// Copyright (c) 2009, 2021, Oracle and/or its affiliates.
//
// This program is free software; you can redistribute it and/or modify
// it under the terms of the GNU General Public License, version 2.0, as
// published by the Free Software Foundation.
//
// This program is also distributed with certain software (including
// but not limited to OpenSSL) that is licensed under separate terms,
// as designated in a particular file or component or in included license
// documentation.  The authors of MySQL hereby grant you an
// additional permission to link the program and your derivative works
// with the separately licensed software that they have included with
// MySQL.
//
// Without limiting anything contained in the foregoing, this file,
// which is part of MySQL Connector/NET, is also subject to the
// Universal FOSS Exception, version 1.0, a copy of which can be found at
// http://oss.oracle.com/licenses/universal-foss-exception.
//
// This program is distributed in the hope that it will be useful, but
// WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
// See the GNU General Public License, version 2.0, for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program; if not, write to the Free Software Foundation, Inc.,
// 51 Franklin St, Fifth Floor, Boston, MA 02110-1301  USA

using Microsoft.Win32.SafeHandles;
using MySql.Data.Common;
using System;
using System.ComponentModel;
using System.IO;
using System.Runtime.InteropServices;
using System.Security;
using System.Threading;
using Sog.Properties;

namespace MySql.Data.MySqlClient.Common
{
    /// <summary>
    /// Summary description for API.
    /// </summary>
    [SuppressUnmanagedCodeSecurity()]
    internal class NamedPipeStream : Stream
    {
        SafeFileHandle handle;
        Stream fileStream;
        int readTimeout = Timeout.Infinite;
        int writeTimeout = Timeout.Infinite;
        const int ERROR_PIPE_BUSY = 231;
        const int ERROR_SEM_TIMEOUT = 121;

        public NamedPipeStream(string path, FileAccess mode, uint timeout)
        {
            this.Open(path, mode, timeout);
        }

        void CancelIo()
        {
            bool ok = NativeMethods.CancelIo(this.handle.DangerousGetHandle());
            if (!ok)
            {
                throw new System.ComponentModel.Win32Exception(Marshal.GetLastWin32Error());
            }
        }

        public void Open(string path, FileAccess mode, uint timeout)
        {
            IntPtr nativeHandle;

            for (; ; )
            {
                NativeMethods.SecurityAttributes security = new NativeMethods.SecurityAttributes();
                security.inheritHandle = true;
                security.Length = Marshal.SizeOf(security);

                nativeHandle = NativeMethods.CreateFile(path, NativeMethods.GENERIC_READ | NativeMethods.GENERIC_WRITE,
                             0, security, NativeMethods.OPEN_EXISTING, NativeMethods.FILE_FLAG_OVERLAPPED, 0);

                if (nativeHandle != IntPtr.Zero)
                {
                    break;
                }

                if (Marshal.GetLastWin32Error() != ERROR_PIPE_BUSY)
                {
                    throw new Win32Exception(
                        Marshal.GetLastWin32Error(),
                        "Error opening pipe");
                }

                MySql.Data.Common.LowResolutionStopwatch sw = MySql.Data.Common.LowResolutionStopwatch.StartNew();
                bool success = NativeMethods.WaitNamedPipe(path, timeout);
                sw.Stop();
                if (!success)
                {
                    if (timeout < sw.ElapsedMilliseconds ||
                        Marshal.GetLastWin32Error() == ERROR_SEM_TIMEOUT)
                    {
                        throw new TimeoutException("Timeout waiting for named pipe");
                    }
                    else
                    {
                        throw new Win32Exception(
                            Marshal.GetLastWin32Error(),
                            "Error waiting for pipe");
                    }
                }

                timeout -= (uint)sw.ElapsedMilliseconds;
            }

            this.handle = new SafeFileHandle(nativeHandle, true);
            this.fileStream = new FileStream(this.handle, mode, 4096, true);
        }

        public override bool CanRead
        {
            get { return this.fileStream.CanRead; }
        }

        public override bool CanWrite
        {
            get { return this.fileStream.CanWrite; }
        }

        public override bool CanSeek
        {
            get { throw new NotSupportedException(Resources.NamedPipeNoSeek); }
        }

        public override long Length
        {
            get { throw new NotSupportedException(Resources.NamedPipeNoSeek); }
        }

        public override long Position
        {
            get { throw new NotSupportedException(Resources.NamedPipeNoSeek); }
            set { }
        }

        public override void Flush()
        {
            this.fileStream.Flush();
        }

        public override int Read(byte[] buffer, int offset, int count)
        {
            if (this.readTimeout == Timeout.Infinite)
            {
                return this.fileStream.Read(buffer, offset, count);
            }

            IAsyncResult result = this.fileStream.BeginRead(buffer, offset, count, null, null);
            if (result.CompletedSynchronously)
            {
                return this.fileStream.EndRead(result);
            }

            if (!result.AsyncWaitHandle.WaitOne(this.readTimeout))
            {
                this.CancelIo();
                throw new TimeoutException("Timeout in named pipe read");
            }

            return this.fileStream.EndRead(result);
        }


        public override void Write(byte[] buffer, int offset, int count)
        {
            if (this.writeTimeout == Timeout.Infinite)
            {
                this.fileStream.Write(buffer, offset, count);
                return;
            }

            IAsyncResult result = this.fileStream.BeginWrite(buffer, offset, count, null, null);
            if (result.CompletedSynchronously)
            {
                this.fileStream.EndWrite(result);
            }

            if (!result.AsyncWaitHandle.WaitOne(this.readTimeout))
            {
                this.CancelIo();
                throw new TimeoutException("Timeout in named pipe write");
            }

            this.fileStream.EndWrite(result);
        }

        public override void Close()
        {
            if (this.handle != null && !this.handle.IsInvalid && !this.handle.IsClosed)
            {
                this.fileStream.Close();
                try
                {
                    this.handle.Close();
                }
                catch (Exception)
                {
                }
            }
        }

        public override void SetLength(long length)
        {
            throw new NotSupportedException(Resources.NamedPipeNoSetLength);
        }


        public override bool CanTimeout
        {
            get
            {
                return true;
            }
        }

        public override int ReadTimeout
        {
            get
            {
                return this.readTimeout;
            }
            set
            {
                this.readTimeout = value;
            }
        }

        public override int WriteTimeout
        {
            get
            {
                return this.writeTimeout;
            }
            set
            {
                this.writeTimeout = value;
            }
        }

        public override long Seek(long offset, SeekOrigin origin)
        {
            throw new NotSupportedException(Resources.NamedPipeNoSeek);
        }

        internal static Stream Create(string pipeName, string hostname, uint timeout)
        {
            string pipePath;
            if (0 == String.Compare(hostname, "localhost", true))
            {
                pipePath = @"\\.\pipe\" + pipeName;
            }
            else
            {
                pipePath = String.Format(@"\\{0}\pipe\{1}", hostname, pipeName);
            }

            return new NamedPipeStream(pipePath, FileAccess.ReadWrite, timeout);
        }
    }
}