using System;
using System.Collections.Generic;
using System.IO;
using System.Runtime.InteropServices;
using System.Threading.Tasks;
using System.Windows;
using System.Windows.Interop;
using System.Windows.Media;
using System.Windows.Media.Imaging;
using System.Windows.Threading;
using Paca.App.Core;

namespace Paca.App.Services;

/// <summary>
/// PACA 데스크톱 애플리케이션 화면 디버깅 캡처 서비스.
/// Win32 GDI / PrintWindow / RenderTargetBitmap 하이브리드 파이프라인으로
/// WPF 및 WebView2(HWND) 자식 컨트롤이 포함된 실제 앱 윈도우 전체를 스크린샷으로 캡처하여 저장한다.
/// </summary>
public static class AppDebugScreenshotService
{
    [StructLayout(LayoutKind.Sequential)]
    private struct RECT
    {
        public int Left;
        public int Top;
        public int Right;
        public int Bottom;
    }

    [DllImport("user32.dll")]
    private static extern bool GetWindowRect(IntPtr hWnd, out RECT lpRect);

    [DllImport("user32.dll")]
    private static extern bool PrintWindow(IntPtr hWnd, IntPtr hdcBkgnd, uint nFlags);

    [DllImport("user32.dll")]
    private static extern bool SetForegroundWindow(IntPtr hWnd);

    [DllImport("user32.dll")]
    private static extern bool BringWindowToTop(IntPtr hWnd);

    [DllImport("user32.dll")]
    private static extern bool ShowWindow(IntPtr hWnd, int nCmdShow);

    private const int SW_RESTORE = 9;
    private const uint PW_RENDERFULLCONTENT = 0x00000002;
    private static DispatcherTimer? _triggerTimer;

    public static string GetDefaultScreenshotPath() =>
        Path.Combine(AppPaths.DataDir, "debug_screenshot.png");

    public static string ResolveTriggerPath(string? input)
    {
        if (string.IsNullOrWhiteSpace(input))
            return GetDefaultScreenshotPath();
        return input.Trim();
    }

    /// <summary>
    /// 대상 Window의 현재 화면을 PNG 파일로 캡처하여 저장한다.
    /// </summary>
    public static bool CaptureWindow(Window window, string outputPath)
    {
        if (window == null) return false;

        try
        {
            var dir = Path.GetDirectoryName(outputPath);
            if (!string.IsNullOrEmpty(dir))
            {
                Directory.CreateDirectory(dir);
            }

            var helper = new WindowInteropHelper(window);
            var hWnd = helper.Handle;

            if (hWnd != IntPtr.Zero && GetWindowRect(hWnd, out var rect))
            {
                try
                {
                    ShowWindow(hWnd, SW_RESTORE);
                    SetForegroundWindow(hWnd);
                    BringWindowToTop(hWnd);
                    System.Threading.Thread.Sleep(200);
                    GetWindowRect(hWnd, out rect);
                }
                catch { }

                int width = rect.Right - rect.Left;
                int height = rect.Bottom - rect.Top;

                if (width > 0 && height > 0)
                {
                    try
                    {
                        using var bmp = new System.Drawing.Bitmap(width, height);
                        using (var g = System.Drawing.Graphics.FromImage(bmp))
                        {
                            var hdc = g.GetHdc();
                            try
                            {
                                PrintWindow(hWnd, hdc, PW_RENDERFULLCONTENT);
                            }
                            finally
                            {
                                g.ReleaseHdc(hdc);
                            }

                            // WebView2 자식 컨트롤 실시간 렌더링 화면 비트맵 오버레이
                            OverlayAdBanners(window, g, width, height);
                        }

                        bmp.Save(outputPath, System.Drawing.Imaging.ImageFormat.Png);
                        if (File.Exists(outputPath) && new FileInfo(outputPath).Length > 0)
                        {
                            return true;
                        }
                    }
                    catch
                    {
                        // GDI 캡처 실패 시 하단 WPF RenderTargetBitmap 폴백 진행
                    }
                }
            }

            // 폴백: 순수 WPF 비주얼 트리 렌더링
            int rtbWidth = (int)Math.Max(1, window.ActualWidth > 0 ? window.ActualWidth : window.Width);
            int rtbHeight = (int)Math.Max(1, window.ActualHeight > 0 ? window.ActualHeight : window.Height);
            if (rtbWidth <= 1) rtbWidth = 1024;
            if (rtbHeight <= 1) rtbHeight = 768;

            var rtb = new RenderTargetBitmap(rtbWidth, rtbHeight, 96, 96, PixelFormats.Pbgra32);
            rtb.Render(window);

            var encoder = new PngBitmapEncoder();
            encoder.Frames.Add(BitmapFrame.Create(rtb));
            using (var fs = File.Create(outputPath))
            {
                encoder.Save(fs);
            }

            return File.Exists(outputPath) && new FileInfo(outputPath).Length > 0;
        }
        catch
        {
            return false;
        }
    }

    /// <summary>
    /// 외부 신호 파일(%AppData%/VideoDownloader/screenshot_trigger.req)을 감지하여
    /// 백그라운드에서 실시간 스크린샷을 찍도록 타이머를 구동한다.
    /// </summary>
    public static void StartFileTriggerWatcher(Window window, Action<string>? onCaptured = null)
    {
        if (_triggerTimer != null) return;

        var triggerFile = Path.Combine(AppPaths.DataDir, "screenshot_trigger.req");

        _triggerTimer = new DispatcherTimer
        {
            Interval = TimeSpan.FromSeconds(1)
        };

        _triggerTimer.Tick += (_, _) =>
        {
            try
            {
                if (File.Exists(triggerFile))
                {
                    string target = "";
                    try
                    {
                        target = File.ReadAllText(triggerFile);
                        File.Delete(triggerFile);
                    }
                    catch
                    {
                        // 읽기 경합 방어
                        return;
                    }

                    var savePath = ResolveTriggerPath(target);
                    bool ok = CaptureWindow(window, savePath);
                    if (ok)
                    {
                        onCaptured?.Invoke(savePath);
                    }
                }
            }
            catch
            {
                // 백그라운드 폴러 방어
            }
        };

        _triggerTimer.Start();
    }

    /// <summary>
    /// 앱 실행 후 指定된 지연 시간(기본 3초) 뒤에 자동으로 스크린샷을 찍어 저장한다.
    /// </summary>
    public static void ScheduleAutoCapture(Window window, int delayMs = 3000, string? targetPath = null)
    {
        Task.Delay(delayMs).ContinueWith(_ =>
        {
            window.Dispatcher.Invoke(() =>
            {
                var dest = ResolveTriggerPath(targetPath);
                CaptureWindow(window, dest);
            });
        });
    }

    private static void OverlayAdBanners(Window window, System.Drawing.Graphics g, int windowWidth, int windowHeight)
    {
        try
        {
            window.Dispatcher.Invoke(() =>
            {
                var banners = FindVisualChildren<Paca.App.Controls.DesktopAdBannerControl>(window);
                foreach (var banner in banners)
                {
                    if (banner.Visibility != Visibility.Visible || banner.ActualWidth <= 0 || banner.ActualHeight <= 0)
                        continue;

                    var previewPath = Path.Combine(AppPaths.DataDir, "ad_previews", $"ad_{banner.Placement}.png");
                    if (!File.Exists(previewPath)) continue;

                    try
                    {
                        var transform = banner.TransformToAncestor(window);
                        var point = transform.Transform(new Point(0, 0));

                        using var fs = new FileStream(previewPath, FileMode.Open, FileAccess.Read, FileShare.ReadWrite);
                        using var adImg = System.Drawing.Image.FromStream(fs);
                        int x = (int)point.X;
                        int y = (int)point.Y;
                        int w = (int)banner.ActualWidth;
                        int h = (int)banner.ActualHeight;

                        if (banner.Placement == Paca.Browser.Ads.DesktopAdPlacement.BottomAppBanner)
                        {
                            x += (w - 728) / 2;
                            y += (h - 90) / 2;
                            w = 728;
                            h = 90;
                        }
                        else if (banner.Placement == Paca.Browser.Ads.DesktopAdPlacement.DownloadViewBanner)
                        {
                            x += (w - 300) / 2;
                            y += (h - 250) / 2;
                            w = 300;
                            h = 250;
                        }

                        g.DrawImage(adImg, x, y, w, h);
                    }
                    catch (Exception ex)
                    {
                        try
                        {
                            var p = Path.Combine(AppPaths.DataDir, "ad_debug.log");
                            File.AppendAllText(p, $"[{DateTime.Now:HH:mm:ss.fff}] Overlay exception for {banner.Placement}: {ex.Message}\n");
                        }
                        catch { }
                    }
                }
            });
        }
        catch { }
    }

    private static IEnumerable<T> FindVisualChildren<T>(DependencyObject depObj) where T : DependencyObject
    {
        if (depObj == null) yield break;
        int count = VisualTreeHelper.GetChildrenCount(depObj);
        for (int i = 0; i < count; i++)
        {
            var child = VisualTreeHelper.GetChild(depObj, i);
            if (child is T match)
            {
                yield return match;
            }

            foreach (var childOfChild in FindVisualChildren<T>(child))
            {
                yield return childOfChild;
            }
        }
    }
}