using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.IO;
using System.Linq;
using System.Net;
using System.Text;
using NLog;
using NzbDrone.Common.Cache;
using NzbDrone.Common.EnvironmentInfo;
using NzbDrone.Common.Extensions;
using NzbDrone.Common.Http.Dispatchers;
using NzbDrone.Common.TPL;

namespace NzbDrone.Common.Http
{
    public interface IHttpClient
    {
        HttpResponse Execute(HttpRequest request);
        void DownloadFile(string url, string fileName);
        HttpResponse Get(HttpRequest request);
        HttpResponse<T> Get<T>(HttpRequest request) where T : new();
        HttpResponse Head(HttpRequest request);
        HttpResponse Post(HttpRequest request);
        HttpResponse<T> Post<T>(HttpRequest request) where T : new();
    }

    public class HttpClient : IHttpClient
    {
        private readonly Logger _logger;
        private readonly IRateLimitService _rateLimitService;
        private readonly ICached<CookieContainer> _cookieContainerCache;
        private readonly List<IHttpRequestInterceptor> _requestInterceptors;
        private readonly IHttpDispatcher _httpDispatcher;

        public HttpClient(IEnumerable<IHttpRequestInterceptor> requestInterceptors, ICacheManager cacheManager, IRateLimitService rateLimitService, IHttpDispatcher httpDispatcher, Logger logger)
        {
            _logger = logger;
            _rateLimitService = rateLimitService;
            _requestInterceptors = requestInterceptors.ToList();
            ServicePointManager.DefaultConnectionLimit = 12;
            _httpDispatcher = httpDispatcher;

            _cookieContainerCache = cacheManager.GetCache<CookieContainer>(typeof(HttpClient));
        }

        public HttpClient(IEnumerable<IHttpRequestInterceptor> requestInterceptors, ICacheManager cacheManager, IRateLimitService rateLimitService, Logger logger)
            : this(requestInterceptors, cacheManager, rateLimitService, null, logger)
        {
            _httpDispatcher = new FallbackHttpDispatcher(cacheManager.GetCache<bool>(typeof(HttpClient), "curlTLSFallback"), _logger);
        }

        public HttpResponse Execute(HttpRequest request)
        {
            foreach (var interceptor in _requestInterceptors)
            {
                request = interceptor.PreRequest(request);
            }

            if (request.RateLimit != TimeSpan.Zero)
            {
                _rateLimitService.WaitAndPulse(request.Url.Host, request.RateLimit);
            }

            _logger.Trace(request);

            var stopWatch = Stopwatch.StartNew();

            var cookies = PrepareRequestCookies(request);

            var response = _httpDispatcher.GetResponse(request, cookies);

            HandleResponseCookies(request, cookies);

            stopWatch.Stop();

            _logger.Trace("{0} ({1:n0} ms)", response, stopWatch.ElapsedMilliseconds);

            foreach (var interceptor in _requestInterceptors)
            {
                response = interceptor.PostResponse(response);
            }

            if (!RuntimeInfoBase.IsProduction &&
                (response.StatusCode == HttpStatusCode.Moved ||
                 response.StatusCode == HttpStatusCode.MovedPermanently ||
                 response.StatusCode == HttpStatusCode.Found))
            {
                _logger.Error("Server requested a redirect to [" + response.Headers["Location"] + "]. Update the request URL to avoid this redirect.");
            }

            if (!request.SuppressHttpError && response.HasHttpError)
            {
                _logger.Warn("HTTP Error - {0}", response);

                if ((int)response.StatusCode == 429)
                {
                    throw new TooManyRequestsException(request, response);
                }
                else
                {
                    throw new HttpException(request, response);
                }
            }

            return response;
        }

        private CookieContainer PrepareRequestCookies(HttpRequest request)
        {
            lock (_cookieContainerCache)
            {
                var persistentCookieContainer = _cookieContainerCache.Get("container", () => new CookieContainer());

                if (request.Cookies.Count != 0)
                {
                    foreach (var pair in request.Cookies)
                    {
                        persistentCookieContainer.Add(new Cookie(pair.Key, pair.Value, "/", request.Url.Host)
                        {
                            // Use Now rather than UtcNow to work around Mono cookie expiry bug.
                            // See https://gist.github.com/ta264/7822b1424f72e5b4c961
                            Expires = DateTime.Now.AddHours(1)
                        });
                    }
                }

                var requestCookies = persistentCookieContainer.GetCookies(request.Url);

                var cookieContainer = new CookieContainer();

                cookieContainer.Add(requestCookies);

                return cookieContainer;
            }
        }

        private void HandleResponseCookies(HttpRequest request, CookieContainer cookieContainer)
        {
            if (!request.StoreResponseCookie)
            {
                return;
            }

            lock (_cookieContainerCache)
            {
                var persistentCookieContainer = _cookieContainerCache.Get("container", () => new CookieContainer());

                var cookies = cookieContainer.GetCookies(request.Url);

                persistentCookieContainer.Add(cookies);
            }
        }

        public void DownloadFile(string url, string fileName)
        {
            try
            {
                var fileInfo = new FileInfo(fileName);
                if (fileInfo.Directory != null && !fileInfo.Directory.Exists)
                {
                    fileInfo.Directory.Create();
                }

                _logger.Debug("Downloading [{0}] to [{1}]", url, fileName);

                var stopWatch = Stopwatch.StartNew();
                var webClient = new GZipWebClient();
                webClient.Headers.Add(HttpRequestHeader.UserAgent, UserAgentBuilder.UserAgent);
                webClient.DownloadFile(url, fileName);
                stopWatch.Stop();
                _logger.Debug("Downloading Completed. took {0:0}s", stopWatch.Elapsed.Seconds);
            }
            catch (WebException e)
            {
                _logger.Warn("Failed to get response from: {0} {1}", url, e.Message);
                throw;
            }
            catch (Exception e)
            {
                _logger.Warn(e, "Failed to get response from: " + url);
                throw;
            }
        }

        public HttpResponse Get(HttpRequest request)
        {
            request.Method = HttpMethod.GET;
            return Execute(request);
        }

        public HttpResponse<T> Get<T>(HttpRequest request) where T : new()
        {
            var response = Get(request);
            return new HttpResponse<T>(response);
        }

        public HttpResponse Head(HttpRequest request)
        {
            request.Method = HttpMethod.HEAD;
            return Execute(request);
        }

        public HttpResponse Post(HttpRequest request)
        {
            request.Method = HttpMethod.POST;
            return Execute(request);
        }

        public HttpResponse<T> Post<T>(HttpRequest request) where T : new()
        {
            var response = Post(request);
            return new HttpResponse<T>(response);
        }
    }
}