/*
 * Copyright 2018 Confluent Inc.
 *
 * Licensed under the Confluent Community License (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.confluent.io/confluent-community-license
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
 * WARRANTIES OF ANY KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations under the License.
 */

package io.confluent.connect.s3.storage;

import org.apache.kafka.connect.errors.ConnectException;

import java.io.InputStream;
import java.io.OutputStream;
import java.util.zip.Deflater;
import java.util.zip.DeflaterOutputStream;
import java.util.zip.GZIPInputStream;
import java.util.zip.GZIPOutputStream;

/**
 * Supported compression types for formats lacking built-in compression.
 *
 * <p>In particular, the compression here is not used for Avro since the
 * Avro libraries have compression codecs built in.
 *
 * <p>Closely modeled on {@link org.apache.kafka.common.record.CompressionType}.</p>
 */
public enum CompressionType {

  NONE("none", ""),

  GZIP("gzip", ".gz") {
    @Override
    public OutputStream wrapForOutput(OutputStream out) {
      return wrapForOutput(out, Deflater.DEFAULT_COMPRESSION);
    }

    @Override
    public OutputStream wrapForOutput(OutputStream out, int level) {
      try {
        return new GZIPOutputStream(out, GZIP_BUFFER_SIZE_BYTES) {
          public OutputStream setLevel(int level) {
            def.setLevel(level);
            return this;
          }
        }.setLevel(level);
      } catch (Exception e) {
        throw new ConnectException(e);
      }
    }

    @Override
    public InputStream wrapForInput(InputStream in) {
      try {
        return new GZIPInputStream(in);
      } catch (Exception e) {
        throw new ConnectException(e);
      }
    }

    @Override
    public void finalize(OutputStream compressionFilter) {
      if (compressionFilter instanceof DeflaterOutputStream) {
        try {
          ((DeflaterOutputStream) compressionFilter).finish();
        } catch (Exception e) {
          throw new ConnectException(e);
        }
      } else {
        throw new ConnectException("Expected compressionFilter to be a DeflaterOutputStream, "
            + "but was passed an instance that does not match that type.");
      }
    }
  };

  private static final int GZIP_BUFFER_SIZE_BYTES = 8 * 1024;

  public final String name;
  public final String extension;

  CompressionType(String name, String extension) {
    this.name = name;
    this.extension = extension;
  }

  /**
   * Return the {@link CompressionType} with given {@code name}.
   *
   * @param name a lowercase compression type name
   * @return a {@link CompressionType} with the given name
   */
  public static CompressionType forName(String name) {
    if (NONE.name.equals(name)) {
      return NONE;
    } else if (GZIP.name.equals(name)) {
      return GZIP;
    } else {
      throw new IllegalArgumentException("Unknown compression name: " + name);
    }
  }

  /**
   * Wrap {@code out} with a filter that will compress data with this CompressionType.
   *
   * @param out the {@link OutputStream} to wrap
   * @return a wrapped version of {@code out} that will apply compression
   */
  public OutputStream wrapForOutput(OutputStream out) {
    return out;
  }

  /**
   * Wrap {@code out} with a filter that will compress data with this CompressionType at the
   * given compression level (optional operation).
   *
   * @param out the {@link OutputStream} to wrap
   * @param level the compression level for this compression type
   * @return a wrapped version of {@code out} that will apply compression at the given level
   */
  public OutputStream wrapForOutput(OutputStream out, int level) {
    return wrapForOutput(out);
  }

  /**
   * Wrap {@code in} with a filter that will decompress data with this CompressionType.
   *
   * @param in the {@link InputStream} to wrap
   * @return a wrapped version of {@code in} that will apply decompression
   */
  public InputStream wrapForInput(InputStream in) {
    return in;
  }

  /**
   * Take any action necessary to finalize filter before the underlying
   * S3OutputStream is committed.
   *
   * <p>Implementations of this method should make sure to handle the case
   * where {@code compressionFilter} is null.
   *
   * @param compressionFilter a wrapped {@link OutputStream}
   */
  public void finalize(OutputStream compressionFilter) {}

}
