package de.lmu.ifi.dbs.elki.utilities.optionhandling.constraints;

/*
 This file is part of ELKI:
 Environment for Developing KDD-Applications Supported by Index-Structures

 Copyright (C) 2015
 Ludwig-Maximilians-Universität München
 Lehr- und Forschungseinheit für Datenbanksysteme
 ELKI Development Team

 This program is free software: you can redistribute it and/or modify
 it under the terms of the GNU Affero General Public License as published by
 the Free Software Foundation, either version 3 of the License, or
 (at your option) any later version.

 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 Affero General Public License for more details.

 You should have received a copy of the GNU Affero General Public License
 along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;

import de.lmu.ifi.dbs.elki.utilities.optionhandling.OptionUtil;
import de.lmu.ifi.dbs.elki.utilities.optionhandling.ParameterException;
import de.lmu.ifi.dbs.elki.utilities.optionhandling.WrongParameterValueException;
import de.lmu.ifi.dbs.elki.utilities.optionhandling.parameters.Flag;
import de.lmu.ifi.dbs.elki.utilities.optionhandling.parameters.Parameter;

/**
 * Global parameter constraint specifying that only one parameter of a list of
 * parameters ({@link Parameter}) is allowed to be set.
 * 
 * @author Steffi Wanka
 * @since 0.2
 */
public class OnlyOneIsAllowedToBeSetGlobalConstraint implements GlobalParameterConstraint {
  /**
   * List of parameters to be checked.
   */
  private List<Parameter<?>> parameters;

  /**
   * Constructs a global parameter constraint for testing if only one parameter
   * of a list of parameters is set.
   * 
   * @param params list of parameters to be checked
   */
  public OnlyOneIsAllowedToBeSetGlobalConstraint(List<Parameter<?>> params) {
    parameters = params;
  }

  /**
   * Constructs a global parameter constraint for testing if only one parameter
   * of a list of parameters is set.
   * 
   * @param params list of parameters to be checked
   */
  public OnlyOneIsAllowedToBeSetGlobalConstraint(Parameter<?>... params) {
    parameters = Arrays.asList(params);
  }

  /**
   * Checks if only one parameter of a list of parameters is set. If not, a
   * parameter exception is thrown.
   */
  @Override
  public void test() throws ParameterException {
    ArrayList<String> set = new ArrayList<>();
    for (Parameter<?> p : parameters) {
      if (p.isDefined()) {
        // FIXME: Retire the use of this constraint for Flags!
        if (p instanceof Flag) {
          if (((Flag) p).getValue().booleanValue()) {
            set.add(p.getName());
          }
        } else {
          set.add(p.getName());
        }
      }
    }
    if (set.size() > 1) {
      throw new WrongParameterValueException("Global Parameter Constraint Error.\n" + "Only one of the parameters " + OptionUtil.optionsNamesToString(parameters) + " is allowed to be set. " + "Parameters currently set: " + set.toString());
    }
  }

  @Override
  public String getDescription() {
    return "Only one of the parameters " + OptionUtil.optionsNamesToString(parameters) + " is allowed to be set.";
  }
}
