using Lskj.Control;
using System;
using System.Collections.Generic;
using System.Drawing;
using System.IO;
using System.Security.Cryptography;
using System.Security.Principal;
using System.Text;
using System.Windows.Forms;

namespace Lskj.GetSecretKey
{
    public partial class LoginFrm : BaseForm
    {
        private ContextMenuStrip _ctx;

        public LoginFrm()
        {
            InitializeComponent();
            SecureUserStore.EnsureInitialized();   // 初始化本地存储（含默认账号）
            InitUi();
            WireEvents();
        }

        #region UI & 事件
        private void InitUi()
        {
            // 密码框设置为 * 掩码（兼容 TextBox / DevExpress TextEdit）
            SetPasswordMask(passWordEidt);

            // 回填上次成功登录账号
            var last = SecureUserStore.GetLastUser();
            if (!string.IsNullOrEmpty(last)) { userNameEdit.Text = last; passWordEidt.Focus(); }
            else userNameEdit.Focus();

            // 提示
            try
            {
                setPanel.Cursor = Cursors.Hand;
                var tip = new ToolTip();
                tip.SetToolTip(setPanel, "左键：修改密码（需当前密码验证）\r\n右键：更多操作（重置密码…）");
            }
            catch { /* ignore */ }

            // 右键菜单
            _ctx = new ContextMenuStrip();
            var miChange = new ToolStripMenuItem("修改密码…", null, (s, e) => DoChangePassword());
            var miReset = new ToolStripMenuItem("重置密码…", null, (s, e) => DoResetPassword());
            _ctx.Items.AddRange(new ToolStripItem[] { miChange, new ToolStripSeparator(), miReset });
            setPanel.ContextMenuStrip = _ctx;
        }

        private void WireEvents()
        {
            // 回车登录
            passWordEidt.KeyDown += (s, e) => { if (e.KeyCode == Keys.Enter) TryLogin(); };

            // 左键点击 setPanel -> 修改密码（需当前密码验证通过）
            setPanel.Click += (s, e) => {
                if (e is MouseEventArgs me && me.Button == MouseButtons.Right) return;
                DoChangePassword();
            };

            // 右键已经由 ContextMenuStrip 处理
        }
        #endregion

        #region 登录/改密/重置
        private void TryLogin()
        {
            string user = (userNameEdit.Text ?? "").Trim();
            string pwd = passWordEidt.Text ?? "";

            if (string.IsNullOrEmpty(user) || string.IsNullOrEmpty(pwd))
            {
                MessageBox.Show("请输入账号和密码。", "提示", MessageBoxButtons.OK, MessageBoxIcon.Information);
                return;
            }

            if (SecureUserStore.Validate(user, pwd))
            {
                SecureUserStore.SetLastUser(user);  // 记住本次成功登录账号
                this.DialogResult = DialogResult.OK;
                this.Close();
            }
            else
            {
                MessageBox.Show("账号或密码错误。", "错误", MessageBoxButtons.OK, MessageBoxIcon.Error);
                passWordEidt.SelectAll();
                passWordEidt.Focus();
            }
        }

        private void DoChangePassword()
        {
            string user = (userNameEdit.Text ?? "").Trim();
            string currPwd = passWordEidt.Text ?? "";

            if (string.IsNullOrEmpty(user))
            {
                MessageBox.Show("请先在账号框输入要修改密码的账号（例如：管理员、管理员1）。", "提示", MessageBoxButtons.OK, MessageBoxIcon.Information);
                userNameEdit.Focus();
                return;
            }
            if (!SecureUserStore.Exists(user))
            {
                MessageBox.Show("账号不存在，仅支持：管理员、管理员1。", "提示", MessageBoxButtons.OK, MessageBoxIcon.Information);
                userNameEdit.Focus(); userNameEdit.SelectAll();
                return;
            }
            // 必须先通过“账号+当前密码”验证
            if (!SecureUserStore.Validate(user, currPwd))
            {
                MessageBox.Show("请先在密码框输入该账号的当前密码并验证通过，然后再修改。", "需要验证", MessageBoxButtons.OK, MessageBoxIcon.Warning);
                passWordEidt.Focus(); passWordEidt.SelectAll();
                return;
            }

            using (var dlg = new ChangePasswordDialog(user))
            {
                if (dlg.ShowDialog(this) == DialogResult.OK)
                {
                    SecureUserStore.SetPassword(user, dlg.NewPassword);
                    MessageBox.Show("密码已更新并安全保存到本地。", "成功", MessageBoxButtons.OK, MessageBoxIcon.Information);
                }
            }
        }

        private void DoResetPassword()
        {
            // 仅管理员权限允许重置
            if (!SecurityUtil.IsAdministrator())
            {
                MessageBox.Show("需要以【管理员身份运行】程序后才能重置密码。", "权限不足", MessageBoxButtons.OK, MessageBoxIcon.Warning);
                return;
            }

            using (var dlg = new ResetConfirmDialog())
            {
                if (dlg.ShowDialog(this) != DialogResult.OK) return;

                // 校验重置口令（你可以修改 SecureReset.ResetSecret 自定义口令）
                if (!SecureReset.VerifyResetCode(dlg.ResetCode))
                {
                    MessageBox.Show("重置口令不正确。", "校验失败", MessageBoxButtons.OK, MessageBoxIcon.Error);
                    return;
                }
            }

            string user = (userNameEdit.Text ?? "").Trim();

            if (string.IsNullOrEmpty(user))
            {
                // 未指定账号 -> 询问是否重置所有内置账号
                if (MessageBox.Show("未填写账号，是否重置所有内置账号为默认密码 123456？",
                    "重置确认", MessageBoxButtons.YesNo, MessageBoxIcon.Question) == DialogResult.Yes)
                {
                    foreach (var u in SecureUserStore.BuiltinUsers) SecureUserStore.ResetToDefault(u);
                    MessageBox.Show("所有内置账号已重置为 123456。", "成功", MessageBoxButtons.OK, MessageBoxIcon.Information);
                }
            }
            else
            {
                if (!SecureUserStore.Exists(user))
                {
                    MessageBox.Show("账号不存在，无法重置。", "提示", MessageBoxButtons.OK, MessageBoxIcon.Information);
                    return;
                }
                if (MessageBox.Show($"确定将「{user}」密码重置为 123456？",
                    "重置确认", MessageBoxButtons.YesNo, MessageBoxIcon.Question) == DialogResult.Yes)
                {
                    SecureUserStore.ResetToDefault(user);
                    MessageBox.Show("已重置为 123456。", "成功", MessageBoxButtons.OK, MessageBoxIcon.Information);
                }
            }
        }
        #endregion

        #region 工具：为控件设置 * 掩码（兼容 TextBox / DevExpress TextEdit）
        private static void SetPasswordMask(System.Windows.Forms.Control ctrl)
        {
            try
            {
                var t = ctrl.GetType();
                var propPwdChar = t.GetProperty("PasswordChar");
                if (propPwdChar != null && propPwdChar.CanWrite) propPwdChar.SetValue(ctrl, '*', null);

                var propUseSys = t.GetProperty("UseSystemPasswordChar");
                if (propUseSys != null && propUseSys.CanWrite) propUseSys.SetValue(ctrl, true, null);

                var propProperties = t.GetProperty("Properties");
                if (propProperties != null)
                {
                    var propsObj = propProperties.GetValue(ctrl, null);
                    if (propsObj != null)
                    {
                        var px = propsObj.GetType();
                        var p1 = px.GetProperty("PasswordChar"); if (p1 != null && p1.CanWrite) p1.SetValue(propsObj, '*', null);
                        var p2 = px.GetProperty("UseSystemPasswordChar"); if (p2 != null && p2.CanWrite) p2.SetValue(propsObj, true, null);
                    }
                }
            }
            catch { /* ignore */ }
        }
        #endregion
    }

    #region 安全工具 & 重置口令校验
    internal static class SecurityUtil
    {
        public static bool IsAdministrator()
        {
            try
            {
                using (var identity = WindowsIdentity.GetCurrent())
                {
                    var principal = new WindowsPrincipal(identity);
                    return principal.IsInRole(WindowsBuiltInRole.Administrator);
                }
            }
            catch { return false; }
        }

        public static string Sha256(string s)
        {
            using (var sha = SHA256.Create())
            {
                var bytes = sha.ComputeHash(Encoding.UTF8.GetBytes(s ?? ""));
                var sb = new StringBuilder(bytes.Length * 2);
                foreach (var b in bytes) sb.Append(b.ToString("x2"));
                return sb.ToString();
            }
        }
    }

    internal static class SecureReset
    {
        // ★ 重置口令（明文）。建议你改成自己的：仅内部人员知悉。
        private const string ResetSecret = "Lskj#Reset2025";
        private static readonly string ResetHash = SecurityUtil.Sha256(ResetSecret);

        public static bool VerifyResetCode(string input)
            => string.Equals(SecurityUtil.Sha256(input ?? ""), ResetHash, StringComparison.OrdinalIgnoreCase);
    }
    #endregion

    #region 本地安全存储（DPAPI 加密 + 记住上次账号）
    internal static class SecureUserStore
    {
        // %LOCALAPPDATA%\Lskj.GetSecretKey\
        private static readonly string AppDir = Path.Combine(Environment.GetFolderPath(Environment.SpecialFolder.LocalApplicationData), "Lskj.GetSecretKey");
        private static readonly string StorePath = Path.Combine(AppDir, "users.sec");      // 用户: 密文
        private static readonly string LastUserPath = Path.Combine(AppDir, "lastuser.dat");   // 纯文本：上一次成功登录账号
        private static readonly byte[] Entropy = Encoding.UTF8.GetBytes("Lskj.GetSecretKey|DPAPI|v1");
        internal static readonly string[] BuiltinUsers = new[] { "管理员", "管理员1" }; // 供外部枚举使用
        private const string DefaultPassword = "123456";

        // 缓存：用户名 -> Base64(Protect(UTF8(pwd)))
        private static readonly Dictionary<string, string> _cipherMap = new Dictionary<string, string>(StringComparer.Ordinal);
        private static bool _initialized;
        private static readonly object _lock = new object();

        public static void EnsureInitialized()
        {
            if (_initialized) return;
            lock (_lock)
            {
                if (_initialized) return;
                Directory.CreateDirectory(AppDir);

                if (!File.Exists(StorePath))
                {
                    foreach (var u in BuiltinUsers) _cipherMap[u] = ProtectToBase64(DefaultPassword);
                    Persist();
                }
                else
                {
                    Load();
                    bool changed = false;
                    foreach (var u in BuiltinUsers)
                        if (!_cipherMap.ContainsKey(u)) { _cipherMap[u] = ProtectToBase64(DefaultPassword); changed = true; }
                    if (changed) Persist();
                }
                _initialized = true;
            }
        }

        public static bool Exists(string user) { EnsureInitialized(); return _cipherMap.ContainsKey(user); }

        public static bool Validate(string user, string plainPwd)
        {
            EnsureInitialized();
            if (!_cipherMap.TryGetValue(user, out var b64)) return false;
            try { return UnprotectFromBase64(b64) == (plainPwd ?? ""); }
            catch { return false; }
        }

        public static void SetPassword(string user, string newPwd)
        {
            EnsureInitialized();
            if (string.IsNullOrEmpty(user)) return;
            _cipherMap[user] = ProtectToBase64(newPwd ?? "");
            Persist();
        }

        public static void ResetToDefault(string user)
        {
            EnsureInitialized();
            if (string.IsNullOrEmpty(user)) return;
            _cipherMap[user] = ProtectToBase64(DefaultPassword);
            Persist();
        }

        public static void SetLastUser(string user)
        {
            try { File.WriteAllText(LastUserPath, user ?? "", Encoding.UTF8); }
            catch { /* ignore */ }
        }

        public static string GetLastUser()
        {
            try { return File.Exists(LastUserPath) ? (File.ReadAllText(LastUserPath, Encoding.UTF8).Trim()) : ""; }
            catch { return ""; }
        }

        private static void Load()
        {
            _cipherMap.Clear();
            foreach (var line in File.ReadAllLines(StorePath, Encoding.UTF8))
            {
                if (string.IsNullOrWhiteSpace(line)) continue;
                var idx = line.IndexOf('=');
                if (idx <= 0) continue;
                var key = line.Substring(0, idx);
                var val = line.Substring(idx + 1);
                if (!_cipherMap.ContainsKey(key)) _cipherMap[key] = val;
            }
        }

        private static void Persist()
        {
            var sb = new StringBuilder();
            foreach (var kv in _cipherMap) sb.Append(kv.Key).Append('=').Append(kv.Value).Append('\n');
            File.WriteAllText(StorePath, sb.ToString(), Encoding.UTF8);
        }

        private static string ProtectToBase64(string plain)
        {
            var bytes = Encoding.UTF8.GetBytes(plain ?? "");
            var cipher = ProtectedData.Protect(bytes, Entropy, DataProtectionScope.CurrentUser);
            return Convert.ToBase64String(cipher);
        }

        private static string UnprotectFromBase64(string base64)
        {
            var cipher = Convert.FromBase64String(base64 ?? "");
            var plain = ProtectedData.Unprotect(cipher, Entropy, DataProtectionScope.CurrentUser);
            return Encoding.UTF8.GetString(plain);
        }
    }
    #endregion

    #region 修改密码对话框
    internal sealed class ChangePasswordDialog : Form
    {
        private readonly string _user;
        private TextBox txtNew, txtConfirm;
        private Button btnOk, btnCancel;
        public string NewPassword { get; private set; }

        public ChangePasswordDialog(string user)
        {
            _user = user;
            BuildUi();
        }

        private void BuildUi()
        {
            this.Text = $"修改密码 - {_user}";
            this.FormBorderStyle = FormBorderStyle.FixedDialog;
            this.StartPosition = FormStartPosition.CenterParent;
            this.ClientSize = new Size(340, 170);
            this.MaximizeBox = false; this.MinimizeBox = false;

            var lbl1 = new Label { Text = "新密码：", AutoSize = true, Location = new Point(20, 28) };
            var lbl2 = new Label { Text = "确认新密码：", AutoSize = true, Location = new Point(20, 68) };

            txtNew = new TextBox { Location = new Point(130, 24), Width = 180, UseSystemPasswordChar = true, PasswordChar = '*' };
            txtConfirm = new TextBox { Location = new Point(130, 64), Width = 180, UseSystemPasswordChar = true, PasswordChar = '*' };

            btnOk = new Button { Text = "确定", DialogResult = DialogResult.OK, Location = new Point(130, 110), Width = 80 };
            btnCancel = new Button { Text = "取消", DialogResult = DialogResult.Cancel, Location = new Point(230, 110), Width = 80 };

            btnOk.Click += (s, e) =>
            {
                if (string.IsNullOrEmpty(txtNew.Text))
                {
                    MessageBox.Show("新密码不能为空。", "提示", MessageBoxButtons.OK, MessageBoxIcon.Information);
                    this.DialogResult = DialogResult.None; return;
                }
                if (txtNew.Text != txtConfirm.Text)
                {
                    MessageBox.Show("两次输入的密码不一致。", "提示", MessageBoxButtons.OK, MessageBoxIcon.Information);
                    this.DialogResult = DialogResult.None; return;
                }
                NewPassword = txtNew.Text;
            };

            this.Controls.AddRange(new System.Windows.Forms.Control[] { lbl1, txtNew, lbl2, txtConfirm, btnOk, btnCancel });
            this.AcceptButton = btnOk; this.CancelButton = btnCancel;
        }
    }
    #endregion

    #region 重置口令对话框
    internal sealed class ResetConfirmDialog : Form
    {
        private TextBox txtCode;
        private Button btnOk, btnCancel;
        public string ResetCode { get; private set; }

        public ResetConfirmDialog() { BuildUi(); }

        private void BuildUi()
        {
            this.Text = "输入重置口令";
            this.FormBorderStyle = FormBorderStyle.FixedDialog;
            this.StartPosition = FormStartPosition.CenterParent;
            this.ClientSize = new Size(360, 150);
            this.MaximizeBox = false; this.MinimizeBox = false;

            var lbl = new Label { Text = "重置口令：", AutoSize = true, Location = new Point(20, 30) };
            txtCode = new TextBox { Location = new Point(100, 26), Width = 220, UseSystemPasswordChar = true, PasswordChar = '*' };

            btnOk = new Button { Text = "确定", DialogResult = DialogResult.OK, Location = new Point(160, 80), Width = 75 };
            btnCancel = new Button { Text = "取消", DialogResult = DialogResult.Cancel, Location = new Point(245, 80), Width = 75 };

            btnOk.Click += (s, e) =>
            {
                if (string.IsNullOrEmpty(txtCode.Text))
                {
                    MessageBox.Show("请输入重置口令。", "提示", MessageBoxButtons.OK, MessageBoxIcon.Information);
                    this.DialogResult = DialogResult.None; return;
                }
                ResetCode = txtCode.Text;
            };

            this.Controls.AddRange(new System.Windows.Forms.Control[] { lbl, txtCode, btnOk, btnCancel });
            this.AcceptButton = btnOk; this.CancelButton = btnCancel;
        }
    }
    #endregion
}