/*
 * This program is free software; you can redistribute it and/or modify it under the
 * terms of the GNU General Public License, version 2 as published by the Free Software
 * Foundation.
 *
 * You should have received a copy of the GNU General Public License along with this
 * program; if not, you can obtain a copy at http://www.gnu.org/licenses/gpl-2.0.html
 * or from the Free Software Foundation, Inc.,
 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY;
 * without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
 * See the GNU General Public License for more details.
 *
 *
 * Copyright 2006 - 2013 Pentaho Corporation.  All rights reserved.
 */

package org.pentaho.platform.engine.core.system.objfac.spring;

import org.apache.commons.lang.StringUtils;
import org.pentaho.platform.api.engine.IPentahoInitializer;
import org.pentaho.platform.api.engine.IPentahoObjectFactory;
import org.pentaho.platform.api.engine.IPentahoObjectReference;
import org.pentaho.platform.api.engine.IPentahoSession;
import org.pentaho.platform.engine.core.system.PentahoSessionHolder;
import org.springframework.beans.factory.config.BeanDefinition;
import org.springframework.context.ConfigurableApplicationContext;

import java.util.HashMap;
import java.util.Map;

/**
 * Spring implementation of {@link IPentahoObjectReference}
 * <p/>
 * {@inheritDoc}
 * <p/>
 * User: nbaker Date: 1/16/13
 */
public class SpringPentahoObjectReference<T> implements IPentahoObjectReference<T> {

  private ConfigurableApplicationContext context;

  private String name;

  private final Class<T> clazz;

  private IPentahoSession session;

  private final SpringBeanAttributes attributes;

  private static String PRIORITY = "priority";

  public SpringPentahoObjectReference( ConfigurableApplicationContext context, String name, Class<T> clazz,
                                       IPentahoSession session, BeanDefinition beanDef ) {
    this.context = context;
    this.name = name;
    this.clazz = clazz;
    this.session = session;
    this.attributes = new SpringBeanAttributes( beanDef );
  }

  @Override public Class<?> getObjectClass() {
    return clazz;
  }

  @Override
  @SuppressWarnings( "unchecked" )
  public T getObject() {
    IPentahoSession sessionToUse = session != null ? session : PentahoSessionHolder.getSession();
    SpringScopeSessionHolder.SESSION.set( sessionToUse );
    ClassLoader originalClassLoader = Thread.currentThread().getContextClassLoader();
    try {
      Thread.currentThread().setContextClassLoader( getClass().getClassLoader() );
      Object obj = context.getBeanFactory().getBean( name );
      SpringScopeSessionHolder.SESSION.set( null );

      if ( obj instanceof IPentahoInitializer ) {
        ( (IPentahoInitializer) obj ).init( sessionToUse );
      }
      return (T) obj;
    } finally {
      Thread.currentThread().setContextClassLoader( originalClassLoader );
    }
  }

  @Override
  public Map<String, Object> getAttributes() {
    return attributes;
  }

  @Override
  public boolean equals( Object o ) {
    if ( this == o ) {
      return true;
    }
    if ( o == null || getClass() != o.getClass() ) {
      return false;
    }

    SpringPentahoObjectReference that = (SpringPentahoObjectReference) o;

    if ( !clazz.equals( that.clazz ) ) {
      return false;
    }
    if ( !name.equals( that.name ) ) {
      return false;
    }
    if ( attributes != null ? !attributes.equals( that.attributes ) : that.attributes != null ) {
      return false;
    }
    if ( session != null ? !session.equals( that.session ) : that.session != null ) {
      return false;
    }

    return true;
  }

  @Override
  public int hashCode() {
    int result = name.hashCode();
    result = 31 * result + clazz.hashCode();
    result = 31 * result + ( session != null ? session.hashCode() : 0 );
    result = 31 * result + ( attributes != null ? attributes.hashCode() : 0 );
    return result;
  }

  @Override
  public int compareTo( IPentahoObjectReference<T> o ) {
    if ( o == null ) {
      return 1;
    }
    if ( o == this ) {
      return 0;
    }
    int pri1 = this.getRanking();
    int pri2 = o.getRanking();
    if ( pri1 == pri2 ) {
      return 0;
    } else if ( pri1 > pri2 ) {
      return 1;
    } else {
      return -1;
    }
  }

  @Override
  public Integer getRanking() {
    return extractPriority( this );
  }

  private int extractPriority( IPentahoObjectReference ref ) {
    if ( ref == null || ref.getAttributes() == null || !ref.getAttributes().containsKey( PRIORITY ) ) {
      // return default
      return IPentahoObjectFactory.DEFAULT_PRIORTIY;
    }

    try {
      return Integer.parseInt( ref.getAttributes().get( PRIORITY ).toString() );
    } catch ( NumberFormatException e ) {
      // return default
      return IPentahoObjectFactory.DEFAULT_PRIORTIY;
    }
  }

  /**
   * Hashmap backed by a Spring BeanDefinition
   */
  private static class SpringBeanAttributes extends HashMap<String, Object> {

    /**
     *
     */
    private static final long serialVersionUID = -5790844158879001752L;

    public SpringBeanAttributes( final BeanDefinition definition ) {
      for ( String s : definition.attributeNames() ) {
        this.put( s, definition.getAttribute( s ) );
      }
      this.put("scope", StringUtils.defaultIfEmpty( definition.getScope(), "singleton") );
    }

  }

}