using System;
using System.IO;
using System.Security.Cryptography;
using System.Text;
using System.Windows;
using System.Windows.Controls;

using iNKORE.UI.WPF.Modern;

using Microsoft.Win32;

using Org.BouncyCastle.Crypto;
using Org.BouncyCastle.Crypto.Generators;
using Org.BouncyCastle.OpenSsl;
using Org.BouncyCastle.Security;

namespace KeyGen
{
    /// <summary>
    /// MainWindow.xaml 的交互逻辑
    /// </summary>
    public partial class MainWindow
    {
        public MainWindow()
        {
            InitializeComponent();
        }
        private void LicenseClick(object sender, RoutedEventArgs e)
        {
            DateTime issueDate = DateTime.Now;
            //DateTime expiryDate = issueDate.AddYears(1);
            var expiryDate = ExpiryDatePicker.SelectedDate;
            if (expiryDate == null)
            {
                Message.Text = ("请选择授权到期时间");
                return;
            }
            if (expiryDate < issueDate)
            {
                Message.Text = ("授权到期时间有误，应比发码日期晚");
                return;
            }
            string mCode = MachineCodeTextBox.Text.Trim().ToUpper();
            if (string.IsNullOrEmpty(mCode))
            {
                Message.Text = ("请先获取机器码");
                return;
            }
            string key = SignData(mCode, issueDate, expiryDate, PrivateKeyTextBox.Text);
            LicenseTextBox.Text = key;
            Clipboard.SetText(key);
            Message.Text = "激活码已复制！";
        }
        private void GenerateKeyClick(object sender, RoutedEventArgs e)
        {
            //using (var rsa = new RSACryptoServiceProvider(2048))
            //{

            //    PublicKeyTextBox.Text = rsa.ToXmlString(false); // 放在插件里
            //    PrivateKeyTextBox.Text = rsa.ToXmlString(true); // 自己妥善保存 
            //}
            // 1. 生成 RSA 密钥对
            RsaKeyPairGenerator generator = new RsaKeyPairGenerator();
            generator.Init(new KeyGenerationParameters(new SecureRandom(), 2048));
            AsymmetricCipherKeyPair keyPair = generator.GenerateKeyPair();

            // 2. 导出公钥为 PEM 格式 (SubjectPublicKeyInfo - OpenSSL 兼容)
            using (StringWriter sw = new StringWriter())
            {
                PemWriter pemWriter = new PemWriter(sw);
                pemWriter.WriteObject(keyPair.Public);
                PublicKeyTextBox.Text = sw.ToString();
            }

            // 3. 导出私钥为 PEM 格式 (PKCS#1 格式)
            using (StringWriter sw = new StringWriter())
            {
                PemWriter pemWriter = new PemWriter(sw);
                pemWriter.WriteObject(keyPair.Private);
                PrivateKeyTextBox.Text = sw.ToString();
            }
        }

        public string SignData(string machineCode, DateTime issue, DateTime? expiry, string privateKeyPem)
        {
            if (expiry == null)
            {
                throw new ArgumentNullException(nameof(expiry), "Expiry date cannot be null.");
            }
            // 1. 严格格式化日期
            string issueStr = issue.ToString("yyyy-MM-dd");
            string expiryStr = expiry?.ToString("yyyy-MM-dd");

            // 2. 拼接原始数据 (必须带上 |)
            string dataToSign = $"{machineCode}{issueStr}{expiryStr}";

            // 3. 使用 BouncyCastle 签名
            ISigner signer = SignerUtilities.GetSigner("SHA-256withRSA");

            using (StringReader sr = new StringReader(privateKeyPem))
            {
                PemReader pr = new PemReader(sr);
                AsymmetricCipherKeyPair keyPair = (AsymmetricCipherKeyPair)pr.ReadObject();
                signer.Init(true, keyPair.Private);
            }

            byte[] dataBytes = Encoding.UTF8.GetBytes(dataToSign);
            signer.BlockUpdate(dataBytes, 0, dataBytes.Length);
            byte[] sigBytes = signer.GenerateSignature();

            string signature = Convert.ToBase64String(sigBytes);

            // 4. 返回最终激活码
            return $"{signature}|{machineCode}|{issueStr}|{expiryStr}";
        }
        private string CreateLicense(string machineCode, DateTime issue, DateTime expiry)
        {
            string issueStr = issue.ToString("yyyy-MM-dd");
            string expiryStr = expiry.ToString("yyyy-MM-dd");

            // 签名原始数据：机器码 + 发码日期 + 过期日期
            string dataToSign = $"{machineCode}|{issueStr}|{expiryStr}";

            using (var rsa = new RSACryptoServiceProvider())
            {
                rsa.FromXmlString(PrivateKeyTextBox.Text);
                var formatter = new RSAPKCS1SignatureFormatter(rsa);
                formatter.SetHashAlgorithm("SHA256");

                byte[] dataBytes = Encoding.UTF8.GetBytes(dataToSign);
                using (var sha = SHA256.Create())
                {
                    byte[] hash = sha.ComputeHash(dataBytes);
                    string signature = Convert.ToBase64String(formatter.CreateSignature(hash));

                    // 最终格式：签名|机器码|发码日期|过期日期
                    return $"{signature}|{machineCode}|{issueStr}|{expiryStr}";
                }
            }
        }
        private void SaveKeysClick(object sender, RoutedEventArgs e)
        {
            VistaFolderBrowserDialog dialog = new VistaFolderBrowserDialog();
            if (dialog.ShowDialog())
            {
                string publicKeyPath = System.IO.Path.Combine(dialog.SelectedPath, "PublicKey.txt");
                File.WriteAllText(publicKeyPath, PublicKeyTextBox.Text);
                string privateKeyPath = System.IO.Path.Combine(dialog.SelectedPath, "PrivateKey.txt");
                File.WriteAllText(privateKeyPath, PrivateKeyTextBox.Text);
                Message.Text = ($"公私密钥已保存到：{dialog.SelectedPath}");
            }
        }

        private void SaveLicenseClick(object sender, RoutedEventArgs e)
        {
            VistaFolderBrowserDialog dialog = new VistaFolderBrowserDialog();
            if (dialog.ShowDialog())
            {
                string path = System.IO.Path.Combine(dialog.SelectedPath, "license.txt");
                File.WriteAllText(path, LicenseTextBox.Text);
                Message.Text = ($"激活码已保存到：{path}");
            }
        }

        private void ImportPrivateKeyClick(object sender, RoutedEventArgs e)
        {
            OpenFileDialog dialog = new OpenFileDialog()
            {
                Filter = "文本文件 (*.txt)|*.txt|所有文件 (*.*)|*.*"
            };
            if (dialog.ShowDialog() == true)
            {
                string privateKey = File.ReadAllText(dialog.FileName);
                PrivateKeyTextBox.Text = privateKey;
                Message.Text = ($"导入文件私钥完成");
            }
        }
        private void ToggleTheme_Click(object sender, RoutedEventArgs e)
        {
            if (ThemeManager.Current.ApplicationTheme == ApplicationTheme.Dark)
            {
                ThemeManager.Current.ApplicationTheme = ApplicationTheme.Light;
            }
            else
            {
                ThemeManager.Current.ApplicationTheme = ApplicationTheme.Dark;
            }
        }
        /// <summary>
        /// 生成通用的 6 位应急码
        /// </summary>
        /// <param name="durationTag">"1D", "7D", 或 "30D"</param>
        public static string GenerateGlobalOTP(string durationTag, string salt)
        {
            string secret = salt + durationTag;

            // 计算天数步长
            long unixTime = (long)(DateTime.UtcNow - new DateTime(1970, 1, 1)).TotalSeconds;
            long step = unixTime / 86400;

            byte[] secretBytes = Encoding.UTF8.GetBytes(secret);
            // 字符表必须严格一致
            string charset = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ";
            // 步长转 8 字节大端
            byte[] stepBytes = BitConverter.GetBytes(step);
            if (BitConverter.IsLittleEndian) Array.Reverse(stepBytes);
            byte[] msg = new byte[8];
            Array.Copy(stepBytes, 0, msg, 8 - stepBytes.Length, stepBytes.Length);

            using (var hmac = new HMACSHA1(Encoding.UTF8.GetBytes(secret)))
            {
                byte[] hash = hmac.ComputeHash(msg);
                int offset = hash[hash.Length - 1] & 0xf;
                uint binary = (uint)(((hash[offset] & 0x7f) << 24) | ((hash[offset + 1] & 0xff) << 16) | ((hash[offset + 2] & 0xff) << 8) | (hash[offset + 3] & 0xff));

                string code = "";
                for (int i = 0; i < 6; i++)
                {
                    code += charset[(int)(binary % (uint)charset.Length)];
                    binary /= (uint)charset.Length;
                }
                return code;
            }
        }

        private void DynamicLicenseClick(object sender, RoutedEventArgs e)
        {
            if (DynamicDurationComboBox.SelectedItem is not ComboBoxItem selectedItem)
            {
                Message.Text = ("请选择授权时长");
                return;
            }
            if (string.IsNullOrEmpty(SaltTextBox.Text))
            {
                Message.Text = ("请设置Salt值");
                return;
            }
            string durationTag = selectedItem.Tag.ToString();
            string salt = SaltTextBox.Text.Trim();
            string globalOTP = GenerateGlobalOTP(durationTag, salt);
            DynamicLicenseTextBox.Text = globalOTP;
            Clipboard.SetText(globalOTP);
            Message.Text = "动态应急码已复制！";
        }
    }
}