using System;
using System.ComponentModel;
using System.Diagnostics;
using System.Runtime.InteropServices;
using System.Windows;
using System.Windows.Controls;                 // ContextMenu, MenuItem
using System.Windows.Controls.Primitives;      // PlacementMode
using System.Windows.Interop;

namespace Bedtimer
{
    public sealed class TrayHost : IDisposable
    {
        // === Win32 interop ===
        [StructLayout(LayoutKind.Sequential, CharSet = CharSet.Unicode)]
        private struct NOTIFYICONDATA
        {
            public int cbSize;
            public IntPtr hWnd;
            public int uID;
            public int uFlags;
            public int uCallbackMessage;
            public IntPtr hIcon;
            [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 128)]
            public string szTip;
            public int dwState;
            public int dwStateMask;
            [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 256)]
            public string szInfo;
            public int uTimeoutOrVersion;
            [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 64)]
            public string szInfoTitle;
            public int dwInfoFlags;
            public Guid guidItem;
            public IntPtr hBalloonIcon;
        }

        private const int NIM_ADD = 0x00000000;
        private const int NIM_MODIFY = 0x00000001;
        private const int NIM_DELETE = 0x00000002;

        private const int NIF_MESSAGE = 0x00000001;
        private const int NIF_ICON = 0x00000002;
        private const int NIF_TIP = 0x00000004;

        private const int WM_APP = 0x8000;
        private const int WM_USER = 0x0400;
        private const int WM_LBUTTONUP = 0x0202;
        private const int WM_LBUTTONDBLCLK = 0x0203;
        private const int WM_RBUTTONUP = 0x0205;

        [DllImport("shell32.dll", CharSet = CharSet.Unicode)]
        private static extern bool Shell_NotifyIcon(int dwMessage, ref NOTIFYICONDATA lpdata);

        [DllImport("user32.dll")] private static extern bool GetCursorPos(out POINT lpPoint);
        [DllImport("user32.dll")] private static extern IntPtr LoadIcon(IntPtr hInstance, IntPtr lpIconName);
        private static readonly IntPtr IDI_INFORMATION = (IntPtr)0x7F04; // stock info icon

        [StructLayout(LayoutKind.Sequential)]
        private struct POINT { public int X; public int Y; }

        // === Fields ===
        private HwndSource? _src;
        private IntPtr _hWnd = IntPtr.Zero;
        private IntPtr _hIcon = IntPtr.Zero;
        private int _iconId = 1;
        private readonly int _callbackMsg = WM_APP + 1;

        private ContextMenu? _menu;
        private OverlayManager _overlay = null!;

        public void Init()
        {
            // Hidden message window for tray callbacks
            var param = new HwndSourceParameters("Bedtimer.TrayHostWindow")
            {
                Width = 0,
                Height = 0,
                WindowStyle = unchecked((int)0x80000000), // WS_POPUP
                UsesPerPixelOpacity = false
            };
            _src = new HwndSource(param);
            _src.AddHook(WndProc);
            _hWnd = _src.Handle;

            // Icon (stock system icon to avoid resources)
            _hIcon = LoadIcon(IntPtr.Zero, IDI_INFORMATION);

            // Add tray icon
            var nid = new NOTIFYICONDATA
            {
                cbSize = Marshal.SizeOf<NOTIFYICONDATA>(),
                hWnd = _hWnd,
                uID = _iconId,
                uFlags = NIF_MESSAGE | NIF_ICON | NIF_TIP,
                uCallbackMessage = _callbackMsg,
                hIcon = _hIcon,
                szTip = "Bedtimer"
            };
            if (!Shell_NotifyIcon(NIM_ADD, ref nid))
                throw new Win32Exception("Shell_NotifyIcon(NIM_ADD) failed.");

            // Build WPF context menu
            _menu = BuildMenu();

            // Start overlay manager
            _overlay = new OverlayManager();
            _overlay.Start();
        }

        private ContextMenu BuildMenu()
        {
            var menu = new ContextMenu();

            var open = new MenuItem { Header = "Open Settings..." };
            open.Click += (_, __) => ShowSettings();
            menu.Items.Add(open);

            var autostart = new MenuItem { Header = "Start with Windows", IsCheckable = true, IsChecked = AutoStart.IsEnabled() };
            autostart.Click += (_, __) =>
            {
                var next = !AutoStart.IsEnabled();
                AutoStart.SetEnabled(next);              // may UAC prompt
                autostart.IsChecked = AutoStart.IsEnabled();  // refresh state after hop
            };

            menu.Items.Add(autostart);

            menu.Items.Add(new Separator());

            var exit = new MenuItem { Header = "Exit" };
            exit.Click += (_, __) => Application.Current.Shutdown();
            menu.Items.Add(exit);

            return menu;
        }

        private void ShowSettings()
        {
            // Bring up settings window (single instance)
            foreach (Window w in Application.Current.Windows)
                if (w is MainWindow mw) { mw.Activate(); return; }

            var win = new MainWindow();
            win.Show();
            win.Activate();
        }

        // Show WPF ContextMenu at the current cursor position
        private void ShowMenuAtCursor()
        {
            if (_menu == null) return;
            if (GetCursorPos(out var pt))
            {
                _menu.Placement = PlacementMode.AbsolutePoint;
                _menu.HorizontalOffset = pt.X;
                _menu.VerticalOffset = pt.Y;
                _menu.IsOpen = true;
                _menu.Focus();
            }
        }

        private IntPtr WndProc(IntPtr hwnd, int msg, IntPtr wParam, IntPtr lParam, ref bool handled)
        {
            if (msg == _callbackMsg)
            {
                int code = lParam.ToInt32();
                switch (code)
                {
                    case WM_LBUTTONUP:
                        ShowSettings();
                        handled = true;
                        break;
                    case WM_LBUTTONDBLCLK:
                        ShowSettings();
                        handled = true;
                        break;
                    case WM_RBUTTONUP:
                        ShowMenuAtCursor();
                        handled = true;
                        break;
                }
            }
            return IntPtr.Zero;
        }

        public void Dispose()
        {
            try
            {
                var nid = new NOTIFYICONDATA
                {
                    cbSize = Marshal.SizeOf<NOTIFYICONDATA>(),
                    hWnd = _hWnd,
                    uID = _iconId
                };
                Shell_NotifyIcon(NIM_DELETE, ref nid);
            }
            catch { /* ignore */ }

            _overlay?.Dispose();
            _src?.RemoveHook(WndProc);
            _src?.Dispose();
            _src = null;
        }
    }
}