using System;
using System.Collections.Generic;
using System.Linq;
using System.Net;
using System.Web.Mvc;
using Portoa.Persistence;
using Portoa.Web.Controllers;
using Portoa.Web.Results;
using Portoa.Web.Util;
using VideoGameQuotes.Api;
using VideoGameQuotes.Web.Models;

namespace VideoGameQuotes.Web.Controllers {


	public interface IApiService {
		IEnumerable<GameDto> GetGames(ApiModel model);
		IEnumerable<SystemDto> GetSystems(ApiModel model);
		IEnumerable<CategoryDto> GetCategories(ApiModel model);
		IEnumerable<PublisherDto> GetPublishers(ApiModel model);
		IEnumerable<QuoteDto> GetQuotes(ApiModel model);
	}

	public class ApiService : IApiService {
		private readonly IRepository<Game> gameRepository;
		private readonly IRepository<GamingSystem> systemRepository;
		private readonly IRepository<Category> categoryRepository;
		private readonly IRepository<Publisher> publisherRepository;
		private readonly IRepository<Quote> quoteRepository;

		private readonly IDictionary<string, CriterionHandler<Category>> categoryHandlers = new Dictionary<string, CriterionHandler<Category>>();
		private readonly IDictionary<string, CriterionHandler<GamingSystem>> systemHandlers = new Dictionary<string, CriterionHandler<GamingSystem>>();
		private readonly IDictionary<string, CriterionHandler<Publisher>> publisherHandlers = new Dictionary<string, CriterionHandler<Publisher>>();
		private readonly IDictionary<string, CriterionHandler<Quote>> quoteHandlers = new Dictionary<string, CriterionHandler<Quote>> {
			{ "game", new Quote.GameCriterionHandler() }
		};
		private readonly IDictionary<string, CriterionHandler<Game>> gameHandlers = new Dictionary<string, CriterionHandler<Game>> {
			{ "system", new Game.SystemCriterionHandler() },
			{ "publisher", new Game.PublisherCriterionHandler() }
		};

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

		private static IEnumerable<T> SetSortMethod<T, TKey>(IEnumerable<T> records, SortMethod sortMethod, SortOrder sortOrder, Func<T, TKey> propertySelector) where T : Entity<int> {
			switch (sortMethod) {
				case SortMethod.Alphabetical:
					return sortOrder == SortOrder.Descending ? records.OrderByDescending(propertySelector) : records.OrderBy(propertySelector);
				case SortMethod.Date:
					return sortOrder == SortOrder.Descending ? records.OrderByDescending(propertySelector) : records.OrderBy(propertySelector);
				default:
					return records;
			}
		}

		private static IEnumerable<TDto> GetRecords<T, TDto>(
			ApiModel model,
			IRepository<T> repository,
			Func<T, object> sortSelector,
			IDictionary<string,
			CriterionHandler<T>> criterionHandlers
		)
			where T : Entity<int>
			where TDto : new() {
			IEnumerable<T> records;
			if (model.FetchAll) {
				records = SetSortMethod(repository.Records, model.SortMethod, model.SortOrder, sortSelector);
				var expressionBuilder = new List<Func<T, bool>>();
				foreach (var kvp in model.Criteria) {
					if (!criterionHandlers.ContainsKey(kvp.Key)) {
						throw new ApiException(string.Format("Unknown criterion: \"{0}\"", kvp.Key));
					}

					expressionBuilder.AddRange(criterionHandlers[kvp.Key].HandleCriterion(kvp.Value));
				}

				if (expressionBuilder.Count > 0) {
					records = records.Where(game => expressionBuilder.Aggregate(false, (current, next) => current || next(game)));
				}
			} else {
				records = new[] { repository.FindById(model.Id) };
			}

			return records.ToArray().Select(entity => entity.ToDto<TDto>());
		}

		[UnitOfWork]
		public IEnumerable<GameDto> GetGames(ApiModel model) {
			return GetRecords<Game, GameDto>(model, gameRepository, game => game.Name, gameHandlers);
		}

		[UnitOfWork]
		public IEnumerable<SystemDto> GetSystems(ApiModel model) {
			return GetRecords<GamingSystem, SystemDto>(model, systemRepository, system => system.Name, systemHandlers);
		}

		[UnitOfWork]
		public IEnumerable<CategoryDto> GetCategories(ApiModel model) {
			return GetRecords<Category, CategoryDto>(model, categoryRepository, category => category.Name, categoryHandlers);
		}

		[UnitOfWork]
		public IEnumerable<PublisherDto> GetPublishers(ApiModel model) {
			return GetRecords<Publisher, PublisherDto>(model, publisherRepository, publisher => publisher.Name, publisherHandlers);
		}

		[UnitOfWork]
		public IEnumerable<QuoteDto> GetQuotes(ApiModel model) {
			return GetRecords<Quote, QuoteDto>(model, quoteRepository, quote => quote.Id, quoteHandlers);
		}
	}

	public class ApiController : Controller {
		private readonly IApiService apiService;

		public ApiController(IApiService apiService) {
			this.apiService = apiService;
		}

		private ActionResult Error(HttpStatusCode statusCode, string message = null) {
			return new StatusOverrideResult(this.SerializeToJson(this.CreateJsonErrorResponse(message ?? "Invalid request"))) { StatusCode = statusCode };
		}

		private ActionResult GetRecords<TDto>(Func<IApiService, IEnumerable<TDto>> recordGetter) {
			if (!ModelState.IsValid) {
				return Error(HttpStatusCode.BadRequest);
			}

			try {
				return this.SerializeToJson(this.CreateJsonResponse(data: new { records = recordGetter(apiService) }));
			} catch (ApiException e) {
				return Error(HttpStatusCode.BadRequest, e.Message);
			} catch {
				return Error(HttpStatusCode.InternalServerError, "An error occurred while trying to fulfill your stupid request");
			}
		}

		public ActionResult Game(ApiModel model) {
			return GetRecords(service => service.GetGames(model));
		}

		public ActionResult System(ApiModel model) {
			return GetRecords(service => service.GetSystems(model));
		}

		public ActionResult Category(ApiModel model) {
			return GetRecords(service => service.GetCategories(model));
		}

		public ActionResult Publisher(ApiModel model) {
			return GetRecords(service => service.GetPublishers(model));
		}

		public ActionResult Quote(ApiModel model) {
			return GetRecords(service => service.GetQuotes(model));
		}
	}
}