using System;
using System.Collections.Generic;
using System.Linq;
using JetBrains.Annotations;
using Portoa.Persistence;
using VideoGameQuotes.Api;
using VideoGameQuotes.Web.Models;

namespace VideoGameQuotes.Web.Services {
	public interface IQuoteService {
		Game GetGame(int id);
		IEnumerable<Game> GetAllGames();
		IEnumerable<GamingSystem> GetAllSystems();
		IEnumerable<Publisher> GetAllPublishers();
		IEnumerable<Category> GetAllCategories();
		Quote SaveQuote(Quote quote);
		Quote GetQuote(int id);
		Publisher GetPublisher(int id);
		GamingSystem GetSystem(int systemId);
		Category GetCategory(int categoryId);
		IEnumerable<Quote> GetRecentQuotes(int start, int end, out int totalCount);
		[CanBeNull]
		Quote GetRandomQuote();
		IEnumerable<Quote> GetBestQuotes(int start, int end, out int totalCount);
		Vote GetVoteOrCreateNew(Quote quote, User voter);
		IEnumerable<Quote> GetBrowsableQuotes(BrowseModel model, int start, int end, out int totalCount);
		Quote GetQuoteForDayOfYear(int day);
	}

	public class QuoteService : IQuoteService {
		private readonly IRepository<Quote> quoteRepository;
		private readonly IRepository<Game> gameRepository;
		private readonly IRepository<GamingSystem> systemRepository;
		private readonly IRepository<Publisher> publisherRepository;
		private readonly IRepository<Category> categoryRepository;
		private readonly IRepository<Vote> voteRepository;
		private static readonly Random random = new Random();
		private static readonly IDictionary<int, Quote> quoteOfTheDayMap = new Dictionary<int, Quote>();

		public QuoteService(
			IRepository<Quote> quoteRepository,
			IRepository<Game> gameRepository,
			IRepository<GamingSystem> systemRepository,
			IRepository<Publisher> publisherRepository, 
			IRepository<Category> categoryRepository,
			IRepository<Vote> voteRepository
		) {
			this.quoteRepository = quoteRepository;
			this.categoryRepository = categoryRepository;
			this.voteRepository = voteRepository;
			this.gameRepository = gameRepository;
			this.systemRepository = systemRepository;
			this.publisherRepository = publisherRepository;
		}

		[UnitOfWork]
		public Game GetGame(int id) {
			return gameRepository.FindById(id);
		}

		[UnitOfWork]
		public IEnumerable<Game> GetAllGames() {
			return gameRepository.Records;
		}

		[UnitOfWork]
		public IEnumerable<GamingSystem> GetAllSystems() {
			return systemRepository.Records;
		}

		[UnitOfWork]
		public IEnumerable<Publisher> GetAllPublishers() {
			return publisherRepository.Records;
		}

		[UnitOfWork]
		public IEnumerable<Category> GetAllCategories() {
			return categoryRepository.Records;
		}

		[UnitOfWork]
		public Quote SaveQuote(Quote quote) {
			return quoteRepository.Save(quote);
		}

		[UnitOfWork]
		public Quote GetQuote(int id) {
			return quoteRepository.FindById(id);
		}

		[UnitOfWork]
		public Publisher GetPublisher(int id) {
			return publisherRepository.FindById(id);
		}

		[UnitOfWork]
		public GamingSystem GetSystem(int systemId) {
			return systemRepository.FindById(systemId);
		}

		[UnitOfWork]
		public Category GetCategory(int categoryId) {
			return categoryRepository.FindById(categoryId);
		}

		[UnitOfWork]
		public IEnumerable<Quote> GetRecentQuotes(int start, int end, out int totalCount) {
			totalCount = quoteRepository.Records.Count();
			return quoteRepository
				.Records
				.OrderByDescending(quote => quote.Created)
				.Skip(start - 1)
				.Take(end - start + 1);
		}

		[UnitOfWork]
		public Quote GetRandomQuote() {
			var length = quoteRepository.Records.Count();
			if (length == 0) {
				return null;
			}

			return GetRandomQuote(quoteRepository.Records);
		}

		private static Quote GetRandomQuote(IEnumerable<Quote> quotes) {
			var length = quotes.Count();
			if (length == 0) {
				return null;
			}

			return quotes
				.Skip(random.Next(length))
				.Take(1)
				.Single();
		}

		[UnitOfWork]
		public IEnumerable<Quote> GetBestQuotes(int start, int end, out int totalCount) {
			totalCount = quoteRepository.Records.Count();

			return quoteRepository.Records
				.OrderByDescending(quote => quote.Score)
				.ThenByDescending(quote => quote.UpVotes)
				.Skip(start - 1)
				.Take(end - start + 1);
		}

		[UnitOfWork]
		public Vote GetVoteOrCreateNew(Quote quote, User voter) {
			var vote = voteRepository.Records.SingleOrDefault(v => v.Quote == quote && v.Voter == voter);
			return vote ?? new Vote {
				Quote = quote,
				Voter = voter
			};
		}

		[UnitOfWork]
		public IEnumerable<Quote> GetBrowsableQuotes(BrowseModel model, int start, int end, out int totalCount) {
			var quotes = quoteRepository.Records;
			if (model.GameIds.Any()) {
				quotes = quotes.Where(quote => model.GameIds.Contains(quote.Game.Id));
			}
			if (model.PublisherIds.Any()) {
				quotes = quotes.Where(quote => quote.Game.Publishers.Any(publisher => model.PublisherIds.Contains(publisher.Id)));
			}
			if (model.SystemIds.Any()) {
				quotes = quotes.Where(quote => quote.Game.Systems.Any(system => model.SystemIds.Contains(system.Id)));
			}
			if (model.CategoryIds.Any()) {
				quotes = quotes.Where(quote => quote.Categories.Any(category => model.CategoryIds.Contains(category.Id)));
			}

			totalCount = quotes.Count();
			return quotes.OrderByDescending(quote => quote.Score).ThenBy(quote => quote.UpVotes).Skip(start - 1).Take(end - start + 1);
		}

		
		[UnitOfWork, CanBeNull]
		public Quote GetQuoteForDayOfYear(int day) {
			if (!quoteOfTheDayMap.ContainsKey(day)) {
				quoteOfTheDayMap[day] = GetRandomQuote(quoteRepository.Records.Where(quote => quote.Score > 0));
			}

			return quoteOfTheDayMap[day];
		}
	}
}