using Microsoft.Win32.SafeHandles;

using System;

using System.Collections.Generic;

using System.Diagnostics;

using System.IO;

using System.Linq;

using System.Runtime.Serialization;

using System.Text;

using System.Threading.Tasks;

using SharpLib.Win32;

using System.ComponentModel;

using System.Runtime.InteropServices;

namespace SharpLib.Ear

{

    [DataContract]

    [AttributeObject(Id = "Action.OpticalDrive.Eject", Name = "Eject", Description = "Eject media from an optical drive.")]

    public class ActionOpticalDriveEject : Action

    {

        [DataMember]

        [AttributeObjectProperty

            (

            Id = "Action.OpticalDrive.Eject.Drive",

            Name = "Drive to eject",

            Description = "Select the drive you want to eject."

            )

        ]

        public PropertyComboBox Drive { get; set; } = new PropertyComboBox();

        protected override void DoConstruct()

        {

            base.DoConstruct();

            PopulateOpticalDrives();

            CheckCurrentItem();

        }

        public override string BriefBase()

        {

            return AttributeName + " " + Drive.CurrentItem ;

        }

        public override bool IsValid()

        {   

            //This object is valid if our current item is contained in our drive list

            return Drive.Items.Contains(Drive.CurrentItem);

        }

        protected override async Task DoExecute()

        {

            DriveEject(Drive.CurrentItem);

        }

        private void CheckCurrentItem()

        {

            if (!Drive.Items.Contains(Drive.CurrentItem) && Drive.Items.Count>0)

            {

                //Current item unknown, reset it then

                Drive.CurrentItem = Drive.Items[0];

            }

        }

        /// <summary>

        /// 

        /// </summary>

        private void PopulateOpticalDrives()

        {

            //Reset our list of drives

            Drive.Items = new List<string>();

            //Go through each drives on our system and collected the optical ones in our list

            DriveInfo[] allDrives = DriveInfo.GetDrives();

            foreach (DriveInfo d in allDrives)

            {

                Debug.WriteLine("Drive " + d.Name);

                Debug.WriteLine("  Drive type: {0}", d.DriveType);

                if (d.DriveType == DriveType.CDRom)

                {

                    //This is an optical drive, add it now

                    Drive.Items.Add(d.Name.Substring(0, 2));

                }

            }

        }

        /// <summary>

        /// 

        /// </summary>

        /// <param name="aPrefix"></param>

        static private void CheckLastError(string aPrefix)

        {

            string errorMessage = new Win32Exception(Marshal.GetLastWin32Error()).Message;

            Debug.WriteLine(aPrefix + Marshal.GetLastWin32Error().ToString() + ": " + errorMessage);

        }

        /// <summary>

        /// 

        /// </summary>

        /// <param name="data"></param>

        /// <returns></returns>

        static private IntPtr MarshalToPointer(object data)

        {

            IntPtr buf = Marshal.AllocHGlobal(

                Marshal.SizeOf(data));

            Marshal.StructureToPtr(data,

                buf, false);

            return buf;

        }

        /// <summary>

        /// 

        /// </summary>

        /// <returns></returns>

        static private SafeFileHandle OpenVolume(string aDriveName)

        {

            return Function.CreateFile("\\\\.\\" + aDriveName,

                               SharpLib.Win32.FileAccess.GENERIC_READ,

                               SharpLib.Win32.FileShare.FILE_SHARE_READ | SharpLib.Win32.FileShare.FILE_SHARE_WRITE,

                               IntPtr.Zero,

                               CreationDisposition.OPEN_EXISTING,

                               0,

                               IntPtr.Zero);

        }

        /// <summary>

        /// 

        /// </summary>

        /// <param name="aVolume"></param>

        /// <returns></returns>

        static private bool LockVolume(SafeFileHandle aVolume)

        {

            //Hope that's doing what I think it does

            IntPtr dwBytesReturned = new IntPtr();

            //Should not be needed but I'm not sure how to pass NULL in there.

            OVERLAPPED overlapped = new OVERLAPPED();

            int tries = 0;

            const int KMaxTries = 100;

            const int KSleepTime = 10;

            bool success = false;

            while (!success && tries < KMaxTries)

            {

                success = Function.DeviceIoControl(aVolume, Const.FSCTL_LOCK_VOLUME, IntPtr.Zero, 0, IntPtr.Zero, 0, dwBytesReturned, ref overlapped);

                System.Threading.Thread.Sleep(KSleepTime);

                tries++;

            }

            CheckLastError("Lock volume: ");

            return success;

        }

        /// <summary>

        /// 

        /// </summary>

        /// <param name="aVolume"></param>

        /// <returns></returns>

        static private bool DismountVolume(SafeFileHandle aVolume)

        {

            //Hope that's doing what I think it does

            IntPtr dwBytesReturned = new IntPtr();

            //Should not be needed but I'm not sure how to pass NULL in there.

            OVERLAPPED overlapped = new OVERLAPPED();

            bool res = Function.DeviceIoControl(aVolume, Const.FSCTL_DISMOUNT_VOLUME, IntPtr.Zero, 0, IntPtr.Zero, 0, dwBytesReturned, ref overlapped);

            CheckLastError("Dismount volume: ");

            return res;

        }

        /// <summary>

        /// 

        /// </summary>

        /// <param name="aVolume"></param>

        /// <param name="aPreventRemoval"></param>

        /// <returns></returns>

        static private bool PreventRemovalOfVolume(SafeFileHandle aVolume, bool aPreventRemoval)

        {

            //Hope that's doing what I think it does

            IntPtr dwBytesReturned = new IntPtr();

            //Should not be needed but I'm not sure how to pass NULL in there.

            OVERLAPPED overlapped = new OVERLAPPED();

            //

            PREVENT_MEDIA_REMOVAL preventMediaRemoval = new PREVENT_MEDIA_REMOVAL();

            preventMediaRemoval.PreventMediaRemoval = Convert.ToByte(aPreventRemoval);

            IntPtr preventMediaRemovalParam = MarshalToPointer(preventMediaRemoval);

            bool result = Function.DeviceIoControl(aVolume, Const.IOCTL_STORAGE_MEDIA_REMOVAL, preventMediaRemovalParam, Convert.ToUInt32(Marshal.SizeOf(preventMediaRemoval)), IntPtr.Zero, 0, dwBytesReturned, ref overlapped);

            CheckLastError("Media removal: ");

            Marshal.FreeHGlobal(preventMediaRemovalParam);

            return result;

        }

        /// <summary>

        /// Eject optical drive media opening the tray if any.

        /// </summary>

        /// <param name="aVolume"></param>

        /// <returns></returns>

        static private bool MediaEject(SafeFileHandle aVolume)

        {

            //Hope that's doing what I think it does

            IntPtr dwBytesReturned = new IntPtr();

            //Should not be needed but I'm not sure how to pass NULL in there.

            OVERLAPPED overlapped = new OVERLAPPED();

            bool res = Function.DeviceIoControl(aVolume, Const.IOCTL_STORAGE_EJECT_MEDIA, IntPtr.Zero, 0, IntPtr.Zero, 0, dwBytesReturned, ref overlapped);

            CheckLastError("Media eject: ");

            return res;

        }

        /// <summary>

        /// Close an optical drive tray.

        /// </summary>

        /// <param name="aVolume"></param>

        /// <returns></returns>

        static private bool MediaLoad(SafeFileHandle aVolume)

        {

            //Hope that's doing what I think it does

            IntPtr dwBytesReturned = new IntPtr();

            //Should not be needed but I'm not sure how to pass NULL in there.

            OVERLAPPED overlapped = new OVERLAPPED();

            bool res = Function.DeviceIoControl(aVolume, Const.IOCTL_STORAGE_LOAD_MEDIA, IntPtr.Zero, 0, IntPtr.Zero, 0, dwBytesReturned, ref overlapped);

            CheckLastError("Media load: ");

            return res;

        }

        /// <summary>

        /// 

        /// </summary>

        /// <param name="aVolume"></param>

        /// <returns></returns>

        static private bool StorageCheckVerify(SafeFileHandle aVolume)

        {

            //Hope that's doing what I think it does

            IntPtr dwBytesReturned = new IntPtr();

            //Should not be needed but I'm not sure how to pass NULL in there.

            OVERLAPPED overlapped = new OVERLAPPED();

            bool res = Function.DeviceIoControl(aVolume, Const.IOCTL_STORAGE_CHECK_VERIFY2, IntPtr.Zero, 0, IntPtr.Zero, 0, dwBytesReturned, ref overlapped);

            CheckLastError("Check verify: ");

            return res;

        }

        /// <summary>

        /// Perform media ejection.

        /// </summary>

        static private void DriveEject(string aDrive)

        {

            string drive = aDrive;

            if (drive.Length != 2)

            {

                //Not a proper drive spec.

                //Probably 'None' selected.

                return;

            }

            SafeFileHandle handle = OpenVolume(drive);

            if (handle.IsInvalid)

            {

                CheckLastError("ERROR: Failed to open volume: ");

                return;

            }

            if (LockVolume(handle) && DismountVolume(handle))

            {

                Debug.WriteLine("Volume was dismounted.");

                if (PreventRemovalOfVolume(handle, false))

                {

                    //StorageCheckVerify(handle);

                    DateTime before;

                    before = DateTime.Now;

                    bool ejectSuccess = MediaEject(handle);

                    double ms = (DateTime.Now - before).TotalMilliseconds;

                    //We assume that if it take more than a certain time to for eject to execute it means we actually ejected.

                    //If our eject completes too rapidly we assume the tray is already open and we will try to close it. 

                    if (ejectSuccess && ms > 100)

                    {

                        Debug.WriteLine("Media was ejected");

                    }

                    else if (MediaLoad(handle))

                    {

                        Debug.WriteLine("Media was loaded");

                    }

                }

            }

            else

            {

                Debug.WriteLine("Volume lock or dismount failed.");

            }

            //This is needed to make sure we can open the volume next time around

            handle.Dispose();

        }

    }

}