/*
    * Copyright 2021 The Netty Project
    *
    * The Netty Project 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:
    *
    *   https://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 io.netty5.buffer;
  
  import io.netty5.buffer.api.Buffer;
  import io.netty5.util.CharsetUtil;
  
  import java.io.DataOutput;
  import java.io.DataOutputStream;
  import java.io.IOException;
  import java.io.OutputStream;
  
  import static java.util.Objects.requireNonNull;
  
  /**
   * An {@link OutputStream} which writes data to a {@link Buffer}.
   * <p>
   * A write operation against this stream will occur at the {@code writerOffset}
   * of its underlying buffer and the {@code writerOffset} will increase during
   * the write operation.
   * <p>
   * This stream implements {@link DataOutput} for your convenience.
   * The endianness of the stream is always big endian.
   *
   * @see BufferInputStream
   */
  public final class BufferOutputStream extends OutputStream implements DataOutput {
      private final Buffer buffer;
      private final int startIndex;
      private DataOutputStream utf8out; // lazily-instantiated
      private boolean closed;
  
      /**
       * Creates a new stream which writes data to the specified {@code buffer}.
       */
      public BufferOutputStream(Buffer buffer) {
          this.buffer = requireNonNull(buffer, "buffer");
          startIndex = buffer.writerOffset();
      }
  
      /**
       * Returns the number of written bytes by this stream so far.
       */
      public int writtenBytes() {
          return buffer.writerOffset() - startIndex;
      }
  
      @Override
      public void write(byte[] b, int off, int len) throws IOException {
          prepareWrite(len);
          if (len > 0) {
              buffer.writeBytes(b, off, len);
          }
      }
  
      @Override
      public void write(byte[] b) throws IOException {
          prepareWrite(b.length);
          if (b.length > 0) {
              buffer.writeBytes(b);
          }
      }
  
      @Override
      public void write(int b) throws IOException {
          prepareWrite(Integer.BYTES);
          buffer.writeByte((byte) b);
      }
  
      @Override
      public void writeBoolean(boolean v) throws IOException {
          prepareWrite(1);
          buffer.writeByte((byte) (v ? 1 : 0));
      }
  
      @Override
      public void writeByte(int v) throws IOException {
          prepareWrite(1);
          buffer.writeByte((byte) v);
      }
  
      @Override
      public void writeBytes(String s) throws IOException {
          prepareWrite(s.length()); // US ASCII has no multibyte values, so this works.
          buffer.writeCharSequence(s, CharsetUtil.US_ASCII);
      }
 
     @Override
     public void writeChar(int v) throws IOException {
         prepareWrite(Character.BYTES);
         buffer.writeChar((char) v);
     }
 
     @Override
     public void writeChars(String s) throws IOException {
         int len = s.length();
         prepareWrite(len * Character.BYTES);
         for (int i = 0 ; i < len ; i ++) {
             buffer.writeChar(s.charAt(i));
         }
     }
 
     @Override
     public void writeDouble(double v) throws IOException {
         prepareWrite(Double.BYTES);
         buffer.writeDouble(v);
     }
 
     @Override
     public void writeFloat(float v) throws IOException {
         prepareWrite(Float.BYTES);
         buffer.writeFloat(v);
     }
 
     @Override
     public void writeInt(int v) throws IOException {
         prepareWrite(Integer.BYTES);
         buffer.writeInt(v);
     }
 
     @Override
     public void writeLong(long v) throws IOException {
         prepareWrite(Long.BYTES);
         buffer.writeLong(v);
     }
 
     @Override
     public void writeShort(int v) throws IOException {
         prepareWrite(Short.BYTES);
         buffer.writeShort((short) v);
     }
 
     @Override
     public void writeUTF(String s) throws IOException {
         if (closed) {
             throw new IOException("The stream is closed");
         }
         DataOutputStream out = utf8out;
         if (out == null) {
             // Suppress a warning since the stream is closed in the close() method
             utf8out = out = new DataOutputStream(this); // lgtm[java/output-resource-leak]
         }
         out.writeUTF(s);
     }
 
     /**
      * Returns the buffer where this stream is writing data.
      */
     public Buffer buffer() {
         return buffer;
     }
 
     @Override
     public void close() throws IOException {
         if (closed) {
             return;
         }
         closed = true;
 
         try {
             super.close();
         } finally {
             if (utf8out != null) {
                 utf8out.close();
             }
         }
     }
 
     private void prepareWrite(int len) throws IOException {
         if (closed) {
             throw new IOException("Stream closed");
         }
         if (len > 0) {
             buffer.ensureWritable(len, buffer.capacity() >> 2, true);
         }
     }
 }