using System;
using System.Net;
using System.Net.Http;
using System.Net.Http.Headers;
using System.Reflection;
using System.Security.Authentication;
using System.Text;

namespace TelegramService.Help
{
    public record HttpResult(int StatusCode, string Html)
    {
        public static readonly HttpResult Empty = new(0, string.Empty);
    }

    public static class HttpHelper
    {
        private static readonly HttpClient DefaultClient;

        static HttpHelper()
        {
            var handler = CreateBestHandler();
            TrySetPooledConnectionLifetime(handler, TimeSpan.FromMinutes(2));

            DefaultClient = new HttpClient(handler, disposeHandler: false)
            {
                Timeout = Timeout.InfiniteTimeSpan
            };
        }

        private static HttpClientHandler CreateBestHandler()
        {
            return new HttpClientHandler
            {
                UseCookies = false,
                AutomaticDecompression = DecompressionMethods.All,
                AllowAutoRedirect = true,
                // 下面这行是终极救命稻草（解决代理返回 407 需要认证的坑）
                Proxy = null,
                UseProxy = false,
                // 防止某些代理服务器返回奇怪的证书
                ServerCertificateCustomValidationCallback = (msg, cert, chain, errors) => true
            };
        }

        private static HttpClient CreateProxyClient(string proxy)
        {
            var (address, credential, isHttpsProxy) = ParseProxy(proxy);

            var handler = CreateBestHandler();
            TrySetPooledConnectionLifetime(handler, TimeSpan.FromMinutes(2));

            var webProxy = new WebProxy(address)
            {
                UseDefaultCredentials = false,
                BypassProxyOnLocal = false
            };

            if (credential != null)
                webProxy.Credentials = credential;

            handler.Proxy = webProxy;
            handler.UseProxy = true;

            // https 代理走 CONNECT 时强制 TLS 1.2/1.3
            if (isHttpsProxy)
            {
                handler.SslProtocols = SslProtocols.Tls12 | SslProtocols.Tls13;
            }

            return new HttpClient(handler, disposeHandler: true)
            {
                Timeout = Timeout.InfiniteTimeSpan
            };
        }
        /// <summary>
        /// 
        /// </summary>
        /// <param name="proxy">http://user123:passABC@127.0.0.1:8080</param>
        /// <returns></returns>
        private static (Uri address, NetworkCredential? credential, bool isHttpsProxy) ParseProxy(string proxy)
        {
            proxy = proxy.Trim();

            var uri = proxy.Contains("://")
                ? new Uri(proxy)
                : new Uri("http://" + proxy);

            NetworkCredential? credential = null;
            if (!string.IsNullOrEmpty(uri.UserInfo))
            {
                var parts = uri.UserInfo.Split(new[] { ':' }, 2);
                credential = new NetworkCredential(
                    parts[0],
                    parts.Length > 1 ? parts[1] : string.Empty
                );
            }

            bool isHttps = uri.Scheme.Equals("https", StringComparison.OrdinalIgnoreCase);

            // 最终给 WebProxy 的地址必须是 http://ip:port 格式
            var address = new Uri($"http://{uri.Host}:{uri.Port}");

            return (address, credential, isHttps);
        }

        public static async Task<HttpResult> SendAsync(
            string url,
            HttpMethod method,
            Dictionary<string, string>? headers = null,
            string? cookies = null,
            HttpContent? content = null,
            int timeoutSeconds = 30,
            string? proxy = null,
            CancellationToken cancellationToken = default)
        {
            var client = string.IsNullOrWhiteSpace(proxy)
                ? DefaultClient
                : CreateProxyClient(proxy);

            try
            {
                using var request = new HttpRequestMessage(method, url);

                if (content != null)
                    request.Content = content;

                if (headers != null)
                {
                    foreach (var h in headers)
                    {
                        if (IsContentHeader(h.Key))
                            request.Content?.Headers.TryAddWithoutValidation(h.Key, h.Value);
                        else
                            request.Headers.TryAddWithoutValidation(h.Key, h.Value);
                    }
                }

                if (!string.IsNullOrWhiteSpace(cookies))
                    request.Headers.TryAddWithoutValidation("Cookie", cookies);

                using var cts = CancellationTokenSource.CreateLinkedTokenSource(cancellationToken);
                cts.CancelAfter(TimeSpan.FromSeconds(timeoutSeconds));

                using var response = await client.SendAsync(request, HttpCompletionOption.ResponseHeadersRead, cts.Token);

                var bytes = await response.Content.ReadAsByteArrayAsync(cts.Token);

                if (!response.IsSuccessStatusCode)
                {
                    var err = Encoding.UTF8.GetString(bytes);
                    return new HttpResult((int)response.StatusCode, $"请求失败 {(int)response.StatusCode} {response.ReasonPhrase}\n{err}".Trim());
                }

                var charset = response.Content.Headers.ContentType?.CharSet;
                string html;

                if (!string.IsNullOrEmpty(charset) && !charset.Equals("utf-8", StringComparison.OrdinalIgnoreCase))
                {
                    try
                    {
                        html = Encoding.GetEncoding(charset).GetString(bytes);
                        return new HttpResult((int)response.StatusCode, html);
                    }
                    catch
                    {
                        html = Encoding.UTF8.GetString(bytes);
                    }
                }
                else
                {
                    html = Encoding.UTF8.GetString(bytes);
                }

                return new HttpResult((int)response.StatusCode, html);
            }
            catch (OperationCanceledException) when (!cancellationToken.IsCancellationRequested)
            {
                return new HttpResult(500, $"请求超时（{timeoutSeconds}s）");
            }
            catch (Exception ex)
            {
                return new HttpResult(500, ex.Message);
            }
            finally
            {
                if (!string.IsNullOrWhiteSpace(proxy))
                    client.Dispose();
            }
        }

        // 下面四个快捷方法和你原来的一模一样
        public static Task<HttpResult> GetAsync(string url, Dictionary<string, string>? headers = null, string? cookies = null, int timeoutSeconds = 30, string? proxy = null)
            => SendAsync(url, HttpMethod.Get, headers, cookies, null, timeoutSeconds, proxy);

        public static Task<HttpResult> PostFormAsync(string url, Dictionary<string, string> form, Dictionary<string, string>? headers = null, string? cookies = null, int timeoutSeconds = 30, string? proxy = null)
        {
            var content = new FormUrlEncodedContent(form);
            return SendAsync(url, HttpMethod.Post, headers, cookies, content, timeoutSeconds, proxy);
        }

        public static Task<HttpResult> PostFormAsync(string url, string form, Dictionary<string, string>? headers = null, string? cookies = null, int timeoutSeconds = 30, string? proxy = null)
        {
            var content = new FormUrlEncodedContent(ParseQueryString(form));
            return SendAsync(url, HttpMethod.Post, headers, cookies, content, timeoutSeconds, proxy);
        }

        public static Task<HttpResult> PostJsonAsync(string url, string json, Dictionary<string, string>? headers = null, string? cookies = null, int timeoutSeconds = 30, string? proxy = null)
        {
            var content = new StringContent(json, Encoding.UTF8, "application/json");
            headers ??= new();
            //headers["Content-Type"] = "application/json; charset=utf-8";
            return SendAsync(url, HttpMethod.Post, headers, cookies, content, timeoutSeconds, proxy);
        }

        public static Dictionary<string, string> ParseQueryString(string query)
        {
            if (string.IsNullOrEmpty(query)) return new();
            return query.Split('&')
                .Select(x => x.Split('='))
                .ToDictionary(
                    x => Uri.UnescapeDataString(x[0]),
                    x => Uri.UnescapeDataString(x.Length > 1 ? x[1] : "")
                );
        }

        private static bool IsContentHeader(string name) =>
            name.StartsWith("Content-", StringComparison.OrdinalIgnoreCase);

        private static void TrySetPooledConnectionLifetime(HttpClientHandler handler, TimeSpan lifetime)
        {
            try
            {

                var prop = handler.GetType().GetProperty("PooledConnectionLifetime", BindingFlags.Instance | BindingFlags.Public | BindingFlags.NonPublic);
                prop?.SetValue(handler, lifetime);
            }
            catch { }
        }
    }
}