using System;
using System.IO;
using System.IO.Compression;
using System.Net;
using NzbDrone.Common.EnvironmentInfo;
using NzbDrone.Common.Extensions;
using NzbDrone.Common.Http.Proxy;
using NzbDrone.Common.Security;

namespace NzbDrone.Common.Http.Dispatchers
{
    public class ManagedHttpDispatcher : IHttpDispatcher
    {
        private readonly IHttpProxySettingsProvider _proxySettingsProvider;
        private readonly ICreateManagedWebProxy _createManagedWebProxy;

        public ManagedHttpDispatcher(IHttpProxySettingsProvider proxySettingsProvider, ICreateManagedWebProxy createManagedWebProxy)
        {
            _proxySettingsProvider = proxySettingsProvider;
            _createManagedWebProxy = createManagedWebProxy;
        }

        public HttpResponse GetResponse(HttpRequest request, CookieContainer cookies)
        {
            HttpWebResponse httpWebResponse = null;
            HttpWebRequest webRequest = null;
            try
            {
                webRequest = (HttpWebRequest) WebRequest.Create((Uri) request.Url);

                if (PlatformInfo.IsMono)
                {
                    // On Mono GZipStream/DeflateStream leaks memory if an exception is thrown, use an intermediate buffer in that case.
                    webRequest.AutomaticDecompression = DecompressionMethods.None;
                    webRequest.Headers.Add("Accept-Encoding", "gzip");
                }
                else
                {
                    // Deflate is not a standard and could break depending on implementation.
                    // we should just stick with the more compatible Gzip
                    //http://stackoverflow.com/questions/8490718/how-to-decompress-stream-deflated-with-java-util-zip-deflater-in-net
                    webRequest.AutomaticDecompression = DecompressionMethods.GZip;
                }
                
                webRequest.Method = request.Method.ToString();
                webRequest.UserAgent = request.UseSimplifiedUserAgent
                    ? UserAgentBuilder.UserAgentSimplified
                    : UserAgentBuilder.UserAgent;
                webRequest.KeepAlive = request.ConnectionKeepAlive;
                webRequest.AllowAutoRedirect = false;
                webRequest.CookieContainer = cookies;

                if (request.RequestTimeout != TimeSpan.Zero)
                {
                    webRequest.Timeout = (int) Math.Ceiling(request.RequestTimeout.TotalMilliseconds);
                }

                AddProxy(webRequest, request);

                if (request.Headers != null)
                {
                    AddRequestHeaders(webRequest, request.Headers);
                }

                if (request.ContentData != null)
                {
                    webRequest.ContentLength = request.ContentData.Length;
                    using (var writeStream = webRequest.GetRequestStream())
                    {
                        writeStream.Write(request.ContentData, 0, request.ContentData.Length);
                    }
                }

                try
                {
                    httpWebResponse = (HttpWebResponse) webRequest.GetResponse();
                }
                catch (WebException e)
                {
                    if (e.Status == WebExceptionStatus.SecureChannelFailure && OsInfo.IsWindows)
                    {
                        SecurityProtocolPolicy.DisableTls12();
                    }

                    httpWebResponse = (HttpWebResponse) e.Response;

                    if (httpWebResponse == null)
                    {
                        throw;
                    }
                }

                byte[] data = null;

                using (var responseStream = httpWebResponse.GetResponseStream())
                {
                    if (responseStream != null)
                    {
                        data = responseStream.ToBytes();

                        if (PlatformInfo.IsMono && httpWebResponse.ContentEncoding == "gzip")
                        {
                            using (var compressedStream = new MemoryStream(data))
                            using (var gzip = new GZipStream(compressedStream, CompressionMode.Decompress))
                            using (var decompressedStream = new MemoryStream())
                            {
                                gzip.CopyTo(decompressedStream);
                                data = decompressedStream.ToArray();
                            }

                            httpWebResponse.Headers.Remove("Content-Encoding");
                        }
                    }
                }

                return new HttpResponse(request, new HttpHeader(httpWebResponse.Headers), data,
                    httpWebResponse.StatusCode);
            }
            finally
            {
                webRequest = null;
                (httpWebResponse as IDisposable)?.Dispose();
                httpWebResponse = null;
            }
        }

        protected virtual void AddProxy(HttpWebRequest webRequest, HttpRequest request)
        {
            var proxySettings = _proxySettingsProvider.GetProxySettings(request);
            if (proxySettings != null)
            {
                webRequest.Proxy = _createManagedWebProxy.GetWebProxy(proxySettings);
            }
        }

        protected virtual void AddRequestHeaders(HttpWebRequest webRequest, HttpHeader headers)
        {
            foreach (var header in headers)
            {
                switch (header.Key)
                {
                    case "Accept":
                        webRequest.Accept = header.Value;
                        break;
                    case "Connection":
                        webRequest.Connection = header.Value;
                        break;
                    case "Content-Length":
                        webRequest.ContentLength = Convert.ToInt64(header.Value);
                        break;
                    case "Content-Type":
                        webRequest.ContentType = header.Value;
                        break;
                    case "Date":
                        webRequest.Date = HttpHeader.ParseDateTime(header.Value);
                        break;
                    case "Expect":
                        webRequest.Expect = header.Value;
                        break;
                    case "Host":
                        webRequest.Host = header.Value;
                        break;
                    case "If-Modified-Since":
                        webRequest.IfModifiedSince = HttpHeader.ParseDateTime(header.Value);
                        break;
                    case "Range":
                        throw new NotImplementedException();
                    case "Referer":
                        webRequest.Referer = header.Value;
                        break;
                    case "Transfer-Encoding":
                        webRequest.TransferEncoding = header.Value;
                        break;
                    case "User-Agent":
                        throw new NotSupportedException("User-Agent other than Radarr not allowed.");
                    case "Proxy-Connection":
                        throw new NotImplementedException();
                    default:
                        webRequest.Headers.Add(header.Key, header.Value);
                        break;
                }
            }
        }
    }
}