using System;
using System.Collections.Generic;
using System.Linq;
using System.Security.Cryptography;
using System.Text;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;

namespace FineUIPro.Web.HSSE.Hazard
{
    public partial class ToHazard : PageBase
    {

        public string url
        {
            get
            {
                return (string)ViewState["url"];
            }
            set
            {
                ViewState["url"] = value;
            }
        }
        protected void Page_Load(object sender, EventArgs e)
        {
            url =  BuildRedirectUrl(CurrUser.Account); 
        }// 密钥（与Java完全一致）
        private const string SECRET_B64 = "y3KXl9sle7+WUpwyVajCyx8LyQdZSwUUgVS69FDvuR8=";
        // 登录接口地址
        private const string API_LOGIN = "https://hse-ai.cwcec.com/api/auth/unified-login";

        /// <summary>
        /// 构建统一登录跳转URL（C#版，与Java逻辑完全一致）
        /// </summary>
        /// <param name="username">用户名</param>
        /// <returns>加密签名字符串</returns>
        public static string BuildRedirectUrl(string username)
        {
            // 1. Base64 解码密钥
            byte[] key = Convert.FromBase64String(SECRET_B64);

            // 2. 生成时间戳（秒）、随机nonce
            long ts = DateTimeOffset.UtcNow.ToUnixTimeSeconds();
            string nonce = Guid.NewGuid().ToString("N"); // 去掉横杠，与Java一致

            // 3. 构建JSON明文
            string json = $"{{\"username\":\"{username}\",\"timestamp\":{ts},\"nonce\":\"{nonce}\"}}";

            // 4. AES-CBC-PKCS7 加密（Hutool默认：随机IV，输出 = IV + 密文）
            string data = AesCbcEncrypt(json, key);

            // 5. 构建签名原文 + HMACSHA256 签名
            string signPayload = $"data={data}&timestamp={ts}&nonce={nonce}";
            string sign = HmacSha256Sign(signPayload, key);

            // 6. 构建有序参数（LinkedHashMap 对应 SortedDictionary / 手动有序）
            var queryParams = new Dictionary<string, string>
        {
            { "data", data },
            { "timestamp", ts.ToString() },
            { "nonce", nonce },
            { "sign", sign }
        };

            // 7. 拼接URL（URL编码）
            StringBuilder sb = new StringBuilder(API_LOGIN).Append('?');
            foreach (var kvp in queryParams)
            {
                sb.Append(HttpUtility.UrlEncode(kvp.Key))
                  .Append('=')
                  .Append(HttpUtility.UrlEncode(kvp.Value))
                  .Append('&');
            }

            // 去掉最后一个 &
            if (sb.Length > 0) sb.Length--;

            return sb.ToString();
        }

        #region 核心加密工具方法（与Java Hutool完全对齐）
        /// <summary>
        /// AES-CBC-PKCS7 加密
        /// 输出格式：IV(16字节) + 密文 → Base64（和Hutool AES.encrypt 行为一致）
        /// </summary>
        private static string AesCbcEncrypt(string plainText, byte[] key)
        {
            using (Aes aes = Aes.Create())
            {
                aes.Key = key;
                aes.Mode = CipherMode.CBC;
                aes.Padding = PaddingMode.PKCS7; // 与Java PKCS5Padding 通用兼容
                aes.GenerateIV(); // 自动生成随机16字节IV（和Java一致）

                using (var encryptor = aes.CreateEncryptor(aes.Key, aes.IV))
                using (var ms = new System.IO.MemoryStream())
                {
                    // 先写入IV（Hutool默认格式：IV + 密文）
                    ms.Write(aes.IV, 0, aes.IV.Length);

                    using (var cs = new CryptoStream(ms, encryptor, CryptoStreamMode.Write))
                    using (var sw = new System.IO.StreamWriter(cs, Encoding.UTF8))
                    {
                        sw.Write(plainText);
                    }

                    // 输出：IV + 密文 → Base64
                    return Convert.ToBase64String(ms.ToArray());
                }
            }
        }

        /// <summary>
        /// HMACSHA256 签名（小写十六进制）
        /// </summary>
        private static string HmacSha256Sign(string payload, byte[] key)
        {
            using (var hmac = new HMACSHA256(key))
            {
                byte[] payloadBytes = Encoding.UTF8.GetBytes(payload);
                byte[] hashBytes = hmac.ComputeHash(payloadBytes);

                // 转小写十六进制（与Java digestHex一致）
                return BitConverter.ToString(hashBytes).Replace("-", "").ToLower();
            }
        }
        #endregion
    }
}