using System;
using System.Windows;
using System.Windows.Forms;
using System.Windows.Threading;

namespace ScreenFrame.Movers;

/// <summary>
/// Mover of <see cref="System.Windows.Window"/> which implements functions for switch window
/// </summary>
public class SwitchWindowMover : StickWindowMover
{
	/// <summary>
	/// Whether the window is departed from the taskbar
	/// </summary>
	public bool IsDeparted
	{
		get => _isDeparted;
		private set
		{
			_isDeparted = value;
			IsDepartedChanged?.Invoke(this, EventArgs.Empty);
		}
	}
	private bool _isDeparted;

	/// <summary>
	/// Occurs when IsDeparted is changed.
	/// </summary>
	public event EventHandler IsDepartedChanged;

	/// <summary>
	/// Time interval before departure
	/// </summary>
	public TimeSpan DepartureInterval
	{
		get => _departureInterval;
		set
		{
			if (value < TimeSpan.Zero)
				return;

			_departureInterval = value;
		}
	}
	private TimeSpan _departureInterval = TimeSpan.FromMilliseconds(100); // Default

	private readonly DispatcherTimer _departureTimer;

	/// <summary>
	/// Constructor
	/// </summary>
	/// <param name="window">Window to be moved</param>
	/// <param name="notifyIcon">NotifyIcon to be referred</param>
	public SwitchWindowMover(Window window, NotifyIcon notifyIcon) : base(window, notifyIcon)
	{
		_departureTimer = new DispatcherTimer();
		_departureTimer.Tick += OnTick;
	}

	/// <summary>
	/// Called when Closed event of window is raised.
	/// </summary>
	protected override void OnClosed(object sender, EventArgs e)
	{
		base.OnClosed(sender, e);

		_departureTimer.Stop();
		_departureTimer.Tick -= OnTick;
	}

	private void OnTick(object sender, EventArgs e)
	{
		_departureTimer.Stop();
		InitiateDeparture();
	}

	/// <summary>
	/// Alignment of pivot
	/// </summary>
	public override PivotAlignment PivotAlignment
	{
		get => IsDeparted ? PivotAlignment.None : base.PivotAlignment;
		protected set => base.PivotAlignment = value;
	}

	private const int WM_ENTERSIZEMOVE = 0x0231;
	private const int WM_EXITSIZEMOVE = 0x0232;
	private const int WM_MOVE = 0x0003;
	private const int WM_SIZE = 0x0005;

	/// <summary>
	/// Handles window messages.
	/// </summary>
	protected override IntPtr WndProc(IntPtr hwnd, int msg, IntPtr wParam, IntPtr lParam, ref bool handled)
	{
		switch (msg)
		{
			case WM_ENTERSIZEMOVE:
				_departureTimer.Interval = DepartureInterval;
				_departureTimer.Start();
				break;

			case WM_EXITSIZEMOVE:
				_departureTimer.Stop();
				CheckDeparture();
				break;

			case WM_MOVE:
			case WM_SIZE:
				CheckDeparture();
				break;
		}
		return base.WndProc(hwnd, msg, wParam, lParam, ref handled);
	}

	private void InitiateDeparture()
	{
		IsDeparted = true;
	}

	private void CheckDeparture()
	{
		if (!IsDeparted)
			return;

		if (!WindowHelper.TryGetTaskbar(null, out Rect taskbarRect, out _, out _, out _, out _))
			return;

		if (!WindowHelper.TryGetDwmWindowRect(_window, out Rect windowRect))
			return;

		if (!windowRect.IntersectsWith(taskbarRect))
			return;

		IsDeparted = false;
	}

	/// <summary>
	/// Attempts to get the adjacent location using specified window width and height.
	/// </summary>
	/// <param name="windowWidth">Window width</param>
	/// <param name="windowHeight">Window height</param>
	/// <param name="location">Location of window</param>
	/// <returns>True if successfully gets</returns>
	protected override bool TryGetAdjacentLocation(double windowWidth, double windowHeight, out Rect location)
	{
		if (IsDeparted)
		{
			location = default;
			return false;
		}
		return base.TryGetAdjacentLocation(windowWidth, windowHeight, out location);
	}
}