using System;
using System.Collections.Generic;
using System.Linq;
using System.Runtime.InteropServices;
using System.Text;
using System.Threading.Tasks;

namespace AIK.Service.Interop
{
    /// <summary>
    /// P/Invoke 方法实现 Windows 卷弹出功能
    /// </summary>
    internal static class WindowsVolumeEjector
    {
        [DllImport("kernel32.dll", SetLastError = true, CharSet = CharSet.Auto)]
        private static extern IntPtr CreateFile(
        string lpFileName,
        uint dwDesiredAccess,
        uint dwShareMode,
        IntPtr lpSecurityAttributes,
        uint dwCreationDisposition,
        uint dwFlagsAndAttributes,
        IntPtr hTemplateFile);

        [DllImport("kernel32.dll", SetLastError = true)]
        private static extern bool DeviceIoControl(
            IntPtr hDevice,
            uint dwIoControlCode,
            IntPtr lpInBuffer,
            uint nInBufferSize,
            IntPtr lpOutBuffer,
            uint nOutBufferSize,
            out uint lpBytesReturned,
            IntPtr lpOverlapped);

        [DllImport("kernel32.dll")]
        private static extern bool CloseHandle(IntPtr hObject);

        private const uint GENERIC_READ = 0x80000000;
        private const uint FILE_SHARE_READ = 0x1;
        private const uint FILE_SHARE_WRITE = 0x2;
        private const uint OPEN_EXISTING = 3;
        private const uint FSCTL_DISMOUNT_VOLUME = 0x00090020;
        private const uint IOCTL_STORAGE_EJECT_MEDIA = 0x2D4808;

        public static async Task<bool> EjectVolumeAsync(string driveLetter)
        {
            return await Task.Run(() =>
            {
                if (string.IsNullOrEmpty(driveLetter))
                    return false;

                // 标准化输入：确保是 "X:" 或 "X:\"
                string cleanDrive = driveLetter.TrimEnd('\\');
                if (!cleanDrive.EndsWith(":"))
                    return false;

                string devicePath = @"\\.\" + cleanDrive + @"\";
                IntPtr handle = IntPtr.Zero;

                try
                {
                    handle = CreateFile(devicePath, GENERIC_READ,
                        FILE_SHARE_READ | FILE_SHARE_WRITE,
                        IntPtr.Zero, OPEN_EXISTING, 0, IntPtr.Zero);

                    if (handle == IntPtr.Zero || handle == new IntPtr(-1))
                    {
                        var errorCode = Marshal.GetLastWin32Error();
                        // 可记录日志：$"CreateFile failed with error {errorCode}"
                        return false;
                    }

                    // 尝试卸载卷（可选，提高成功率）
                    DeviceIoControl(handle, FSCTL_DISMOUNT_VOLUME,
                        IntPtr.Zero, 0, IntPtr.Zero, 0, out _, IntPtr.Zero);

                    // 弹出介质
                    bool result = DeviceIoControl(handle, IOCTL_STORAGE_EJECT_MEDIA,
                        IntPtr.Zero, 0, IntPtr.Zero, 0, out _, IntPtr.Zero);

                    return result;
                }
                catch (Exception ex)
                {
                    // 可记录异常
                    return false;
                }
                finally
                {
                    if (handle != IntPtr.Zero && handle != new IntPtr(-1))
                    {
                        CloseHandle(handle);
                    }
                }
            });
        }
    }
}