using anjianjingling.Native;
using System.Runtime.InteropServices;

namespace anjianjingling.Input
{
    public enum MouseButton { Left, Right, Middle }

    /// <summary>
    /// 系统级鼠标模拟（SendInput）。
    /// </summary>
    public sealed class MouseInput
    {
        private static readonly Random Rng = new();

        /// <summary>虚拟桌面（含多显示器）尺寸与原点。</summary>
        private static Rectangle VirtualScreen()
        {
            int x = Win32.GetSystemMetrics(Win32.SM_XVIRTUALSCREEN);
            int y = Win32.GetSystemMetrics(Win32.SM_YVIRTUALSCREEN);
            int w = Win32.GetSystemMetrics(Win32.SM_CXVIRTUALSCREEN);
            int h = Win32.GetSystemMetrics(Win32.SM_CYVIRTUALSCREEN);
            return new Rectangle(x, y, w, h);
        }

        /// <summary>把屏幕物理坐标换算为 SendInput 绝对坐标（0..65535，含虚拟桌面偏移）。</summary>
        private static void ToAbsolute(int x, int y, out int ax, out int ay)
        {
            var vs = VirtualScreen();
            ax = (int)((x - vs.Left) * 65535.0 / (vs.Width - 1));
            ay = (int)((y - vs.Top) * 65535.0 / (vs.Height - 1));
        }

        private static void SendSingle(Win32.MOUSEINPUT mi)
        {
            var input = new Win32.INPUT
            {
                type = Win32.INPUT_MOUSE,
                u = new Win32.INPUTUNION { mi = mi }
            };
            Win32.SendInput(1, new[] { input }, Marshal.SizeOf<Win32.INPUT>());
        }

        /// <summary>移动鼠标到指定屏幕坐标（瞬时）。</summary>
        public void MoveTo(int x, int y)
        {
            ToAbsolute(x, y, out int ax, out int ay);
            SendSingle(new Win32.MOUSEINPUT
            {
                dx = ax,
                dy = ay,
                dwFlags = Win32.MOUSEEVENTF_MOVE | Win32.MOUSEEVENTF_ABSOLUTE | Win32.MOUSEEVENTF_VIRTUALDESK
            });
        }

        /// <summary>相对移动。</summary>
        public void MoveR(int dx, int dy)
        {
            var p = Position;
            MoveTo(p.X + dx, p.Y + dy);
        }

        /// <summary>带随机偏移的移动（拟人化）。</summary>
        public void MoveToJitter(int x, int y, int jitterPx = 3)
        {
            MoveTo(x + Rng.Next(-jitterPx, jitterPx + 1),
                   y + Rng.Next(-jitterPx, jitterPx + 1));
        }

        public void ButtonDown(MouseButton button)
            => SendSingle(new Win32.MOUSEINPUT { dwFlags = button switch
            {
                MouseButton.Left => Win32.MOUSEEVENTF_LEFTDOWN,
                MouseButton.Right => Win32.MOUSEEVENTF_RIGHTDOWN,
                MouseButton.Middle => Win32.MOUSEEVENTF_MIDDLEDOWN,
                _ => throw new ArgumentOutOfRangeException(nameof(button))
            } });

        public void ButtonUp(MouseButton button)
            => SendSingle(new Win32.MOUSEINPUT { dwFlags = button switch
            {
                MouseButton.Left => Win32.MOUSEEVENTF_LEFTUP,
                MouseButton.Right => Win32.MOUSEEVENTF_RIGHTUP,
                MouseButton.Middle => Win32.MOUSEEVENTF_MIDDLEUP,
                _ => throw new ArgumentOutOfRangeException(nameof(button))
            } });

        /// <summary>在当前位置点击；jitter=true 时落点带 ±3px 随机偏移（仅当指定坐标时）。</summary>
        public void Click(MouseButton button, int? x = null, int? y = null, bool jitter = false)
        {
            if (x.HasValue && y.HasValue)
            {
                if (jitter) MoveToJitter(x.Value, y.Value);
                else MoveTo(x.Value, y.Value);
                Thread.Sleep(60 + Rng.Next(0, 50));
            }
            ButtonDown(button);
            Thread.Sleep(40 + Rng.Next(0, 40));
            ButtonUp(button);
        }

        /// <summary>双击（左键）。</summary>
        public void DoubleClick(int? x = null, int? y = null, bool jitter = false)
        {
            Click(MouseButton.Left, x, y, jitter);
            Thread.Sleep(50 + Rng.Next(0, 60));
            Click(MouseButton.Left);
        }

        /// <summary>滚轮：正值向上滚，负值向下滚，单位为格（每格 120）。</summary>
        public void Wheel(int delta)
        {
            SendSingle(new Win32.MOUSEINPUT
            {
                mouseData = (uint)(delta * Win32.WHEEL_DELTA),
                dwFlags = Win32.MOUSEEVENTF_WHEEL
            });
        }

        /// <summary>从一点拖拽到另一点，按 duration 插值移动，模拟人手。</summary>
        public void Drag(int x1, int y1, int x2, int y2, int durationMs = 400)
        {
            MoveTo(x1, y1);
            Thread.Sleep(100);
            ButtonDown(MouseButton.Left);

            int steps = Math.Max(5, durationMs / 16);
            for (int i = 1; i <= steps; i++)
            {
                double t = (double)i / steps;
                // 轻微非线性，模拟加减速
                double e = t * t * (3 - 2 * t);
                int cx = (int)(x1 + (x2 - x1) * e);
                int cy = (int)(y1 + (y2 - y1) * e);
                MoveTo(cx, cy);
                Thread.Sleep(16);
            }
            Thread.Sleep(80);
            ButtonUp(MouseButton.Left);
        }

        /// <summary>当前鼠标屏幕坐标。</summary>
        public Point Position
        {
            get
            {
                Win32.GetCursorPos(out var p);
                return p;
            }
        }
    }
}