/**
 * 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.solr.handler.dataimport;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.io.ByteArrayInputStream;
import java.io.InputStream;
import java.lang.reflect.Method;
import java.lang.reflect.Modifier;
import java.sql.Blob;
import java.util.Properties;

import static org.apache.solr.handler.dataimport.DataImportHandlerException.SEVERE;


/**
 * This can be useful for users who have a DB field containing BLOBs which may be Rich documents
 * <p/>
 * The datasouce may be configured as follows
 * <p/>
 * <datasource name="f1" type="FieldStreamDataSource" />
 * <p/>
 * The enity which uses this datasource must keep and attribute dataField
 * <p/>
 * The fieldname must be resolvable from VariableResolver
 * <p/>
 * This may be used with any EntityProcessor which uses a DataSource<InputStream> eg:TikaEntityProcessor
 * <p/>
 *
 * @version $Id: FieldStreamDataSource.java 930161 2010-04-02 04:36:13Z rmuir $
 * @since 1.5
 */
public class FieldStreamDataSource extends DataSource<InputStream> {
  private static final Logger LOG = LoggerFactory.getLogger(FieldReaderDataSource.class);
  protected VariableResolver vr;
  protected String dataField;
  private EntityProcessorWrapper wrapper;

  public void init(Context context, Properties initProps) {
    dataField = context.getEntityAttribute("dataField");
    wrapper = (EntityProcessorWrapper) context.getEntityProcessor();
    /*no op*/
  }

  public InputStream getData(String query) {
    Object o = wrapper.getVariableResolver().resolve(dataField);
    if (o == null) {
      throw new DataImportHandlerException(SEVERE, "No field available for name : " + dataField);
    }
    if (o instanceof Blob) {
      Blob blob = (Blob) o;
      try {
        //Most of the JDBC drivers have getBinaryStream defined as public
        // so let us just check it
        Method m = blob.getClass().getDeclaredMethod("getBinaryStream");
        if (Modifier.isPublic(m.getModifiers())) {
          return (InputStream) m.invoke(blob);
        } else {
          // force invoke
          m.setAccessible(true);
          return (InputStream) m.invoke(blob);
        }
      } catch (Exception e) {
        LOG.info("Unable to get data from BLOB");
        return null;

      }
    } else if (o instanceof byte[]) {
      byte[] bytes = (byte[]) o;
      return new ByteArrayInputStream(bytes);
    } else {
      throw new RuntimeException("unsupported type : " + o.getClass());
    } 

  }

  public void close() {
  }
}