/**
 * 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.camel.converter.stream;

import java.io.BufferedOutputStream;
import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.security.GeneralSecurityException;

import javax.crypto.CipherOutputStream;

import org.apache.camel.Exchange;
import org.apache.camel.StreamCache;
import org.apache.camel.converter.stream.FileInputStreamCache.FileInputStreamCloser;
import org.apache.camel.spi.StreamCachingStrategy;
import org.apache.camel.spi.Synchronization;
import org.apache.camel.spi.UnitOfWork;
import org.apache.camel.support.SynchronizationAdapter;
import org.apache.camel.util.FileUtil;
import org.apache.camel.util.ObjectHelper;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * This output stream will store the content into a File if the stream context size is exceed the
 * THRESHOLD value. The default THRESHOLD value is {@link StreamCache#DEFAULT_SPOOL_THRESHOLD} bytes .
 * <p/>
 * The temp file will store in the temp directory, you can configure it by setting the TEMP_DIR property.
 * If you don't set the TEMP_DIR property, it will choose the directory which is set by the
 * system property of "java.io.tmpdir".
 * <p/>
 * You can get a cached input stream of this stream. The temp file which is created with this 
 * output stream will be deleted when you close this output stream or the cached 
 * fileInputStream(s) is/are closed after the exchange is completed.
 */
public class CachedOutputStream extends OutputStream {
    @Deprecated
    public static final String THRESHOLD = "CamelCachedOutputStreamThreshold";
    @Deprecated
    public static final String BUFFER_SIZE = "CamelCachedOutputStreamBufferSize";
    @Deprecated
    public static final String TEMP_DIR = "CamelCachedOutputStreamOutputDirectory";
    @Deprecated
    public static final String CIPHER_TRANSFORMATION = "CamelCachedOutputStreamCipherTransformation";
    private static final Logger LOG = LoggerFactory.getLogger(CachedOutputStream.class);

    private final StreamCachingStrategy strategy;
    private OutputStream currentStream;
    private boolean inMemory = true;
    private int totalLength;
    private File tempFile;
    private FileInputStreamCache fileInputStreamCache;
    private final FileInputStreamCloser fileInputStreamCloser = new FileInputStreamCloser();
    private CipherPair ciphers;
    private final boolean closedOnCompletion;

    public CachedOutputStream(Exchange exchange) {
        this(exchange, true);
    }

    public CachedOutputStream(Exchange exchange, final boolean closedOnCompletion) {
        this.closedOnCompletion = closedOnCompletion;
        this.strategy = exchange.getContext().getStreamCachingStrategy();
        currentStream = new CachedByteArrayOutputStream(strategy.getBufferSize());
        if (closedOnCompletion) {
            // add on completion so we can cleanup after the exchange is done such as deleting temporary files
            Synchronization onCompletion = new SynchronizationAdapter() {
                @Override
                public void onDone(Exchange exchange) {
                    try {
                        closeFileInputStreams();
                        close();
                        try {
                            cleanUpTempFile();
                        } catch (Exception e) {
                            LOG.warn("Error deleting temporary cache file: " + tempFile + ". This exception will be ignored.", e);
                        }
                    } catch (Exception e) {
                        LOG.warn("Error closing streams. This exception will be ignored.", e);
                    }
                }

                @Override
                public String toString() {
                    return "OnCompletion[CachedOutputStream]";
                }
            };

            UnitOfWork streamCacheUnitOfWork = exchange.getProperty(Exchange.STREAM_CACHE_UNIT_OF_WORK, UnitOfWork.class);
            if (streamCacheUnitOfWork != null) {
                // The stream cache must sometimes not be closed when the exchange is deleted. This is for example the
                // case in the splitter and multi-cast case with AggregationStrategy where the result of the sub-routes
                // are aggregated later in the main route. Here, the cached streams of the sub-routes must be closed with
                // the Unit of Work of the main route.
                streamCacheUnitOfWork.addSynchronization(onCompletion);
            } else {
                // add on completion so we can cleanup after the exchange is done such as deleting temporary files
                exchange.addOnCompletion(onCompletion);
            }
        }
    }

    public void flush() throws IOException {
        currentStream.flush();       
    }

    public void close() throws IOException {
        currentStream.close();
        // need to clean up the temp file this time
        if (!closedOnCompletion) {
            closeFileInputStreams();
            try {
                cleanUpTempFile();
            } catch (Exception e) {
                LOG.warn("Error deleting temporary cache file: " + tempFile + ". This exception will be ignored.", e);
            }
        }
    }

    public boolean equals(Object obj) {
        return currentStream.equals(obj);
    }

    public int hashCode() {
        return currentStream.hashCode();
    }

    public OutputStream getCurrentStream() {
        return currentStream;
    }

    public String toString() {
        return "CachedOutputStream[size: " + totalLength + "]";
    }

    public void write(byte[] b, int off, int len) throws IOException {
        this.totalLength += len;
        if (inMemory && currentStream instanceof ByteArrayOutputStream && strategy.shouldSpoolCache(totalLength)) {
            pageToFileStream();
        }
        currentStream.write(b, off, len);
    }

    public void write(byte[] b) throws IOException {
        this.totalLength += b.length;
        if (inMemory && currentStream instanceof ByteArrayOutputStream && strategy.shouldSpoolCache(totalLength)) {
            pageToFileStream();
        }
        currentStream.write(b);
    }

    public void write(int b) throws IOException {
        this.totalLength++;
        if (inMemory && currentStream instanceof ByteArrayOutputStream && strategy.shouldSpoolCache(totalLength)) {
            pageToFileStream();
        }
        currentStream.write(b);
    }

    public InputStream getInputStream() throws IOException {
        return (InputStream)newStreamCache();
    }    

    public InputStream getWrappedInputStream() throws IOException {
        // The WrappedInputStream will close the CachedOutputStream when it is closed
        return new WrappedInputStream(this, (InputStream)newStreamCache());
    }

    /**
     * @deprecated  use {@link #newStreamCache()}
     */
    @Deprecated
    public StreamCache getStreamCache() throws IOException {
        return newStreamCache();
    }

    /**
     * Creates a new {@link StreamCache} from the data cached in this {@link OutputStream}.
     */
    public StreamCache newStreamCache() throws IOException {
        flush();

        if (inMemory) {
            if (currentStream instanceof CachedByteArrayOutputStream) {
                return ((CachedByteArrayOutputStream) currentStream).newInputStreamCache();
            } else {
                throw new IllegalStateException("CurrentStream should be an instance of CachedByteArrayOutputStream but is: " + currentStream.getClass().getName());
            }
        } else {
            try {
                if (fileInputStreamCache == null) {
                    fileInputStreamCache = new FileInputStreamCache(tempFile, ciphers, fileInputStreamCloser);
                }
                return fileInputStreamCache;
            } catch (FileNotFoundException e) {
                throw new IOException("Cached file " + tempFile + " not found", e);
            }
        }
    }
    
    private void closeFileInputStreams() {
        fileInputStreamCloser.close();
        fileInputStreamCache = null;
    } 

    private void cleanUpTempFile() {
        // cleanup temporary file
        if (tempFile != null) {
            FileUtil.deleteFile(tempFile);
            tempFile = null;
        }
    }

    private void pageToFileStream() throws IOException {
        flush();

        ByteArrayOutputStream bout = (ByteArrayOutputStream)currentStream;
        tempFile = FileUtil.createTempFile("cos", ".tmp", strategy.getSpoolDirectory());

        LOG.trace("Creating temporary stream cache file: {}", tempFile);

        try {
            currentStream = createOutputStream(tempFile);
            bout.writeTo(currentStream);
        } finally {
            // ensure flag is flipped to file based
            inMemory = false;
        }
    }

    /**
     * @deprecated  use {@link #getStrategyBufferSize()}
     */
    @Deprecated
    public int getBufferSize() {
        return getStrategyBufferSize();
    }
    
    public int getStrategyBufferSize() {
        return strategy.getBufferSize();
    }

    // This class will close the CachedOutputStream when it is closed
    private static class WrappedInputStream extends InputStream {
        private CachedOutputStream cachedOutputStream;
        private InputStream inputStream;
        
        WrappedInputStream(CachedOutputStream cos, InputStream is) {
            cachedOutputStream = cos;
            inputStream = is;
        }
        
        @Override
        public int read() throws IOException {
            return inputStream.read();
        }
        
        @Override
        public int available() throws IOException {
            return inputStream.available();
        }
        
        @Override
        public void reset() throws IOException {
            inputStream.reset();
        }
        
        @Override
        public void close() throws IOException {
            inputStream.close();
            cachedOutputStream.close();
        }
    }

    private OutputStream createOutputStream(File file) throws IOException {
        OutputStream out = new BufferedOutputStream(new FileOutputStream(file));
        if (ObjectHelper.isNotEmpty(strategy.getSpoolChiper())) {
            try {
                if (ciphers == null) {
                    ciphers = new CipherPair(strategy.getSpoolChiper());
                }
            } catch (GeneralSecurityException e) {
                throw new IOException(e.getMessage(), e);
            }
            out = new CipherOutputStream(out, ciphers.getEncryptor()) {
                boolean closed;
                public void close() throws IOException {
                    if (!closed) {
                        super.close();
                        closed = true;
                    }
                }
            };
        }
        return out;
    }
}