/*
    * Licensed to the Apache Software Foundation (ASF) under one or more
    * contributor license agreements.  See the NOTICE file distributed with
    * this work for additional information regarding copyright ownership.
    * The ASF licenses this file to You under the Apache License, Version 2.0
    * (the "License"); you may not use this file except in compliance with
    * the License.  You may obtain a copy of the License at
    *
    *     http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  
  package org.apache.shardingsphere.db.protocol.postgresql.payload;
  
  import io.netty.buffer.ByteBuf;
  import lombok.Getter;
  import lombok.RequiredArgsConstructor;
  import org.apache.shardingsphere.db.protocol.payload.PacketPayload;
  
  import java.nio.charset.Charset;
  
  /**
   * Payload operation for PostgreSQL packet data types.
   *
   * @see <a href="https://www.postgresql.org/docs/current/protocol-message-types.html">Message Data Types</a>
   */
  @RequiredArgsConstructor
  @Getter
  public final class PostgreSQLPacketPayload implements PacketPayload {
      
      private final ByteBuf byteBuf;
      
      private final Charset charset;
      
      /**
       * Read 1 byte fixed length integer from byte buffers.
       *
       * @return 1 byte fixed length integer
       */
      public int readInt1() {
          return byteBuf.readUnsignedByte();
      }
      
      /**
       * Write 1 byte fixed length integer to byte buffers.
       *
       * @param value 1 byte fixed length integer
       */
      public void writeInt1(final int value) {
          byteBuf.writeByte(value);
      }
      
      /**
       * Read 2 byte fixed length integer from byte buffers.
       *
       * @return 2 byte fixed length integer
       */
      public int readInt2() {
          return byteBuf.readUnsignedShort();
      }
      
      /**
       * Write 2 byte fixed length integer to byte buffers.
       *
       * @param value 2 byte fixed length integer
       */
      public void writeInt2(final int value) {
          byteBuf.writeShort(value);
      }
      
      /**
       * Read 4 byte fixed length integer from byte buffers.
       *
       * @return 4 byte fixed length integer
       */
      public int readInt4() {
          return byteBuf.readInt();
      }
      
      /**
       * Write 4 byte fixed length integer to byte buffers.
       *
       * @param value 4 byte fixed length integer
       */
      public void writeInt4(final int value) {
          byteBuf.writeInt(value);
      }
      
      /**
       * Read 8 byte fixed length integer from byte buffers.
       *
       * @return 8 byte fixed length integer
       */
      public long readInt8() {
         return byteBuf.readLong();
     }
     
     /**
      * Write 8 byte fixed length integer to byte buffers.
      *
      * @param value 8 byte fixed length integer
      */
     public void writeInt8(final long value) {
         byteBuf.writeLong(value);
     }
     
     /**
      * Write variable length bytes to byte buffers.
      * 
      * @param value fixed length bytes
      */
     public void writeBytes(final byte[] value) {
         byteBuf.writeBytes(value);
     }
     
     /**
      * Bytes before zero.
      *
      * @return the number of bytes before zero
      */
     public int bytesBeforeZero() {
         return byteBuf.bytesBefore((byte) 0);
     }
     
     /**
      * Read null terminated string from byte buffers.
      * 
      * @return null terminated string
      */
     public String readStringNul() {
         String result = byteBuf.readCharSequence(byteBuf.bytesBefore((byte) 0), charset).toString();
         byteBuf.skipBytes(1);
         return result;
     }
     
     /**
      * Write null terminated string to byte buffers.
      * 
      * @param value null terminated string
      */
     public void writeStringNul(final String value) {
         byteBuf.writeBytes(value.getBytes(charset));
         byteBuf.writeByte(0);
     }
     
     /**
      * Write rest of packet string to byte buffers.
      * 
      * @param value rest of packet string
      */
     public void writeStringEOF(final String value) {
         byteBuf.writeBytes(value.getBytes(charset));
     }
     
     /**
      * Skip reserved from byte buffers.
      * 
      * @param length length of reserved
      */
     public void skipReserved(final int length) {
         byteBuf.skipBytes(length);
     }
     
     /**
      * Check if there has complete packet in ByteBuf.
      * PostgreSQL Message: (byte1) message type + (int4) length + (length - 4) payload
      *
      * @return has complete packet
      */
     public boolean hasCompletePacket() {
         return byteBuf.readableBytes() >= 5 && byteBuf.readableBytes() - 1 >= byteBuf.getInt(byteBuf.readerIndex() + 1);
     }
 }