author;
            spec.UserInvokedSearch = userInvokedSearch;
            spec.InteractiveSearch = interactiveSearch;

            return spec;
        }

        private static TSpec Get<TSpec>(Author author, bool userInvokedSearch, bool interactiveSearch)
            where TSpec : SearchCriteriaBase, new()
        {
            var spec = new TSpec();
            spec.Author = author;
            spec.UserInvokedSearch = userInvokedSearch;
            spec.InteractiveSearch = interactiveSearch;

            return spec;
        }

        private List<DownloadDecision> Dispatch(Func<IIndexer, IEnumerable<ReleaseInfo>> searchAction, SearchCriteriaBase criteriaBase)
        {
            var indexers = criteriaBase.InteractiveSearch ?
                _indexerFactory.InteractiveSearchEnabled() :
                _indexerFactory.AutomaticSearchEnabled();

            // Filter indexers to untagged indexers and indexers with intersecting tags
            indexers = indexers.Where(i => i.Definition.Tags.Empty() || i.Definition.Tags.Intersect(criteriaBase.Author.Tags).Any()).ToList();

            var reports = new List<ReleaseInfo>();

            _logger.ProgressInfo("Searching indexers for {0}. {1} active indexers", criteriaBase, indexers.Count);

            var taskList = new List<Task>();
            var taskFactory = new TaskFactory(TaskCreationOptions.LongRunning, TaskContinuationOptions.None);

            foreach (var indexer in indexers)
            {
                var indexerLocal = indexer;

                taskList.Add(taskFactory.StartNew(() =>
                {
                    try
                    {
                        var indexerReports = searchAction(indexerLocal);

                        lock (reports)
                        {
                            reports.AddRange(indexerReports);
                        }
                    }
                    catch (Exception e)
                    {
                        _logger.Error(e, "Error while searching for {0}", criteriaBase);
                    }
                }).LogExceptions());
            }

            Task.WaitAll(taskList.ToArray());

            _logger.Debug("Total of {0} reports were found for {1} from {2} indexers", reports.Count, criteriaBase, indexers.Count);

            return _makeDownloadDecision.GetSearchDecision(reports, criteriaBase).ToList();
        }
    }
}