// Copyright (c) 2004, 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 System;
using System.IO;
using System.Net.Sockets;
using System.Text;
using Sog.Properties;

namespace MySql.Data.MySqlClient
{
    /// <summary>
    /// Summary description for MySqlStream.
    /// </summary>
    internal class MySqlStream
    {
        private byte sequenceByte;
        private int maxBlockSize;
        private ulong maxPacketSize;
        private byte[] packetHeader = new byte[4];
        MySqlPacket packet;
        TimedStream timedStream;
        Stream inStream;
        Stream outStream;
        Socket socket;
        public Socket Socket { get => this.socket; set => this.socket = value; }

        internal Stream BaseStream
        {
            get
            {
                return this.timedStream;
            }
        }

        public MySqlStream(Encoding encoding)
        {
            // we have no idea what the real value is so we start off with the max value
            // The real value will be set in NativeDriver.Configure()
            this.maxPacketSize = ulong.MaxValue;

            // we default maxBlockSize to MaxValue since we will get the 'real' value in 
            // the authentication handshake and we know that value will not exceed 
            // true maxBlockSize prior to that.
            this.maxBlockSize = Int32.MaxValue;

            this.packet = new MySqlPacket(encoding);
        }

        public MySqlStream(Stream baseStream, Encoding encoding, bool compress, Socket pSocket = null)
          : this(encoding)
        {
            this.timedStream = new TimedStream(baseStream);
            Stream stream;
            if (compress)
            {
                stream = new CompressedStream(this.timedStream);
            }
            else
            {
                stream = this.timedStream;
            }

            this.inStream = stream;
            this.outStream = stream;
            this.socket = pSocket;
        }

        public void Close()
        {
            this.outStream.Dispose();
            this.inStream.Dispose();
            this.timedStream.Close();
        }

        #region Properties

        public Encoding Encoding
        {
            get { return this.packet.Encoding; }
            set { this.packet.Encoding = value; }
        }

        public void ResetTimeout(int timeout)
        {
            this.timedStream.ResetTimeout(timeout);
        }

        public byte SequenceByte
        {
            get { return this.sequenceByte; }
            set { this.sequenceByte = value; }
        }

        public int MaxBlockSize
        {
            get { return this.maxBlockSize; }
            set { this.maxBlockSize = value; }
        }

        public ulong MaxPacketSize
        {
            get { return this.maxPacketSize; }
            set { this.maxPacketSize = value; }
        }

        #endregion

        #region Packet methods

        /// <summary>
        /// ReadPacket is called by NativeDriver to start reading the next
        /// packet on the stream.
        /// </summary>
        public MySqlPacket ReadPacket()
        {
            // Debug.Assert(packet.Position == packet.Length);

            // make sure we have read all the data from the previous packet
            // Debug.Assert(HasMoreData == false, "HasMoreData is true in OpenPacket");

            this.LoadPacket();

            // now we check if this packet is a server error
            if (this.packet.Buffer[0] == 0xff)
            {
                this.packet.ReadByte();  // read off the 0xff

                int code = this.packet.ReadInteger(2);
                string msg = String.Empty;

                if (this.packet.Version.isAtLeast(5, 5, 0))
                {
                    msg = this.packet.ReadString(Encoding.UTF8);
                }
                else
                {
                    msg = this.packet.ReadString();
                }

                if (msg.StartsWith("#", StringComparison.Ordinal))
                {
                    msg.Substring(1, 5);  /* state code */
                    msg = msg.Substring(6);
                }

                switch (code)
                {
                    case 4031:
                        throw new MySqlException(msg, code, true);
                    default:
                        throw new MySqlException(msg, code);
                }
            }

            return this.packet;
        }

        /// <summary>
        /// Reads the specified number of bytes from the stream and stores them at given 
        /// offset in the buffer.
        /// Throws EndOfStreamException if not all bytes can be read.
        /// </summary>
        /// <param name="stream">Stream to read from</param>
        /// <param name="buffer"> Array to store bytes read from the stream </param>
        /// <param name="offset">The offset in buffer at which to begin storing the data read from the current stream. </param>
        /// <param name="count">Number of bytes to read</param>
        internal static void ReadFully(Stream stream, byte[] buffer, int offset, int count)
        {
            int numRead = 0;
            int numToRead = count;
            while (numToRead > 0)
            {
                int read = stream.Read(buffer, offset + numRead, numToRead);
                if (read == 0)
                {
                    throw new EndOfStreamException();
                }

                numRead += read;
                numToRead -= read;
            }
        }

        /// <summary>
        /// LoadPacket loads up and decodes the header of the incoming packet.
        /// </summary>
        public void LoadPacket()
        {
            try
            {
                this.packet.Length = 0;
                int offset = 0;
                while (true)
                {
                    ReadFully(this.inStream, this.packetHeader, 0, 4);
                    this.sequenceByte = (byte)(this.packetHeader[3] + 1);
                    int length = (int)(this.packetHeader[0] + (this.packetHeader[1] << 8) +
                        (this.packetHeader[2] << 16));

                    // make roo for the next block
                    this.packet.Length += length;
                    ReadFully(this.inStream, this.packet.Buffer, offset, length);
                    offset += length;

                    // if this block was < maxBlock then it's last one in a multipacket series
                    if (length < this.maxBlockSize)
                    {
                        break;
                    }
                }

                this.packet.Position = 0;
            }
            catch (IOException ioex)
            {
                throw new MySqlException(Resources.ReadFromStreamFailed, true, ioex);
            }
        }

        public void SendPacket(MySqlPacket packet)
        {
            byte[] buffer = packet.Buffer;
            int length = packet.Position - 4;

            if ((ulong)length > this.maxPacketSize)
            {
                throw new MySqlException(Resources.QueryTooLarge, (int)MySqlErrorCode.PacketTooLarge);
            }

            int offset = 0;
            do
            {
                int lenToSend = length > this.maxBlockSize ? this.maxBlockSize : length;
                buffer[offset] = (byte)(lenToSend & 0xff);
                buffer[offset + 1] = (byte)((lenToSend >> 8) & 0xff);
                buffer[offset + 2] = (byte)((lenToSend >> 16) & 0xff);
                buffer[offset + 3] = this.sequenceByte++;
                if (this.Socket != null && this.Socket.Available > 0)
                {
                    this.ReadPacket();
                }

                this.outStream.Write(buffer, offset, lenToSend + 4);
                this.outStream.Flush();
                length -= lenToSend;
                offset += lenToSend;
            } while (length > 0);
        }

        public void SendEntirePacketDirectly(byte[] buffer, int count)
        {
            buffer[0] = (byte)(count & 0xff);
            buffer[1] = (byte)((count >> 8) & 0xff);
            buffer[2] = (byte)((count >> 16) & 0xff);
            buffer[3] = this.sequenceByte++;
            this.outStream.Write(buffer, 0, count + 4);
            this.outStream.Flush();
        }

        #endregion
    }
}