using System;
using System.IO;
using System.Security.Cryptography;
using System.Text;
using System.Text.Json;
using System.Net.Http;
using System.Threading.Tasks;

public class Program
{
    // ==================== 配置区域 ====================
    // 请根据实际情况修改以下配置参数
    
    // AES加密密钥 (16进制字符串，32位)
    
    // API接口配置
    private const string InterfaceName = "XXXXXXXX";  // 接口编号
    private const string AccessId = "XXXXXXXXXXX";    // 访问ID
    private const string EncryptionKey = "XXXXXXXXXXXXXXXXXXX"; // 加密密钥
    private const string BaseUrl = "https://api.tianyuanapi.com";  // API基础URL
    
    // 测试数据配置
    private const string TestMobileNo = "13700000000";  // 测试手机号
    private const string TestIdCard = "XXXXXXXXXXXXX";    // 测试身份证号
    private const string TestName = "XXXXXXXX";           // 测试姓名
    private const string TestAuthDate = "20250318-20270318";  // 测试授权日期
    
    // HTTP请求配置
    private const int RequestTimeout = 30000;  // 请求超时时间(毫秒)
    
    // ==================== 主程序 ====================
    public static async Task Main()
    {
        Console.WriteLine("===== AES CBC 加密解密演示 =====");
        
        // 1. 创建一个JSON对象
        var data = new
        {
            mobile_no = TestMobileNo
        };
        
        // 将JSON对象序列化为字符串
        string jsonString = JsonSerializer.Serialize(data, new JsonSerializerOptions { WriteIndented = true });
        
        Console.WriteLine("\n原始JSON:");
        Console.WriteLine(jsonString);
        
        // 2. 加密JSON
        Console.WriteLine("\n开始加密...");
        string encryptedJson = Encrypt(jsonString);
        Console.WriteLine($"加密成功! 加密后Base64:");
        Console.WriteLine(encryptedJson);
        
        // 3. 解密JSON
        Console.WriteLine("\n开始解密...");
        string decryptedJson = Decrypt(encryptedJson);
        Console.WriteLine($"解密成功! 解密后的原始JSON:");
        Console.WriteLine(decryptedJson);
        
        // 4. 验证加解密一致性
        Console.WriteLine("\n验证结果:");
        if (jsonString == decryptedJson)
        {
            Console.WriteLine("✅ 加解密前后内容完全一致");
            
            // 验证原始数据是否可用
            Console.WriteLine("\n尝试解析解密后的JSON:");
            try
            {
                var deserializedObject = JsonSerializer.Deserialize(decryptedJson, typeof(object));
                Console.WriteLine($"✅ JSON解析成功，类型: {deserializedObject.GetType()}");
            }
            catch (Exception ex)
            {
                Console.WriteLine($"❌ JSON解析失败: {ex.Message}");
            }
        }
        else
        {
            Console.WriteLine("❌ 加解密前后内容不一致!");
            Console.WriteLine("原始长度: " + jsonString.Length);
            Console.WriteLine("解密后长度: " + decryptedJson.Length);
            
            // 找出第一个不同的位置
            for (int i = 0; i < Math.Min(jsonString.Length, decryptedJson.Length); i++)
            {
                if (jsonString[i] != decryptedJson[i])
                {
                    Console.WriteLine($"第一个差异在位置 {i}:");
                    Console.WriteLine($"原始字符: '{jsonString[i]}' ({(int)jsonString[i]})");
                    Console.WriteLine($"解密字符: '{decryptedJson[i]}' ({(int)decryptedJson[i]})");
                    break;
                }
            }
        }
        
        // 5. 演示API调用流程（可选）
        Console.WriteLine("\n===== 演示API调用流程 =====");
        await DemonstrateApiCall();
    }
    
    // ==================== AES加密解密方法 ====================
    
    /// <summary>
    /// AES CBC 加密函数
    /// 使用PKCS7填充，随机IV，返回Base64编码的密文
    /// </summary>
    /// <param name="plainText">要加密的明文</param>
    /// <returns>Base64编码的密文</returns>
    public static string Encrypt(string plainText)
    {
        byte[] key = HexToBytes(EncryptionKey);
        using Aes aes = Aes.Create();
        aes.Key = key;
        aes.Mode = CipherMode.CBC;
        aes.Padding = PaddingMode.PKCS7;

        aes.GenerateIV();
        byte[] iv = aes.IV;

        using ICryptoTransform encryptor = aes.CreateEncryptor();
        using MemoryStream ms = new();
        // 先写入IV
        ms.Write(iv, 0, iv.Length);

        using (CryptoStream cs = new(ms, encryptor, CryptoStreamMode.Write))
        using (StreamWriter sw = new(cs))
        {
            sw.Write(plainText);
        }

        return Convert.ToBase64String(ms.ToArray());
    }

    /// <summary>
    /// AES CBC 解密函数
    /// 从Base64密文中提取IV和密文数据，进行解密
    /// </summary>
    /// <param name="cipherText">Base64编码的密文</param>
    /// <returns>解密后的明文</returns>
    public static string Decrypt(string cipherText)
    {
        byte[] key = HexToBytes(EncryptionKey);
        byte[] fullData = Convert.FromBase64String(cipherText);

        // 提取前16字节作为IV
        byte[] iv = new byte[16];
        Buffer.BlockCopy(fullData, 0, iv, 0, iv.Length);

        // 实际密文数据
        byte[] cipherData = new byte[fullData.Length - 16];
        Buffer.BlockCopy(fullData, 16, cipherData, 0, cipherData.Length);

        using Aes aes = Aes.Create();
        aes.Key = key;
        aes.IV = iv;
        aes.Mode = CipherMode.CBC;
        aes.Padding = PaddingMode.PKCS7;

        using ICryptoTransform decryptor = aes.CreateDecryptor();
        using MemoryStream ms = new(cipherData);
        using CryptoStream cs = new(ms, decryptor, CryptoStreamMode.Read);
        using StreamReader sr = new(cs);
        return sr.ReadToEnd();
    }

    /// <summary>
    /// 将16进制字符串转换为字节数组
    /// </summary>
    /// <param name="hex">16进制字符串</param>
    /// <returns>字节数组</returns>
    private static byte[] HexToBytes(string hex)
    {
        byte[] bytes = new byte[hex.Length / 2];
        for (int i = 0; i < hex.Length; i += 2)
        {
            bytes[i / 2] = Convert.ToByte(hex.Substring(i, 2), 16);
        }
        return bytes;
    }
    
    // ==================== API调用演示方法 ====================
    
    /// <summary>
    /// 演示完整的API调用流程
    /// 包括：参数构建、加密、发送请求、接收响应、解密响应
    /// </summary>
    private static async Task DemonstrateApiCall()
    {
        try
        {
            // 构建完整的API URL
            string url = $"{BaseUrl}/api/v1/{InterfaceName}";
            
            // 构建请求参数
            var apiParams = new
            {
                mobile_no = TestMobileNo,
                id_card = TestIdCard,
                auth_date = TestAuthDate,
                name = TestName
            };
            
            // 将参数转换为JSON字符串并加密
            string jsonStr = JsonSerializer.Serialize(apiParams);
            Console.WriteLine($"请求参数: {jsonStr}");
            
            string encryptedData = Encrypt(jsonStr);
            Console.WriteLine($"加密后的数据: {encryptedData}");
            
            // 构建请求体
            var payload = new { data = encryptedData };
            string requestBody = JsonSerializer.Serialize(payload);
            
            Console.WriteLine($"发送请求到: {url}");
            
            // 发送HTTP请求
            using (var httpClient = new HttpClient())
            {
                // 设置请求头
                httpClient.DefaultRequestHeaders.Add("Access-Id", AccessId);
                httpClient.DefaultRequestHeaders.Add("Content-Type", "application/json");
                
                // 设置超时时间
                httpClient.Timeout = TimeSpan.FromMilliseconds(RequestTimeout);
                
                var content = new StringContent(requestBody, Encoding.UTF8, "application/json");
                var response = await httpClient.PostAsync(url, content);
                
                Console.WriteLine($"响应状态码: {response.StatusCode}");
                
                if (response.IsSuccessStatusCode)
                {
                    string responseBody = await response.Content.ReadAsStringAsync();
                    Console.WriteLine($"API响应: {responseBody}");
                    
                    // 解析响应
                    try
                    {
                        var responseData = JsonSerializer.Deserialize<JsonElement>(responseBody);
                        
                        if (responseData.TryGetProperty("code", out var codeElement))
                        {
                            int code = codeElement.GetInt32();
                            string message = responseData.TryGetProperty("message", out var msgElement) ? msgElement.GetString() : "";
                            string encryptedResponse = responseData.TryGetProperty("data", out var dataElement) ? dataElement.GetString() : "";
                            
                            Console.WriteLine($"API响应码: {code}");
                            Console.WriteLine($"API消息: {message}");
                            
                            if (code == 0 && !string.IsNullOrEmpty(encryptedResponse))
                            {
                                // 解密响应数据
                                try
                                {
                                    string decryptedResponse = Decrypt(encryptedResponse);
                                    Console.WriteLine($"解密后的响应: {decryptedResponse}");
                                }
                                catch (Exception ex)
                                {
                                    Console.WriteLine($"解密响应数据失败: {ex.Message}");
                                }
                            }
                        }
                    }
                    catch (Exception ex)
                    {
                        Console.WriteLine($"解析响应失败: {ex.Message}");
                    }
                }
                else
                {
                    Console.WriteLine($"请求失败: {response.StatusCode}");
                }
            }
        }
        catch (Exception ex)
        {
            Console.WriteLine($"API调用异常: {ex.Message}");
        }
    }
}