Program.cs

using System;
using System.Drawing;
using System.IO;
using System.Collections.Generic;
using System.Globalization;
using System.Runtime.InteropServices;
using System.Windows.Forms;
using Windows.Devices.Enumeration;
using Microsoft.Win32;

namespace MagicKeyBattery;

static class Program
{
    private static System.Windows.Forms.Timer? _timer;
    private static NotifyIcon? _trayIcon;
    private static ToolStripMenuItem? _batteryMenu;

    // 内部設定値（レジストリ同期用）
    private static int _intervalMinutes = 3;
    private static int _notifyThreshold = 20;
    private static string _language = "en"; // デフォルトは英語（Reddit想定）
    private static bool _hasNotifiedLowBattery = false;

    [DllImport("user32.dll", CharSet = CharSet.Auto)]
    private static extern bool DestroyIcon(IntPtr handle);
    private static IntPtr _currentIconHandle = IntPtr.Zero;

    private const string REG_RUN_KEY = @"SOFTWARE\Microsoft\Windows\CurrentVersion\Run";
    private const string REG_APP_KEY = @"SOFTWARE\MagicKeyBattery\Settings";
    private const string APP_NAME = "MagicKeyBattery";

    // --- Win32 API 宣言 ---
    [DllImport("kernel32.dll", SetLastError = true, CharSet = CharSet.Auto)]
    private static extern IntPtr CreateFile(string lpFileName, uint dwDesiredAccess, uint dwShareMode, IntPtr lpSecurityAttributes, uint dwCreationDisposition, uint dwFlagsAndAttributes, IntPtr hTemplateFile);
    [DllImport("kernel32.dll", SetLastError = true)]
    private static extern bool CloseHandle(IntPtr hObject);
    [DllImport("hid.dll", SetLastError = true)]
    private static extern bool HidD_GetInputReport(IntPtr HidDeviceObject, byte[] ReportBuffer, uint ReportBufferLength);

    private const uint FILE_SHARE_READ = 0x00000001;
    private const uint FILE_SHARE_WRITE = 0x00000002;
    private const uint OPEN_EXISTING = 3;
    private static readonly IntPtr INVALID_HANDLE_VALUE = new IntPtr(-1);

    // --- 多言語辞書 ---
    private static readonly Dictionary<string, Dictionary<string, string>> LocalizedText = new()
    {
        ["en"] = new()
        {
            ["checking"] = "Checking connection...",
            ["not_connected"] = "Not Connected",
            ["click_retry"] = "Not Connected (Click to retry)",
            ["click_refresh"] = "Click to refresh now",
            ["open_settings"] = "⚙️ Settings...",
            ["exit_app"] = "❌ Exit Application",
            ["dialog_title"] = "MagicKeyBattery Settings",
            ["lbl_interval"] = "Update Interval (Min):",
            ["lbl_threshold"] = "Low Battery Notification (%):",
            ["lbl_hint"] = "*Set to 0 to disable notifications",
            ["chk_startup"] = "Run at Windows Startup",
            ["btn_save"] = "Save",
            ["notify_title"] = "Low Battery Warning",
            ["notify_body"] = "Magic Keyboard battery is below {0}% (Current: {1}%)"
        },
        ["ja"] = new()
        {
            ["checking"] = "接続確認中...",
            ["not_connected"] = "未接続",
            ["click_retry"] = "未接続 (クリックで再試行)",
            ["click_refresh"] = "クリックで今すぐ更新",
            ["open_settings"] = "⚙️ 設定を開く...",
            ["exit_app"] = "❌ アプリを終了",
            ["dialog_title"] = "MagicKeyBattery 設定",
            ["lbl_interval"] = "自動更新間隔 (分):",
            ["lbl_threshold"] = "低残量通知を行う基準 (%):",
            ["lbl_hint"] = "※0に設定すると通知オフになります",
            ["chk_startup"] = "Windows起動時に実行する",
            ["btn_save"] = "保存",
            ["notify_title"] = "バッテリー残量警告",
            ["notify_body"] = "Magic Keyboard の残量が {0}% 以下（現在: {1}%）になりました。"
        }
    };

    private static string T(string key) => LocalizedText[_language].ContainsKey(key) ? LocalizedText[_language][key] : key;

    [STAThread]
    static void Main()
    {
        ApplicationConfiguration.Initialize();

        // レジストリから保存された設定をロード
        LoadSettings();

        _trayIcon = new NotifyIcon();
        _trayIcon.Text = $"Magic Keyboard: {T("checking")}";
        _trayIcon.Icon = SystemIcons.Application;

        BuildContextMenu();

        _trayIcon.Visible = true;

        _timer = new System.Windows.Forms.Timer();
        _timer.Interval = _intervalMinutes * 60 * 1000;
        _timer.Tick += async (s, e) => await UpdateBatteryLevelAsync();
        _timer.Start();

        _ = UpdateBatteryLevelAsync();

        Application.Run();
    }

    private static void BuildContextMenu()
    {
        if (_trayIcon == null) return;

        ContextMenuStrip contextMenu = new ContextMenuStrip();

        string currentText = _batteryMenu?.Text ?? $"🔋 Magic Keyboard: {T("checking")}";
        _batteryMenu = new ToolStripMenuItem(currentText, null, async (s, e) => {
            await UpdateBatteryLevelAsync();
        });
        contextMenu.Items.Add(_batteryMenu);
        contextMenu.Items.Add(new ToolStripSeparator());

        contextMenu.Items.Add(T("open_settings"), null, (s, e) => {
            ShowSettingsDialog();
        });
        contextMenu.Items.Add(new ToolStripSeparator());

        contextMenu.Items.Add(T("exit_app"), null, (s, e) => {
            _timer?.Stop();
            _trayIcon.Visible = false;
            if (_currentIconHandle != IntPtr.Zero) DestroyIcon(_currentIconHandle);
            Application.Exit();
        });

        _trayIcon.ContextMenuStrip = contextMenu;
    }

    private static async Task UpdateBatteryLevelAsync()
    {
        try
        {
            string[] endpointProperties = { "System.Devices.Aep.ContainerId", "System.Devices.Aep.IsConnected" };
            var endpoints = await DeviceInformation.FindAllAsync("", endpointProperties, DeviceInformationKind.AssociationEndpoint);

            Guid? targetContainerId = null;
            bool isConnected = false;

            foreach (var ep in endpoints)
            {
                if (string.IsNullOrEmpty(ep.Name)) continue;
                if (ep.Name.Contains("Magic Keyboard", StringComparison.OrdinalIgnoreCase))
                {
                    if (ep.Properties.ContainsKey("System.Devices.Aep.ContainerId"))
                    {
                        targetContainerId = (Guid?)ep.Properties["System.Devices.Aep.ContainerId"];
                        isConnected = (bool?)ep.Properties["System.Devices.Aep.IsConnected"] ?? false;
                        break;
                    }
                }
            }

            if (targetContainerId == null || !isConnected)
            {
                UpdateUI(0, false);
                return;
            }

            string interfaceAqs = $"System.Devices.ContainerId:=\"{{{targetContainerId}}}\"";
            var interfaces = await DeviceInformation.FindAllAsync(interfaceAqs, null, DeviceInformationKind.DeviceInterface);

            foreach (var iface in interfaces)
            {
                if (iface.Id.Contains("hid", StringComparison.OrdinalIgnoreCase) && iface.Id.Contains("Col02", StringComparison.OrdinalIgnoreCase))
                {
                    IntPtr handle = CreateFile(iface.Id, 0, FILE_SHARE_READ | FILE_SHARE_WRITE, IntPtr.Zero, OPEN_EXISTING, 0, IntPtr.Zero);

                    if (handle != INVALID_HANDLE_VALUE)
                    {
                        byte[] buffer = new byte[8];
                        buffer[0] = 0x90;

                        if (HidD_GetInputReport(handle, buffer, (uint)buffer.Length))
                        {
                            byte batteryLevel = buffer[2];
                            if (batteryLevel <= 100 && batteryLevel > 0)
                            {
                                UpdateUI(batteryLevel, true);
                            }
                        }
                        CloseHandle(handle);
                        break;
                    }
                }
            }
        }
        catch { }
    }

    private static void UpdateUI(byte level, bool connected)
    {
        if (_trayIcon == null || _batteryMenu == null) return;

        if (!connected)
        {
            _trayIcon.Text = $"Magic Keyboard: {T("not_connected")}";
            _batteryMenu.Text = $"📴 Magic Keyboard: {T("click_retry")}";
            SetDynamicIcon(0, false);
            _hasNotifiedLowBattery = false;
            return;
        }

        _trayIcon.Text = $"Magic Keyboard: {level}%";
        string emoji = level >= 50 ? "🔋" : (level >= 20 ? "🔋" : "🪫");
        _batteryMenu.Text = $"{emoji} Magic Keyboard: {level}% ({T("click_refresh")})";

        SetDynamicIcon(level, true);

        if (_notifyThreshold > 0 && level <= _notifyThreshold)
        {
            if (!_hasNotifiedLowBattery)
            {
                _trayIcon.ShowBalloonTip(
                    5000,
                    T("notify_title"),
                    string.Format(T("notify_body"), _notifyThreshold, level),
                    ToolTipIcon.Warning
                );
                _hasNotifiedLowBattery = true;
            }
        }
        else
        {
            _hasNotifiedLowBattery = false;
        }
    }

    private static void SetDynamicIcon(byte level, bool connected)
    {
        if (_trayIcon == null) return;

        using (Bitmap bmp = new Bitmap(16, 16))
        using (Graphics g = Graphics.FromImage(bmp))
        {
            g.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.None;
            g.Clear(Color.Transparent);

            if (!connected)
            {
                using (Pen grayPen = new Pen(Color.FromArgb(120, 120, 120), 1))
                using (Pen redPen = new Pen(Color.Crimson, 2))
                {
                    g.DrawRectangle(grayPen, 1, 3, 11, 9);
                    g.DrawLine(redPen, 3, 3, 11, 11);
                    g.DrawLine(redPen, 11, 3, 3, 11);
                }
            }
            else
            {
                Color statusColor = level >= 50 ? Color.LimeGreen : (level >= 20 ? Color.Orange : Color.Crimson);
                using (Pen framePen = new Pen(statusColor, 1))
                using (Brush solidBrush = new SolidBrush(statusColor))
                {
                    g.DrawRectangle(framePen, 0, 3, 12, 9);
                    g.FillRectangle(solidBrush, 13, 6, 2, 4);

                    int barWidth = (int)Math.Max(1, Math.Round((level / 100.0) * 10.0));
                    if (barWidth > 10) barWidth = 10;
                    g.FillRectangle(solidBrush, 2, 5, barWidth, 6);
                }
            }

            IntPtr hIcon = bmp.GetHicon();
            _trayIcon.Icon = Icon.FromHandle(hIcon);

            if (_currentIconHandle != IntPtr.Zero) DestroyIcon(_currentIconHandle);
            _currentIconHandle = hIcon;
        }
    }

    private static void ShowSettingsDialog()
    {
        Form configForm = new Form
        {
            Width = 340,
            Height = 280,
            Text = T("dialog_title"),
            StartPosition = FormStartPosition.CenterScreen,
            FormBorderStyle = FormBorderStyle.FixedDialog,
            MaximizeBox = false,
            MinimizeBox = false,
            BackColor = Color.FromArgb(30, 30, 30),
            ForeColor = Color.White
        };

        Label lblInterval = new Label { Text = T("lbl_interval"), Left = 20, Top = 20, Width = 150, ForeColor = Color.LightGray };
        NumericUpDown numInterval = new NumericUpDown { Left = 180, Top = 18, Width = 80, Minimum = 1, Maximum = 60, Value = _intervalMinutes, BackColor = Color.FromArgb(50, 50, 50), ForeColor = Color.White };

        Label lblThreshold = new Label { Text = T("lbl_threshold"), Left = 20, Top = 60, Width = 150, ForeColor = Color.LightGray };
        NumericUpDown numThreshold = new NumericUpDown { Left = 180, Top = 58, Width = 80, Minimum = 0, Maximum = 100, Value = _notifyThreshold, BackColor = Color.FromArgb(50, 50, 50), ForeColor = Color.White };
        Label lblHint = new Label { Text = T("lbl_hint"), Left = 20, Top = 85, Width = 280, Font = new Font(configForm.Font.FontFamily, 7.5f), ForeColor = Color.Gray };

        Label lblLang = new Label { Text = "Language / 言語:", Left = 20, Top = 115, Width = 150, ForeColor = Color.LightGray };
        ComboBox cmbLang = new ComboBox { Left = 180, Top = 112, Width = 80, DropDownStyle = ComboBoxStyle.DropDownList, BackColor = Color.FromArgb(50, 50, 50), ForeColor = Color.White };
        cmbLang.Items.AddRange(new object[] { "en", "ja" });
        cmbLang.SelectedItem = _language;

        CheckBox chkStartup = new CheckBox { Text = T("chk_startup"), Left = 20, Top = 155, Width = 250, Checked = IsStartupEnabled(), ForeColor = Color.LightGray };

        Button btnSave = new Button { Text = T("btn_save"), Left = 115, Top = 200, Width = 90, Height = 30, FlatStyle = FlatStyle.Flat, BackColor = Color.FromArgb(0, 122, 204), ForeColor = Color.White };
        btnSave.FlatAppearance.BorderSize = 0;

        // 💡 修正: イベントハンドラを async (s, e) => に変更し、内部の await を有効化
        btnSave.Click += async (s, e) =>
        {
            _intervalMinutes = (int)numInterval.Value;
            _notifyThreshold = (int)numThreshold.Value;
            _language = cmbLang.SelectedItem?.ToString() ?? "en";

            SaveSettings();
            ToggleStartup(chkStartup.Checked);

            if (_timer != null) _timer.Interval = _intervalMinutes * 60 * 1000;

            BuildContextMenu();
            await UpdateBatteryLevelAsync();

            configForm.Close();
        };

        configForm.Controls.AddRange(new Control[] { lblInterval, numInterval, lblThreshold, numThreshold, lblHint, lblLang, cmbLang, chkStartup, btnSave });
        configForm.ShowDialog();
    }

    private static void SaveSettings()
    {
        try
        {
            using (RegistryKey key = Registry.CurrentUser.CreateSubKey(REG_APP_KEY))
            {
                key.SetValue("IntervalMinutes", _intervalMinutes);
                key.SetValue("NotifyThreshold", _notifyThreshold);
                key.SetValue("Language", _language);
            }
        }
        catch { }
    }

    private static void LoadSettings()
    {
        try
        {
            // 💡 RegistryKey を RegistryKey? (Null許容型) に修正
            using (RegistryKey? key = Registry.CurrentUser.OpenSubKey(REG_APP_KEY))
            {
                if (key != null)
                {
                    // int キャストの末尾の「!」は値型に対して不要なため除去
                    _intervalMinutes = (int)key.GetValue("IntervalMinutes", 3);
                    _notifyThreshold = (int)key.GetValue("NotifyThreshold", 20);
                    _language = key.GetValue("Language", "en")?.ToString() ?? "en";
                }
            }

            if (string.IsNullOrEmpty(_language))
            {
                string currentCulture = CultureInfo.CurrentCulture.Name.ToLower();
                _language = currentCulture.StartsWith("ja") ? "ja" : "en";
            }
        }
        catch
        {
            _language = "en";
        }
    }

    private static void ToggleStartup(bool enable)
    {
        try
        {
            using (RegistryKey? key = Registry.CurrentUser.OpenSubKey(REG_RUN_KEY, true))
            {
                if (key == null) return;
                if (enable) key.SetValue(APP_NAME, Application.ExecutablePath);
                else key.DeleteValue(APP_NAME, false);
            }
        }
        catch { }
    }

    private static bool IsStartupEnabled()
    {
        try
        {
            // 💡 RegistryKey? で安全に受け、内部の null チェックと同期させます
            using (RegistryKey? key = Registry.CurrentUser.OpenSubKey(REG_RUN_KEY, false))
            {
                return key != null && key.GetValue(APP_NAME) != null;
            }
        }
        catch { return false; }
    }
}