using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.Linq;
using System.Net;
using System.Net.Http;
using System.Net.Security;
using System.Security.Cryptography.X509Certificates;
using System.Text;
using System.Threading.Tasks;
using CloudflareSolverRe;
using com.LandonKey.SocksWebProxy;
using com.LandonKey.SocksWebProxy.Proxy;
using Jackett.Common.Helpers;
using Jackett.Common.Models.Config;
using Jackett.Common.Services.Interfaces;
using NLog;

namespace Jackett.Common.Utils.Clients
{
    public class HttpWebClient : WebClient
    {
        protected static Dictionary<string, ICollection<string>> trustedCertificates = new Dictionary<string, ICollection<string>>();
        protected static string webProxyUrl;
        protected static IWebProxy webProxy;

        [DebuggerNonUserCode] // avoid "Exception User-Unhandled" Visual Studio messages
        public static bool ValidateCertificate(object sender, X509Certificate certificate, X509Chain chain, SslPolicyErrors sslPolicyErrors)
        {
            if (sender.GetType() != typeof(HttpWebRequest))
                return sslPolicyErrors == SslPolicyErrors.None;

            var request = (HttpWebRequest)sender;
            var hash = certificate.GetCertHashString();


            trustedCertificates.TryGetValue(hash, out var hosts);
            if (hosts != null)
            {
                if (hosts.Contains(request.Host))
                    return true;
            }

            if (sslPolicyErrors != SslPolicyErrors.None)
            {
                // Throw exception with certificate details, this will cause a "Exception User-Unhandled" when running it in the Visual Studio debugger.
                // The certificate is only available inside this function, so we can't catch it at the calling method.
                throw new Exception("certificate validation failed: " + certificate.ToString());
            }

            return sslPolicyErrors == SslPolicyErrors.None;
        }

        public static void InitProxy(ServerConfig serverConfig)
        {
            // dispose old SocksWebProxy
            if (webProxy != null && webProxy is SocksWebProxy)
            {
                ((SocksWebProxy)webProxy).Dispose();
                webProxy = null;
            }

            webProxyUrl = serverConfig.GetProxyUrl();
            if (!string.IsNullOrWhiteSpace(webProxyUrl))
            {
                if (serverConfig.ProxyType != ProxyType.Http)
                {
                    var addresses = Dns.GetHostAddressesAsync(serverConfig.ProxyUrl).Result;
                    var socksConfig = new ProxyConfig
                    {
                        SocksAddress = addresses.FirstOrDefault(),
                        Username = serverConfig.ProxyUsername,
                        Password = serverConfig.ProxyPassword,
                        Version = serverConfig.ProxyType == ProxyType.Socks4 ?
                        ProxyConfig.SocksVersion.Four :
                        ProxyConfig.SocksVersion.Five
                    };
                    if (serverConfig.ProxyPort.HasValue)
                    {
                        socksConfig.SocksPort = serverConfig.ProxyPort.Value;
                    }
                    webProxy = new SocksWebProxy(socksConfig, false);
                }
                else
                {
                    NetworkCredential creds = null;
                    if (!serverConfig.ProxyIsAnonymous)
                    {
                        var username = serverConfig.ProxyUsername;
                        var password = serverConfig.ProxyPassword;
                        creds = new NetworkCredential(username, password);
                    }
                    webProxy = new WebProxy(webProxyUrl)
                    {
                        BypassProxyOnLocal = false,
                        Credentials = creds
                    };
                }
            }
        }

        public HttpWebClient(IProcessService p, Logger l, IConfigurationService c, ServerConfig sc)
            : base(p: p,
                   l: l,
                   c: c,
                   sc: sc)
        {
            if (webProxyUrl == null)
                InitProxy(sc);
        }

        // Called everytime the ServerConfig changes
        public override void OnNext(ServerConfig value)
        {
            var newProxyUrl = serverConfig.GetProxyUrl();
            if (webProxyUrl != newProxyUrl) // if proxy URL changed
                InitProxy(serverConfig);
        }

        public override void Init()
        {
            ServicePointManager.DefaultConnectionLimit = 1000;

            if (serverConfig.RuntimeSettings.IgnoreSslErrors == true)
            {
                logger.Info(string.Format("HttpWebClient: Disabling certificate validation"));
                ServicePointManager.ServerCertificateValidationCallback += (sender, certificate, chain, sslPolicyErrors) => { return true; };
            }

            // custom handler for our own internal certificates
            ServicePointManager.ServerCertificateValidationCallback += ValidateCertificate;
        }

        protected override async Task<WebClientByteResult> Run(WebRequest webRequest)
        {
            ServicePointManager.SecurityProtocol = (SecurityProtocolType)192 | (SecurityProtocolType)768 | (SecurityProtocolType)3072;

            var cookies = new CookieContainer();
            if (!string.IsNullOrEmpty(webRequest.Cookies))
            {
                var uri = new Uri(webRequest.Url);
                var cookieUrl = new Uri(uri.Scheme + "://" + uri.Host); // don't include the path, Scheme is needed for mono compatibility
                foreach (var c in webRequest.Cookies.Split(';'))
                {
                    try
                    {
                        cookies.SetCookies(cookieUrl, c.Trim());
                    }
                    catch (CookieException ex)
                    {
                        logger.Info("(Non-critical) Problem loading cookie {0}, {1}, {2}", uri, c, ex.Message);
                    }
                }
            }

            var userAgent = webRequest.EmulateBrowser.Value ? BrowserUtil.ChromeUserAgent : "Jackett/" + configService.GetVersion();

            using (var clearanceHandlr = new ClearanceHandler(userAgent))
            {
                clearanceHandlr.MaxTries = 30;
                using (var clientHandlr = new HttpClientHandler
                {
                    CookieContainer = cookies,
                    AllowAutoRedirect = false, // Do not use this - Bugs ahoy! Lost cookies and more.
                    UseCookies = true,
                    Proxy = webProxy,
                    UseProxy = (webProxy != null),
                    AutomaticDecompression = DecompressionMethods.GZip | DecompressionMethods.Deflate
                })
                {
                    clearanceHandlr.InnerHandler = clientHandlr;
                    using (var client = new HttpClient(clearanceHandlr))
                    {
                        if (webRequest.EmulateBrowser == true)
                            client.DefaultRequestHeaders.Add("User-Agent", BrowserUtil.ChromeUserAgent);
                        else
                            client.DefaultRequestHeaders.Add("User-Agent", "Jackett/" + configService.GetVersion());

                        HttpResponseMessage response = null;
                        using (var request = new HttpRequestMessage())
                        {
                            request.Headers.ExpectContinue = false;
                            request.RequestUri = new Uri(webRequest.Url);

                            if (webRequest.Headers != null)
                            {
                                foreach (var header in webRequest.Headers)
                                {
                                    if (header.Key != "Content-Type")
                                    {
                                        request.Headers.TryAddWithoutValidation(header.Key, header.Value);
                                    }
                                }
                            }

                            if (!string.IsNullOrEmpty(webRequest.Referer))
                                request.Headers.Referrer = new Uri(webRequest.Referer);

                            if (!string.IsNullOrEmpty(webRequest.RawBody))
                            {
                                var type = webRequest.Headers.Where(h => h.Key == "Content-Type").Cast<KeyValuePair<string, string>?>().FirstOrDefault();
                                if (type.HasValue)
                                {
                                    var str = new StringContent(webRequest.RawBody);
                                    str.Headers.Remove("Content-Type");
                                    str.Headers.Add("Content-Type", type.Value.Value);
                                    request.Content = str;
                                }
                                else
                                    request.Content = new StringContent(webRequest.RawBody);
                                request.Method = HttpMethod.Post;
                            }
                            else if (webRequest.Type == RequestType.POST)
                            {
                                if (webRequest.PostData != null)
                                    request.Content = FormUrlEncodedContentWithEncoding(webRequest.PostData, webRequest.Encoding);
                                request.Method = HttpMethod.Post;
                            }
                            else
                            {
                                request.Method = HttpMethod.Get;
                            }

                            using (response = await client.SendAsync(request))
                            {
                                var result = new WebClientByteResult
                                {
                                    Content = await response.Content.ReadAsByteArrayAsync()
                                };

                                foreach (var header in response.Headers)
                                {
                                    var value = header.Value;
                                    result.Headers[header.Key.ToLowerInvariant()] = value.ToArray();
                                }

                                // some cloudflare clients are using a refresh header
                                // Pull it out manually 
                                if (response.StatusCode == HttpStatusCode.ServiceUnavailable && response.Headers.Contains("Refresh"))
                                {
                                    var refreshHeaders = response.Headers.GetValues("Refresh");
                                    var redirval = "";
                                    var redirtime = 0;
                                    if (refreshHeaders != null)
                                    {
                                        foreach (var value in refreshHeaders)
                                        {
                                            var start = value.IndexOf("=");
                                            var end = value.IndexOf(";");
                                            var len = value.Length;
                                            if (start > -1)
                                            {
                                                redirval = value.Substring(start + 1);
                                                result.RedirectingTo = redirval;
                                                // normally we don't want a serviceunavailable (503) to be a redirect, but that's the nature
                                                // of this cloudflare approach..don't want to alter BaseWebResult.IsRedirect because normally
                                                // it shoudln't include service unavailable..only if we have this redirect header.
                                                response.StatusCode = System.Net.HttpStatusCode.Redirect;
                                                redirtime = int.Parse(value.Substring(0, end));
                                                System.Threading.Thread.Sleep(redirtime * 1000);
                                            }
                                        }
                                    }
                                }
                                if (response.Headers.Location != null)
                                {
                                    result.RedirectingTo = response.Headers.Location.ToString();
                                }
                                // Mono won't add the baseurl to relative redirects.
                                // e.g. a "Location: /index.php" header will result in the Uri "file:///index.php"
                                // See issue #1200
                                if (result.RedirectingTo != null && result.RedirectingTo.StartsWith("file://"))
                                {
                                    // URL decoding apparently is needed to, without it e.g. Demonoid download is broken
                                    // TODO: is it always needed (not just for relative redirects)?
                                    var newRedirectingTo = WebUtilityHelpers.UrlDecode(result.RedirectingTo, webRequest.Encoding);
                                    if (newRedirectingTo.StartsWith("file:////")) // Location without protocol but with host (only add scheme)
                                        newRedirectingTo = newRedirectingTo.Replace("file://", request.RequestUri.Scheme + ":");
                                    else
                                        newRedirectingTo = newRedirectingTo.Replace("file://", request.RequestUri.Scheme + "://" + request.RequestUri.Host);
                                    logger.Debug("[MONO relative redirect bug] Rewriting relative redirect URL from " + result.RedirectingTo + " to " + newRedirectingTo);
                                    result.RedirectingTo = newRedirectingTo;
                                }
                                result.Status = response.StatusCode;

                                // Compatiblity issue between the cookie format and httpclient
                                // Pull it out manually ignoring the expiry date then set it manually
                                // http://stackoverflow.com/questions/14681144/httpclient-not-storing-cookies-in-cookiecontainer
                                var responseCookies = new List<Tuple<string, string>>();

                                if (response.Headers.TryGetValues("set-cookie", out var cookieHeaders))
                                {
                                    foreach (var value in cookieHeaders)
                                    {
                                        var nameSplit = value.IndexOf('=');
                                        if (nameSplit > -1)
                                        {
                                            responseCookies.Add(new Tuple<string, string>(value.Substring(0, nameSplit), value.Substring(0, value.IndexOf(';') == -1 ? value.Length : (value.IndexOf(';'))) + ";"));
                                        }
                                    }

                                    var cookieBuilder = new StringBuilder();
                                    foreach (var cookieGroup in responseCookies.GroupBy(c => c.Item1))
                                    {
                                        cookieBuilder.AppendFormat("{0} ", cookieGroup.Last().Item2);
                                    }
                                    result.Cookies = cookieBuilder.ToString().Trim();
                                }
                                ServerUtil.ResureRedirectIsFullyQualified(webRequest, result);
                                return result;
                            }
                        }
                    }
                }
            }
        }

        public override void AddTrustedCertificate(string host, string hash)
        {
            hash = hash.ToUpper();
            trustedCertificates.TryGetValue(hash.ToUpper(), out var hosts);
            if (hosts == null)
            {
                hosts = new HashSet<string>();
                trustedCertificates[hash] = hosts;
            }
            hosts.Add(host);
        }
    }
}