/**
 * 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.mahout.cf.taste.example;

import java.io.File;

import org.apache.commons.cli2.CommandLine;
import org.apache.commons.cli2.Group;
import org.apache.commons.cli2.Option;
import org.apache.commons.cli2.OptionException;
import org.apache.commons.cli2.builder.ArgumentBuilder;
import org.apache.commons.cli2.builder.DefaultOptionBuilder;
import org.apache.commons.cli2.builder.GroupBuilder;
import org.apache.commons.cli2.commandline.Parser;
import org.apache.mahout.common.CommandLineUtil;
import org.apache.mahout.common.commandline.DefaultOptionCreator;

/**
 * This class provides a common implementation for parsing input parameters for
 * all taste examples. Currently they only need the path to the recommendations
 * file as input.
 * 
 * The class is safe to be used in threaded contexts.
 */
public final class TasteOptionParser {
  
  private TasteOptionParser() {
  }
  
  /**
   * Parse the given command line arguments.
   * @param args the arguments as given to the application.
   * @return the input file if a file was given on the command line, null otherwise.
   */
  public static File getRatings(String[] args) throws OptionException {
    DefaultOptionBuilder obuilder = new DefaultOptionBuilder();
    ArgumentBuilder abuilder = new ArgumentBuilder();
    GroupBuilder gbuilder = new GroupBuilder();
    
    Option inputOpt = obuilder.withLongName("input").withRequired(false).withShortName("i")
        .withArgument(abuilder.withName("input").withMinimum(1).withMaximum(1).create())
        .withDescription("The Path for input data directory.").create();
    
    Option helpOpt = DefaultOptionCreator.helpOption();
    
    Group group = gbuilder.withName("Options").withOption(inputOpt).withOption(helpOpt).create();
    
    Parser parser = new Parser();
    parser.setGroup(group);
    CommandLine cmdLine = parser.parse(args);
    
    if (cmdLine.hasOption(helpOpt)) {
      CommandLineUtil.printHelp(group);
      return null;
    }

    return cmdLine.hasOption(inputOpt) ? new File(cmdLine.getValue(inputOpt).toString()) : null;
  }
  
}