/*

  * Copyright (c) 2006 - 2011 Michael Schierl

  * All rights reserved.

  * 

  * This program is free software: you can redistribute it and/or modify

  * it under the terms of the GNU General Public License as published by

  * the Free Software Foundation, either version 2 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 General Public License for more details.

  * 

  * You should have received a copy of the GNU General Public License

  * along with this program.  If not, see <http://www.gnu.org/licenses/>.

  */

 package net.sf.jmatchparser.template.engine.template.command.plain;

 import net.sf.jmatchparser.template.engine.operation.ForkOperation;

 import net.sf.jmatchparser.template.engine.operation.JumpOperation;

 import net.sf.jmatchparser.template.engine.operation.Label;

 import net.sf.jmatchparser.template.engine.template.PlainBlockCommandState;

 import net.sf.jmatchparser.template.engine.template.MatchTemplateImpl;

 public class AlternativeCommand extends ParameterlessCommand {

         private final boolean optional;

         public AlternativeCommand(boolean optional) {

                 this.optional = optional;

         }

         @Override

         protected PlainBlockCommandState parse(MatchTemplateImpl template) {

                 Label endLabel = new Label(), nextPartLabel = new Label(), forkLabel = new Label();

                 if (optional) {

                         // jump around here to make sure every path has at least one unique

                         // operation

                         Label dummyEndLabel = new Label();

                         Label dummyContLabel = new Label();

                         template.appendOperation(new ForkOperation(template.getCurrentTemplatePosition(), dummyEndLabel, false));

                         template.appendOperation(new JumpOperation(template.getCurrentTemplatePosition(), dummyContLabel));

                         dummyEndLabel.setDestinationToNextCommand(template);

                         template.appendOperation(new JumpOperation(template.getCurrentTemplatePosition(), endLabel));

                         dummyContLabel.setDestinationToNextCommand(template);

                 }

                 int lastForkPoint = template.getNextOperationIndex();

                 template.appendOperation(new ForkOperation(template.getCurrentTemplatePosition(), forkLabel, false));

                 template.appendOperation(new JumpOperation(template.getCurrentTemplatePosition(), nextPartLabel));

                 forkLabel.setDestinationToNextCommand(template);

                 return new AlternativeCommandState(template, lastForkPoint, nextPartLabel, endLabel);

         }

         private class AlternativeCommandState extends PlainBlockCommandState {

                 private Label nextPartLabel;

                 private final Label endLabel;

                 private int lastForkPoint;

                 public AlternativeCommandState(MatchTemplateImpl template, int lastForkPoint,

                                 Label nextPartLabel, Label endLabel) {

                         super(template);

                         this.lastForkPoint = lastForkPoint;

                         this.nextPartLabel = nextPartLabel;

                         this.endLabel = endLabel;

                 }

                 @Override

                 public boolean canParse(String commandName) {

                         return commandName.equals("nextalternative") || commandName.equals("nextalt") || commandName.equals("endalternative") || commandName.equals("endalt");

                 }

                 @Override

                 public PlainBlockCommandState parseCommand(MatchTemplateImpl template,

                                 String commandName, String parameters) {

                         if (commandName.startsWith("end")) {

                                 template.nopOperation(lastForkPoint);

                                 template.nopOperation(lastForkPoint + 1);

                                 endLabel.setDestinationToNextCommand(template);

                                 return null;

                         } else {

                                 template.appendOperation(new JumpOperation(template.getCurrentTemplatePosition(), endLabel));

                                 nextPartLabel.setDestinationToNextCommand(template);

                                 nextPartLabel = new Label();

                                 Label forkLabel = new Label();

                                 lastForkPoint = template.getNextOperationIndex();

                                 template.appendOperation(new ForkOperation(template.getCurrentTemplatePosition(), forkLabel, false));

                                 template.appendOperation(new JumpOperation(template.getCurrentTemplatePosition(), nextPartLabel));

                                 forkLabel.setDestinationToNextCommand(template);

                                 return this;

                         }

                 }

         }

 }