using System.Net;
using System.Text;
using System.Text.Json;
using System.Text.Json.Serialization;
using Microsoft.Extensions.Caching.Memory;

namespace MegghysAPI.Modules
{
    /// <summary>
    /// 代理IP管理器
    /// </summary>
    public static class ProxyManager
    {
        // 用于获取代理IP的客户端，不使用代理
        private static readonly HttpClient ProxyApiHttpClient = new();
        // 缓存代理IP的响应
        private static readonly MemoryCache ProxyResponseCache = new(new MemoryCacheOptions());
        // 缓存配置了代理的HttpClient
        private static readonly MemoryCache HttpClientCache = new(new MemoryCacheOptions());

        private const string BaseUrl = "https://share.proxy.qg.net/get";
        private const string DefaultKey = "9IK2T3XL";
        private const string DefaultPassword = "04BC86C88CDB";

        /// <summary>
        /// 获取配置了代理的 HttpClient，带缓存和自动释放功能
        /// </summary>
        /// <param name="proxyAddress">可选的代理地址。如果为空，则自动获取。</param>
        /// <param name="key">代理用户名</param>
        /// <param name="password">代理密码</param>
        /// <returns>配置好代理的 HttpClient</returns>
        public static async Task<HttpClient> GetHttpClientAsync(string? proxyAddress = null, string key = DefaultKey, string password = DefaultPassword)
        {
            // 如果未提供代理地址，则从API获取
            if (string.IsNullOrWhiteSpace(proxyAddress))
            {
                var proxyResponse = await GetProxyAsync(key: key);
                var proxyIp = proxyResponse?.Data?.FirstOrDefault();

                if (proxyIp?.Server == null || proxyIp.Deadline == null)
                {
                    // 如果无法获取有效代理，返回一个不带代理的普通HttpClient
                    return new HttpClient();
                }

                // 检查缓存中是否已有此代理的HttpClient
                if (HttpClientCache.TryGetValue(proxyIp.Server, out HttpClient? cachedClient))
                {
                    return cachedClient!;
                }

                // 创建新的HttpClient并配置缓存
                var client = CreateConfiguredHttpClient(proxyIp.Server, key, password);
                var deadline = DateTime.Parse(proxyIp.Deadline);

                var cacheEntryOptions = new MemoryCacheEntryOptions()
                    .SetAbsoluteExpiration(deadline)
                    .RegisterPostEvictionCallback((cacheKey, value, reason, state) =>
                    {
                        (value as HttpClient)?.Dispose();
                    });

                HttpClientCache.Set(proxyIp.Server, client, cacheEntryOptions);
                return client;
            }
            else
            {
                // 如果用户手动提供了代理地址，我们无法知道其过期时间，因此不进行缓存
                return CreateConfiguredHttpClient(proxyAddress, key, password);
            }
        }

        private static HttpClient CreateConfiguredHttpClient(string proxyAddress, string key, string password)
        {
            var handler = new HttpClientHandler
            {
                AutomaticDecompression = DecompressionMethods.All,
                Proxy = new WebProxy(proxyAddress, false)
                {
                    Credentials = new NetworkCredential(key, password)
                },
                UseProxy = true
            };
            var client = new HttpClient(handler, disposeHandler: true);
            client.DefaultRequestHeaders.Add("User-Agent", "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/122.0.0.0 Safari/537.36");

            return client;
        }

        /// <summary>
        /// 异步获取代理IP, 带缓存功能
        /// </summary>
        public static async Task<ProxyResponse?> GetProxyAsync(string key = DefaultKey, string? area = null, string? areaEx = null, int? isp = null, int? num = null, bool? distinct = null)
        {
            var queryParams = new Dictionary<string, string?>
            {
                { "key", key },
                { "area", area },
                { "area_ex", areaEx },
                { "isp", isp?.ToString() },
                { "num", num?.ToString() },
                { "distinct", distinct?.ToString().ToLower() }
            };

            var queryString = string.Join("&", queryParams
                .Where(kvp => !string.IsNullOrEmpty(kvp.Value))
                .Select(kvp => $"{kvp.Key}={Uri.EscapeDataString(kvp.Value!)}"));

            var cacheKey = $"ProxyResponse_{queryString}";

            if (ProxyResponseCache.TryGetValue(cacheKey, out ProxyResponse? cachedResponse))
            {
                return cachedResponse;
            }

            var requestUrl = $"{BaseUrl}?{queryString}";

            try
            {
                var response = await ProxyApiHttpClient.GetAsync(requestUrl);
                response.EnsureSuccessStatusCode();
                var json = await response.Content.ReadAsStringAsync();
                var proxyResponse = JsonSerializer.Deserialize<ProxyResponse>(json);

                if (proxyResponse?.Code == "SUCCESS" && proxyResponse.Data?.Any() == true)
                {
                    // 使用代理的过期时间作为缓存的过期时间
                    var deadline = DateTime.Parse(proxyResponse.Data.First().Deadline!);
                    ProxyResponseCache.Set(cacheKey, proxyResponse, deadline);
                }

                return proxyResponse;
            }
            catch (HttpRequestException e)
            {
                Console.WriteLine($"请求代理IP时发生错误: {e.Message}");
                return null;
            }
        }
    }

    /// <summary>
    /// 代理IP接口响应
    /// </summary>
    public class ProxyResponse
    {
        [JsonPropertyName("code")]
        public string? Code { get; set; }

        [JsonPropertyName("data")]
        public List<ProxyIp>? Data { get; set; }

        [JsonPropertyName("request_id")]
        public string? RequestId { get; set; }
    }

    /// <summary>
    /// 代理IP信息
    /// </summary>
    public class ProxyIp
    {
        [JsonPropertyName("proxy_ip")]
        public string? ProxyIpAddress { get; set; }

        [JsonPropertyName("server")]
        public string? Server { get; set; }

        [JsonPropertyName("area")]
        public string? Area { get; set; }

        [JsonPropertyName("isp")]
        public string? Isp { get; set; }

        [JsonPropertyName("deadline")]
        public string? Deadline { get; set; }
    }
}