using System.Diagnostics;
using System.Runtime.InteropServices;
using System.Text;

namespace CVRManager.Services;

public static class GameWindow
{
    const uint WM_SETICON = 0x0080;
    const int ICON_SMALL = 0;
    const int ICON_BIG = 1;
    const int SM_CXICON = 11;
    const int SM_CXSMICON = 49;

    delegate bool EnumProc(IntPtr hwnd, IntPtr lParam);

    [DllImport("user32.dll")]
    static extern bool EnumWindows(EnumProc proc, IntPtr lParam);

    [DllImport("user32.dll")]
    static extern uint GetWindowThreadProcessId(IntPtr hwnd, out uint pid);

    [DllImport("user32.dll")]
    static extern bool IsWindowVisible(IntPtr hwnd);

    [DllImport("user32.dll", CharSet = CharSet.Unicode)]
    static extern int GetClassName(IntPtr hwnd, StringBuilder name, int max);

    [DllImport("user32.dll", SetLastError = true)]
    static extern IntPtr SendMessageTimeout(IntPtr hwnd, uint msg, IntPtr wParam, IntPtr lParam, uint flags, uint timeout, out IntPtr result);

    const uint SMTO_ABORTIFHUNG = 2;

    [DllImport("user32.dll")]
    static extern int GetSystemMetrics(int index);

    [DllImport("user32.dll", CharSet = CharSet.Unicode)]
    static extern uint PrivateExtractIcons(string file, int index, int cx, int cy, IntPtr[] icons, uint[] ids, uint count, uint flags);

    static IntPtr FindUnityWindow(int pid)
    {
        var found = IntPtr.Zero;
        var name = new StringBuilder(64);
        EnumWindows((hwnd, _) =>
        {
            GetWindowThreadProcessId(hwnd, out var owner);
            if (owner != pid || !IsWindowVisible(hwnd)) return true;
            name.Clear();
            GetClassName(hwnd, name, name.Capacity);
            if (name.ToString() == "UnityWndClass") found = hwnd;
            return true;
        }, IntPtr.Zero);
        return found;
    }

    static void SetIcons(IntPtr hwnd, string exe)
    {
        foreach (var (kind, size) in new[] { (ICON_SMALL, GetSystemMetrics(SM_CXSMICON)), (ICON_BIG, GetSystemMetrics(SM_CXICON)) })
        {
            var icons = new IntPtr[1];
            var ids = new uint[1];
            if (PrivateExtractIcons(exe, 0, size, size, icons, ids, 1, 0) > 0 && icons[0] != IntPtr.Zero)
                SendMessageTimeout(hwnd, WM_SETICON, (IntPtr)kind, icons[0], SMTO_ABORTIFHUNG, 1000, out _);
        }
    }

    public static async Task ApplyIconWhenReadyAsync(Process proc, string exe)
    {
        if (!OperatingSystem.IsWindows()) return;
        try
        {
            var hwnd = IntPtr.Zero;
            for (var i = 0; i < 240 && hwnd == IntPtr.Zero; i++)
            {
                if (proc.HasExited) return;
                hwnd = FindUnityWindow(proc.Id);
                if (hwnd == IntPtr.Zero) await Task.Delay(250);
            }
            if (hwnd == IntPtr.Zero) return;

            foreach (var wait in new[] { 0, 3000, 7000, 20000 })
            {
                await Task.Delay(wait);
                if (proc.HasExited) return;
                var current = FindUnityWindow(proc.Id);
                if (current != IntPtr.Zero) SetIcons(current, exe);
            }
        }
        catch (InvalidOperationException) { }
    }
}