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package org.glassfish.jersey.message.internal;

import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.lang.annotation.Annotation;
import java.lang.reflect.Type;

import javax.ws.rs.Consumes;
import javax.ws.rs.Produces;
import javax.ws.rs.core.MediaType;
import javax.ws.rs.core.MultivaluedMap;

import javax.activation.DataSource;

/**
 * Provider for marshalling/un-marshalling of {@code application/octet-stream}
 * entity type to/from a {@link DataSource} instance.
 *
 * @author Paul Sandoz
 * @author Marek Potociar (marek.potociar at oracle.com)
 */
@Produces({"application/octet-stream", "*/*"})
@Consumes({"application/octet-stream", "*/*"})
public class DataSourceProvider extends AbstractMessageReaderWriterProvider<DataSource> {

    /**
     * Modified from javax.mail.util.ByteArrayDataSource
     *
     * A DataSource backed by a byte array.  The byte array may be
     * passed in directly, or may be initialized from an InputStream
     * or a String.
     *
     * @since JavaMail 1.4
     * @author John Mani
     * @author Bill Shannon
     * @author Max Spivak
     */
    public static class ByteArrayDataSource implements DataSource {

        private final String type;

        private byte[] data;
        private int len = -1;
        private String name = "";

        static class DSByteArrayOutputStream extends ByteArrayOutputStream {

            public byte[] getBuf() {
                return buf;
            }

            public int getCount() {
                return count;
            }
        }

        public ByteArrayDataSource(final InputStream is, final String type) throws IOException {
            final DSByteArrayOutputStream os = new DSByteArrayOutputStream();
            ReaderWriter.writeTo(is, os);
            this.data = os.getBuf();
            this.len = os.getCount();

            /*
             * ByteArrayOutputStream doubles the size of the buffer every time
             * it needs to expand, which can waste a lot of memory in the worst
             * case with large buffers.  Check how much is wasted here and if
             * it's too much, copy the data into a new buffer and allow the
             * old buffer to be garbage collected.
             */
            if (this.data.length - this.len > 256 * 1024) {
                this.data = os.toByteArray();
                this.len = this.data.length;    // should be the same
            }
            this.type = type;
        }

        @Override
        public InputStream getInputStream() throws IOException {
            if (data == null) {
                throw new IOException("no data");
            }
            if (len < 0) {
                len = data.length;
            }
            return new ByteArrayInputStream(data, 0, len);
        }

        @Override
        public OutputStream getOutputStream() throws IOException {
            throw new IOException("cannot do this");
        }

        @Override
        public String getContentType() {
            return type;
        }

        @Override
        public String getName() {
            return name;
        }

        public void setName(final String name) {
            this.name = name;
        }
    }

    @Override
    public boolean isReadable(final Class<?> type,
                              final Type genericType,
                              final Annotation[] annotations,
                              final MediaType mediaType) {
        return DataSource.class == type;
    }

    @Override
    public DataSource readFrom(
            final Class<DataSource> type,
            final Type genericType,
            final Annotation[] annotations,
            final MediaType mediaType,
            final MultivaluedMap<String, String> httpHeaders,
            final InputStream entityStream) throws IOException {
        return new ByteArrayDataSource(entityStream, (mediaType == null) ? null : mediaType.toString());
    }

    @Override
    public boolean isWriteable(final Class<?> type,
                               final Type genericType,
                               final Annotation[] annotations,
                               final MediaType mediaType) {
        return DataSource.class.isAssignableFrom(type);
    }

    @Override
    public void writeTo(
            final DataSource t,
            final Class<?> type,
            final Type genericType,
            final Annotation[] annotations,
            final MediaType mediaType,
            final MultivaluedMap<String, Object> httpHeaders,
            final OutputStream entityStream) throws IOException {
        final InputStream in = t.getInputStream();
        try {
            writeTo(in, entityStream);
        } finally {
            in.close();
        }
    }
}
