using System;
using System.Collections.Generic;
using System.IO;
using System.Windows;
using Microsoft.Data.Sqlite;
using Xunit;
using ytLive.Services;
using ytLive.ViewModels;

namespace ytLive.Tests;

/// <summary>
/// The desktop-"lock" bug (2026-10-10): at launch the main window ACTIVES
/// (WPF default <c>ShowActivated = true</c>), and when the creator is already
/// playing an exclusive-fullscreen game, activating LlamaCasty makes Windows
/// drop that game to the taskbar; the app's 1920×1040 window then sits over the
/// whole work area, so the desktop looks locked and the game can't be reached
/// with the mouse. Fix: the window opens WITHOUT activating when a full-screen
/// game owns the foreground at launch — <c>ShowActivated = !FullscreenGameRunningNow</c>.
/// These tests pin that rule using the <c>FullScreenDetectorOverride</c> seam,
/// so no real Win32 foreground state is touched.
/// </summary>
[Collection("RealApp")]
public sealed class DesktopLockTests
{
    private readonly RealAppHost _app;

    public DesktopLockTests(RealAppHost app) => _app = app;

    [Fact]
    public void MainWindow_Does_Not_Steal_Focus_When_A_Fullscreen_Game_Is_Foreground()
    {
        _app.Run(() =>
        {
            using var _ = new TempLayout();
            MainViewModel.FullScreenDetectorOverride = new StubFullScreenDetector(foregroundMonitor: 0);
            try
            {
                var window = new MainWindow();
                try
                {
                    // The regression: a full-screen game already owns the screen, so
                    // the window must open WITHOUT activating to keep the game live.
                    Assert.False(window.ShowActivated,
                        "launching while a full-screen game owns the foreground must not steal focus");
                }
                finally
                {
                    window.Close();
                }
            }
            finally
            {
                MainViewModel.FullScreenDetectorOverride = null;
            }
        });
    }

    [Fact]
    public void MainWindow_Normal_Launch_Still_Activates()
    {
        _app.Run(() =>
        {
            using var _ = new TempLayout();
            MainViewModel.FullScreenDetectorOverride = new StubFullScreenDetector(foregroundMonitor: null);
            try
            {
                var window = new MainWindow();
                try
                {
                    // No game running: behaviour is exactly as before the fix.
                    Assert.True(window.ShowActivated,
                        "a normal launch (no full-screen game) must keep the default activate-on-show");
                }
                finally
                {
                    window.Close();
                }
            }
            finally
            {
                MainViewModel.FullScreenDetectorOverride = null;
            }
        });
    }

    [Fact]
    public void FullscreenGameRunningNow_Reflects_The_Foreground_Monitor()
    {
        _app.Run(() =>
        {
            MainViewModel.FullScreenDetectorOverride = new StubFullScreenDetector(foregroundMonitor: 0);
            try
            {
                var gameVm = new MainViewModel();
                Assert.True(gameVm.FullscreenGameRunningNow);
            }
            finally
            {
                MainViewModel.FullScreenDetectorOverride = null;
            }

            MainViewModel.FullScreenDetectorOverride = new StubFullScreenDetector(foregroundMonitor: null);
            try
            {
                var idleVm = new MainViewModel();
                Assert.False(idleVm.FullscreenGameRunningNow);
            }
            finally
            {
                MainViewModel.FullScreenDetectorOverride = null;
            }
        });
    }

    private sealed class TempLayout : IDisposable
    {
        private readonly string _path;

        public TempLayout()
        {
            _path = Path.Combine(Path.GetTempPath(), $"ytLive-desktoplock-{Guid.NewGuid():N}.db");
            using (var schema = new LayoutStore(_path)) { }
            SqliteConnection.ClearAllPools();
            MainViewModel.LayoutPathOverride = _path;
        }

        public void Dispose()
        {
            MainViewModel.LayoutPathOverride = null;
            SqliteConnection.ClearAllPools();
            try { File.Delete(_path); } catch { /* best-effort cleanup */ }
        }
    }

    /// <summary>A deterministic stand-in for <see cref="Win32FullScreenDetector"/>:
    /// claims a full-screen window owns the given foreground monitor (or none).</summary>
    #pragma warning disable CS0067 // fullscreen-changed wiring is not part of this seam
    private sealed class StubFullScreenDetector : IFullScreenDetector
    {
        private readonly int? _foregroundMonitor;

        public StubFullScreenDetector(int? foregroundMonitor) => _foregroundMonitor = foregroundMonitor;

        public int? GetForegroundFullScreenMonitorIndex() => _foregroundMonitor;
        public int PrimaryMonitorIndex() => 0;
        public IReadOnlyList<DisplayInfo> GetDisplays() => Array.Empty<DisplayInfo>();
        public event Action<int?>? FullscreenMonitorChanged;
        public void StartWatching() { }
        public void StopWatching() { }
    }
}