/*
 * Copyright (c) 1998-2006 Caucho Technology -- all rights reserved
 *
 * This file is part of Resin(R) Open Source
 *
 * Each copy or derived work must preserve the copyright notice and this
 * notice unmodified.
 *
 * Resin Open Source 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.
 *
 * Resin Open Source 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, or any warranty
 * of NON-INFRINGEMENT.  See the GNU General Public License for more
 * details.
 *
 * You should have received a copy of the GNU General Public License
 * along with Resin Open Source; if not, write to the
 *   Free Software Foundation, Inc.
 *   59 Temple Place, Suite 330
 *   Boston, MA 02111-1307  USA
 *
 * @author Scott Ferguson
 */

package com.caucho.amber.query;

import java.util.ArrayList;

import com.caucho.util.CharBuffer;

/**
 * A disjunction.
 */
public class OrExpr extends AbstractAmberExpr {
  private ArrayList<AmberExpr> _components = new ArrayList<AmberExpr>();

  /**
   * Returns true for a boolean expression.
   */
  public boolean isBoolean()
  {
    return true;
  }

  /**
   * Adds a new component.
   */
  void add(AmberExpr expr)
    throws QueryParseException
  {
    _components.add(expr.createBoolean());
  }

  /**
   * Binds the expression as a select item.
   */
  public AmberExpr bindSelect(QueryParser parser)
  {
    for (int i = 0; i < _components.size(); i++) {
      AmberExpr expr = _components.get(i);
      
      expr = expr.bindSelect(parser);

      _components.set(i, expr);
    }
    
    return this;
  }

  /**
   * Returns true if the expression uses the from item.
   */
  public boolean usesFrom(FromItem from, int type, boolean isNot)
  {
    if (type == IS_INNER_JOIN) {
      // returns true if the from item is used in every term of the disjunction
      for (int i = 0; i < _components.size(); i++) {
	AmberExpr expr = _components.get(i);

	if (! isNot && ! expr.usesFrom(from, type, isNot))
	  return false;
	else if (isNot && expr.usesFrom(from, type, isNot))
	  return true;
      }

      return false;
    }
    else {
      for (int i = 0; i < _components.size(); i++) {
	AmberExpr expr = _components.get(i);

	if (expr.usesFrom(from, type))
	  return true;
      }

      return false;
    }
  }

  /**
   * Returns true if the expression uses the from item.
   */
  public AmberExpr replaceJoin(JoinExpr join)
  {
    for (int i = 0; i < _components.size(); i++) {
      AmberExpr expr = _components.get(i);
      
      expr = expr.replaceJoin(join);

      _components.set(i, expr);
    }
    
    return this;
  }

  /**
   * Returns a single expression.
   */
  AmberExpr getSingle()
  {
    if (_components.size() == 0)
      return null;
    else if (_components.size() == 1)
      return _components.get(0);
    else
      return this;
  }
  
  /**
   * Generates the where expression.
   */
  public void generateWhere(CharBuffer cb)
  {
    cb.append('(');

    for (int i = 0; i < _components.size(); i++) {
      if (i != 0)
	cb.append(" OR ");
	
      AmberExpr expr = _components.get(i);

      expr.generateWhere(cb);
    }
      
    cb.append(')');
  }
  
  /**
   * Generates the join expression.
   */
  public void generateJoin(CharBuffer cb)
  {
    cb.append('(');

    for (int i = 0; i < _components.size(); i++) {
      if (i != 0)
	cb.append(" OR ");
	
      AmberExpr expr = _components.get(i);

      expr.generateJoin(cb);
    }
      
    cb.append(')');
  }

  public String toString()
  {
    if (_components.size() == 1) {
      return _components.get(0).toString();
    }
    else {
      CharBuffer cb = new CharBuffer();
      
      cb.append('(');

      for (int i = 0; i < _components.size(); i++) {
	if (i != 0)
	  cb.append(" OR ");
	
	AmberExpr expr = _components.get(i);

	cb.append(expr);
      }
      
      cb.append(')');

      return cb.toString();
    }
  }
}
