/**
 *
 */
package org.jboss.resteasy.plugins.providers;

import org.jboss.resteasy.plugins.server.servlet.Cleanable;
import org.jboss.resteasy.plugins.server.servlet.Cleanables;
import org.jboss.resteasy.resteasy_jaxrs.i18n.LogMessages;
import org.jboss.resteasy.resteasy_jaxrs.i18n.Messages;
import org.jboss.resteasy.spi.ResteasyProviderFactory;
import org.jboss.resteasy.util.MediaTypeHelper;
import org.jboss.resteasy.util.NoContent;

import java.io.ByteArrayInputStream;
import java.io.File;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.SequenceInputStream;
import java.lang.annotation.Annotation;
import java.lang.reflect.Type;
import java.nio.file.Files;
import java.nio.file.Path;

import javax.activation.DataSource;
import javax.ws.rs.Consumes;
import javax.ws.rs.Produces;
import javax.ws.rs.core.MediaType;
import javax.ws.rs.core.MultivaluedMap;
import javax.ws.rs.ext.Provider;

/**
 * @author <a href="mailto:ryan@damnhandy.com">Ryan J. McDonough</a>
 * @version $Revision:$
 */
@Provider
@Consumes("*/*")
@Produces("*/*")
public class DataSourceProvider extends AbstractEntityProvider<DataSource>
{

   protected static class SequencedDataSource implements DataSource
   {
      private final byte[] byteBuffer;
      private final int byteBufferOffset;
      private final int byteBufferLength;
      private final Path tempFile;
      private final String type;

      protected SequencedDataSource(final byte[] byteBuffer, final int byteBufferOffset,
                                    final int byteBufferLength, final File tempFile, final String type) {
         this(byteBuffer, byteBufferOffset, byteBufferLength, tempFile.toPath(), type);
      }

      protected SequencedDataSource(final byte[] byteBuffer, final int byteBufferOffset,
                                    final int byteBufferLength, final Path tempFile, final String type)
      {
         super();
         this.byteBuffer = byteBuffer;
         this.byteBufferOffset = byteBufferOffset;
         this.byteBufferLength = byteBufferLength;
         this.tempFile = tempFile;
         this.type = type;
      }

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

      @Override
      public InputStream getInputStream() throws IOException
      {
         InputStream bis = new ByteArrayInputStream(byteBuffer, byteBufferOffset, byteBufferLength);
         if (tempFile == null)
            return bis;
         return new SequenceInputStream(bis, Files.newInputStream(tempFile));
      }

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

      @Override
      public OutputStream getOutputStream() throws IOException
      {
         throw new IOException(Messages.MESSAGES.noOutputStreamAllowed());
      }

   }


   /**
    * @param in input stream
    * @param mediaType media type
    * @return data source
    * @throws IOException if I/O error occurred
    */
   public static DataSource readDataSource(final InputStream in, final MediaType mediaType) throws IOException
   {
      byte[] memoryBuffer = new byte[4096];
      int readCount = in.read(memoryBuffer, 0, memoryBuffer.length);

      Path tempFile = null;
      if (readCount > 0)
      {
         byte[] buffer = new byte[4096];
         int count = in.read(buffer, 0, buffer.length);
         if (count > -1) {
            tempFile = Files.createTempFile("resteasy-provider-datasource", null);
            Cleanables cleanables = ResteasyProviderFactory.getContextData(Cleanables.class);
            if (cleanables != null)
            {
               cleanables.addCleanable(new TempFileCleanable(tempFile));
            }
            try (OutputStream fos = Files.newOutputStream(tempFile)) {
               fos.write(buffer, 0, count);
               ProviderHelper.writeTo(in, fos);
            }
         }
      }

      if (readCount == -1)
         readCount = 0;

      return new SequencedDataSource(memoryBuffer, 0, readCount, tempFile, mediaType.toString());
   }

   /**
    * Ascertain if the MessageBodyReader can produce an instance of a
    * particular type. The {@code type} parameter gives the
    * class of the instance that should be produced, the {@code genericType} parameter
    * gives the {@link java.lang.reflect.Type java.lang.reflect.Type} of the instance
    * that should be produced.
    * E.g. if the instance to be produced is {@code List<String>}, the {@code type} parameter
    * will be {@code java.util.List} and the {@code genericType} parameter will be
    * {@link java.lang.reflect.ParameterizedType java.lang.reflect.ParameterizedType}.
    *
    * @param type        the class of instance to be produced.
    * @param genericType the type of instance to be produced. E.g. if the
    *                    message body is to be converted into a method parameter, this will be
    *                    the formal type of the method parameter as returned by
    *                    {@code Method.getGenericParameterTypes}.
    * @param annotations an array of the annotations on the declaration of the
    *                    artifact that will be initialized with the produced instance. E.g. if the
    *                    message body is to be converted into a method parameter, this will be
    *                    the annotations on that parameter returned by
    *                    {@code Method.getParameterAnnotations}.
    * @param mediaType   the media type of the HTTP entity, if one is not
    *                    specified in the request then {@code application/octet-stream} is
    *                    used.
    * @return {@code true} if the type is supported, otherwise {@code false}.
    */
   @Override
   public boolean isReadable(Class<?> type,
                             Type genericType,
                             Annotation[] annotations, MediaType mediaType)
   {
      return DataSource.class.isAssignableFrom(type);
   }


   /**
    * Read a type from the {@link InputStream}.
    * <p>
    * In case the entity input stream is empty, the reader is expected to either return a
    * Java representation of a zero-length entity or throw a {@link javax.ws.rs.core.NoContentException}
    * in case no zero-length entity representation is defined for the supported Java type.
    * A {@code NoContentException}, if thrown by a message body reader while reading a server
    * request entity, is automatically translated by JAX-RS server runtime into a {@link javax.ws.rs.BadRequestException}
    * wrapping the original {@code NoContentException} and rethrown for a standard processing by
    * the registered {@link javax.ws.rs.ext.ExceptionMapper exception mappers}.
    * </p>
    *
    * @param type         the type that is to be read from the entity stream.
    * @param genericType  the type of instance to be produced. E.g. if the
    *                     message body is to be converted into a method parameter, this will be
    *                     the formal type of the method parameter as returned by
    *                     {@code Method.getGenericParameterTypes}.
    * @param annotations  an array of the annotations on the declaration of the
    *                     artifact that will be initialized with the produced instance. E.g.
    *                     if the message body is to be converted into a method parameter, this
    *                     will be the annotations on that parameter returned by
    *                     {@code Method.getParameterAnnotations}.
    * @param mediaType    the media type of the HTTP entity.
    * @param httpHeaders  the read-only HTTP headers associated with HTTP entity.
    * @param entityStream the {@link InputStream} of the HTTP entity. The
    *                     caller is responsible for ensuring that the input stream ends when the
    *                     entity has been consumed. The implementation should not close the input
    *                     stream.
    * @return the type that was read from the stream. In case the entity input stream is empty, the reader
    *         is expected to either return an instance representing a zero-length entity or throw
    *         a {@link javax.ws.rs.core.NoContentException} in case no zero-length entity representation is
    *         defined for the supported Java type.
    * @throws java.io.IOException if an IO error arises. In case the entity input stream is empty
    *                             and the reader is not able to produce a Java representation for
    *                             a zero-length entity, {@code NoContentException} is expected to
    *                             be thrown.
    * @throws javax.ws.rs.WebApplicationException
    *                             if a specific HTTP error response needs to be produced.
    *                             Only effective if thrown prior to the response being committed.
    */
   @Override
   public DataSource readFrom(Class<DataSource> type,
                              Type genericType,
                              Annotation[] annotations,
                              MediaType mediaType,
                              MultivaluedMap<String, String> httpHeaders,
                              InputStream entityStream) throws IOException
   {
      LogMessages.LOGGER.debugf("Provider : %s,  Method : readFrom", getClass().getName());
      if (NoContent.isContentLengthZero(httpHeaders)) return readDataSource(new ByteArrayInputStream(new byte[0]), mediaType);
      return readDataSource(entityStream, mediaType);
   }


   /**
    * Ascertain if the MessageBodyWriter supports a particular type.
    *
    * @param type        the class of instance that is to be written.
    * @param genericType the type of instance to be written, obtained either
    *                    by reflection of a resource method return type or via inspection
    *                    of the returned instance. {@link javax.ws.rs.core.GenericEntity}
    *                    provides a way to specify this information at runtime.
    * @param annotations an array of the annotations attached to the message entity instance.
    * @param mediaType   the media type of the HTTP entity.
    * @return {@code true} if the type is supported, otherwise {@code false}.
    */
   @Override
   public boolean isWriteable(Class<?> type, Type genericType, Annotation[] annotations, MediaType mediaType)
   {
      return DataSource.class.isAssignableFrom(type) && !MediaTypeHelper.isBlacklisted(mediaType);
   }

   /**
    * Write a type to an HTTP message. The message header map is mutable
    * but any changes must be made before writing to the output stream since
    * the headers will be flushed prior to writing the message body.
    *
    * @param dataSource   the instance to write.
    * @param type         the class of instance that is to be written.
    * @param genericType  the type of instance to be written. {@link javax.ws.rs.core.GenericEntity}
    *                     provides a way to specify this information at runtime.
    * @param annotations  an array of the annotations attached to the message entity instance.
    * @param mediaType    the media type of the HTTP entity.
    * @param httpHeaders  a mutable map of the HTTP message headers.
    * @param entityStream the {@link OutputStream} for the HTTP entity. The
    *                     implementation should not close the output stream.
    * @throws java.io.IOException if an IO error arises.
    * @throws javax.ws.rs.WebApplicationException
    *                             if a specific HTTP error response needs to be produced.
    *                             Only effective if thrown prior to the message being committed.
    */
   @Override
   public void writeTo(DataSource dataSource,
                       Class<?> type,
                       Type genericType,
                       Annotation[] annotations,
                       MediaType mediaType,
                       MultivaluedMap<String, Object> httpHeaders,
                       OutputStream entityStream) throws IOException
   {
      LogMessages.LOGGER.debugf("Provider : %s,  Method : writeTo", getClass().getName());
      InputStream in = dataSource.getInputStream();
      try
      {
         ProviderHelper.writeTo(in, entityStream);
      }
      finally
      {
         in.close();
      }

   }

   private static class TempFileCleanable implements Cleanable {

      private final Path tempFile;

      TempFileCleanable(final Path tempFile) {
         this.tempFile = tempFile;
      }

      @Override
      public void clean() throws Exception {
         Files.deleteIfExists(tempFile);
      }
   }
}
