using System.Windows;
using System.Windows.Interop;
using CursorLang.Core.Interop;
using CursorLang.Settings.Interop;
using CursorLang.Settings.Tests.Infrastructure;

namespace CursorLang.Settings.Tests.Interop;

/// <summary>
/// The Win32 wrappers: what is checked is that the calls are put together
/// right — structures of the expected size, flags in place, and the answers
/// of the system read correctly.
/// </summary>
public sealed class NativeWrappersTests
{
    [Fact]
    public void The_cursor_position_is_read()
    {
        PopupWindowNative.Point cursor = PopupWindowNative.GetCursorPosition();

        // The virtual screen may run into negative coordinates, but not beyond
        // reason: a misread structure would give garbage
        Assert.InRange(cursor.X, -32_000, 32_000);
        Assert.InRange(cursor.Y, -32_000, 32_000);
    }

    [Fact]
    public void The_scale_of_the_monitor_under_the_cursor_is_positive()
    {
        double scale = PopupWindowNative.GetScaleAt(PopupWindowNative.GetCursorPosition());

        Assert.InRange(scale, 0.5, 8.0);
    }

    [Fact]
    public void The_work_area_of_the_active_monitor_is_not_empty()
    {
        (PopupWindowNative.Rect work, double scale) = PopupWindowNative.GetActiveMonitorWorkArea();

        Assert.True(work.Right > work.Left);
        Assert.True(work.Bottom > work.Top);
        Assert.InRange(scale, 0.5, 8.0);
    }

    [Fact]
    public void The_window_bounds_are_read_from_the_system()
    {
        Sta.Run(() =>
        {
            using var window = new HandleWindow();

            PopupWindowNative.Rect? bounds = WindowPlacementNative.TryGetBounds(window.Handle);

            Assert.NotNull(bounds);
            Assert.True(bounds.Value.Right > bounds.Value.Left);
            Assert.True(bounds.Value.Bottom > bounds.Value.Top);
        });
    }

    [Fact]
    public void A_window_that_does_not_exist_has_no_bounds()
    {
        Assert.Null(WindowPlacementNative.TryGetBounds(IntPtr.Zero));
    }

    [Fact]
    public void A_window_is_moved_to_the_given_point()
    {
        Sta.Run(() =>
        {
            using var window = new HandleWindow();

            PopupWindowNative.MoveTo(window.Handle, 120, 90);

            PopupWindowNative.Rect bounds = WindowPlacementNative.TryGetBounds(window.Handle)!.Value;
            Assert.Equal(120, bounds.Left);
            Assert.Equal(90, bounds.Top);
        });
    }

    [Fact]
    public void Moving_does_not_change_the_window_size()
    {
        Sta.Run(() =>
        {
            using var window = new HandleWindow();

            PopupWindowNative.Rect before = WindowPlacementNative.TryGetBounds(window.Handle)!.Value;
            PopupWindowNative.MoveTo(window.Handle, 200, 150);
            PopupWindowNative.Rect after = WindowPlacementNative.TryGetBounds(window.Handle)!.Value;

            Assert.Equal(before.Right - before.Left, after.Right - after.Left);
            Assert.Equal(before.Bottom - before.Top, after.Bottom - after.Top);
        });
    }

    [Fact]
    public void The_work_area_is_found_by_the_rectangle_of_the_window()
    {
        Sta.Run(() =>
        {
            using var window = new HandleWindow();
            PopupWindowNative.Rect bounds = WindowPlacementNative.TryGetBounds(window.Handle)!.Value;

            PopupWindowNative.Rect? work = WindowPlacementNative.TryGetWorkAreaNear(bounds);

            Assert.NotNull(work);
            Assert.True(work.Value.Right > work.Value.Left);
            Assert.True(work.Value.Bottom > work.Value.Top);
        });
    }

    // The nearest monitor is picked, so an area is found even for a point far off screen
    [Fact]
    public void For_a_rectangle_off_every_screen_the_nearest_monitor_is_taken()
    {
        var far = new PopupWindowNative.Rect { Left = 30_000, Top = 30_000, Right = 30_100, Bottom = 30_100 };

        PopupWindowNative.Rect? work = WindowPlacementNative.TryGetWorkAreaNear(far);

        Assert.NotNull(work);
        Assert.True(work.Value.Right > work.Value.Left);
    }

    [Fact]
    public void The_layout_of_the_foreground_window_is_read()
    {
        int localeId = KeyboardLayoutNative.GetActiveLocaleId();

        // The low word of the HKL is the locale identifier, and it is never zero
        Assert.NotEqual(0, localeId);
        Assert.InRange(localeId, 1, 0xFFFF);
    }

    [Fact]
    public void The_layout_is_read_for_any_window()
    {
        int localeId = KeyboardLayoutNative.GetLocaleIdOf(KeyboardLayoutNative.GetForegroundWindow());

        Assert.InRange(localeId, 0, 0xFFFF);
    }

    [Fact]
    public void The_input_state_of_the_foreground_is_read()
    {
        bool received = ForegroundInputNative.TryGetInfo(out ForegroundInputNative.GuiThreadInfo info);

        if (received)
        {
            // The structure size is filled in by the wrapper itself, and it has
            // to match what Windows expects
            Assert.Equal(System.Runtime.InteropServices.Marshal.SizeOf<ForegroundInputNative.GuiThreadInfo>(),
                info.cbSize);
        }
    }

    [Fact]
    public void The_right_to_show_a_window_is_given_away_without_errors()
    {
        ForegroundPermissionNative.GrantToAnyProcess();
    }

    [Fact]
    public void The_window_title_bar_is_repainted()
    {
        Sta.Run(() =>
        {
            using var window = new HandleWindow();

            WindowThemeNative.SetDarkTitleBar(window.Handle, isDark: true);
            WindowThemeNative.SetDarkTitleBar(window.Handle, isDark: false);
        });
    }

    // The window may be gone by the time of the repaint
    [Fact]
    public void Repainting_a_window_that_does_not_exist_passes_silently()
    {
        WindowThemeNative.SetDarkTitleBar(IntPtr.Zero, isDark: true);
    }

    [Fact]
    public void The_package_flag_is_computed_once_and_does_not_change()
    {
        bool first = PackageIdentityNative.IsPackaged;

        Assert.Equal(first, PackageIdentityNative.IsPackaged);
    }

    /// <summary>A window with a created handle that never appears on screen.</summary>
    private sealed class HandleWindow : IDisposable
    {
        private readonly Window _window;

        internal HandleWindow()
        {
            _window = new Window
            {
                Width = 300,
                Height = 200,
                ShowInTaskbar = false,
                WindowStartupLocation = WindowStartupLocation.Manual,
            };

            Handle = new WindowInteropHelper(_window).EnsureHandle();
        }

        internal IntPtr Handle { get; }

        public void Dispose() => _window.Close();
    }
}