/*!
 * This program is free software; you can redistribute it and/or modify it under the
 * terms of the GNU Lesser General Public License, version 2.1 as published by the Free Software
 * Foundation.
 *
 * You should have received a copy of the GNU Lesser General Public License along with this
 * program; if not, you can obtain a copy at http://www.gnu.org/licenses/old-licenses/lgpl-2.1.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 Lesser General Public License for more details.
 *
 * Copyright (c) 2002-2013 Pentaho Corporation..  All rights reserved.
 */

package org.pentaho.platform.config;

import org.pentaho.platform.api.engine.IConfiguration;
import org.pentaho.platform.api.engine.ISystemConfig;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.io.IOException;
import java.util.Collection;
import java.util.List;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

/**
 * User: nbaker Date: 4/2/13
 */
public class SystemConfig implements ISystemConfig {
  private final Map<String, IConfiguration> configs = new ConcurrentHashMap<String, IConfiguration>();
  private static final Pattern pattern = Pattern.compile( "([^\\.]+)\\.(.+)" );
  private Logger logger = LoggerFactory.getLogger( getClass() );

  public SystemConfig() {

  }

  public SystemConfig( List<IConfiguration> startingConfigs ) throws IOException {
    for ( IConfiguration startingConfig : startingConfigs ) {
      this.registerConfiguration( startingConfig );
    }
  }

  public String getProperty( String placeholder ) {
    // placeholder must be in the form of ID.PROP where
    if ( !pattern.matcher( placeholder ).matches() ) {
      throw new IllegalArgumentException( "property does not follow the pattern ID.PROP" );
    }
    return this.resolveValue( placeholder );
  }

  private String resolveValue( String placeholder ) {
    Matcher matcher = pattern.matcher( placeholder );
    matcher.find();
    String pid = matcher.group( 1 );
    String key = matcher.group( 2 );
    IConfiguration con = getConfiguration( pid );
    if ( con == null ) {
      logger.info( "Error resolving key replacement: " + placeholder );
      return null;
    }
    try {
      return con.getProperties().getProperty( key );
    } catch ( IOException e ) {
      logger.error( "Error getting properties for configuration: " + key );
      return null;
    }
  }

  @Override
  public IConfiguration getConfiguration( String configId ) {
    return configs.get( configId );
  }

  @Override
  public void registerConfiguration( IConfiguration configuration ) throws IOException {
    String configId = configuration.getId();
    if ( configId == null ) {
      throw new IllegalStateException( "Config id is null" );
    }
    if ( configs.containsKey( configId ) ) {
      // existing config, update current instance
      try {
        configs.get( configId ).update( configuration.getProperties() );
      } catch ( UnsupportedOperationException e ) {
        // ignored
      }
    } else {
      configs.put( configId, configuration );
    }
  }

  @Override
  public IConfiguration[] listConfigurations() {
    Collection<IConfiguration> entries = configs.values();
    return entries.toArray( new IConfiguration[entries.size()] );
  }

}