using System;
using System.Collections.Generic;
using System.Collections.ObjectModel;
using System.Linq;
using System.Windows.Input;
using ytLive.Helpers;
using ytLive.Models;

namespace ytLive.ViewModels;

public partial class MainViewModel
{
    private const string WindowKeyPrefix = "window:";
    private const string PickerKeyPrefix = "picker:";

    /// <summary>True for session-scoped capture keys that must not persist
    /// across a reload: "picker:" picks (OS GraphicsCapturePicker) and "window:"
    /// pins (an HWND can be recycled to a different window after restart).</summary>
    private static bool IsTransientCaptureKey(string? key)
    {
        if (string.IsNullOrWhiteSpace(key)) return false;
        return key.StartsWith(WindowKeyPrefix, StringComparison.OrdinalIgnoreCase)
            || key.StartsWith(PickerKeyPrefix, StringComparison.OrdinalIgnoreCase);
    }

    /// <summary>True when the given capture key is a window pin whose window is
    /// still among the enumerated open windows — the pin then outranks
    /// auto-detection (see OnFullscreenMonitorChanged).</summary>
    private bool IsAliveWindowPin(string? key)
    {
        if (string.IsNullOrWhiteSpace(key)
            || !key.StartsWith(WindowKeyPrefix, StringComparison.OrdinalIgnoreCase)) return false;

        var hwndText = key.AsSpan(WindowKeyPrefix.Length).TrimStart();
        if (hwndText.Length >= 2 && hwndText[0] == '0' && (hwndText[1] == 'x' || hwndText[1] == 'X'))
            hwndText = hwndText[2..];
        var hwnd = long.TryParse(hwndText, System.Globalization.NumberStyles.HexNumber,
            System.Globalization.CultureInfo.InvariantCulture, out var value) ? value : 0;
        foreach (var window in _windowEnumerator.Enumerate())
            if (window.Hwnd == hwnd)
                return true;
        return false;
    }

    /// <summary>ScreenCaptureManager's session failed (the pinned window closed,
    /// a monitor went away, a transient pick expired, …). For a transient
    /// session-scoped key the pin no longer resolves — fall back to the automatic
    /// capture (game → desktop → static), mirroring the reload heal.</summary>
    private void OnScreenCaptureFailed(string key, string message)
    {
        AppLog.Write($"ScreenCaptureManager: capture '{key}' failed: {message}");
        if (!IsTransientCaptureKey(key)) return;

        var pinned = AllBackgrounds().FirstOrDefault(b => b.CaptureKey == key);
        if (pinned == null) return;
        ReacquireScreenCaptures();
    }

    /// <summary>Open windows offered to the "Capture Window…" submenu (session
    /// snapshot; refresh via <see cref="RefreshWindowsCommand"/>).</summary>
    public ObservableCollection<WindowInfo> OpenWindows { get; } = new();

    public ICommand RefreshWindowsCommand { get; }
    public ICommand CaptureWindowCommand { get; }

private void RefreshOpenWindows()
    {
        var windows = _windowEnumerator.Enumerate();
        OpenWindows.Clear();
        foreach (var window in windows)
            OpenWindows.Add(window);
    }
}