/*******************************************************************************
    * Copyright (c) 2007, 2014 Massimiliano Ziccardi
    *
    * Licensed 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 it.jnrpe.utils.thresholds;
  
  /**
   * The configured threshold parser.
   * 
   * @author Massimiliano Ziccardi
   */
  final class RangeStringParser {
  
  	/**
  	 * The root of the parsing state machine.
  	 */
  	private static final Stage ROOT_STAGE = configureParser();
  
  	/**
  	 * Private default constructor.
  	 */
  	private RangeStringParser() {
  
  	}
  
  	/**
  	 * Configures the state machine.
  	 * 
  	 * @return The configured state machine.
  	 */
  	private static Stage configureParser() {
  		Stage startStage = new StartStage();
  		Stage negativeInfinityStage = new NegativeInfinityStage();
  		Stage positiveInfinityStage = new PositiveInfinityStage();
  		NegateStage negateStage = new NegateStage();
  		BracketStage.OpenBracketStage openBraceStage = new BracketStage.OpenBracketStage();
  		NumberBoundaryStage.LeftBoundaryStage startBoundaryStage = new NumberBoundaryStage.LeftBoundaryStage();
  		NumberBoundaryStage.RightBoundaryStage rightBoundaryStage = new NumberBoundaryStage.RightBoundaryStage();
  		SeparatorStage separatorStage = new SeparatorStage();
  		BracketStage.ClosedBracketStage closedBraketStage = new BracketStage.ClosedBracketStage();
  
  		startStage.addTransition(negateStage);
  		startStage.addTransition(openBraceStage);
  		startStage.addTransition(negativeInfinityStage);
  		startStage.addTransition(startBoundaryStage);
  
  		negateStage.addTransition(negativeInfinityStage);
  		negateStage.addTransition(openBraceStage);
  		negateStage.addTransition(startBoundaryStage);
  
  		openBraceStage.addTransition(startBoundaryStage);
  		startBoundaryStage.addTransition(separatorStage);
  		negativeInfinityStage.addTransition(separatorStage);
  
  		separatorStage.addTransition(positiveInfinityStage);
  		separatorStage.addTransition(rightBoundaryStage);
  
  		rightBoundaryStage.addTransition(closedBraketStage);
  
  		return startStage;
  	}
  
  	/**
  	 * Parses the threshold.
  	 * 
  	 * @param range
  	 *            The threshold to be parsed
  	 * @param tc
  	 *            The configuration
  	 * @throws RangeException
  	 *             -
  	 */
  	public static void parse(final String range, final RangeConfig tc)
  			throws RangeException {
  		if (range == null) {
  			throw new RangeException("Null range specified");
  		}
  		ROOT_STAGE.parse(range, tc);
  		checkBoundaries(tc);
  	}
  
  	/**
  	 * Checks that right boundary is greater than left boundary.
  	 * 
  	 * @param rc
  	 *            The range configuration
  	 * @throws RangeException
  	 *             If right < left
 	 */
 	private static void checkBoundaries(final RangeConfig rc)
 			throws RangeException {
 		if (rc.isNegativeInfinity()) {
 			// No other checks necessary. Negative infinity is less than any
 			// number
 			return;
 		}
 
 		if (rc.isPositiveInfinity()) {
 			// No other checks necessary. Positive infinity is greater than any
 			// number
 			return;
 		}
 
 		if (rc.getLeftBoundary().compareTo(rc.getRightBoundary()) > 0) {
 			throw new RangeException(
 					"Left boundary must be less than right boundary (left:"
 							+ rc.getLeftBoundary() + ", right:"
 							+ rc.getRightBoundary() + ")");
 		}
 	}
 }