using System.Runtime.InteropServices;

namespace AgentWorker.WindowsRunner;

// 输入类 P/Invoke 独立成类：NativeWindows 保持对面"只读编译边界"原样不动。
// 本层没有进程启动接口；所有输入只作用于经策略核验后的前台窗口。
// 坐标一律物理屏幕像素——进程入口（ActuateService.EnsureDpiAwareness）声明
// Per-Monitor V2 DPI 感知，与 RPA 侧 PowerShell 驱动每脚本声明的
// SetProcessDpiAwarenessContext(-4) 语义一致，保证 SetCursorPos 全程物理像素。
// 抢前台五招兜底从 RPA 驱动 activateWindowScript 逐行移植：
// Windows 前台锁定策略会拒绝普通 SetForegroundWindow（应用点击"运行"后自身是前台），
// 五招顺序与睡眠时间是踩坑调出来的实战参数，一行语义都不允许改动。
internal static class NativeInput
{
    private const uint InputMouse = 0;
    private const uint MouseEventfMove = 0x0001;
    private const uint MouseEventfLeftDown = 0x0002;
    private const uint MouseEventfLeftUp = 0x0004;
    private const uint MouseEventfRightDown = 0x0008;
    private const uint MouseEventfRightUp = 0x0010;
    private const uint MouseEventfWheel = 0x0800;
    internal const int SwRestore = 9;
    internal const int SwMinimize = 6;
    internal const int SwMaximize = 3;
    private const uint WmClose = 0x0010;
    private const byte VkMenu = 0x12; // ALT
    private const uint KeyeventfKeyup = 0x0002;

    [DllImport("user32.dll")]
    [return: MarshalAs(UnmanagedType.Bool)]
    internal static extern bool SetCursorPos(int x, int y);

    [DllImport("user32.dll")]
    [return: MarshalAs(UnmanagedType.Bool)]
    private static extern bool GetCursorPos(out Point point);

    [DllImport("user32.dll")]
    [return: MarshalAs(UnmanagedType.Bool)]
    internal static extern bool SetForegroundWindow(nint handle);

    [DllImport("user32.dll")]
    [return: MarshalAs(UnmanagedType.Bool)]
    internal static extern bool ShowWindow(nint handle, int command);

    [DllImport("user32.dll")]
    [return: MarshalAs(UnmanagedType.Bool)]
    internal static extern bool IsIconic(nint handle);

    [DllImport("user32.dll")]
    internal static extern void keybd_event(byte virtualKey, byte scanCode, uint flags, nint extraInfo);

    [DllImport("user32.dll")]
    [return: MarshalAs(UnmanagedType.Bool)]
    private static extern bool AttachThreadInput(uint currentThread, uint targetThread, bool attach);

    [DllImport("user32.dll")]
    private static extern void SwitchToThisWindow(nint handle, bool altTab);

    [DllImport("kernel32.dll")]
    private static extern uint GetCurrentThreadId();

    [DllImport("user32.dll")]
    [return: MarshalAs(UnmanagedType.Bool)]
    private static extern bool SetProcessDpiAwarenessContext(nint value);

    [DllImport("user32.dll")]
    [return: MarshalAs(UnmanagedType.Bool)]
    private static extern bool SetWindowPos(nint handle, nint after, int x, int y,
        int width, int height, uint flags);

    [DllImport("user32.dll")]
    [return: MarshalAs(UnmanagedType.Bool)]
    private static extern bool PostMessage(nint handle, uint message, nint wParam, nint lParam);

    [DllImport("user32.dll", SetLastError = true)]
    private static extern uint SendInput(uint count, Input[] inputs, int size);

    [StructLayout(LayoutKind.Sequential)]
    internal struct Point { public int X; public int Y; }

    [StructLayout(LayoutKind.Sequential)]
    private struct Input
    {
        public uint Type;
        public InputUnion Union;
    }

    [StructLayout(LayoutKind.Explicit)]
    private struct InputUnion
    {
        [FieldOffset(0)] public MouseInput Mouse;
    }

    [StructLayout(LayoutKind.Sequential)]
    private struct MouseInput
    {
        public int Dx;
        public int Dy;
        public uint MouseData;
        public uint Flags;
        public uint Time;
        public nint ExtraInfo;
    }

    // DPI 感知声明是进程级一次性设置；失败（如已被宿主先行声明）不影响后续调用。
    internal static void EnsureDpiAwareness()
    {
        try { _ = SetProcessDpiAwarenessContext(new nint(-4)); }
        catch { /* 旧系统无此 API 时按物理像素继续；对面 CoordinateSpace 以 GetDpiForWindow 实测为准。 */ }
    }

    // SendInput 批量提交鼠标标志组合；单次失败按 input_failed 处理由上层转稳定错误码。
    internal static void SendMouse(uint flags, uint data)
    {
        var input = new Input
        {
            Type = InputMouse,
            Union = new InputUnion
            {
                Mouse = new MouseInput { Dx = 0, Dy = 0, MouseData = data, Flags = flags }
            }
        };
        if (SendInput(1, [input], Marshal.SizeOf<Input>()) != 1)
            throw new RunnerException("input_failed");
    }

    internal static void SendWheel(int amount) =>
        SendMouse(MouseEventfWheel, unchecked((uint)amount));

    internal static void Click(bool right, int repeats, int settleMs)
    {
        var down = right ? MouseEventfRightDown : MouseEventfLeftDown;
        var up = right ? MouseEventfRightUp : MouseEventfLeftUp;
        for (var i = 0; i < repeats; i++)
        {
            SendMouse(down, 0);
            SendMouse(up, 0);
            if (settleMs > 0) Thread.Sleep(settleMs);
        }
    }

    internal static Point CursorPosition()
    {
        if (!GetCursorPos(out var point)) throw new RunnerException("input_failed");
        return point;
    }

    // 窗口拖拽时序：按下→hold→移动→release→抬起，与 RPA 驱动逐段一致。
    internal static void DragSequence(bool right, int fromX, int fromY, int toX, int toY,
        int holdMs, int releaseDelayMs)
    {
        var down = right ? MouseEventfRightDown : MouseEventfLeftDown;
        var up = right ? MouseEventfRightUp : MouseEventfLeftUp;
        if (!SetCursorPos(fromX, fromY)) throw new RunnerException("input_failed");
        SendMouse(down, 0);
        if (holdMs > 0) Thread.Sleep(holdMs);
        if (!SetCursorPos(toX, toY)) throw new RunnerException("input_failed");
        if (releaseDelayMs > 0) Thread.Sleep(releaseDelayMs);
        SendMouse(up, 0);
    }

    // 抢前台五招兜底（RPA 驱动 activateWindowScript 的逐行移植）：
    // ①最小化则恢复 +150ms ②SwitchToThisWindow +150ms ③ALT 借位 + SetForegroundWindow +200ms
    // ④AttachThreadInput 挂到前台线程 + SetForegroundWindow +200ms ⑤最小化再恢复 +450ms
    // 五招全失败抛 focus_failed——对应 PS 版 RPA_ERROR '无法把窗口带到前台'。
    internal static void FocusChain(nint handle)
    {
        if (IsIconic(handle))
        {
            _ = ShowWindow(handle, SwRestore);
            Thread.Sleep(150);
        }
        if (NativeWindows.GetForegroundWindow() != handle)
        {
            SwitchToThisWindow(handle, true);
            Thread.Sleep(150);
        }
        if (NativeWindows.GetForegroundWindow() != handle)
        {
            keybd_event(VkMenu, 0, 0, nint.Zero);
            _ = SetForegroundWindow(handle);
            keybd_event(VkMenu, 0, KeyeventfKeyup, nint.Zero);
            Thread.Sleep(200);
        }
        if (NativeWindows.GetForegroundWindow() != handle)
        {
            // 返回值即前台窗口的线程号；PID 出参不需要。
            var foregroundThread = NativeWindows.GetWindowThreadProcessId(
                NativeWindows.GetForegroundWindow(), out _);
            var currentThread = GetCurrentThreadId();
            var attached = AttachThreadInput(currentThread, foregroundThread, true);
            try { _ = SetForegroundWindow(handle); }
            finally { if (attached) _ = AttachThreadInput(currentThread, foregroundThread, false); }
            Thread.Sleep(200);
        }
        if (NativeWindows.GetForegroundWindow() != handle)
        {
            _ = ShowWindow(handle, SwMinimize);
            Thread.Sleep(150);
            _ = ShowWindow(handle, SwRestore);
            Thread.Sleep(300);
        }
        if (NativeWindows.GetForegroundWindow() != handle)
            throw new RunnerException("focus_failed");
    }

    internal static void MoveWindowBounds(nint handle, int x, int y, int width, int height) =>
        _ = SetWindowPos(handle, nint.Zero, x, y, width, height, 4); // flags=4 SWP_NOZORDER，与 RPA 驱动一致

    internal static void CloseWindow(nint handle) =>
        _ = PostMessage(handle, WmClose, nint.Zero, nint.Zero);
}