using Avalonia;
using Avalonia.Controls;
using Avalonia.Input;

namespace DodoSSH.Client.App.Views;

/// <summary>
/// Tells a drawn titlebar's double-click from a press that starts a drag.
/// </summary>
/// <remarks>
/// <para>
/// Both titlebars used to answer a double-click through <c>DoubleTapped</c> and start a drag on every press.
/// The two do not mix: <c>BeginMoveDrag</c> hands the press to the operating system's own move loop, which
/// eats the release — and a double tap is a gesture Avalonia assembles from presses <em>and</em> releases,
/// so the second click often never completed one and the window did not maximise. The convention it was
/// imitating is one nobody thinks about until it does not work.
/// </para>
/// <para>
/// So the press decides, before the drag begins: a second press inside the platform's double-click time and
/// distance is the maximise, and does not start a drag at all. The click count is honoured where the platform
/// reports one, and the time and distance are measured here for where the move loop kept it from counting.
/// </para>
/// </remarks>
internal sealed class CaptionPresses
{
    private ulong lastAt;

    private Point lastWhere;

    private bool waitingForASecond;

    /// <summary>Whether this press is the second of a double-click on <paramref name="bar"/>.</summary>
    internal bool IsSecond(PointerPressedEventArgs e, Visual bar)
    {
        var settings = Application.Current?.PlatformSettings;
        var time = settings?.GetDoubleTapTime(e.Pointer.Type) ?? TimeSpan.FromMilliseconds(500);
        var size = settings?.GetDoubleTapSize(e.Pointer.Type) ?? new Size(4, 4);
        var where = e.GetPosition(bar);

        var second = e.ClickCount == 2
            || (waitingForASecond
                && e.Timestamp - lastAt <= (ulong)time.TotalMilliseconds
                && Math.Abs(where.X - lastWhere.X) <= size.Width
                && Math.Abs(where.Y - lastWhere.Y) <= size.Height);

        // A double-click spends both presses: a third that follows quickly starts again rather than toggling
        // the window straight back.
        waitingForASecond = !second;
        lastAt = e.Timestamp;
        lastWhere = where;

        return second;
    }
}