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

namespace anjianjingling.Input
{
    /// <summary>
    /// 系统级键盘模拟（SendInput）：单键、组合键、Unicode 文本。
    /// </summary>
    public sealed class KeyboardInput
    {
        private static void SendKey(Win32.KEYBDINPUT ki)
        {
            var input = new Win32.INPUT
            {
                type = Win32.INPUT_KEYBOARD,
                u = new Win32.INPUTUNION { ki = ki }
            };
            Win32.SendInput(1, new[] { input }, Marshal.SizeOf<Win32.INPUT>());
        }

        /// <summary>发送一次按键（按下并弹起）。</summary>
        public void KeyPress(string keyName)
        {
            ushort vk = ResolveOrThrow(keyName);
            KeyDownVk(vk);
            Thread.Sleep(30);
            KeyUpVk(vk);
        }

        public void KeyDown(string keyName) => KeyDownVk(ResolveOrThrow(keyName));

        public void KeyUp(string keyName) => KeyUpVk(ResolveOrThrow(keyName));

        private static void KeyDownVk(ushort vk)
        {
            ushort scan = (ushort)Win32.MapVirtualKey(vk, Win32.MAPVK_VK_TO_VSC);
            uint flags = Win32.KEYEVENTF_SCANCODE;
            if (VirtualKeys.IsExtended(vk)) flags |= Win32.KEYEVENTF_EXTENDEDKEY;
            SendKey(new Win32.KEYBDINPUT { wVk = vk, wScan = scan, dwFlags = flags });
        }

        private static void KeyUpVk(ushort vk)
        {
            ushort scan = (ushort)Win32.MapVirtualKey(vk, Win32.MAPVK_VK_TO_VSC);
            uint flags = Win32.KEYEVENTF_SCANCODE | Win32.KEYEVENTF_KEYUP;
            if (VirtualKeys.IsExtended(vk)) flags |= Win32.KEYEVENTF_EXTENDEDKEY;
            SendKey(new Win32.KEYBDINPUT { wVk = vk, wScan = scan, dwFlags = flags });
        }

        /// <summary>
        /// 组合键，如 "Ctrl+A"、"Ctrl+Shift+Esc"：修饰键依次按下，主键按下弹起，修饰键逆序弹起。
        /// </summary>
        public void HotKey(string expression)
        {
            var parts = expression.Split('+', StringSplitOptions.TrimEntries | StringSplitOptions.RemoveEmptyEntries);
            if (parts.Length == 0) throw new ArgumentException($"无法解析组合键：{expression}");

            var vks = parts.Select(ResolveOrThrow).ToArray();
            for (int i = 0; i < vks.Length - 1; i++) KeyDownVk(vks[i]);
            Thread.Sleep(40);
            KeyDownVk(vks[^1]);
            Thread.Sleep(40);
            KeyUpVk(vks[^1]);
            for (int i = vks.Length - 2; i >= 0; i--)
            {
                Thread.Sleep(20);
                KeyUpVk(vks[i]);
            }
        }

        /// <summary>
        /// 输入整段文本（含中文），使用 KEYEVENTF_UNICODE，不依赖键盘布局。
        /// </summary>
        public void TypeText(string text)
        {
            foreach (char c in text)
            {
                SendKey(new Win32.KEYBDINPUT { wScan = c, dwFlags = Win32.KEYEVENTF_UNICODE });
                SendKey(new Win32.KEYBDINPUT { wScan = c, dwFlags = Win32.KEYEVENTF_UNICODE | Win32.KEYEVENTF_KEYUP });
            }
        }

        private static ushort ResolveOrThrow(string name)
            => VirtualKeys.Resolve(name)
               ?? throw new ArgumentException($"未知按键名：\"{name}\"（可用如 A、F5、ENTER、SPACE、方向键等）");
    }
}