/*
 * Copyright Red Hat, Inc. and/or its affiliates
 * and other contributors as indicated by the @author tags and
 * the COPYRIGHT.txt file distributed with this work.
 *
 * 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 org.teiid.query.sql.symbol;

import java.util.LinkedList;
import java.util.List;

import org.teiid.core.util.EquivalenceUtil;
import org.teiid.core.util.HashCodeUtil;
import org.teiid.query.sql.LanguageObject;
import org.teiid.query.sql.LanguageVisitor;
import org.teiid.query.sql.visitor.SQLStringVisitor;

/**
 * <p>This is a subclass of Symbol representing multiple output columns.</p>
 */
public class MultipleElementSymbol implements Expression {
    private List<ElementSymbol> elementSymbols;
    private GroupSymbol group;

    public MultipleElementSymbol() {
    }
    
    /**
     * Construct a multiple element symbol
     * @param name Name of the symbol
     */
    public MultipleElementSymbol(String name){
        this.group = new GroupSymbol(name);
    }
    
    @Override
    public Class<?> getType() {
    	return null;
    }

    /**
     * Set the {@link ElementSymbol}s that this symbol refers to
     * @param elementSymbols List of {@link ElementSymbol}
     */
    public void setElementSymbols(List<ElementSymbol> elementSymbols){
        this.elementSymbols = elementSymbols;
    }

    /**
     * Get the element symbols referred to by this multiple element symbol
     * @return List of {@link ElementSymbol}s, may be null
     */
    public List<ElementSymbol> getElementSymbols(){
        return this.elementSymbols;
    }

    /**
     * Add an element symbol referenced by this multiple element symbol
     * @param symbol Element symbol referenced by this multiple element symbol
     */
    public void addElementSymbol(ElementSymbol symbol) {
		if(getElementSymbols() == null) { 
			setElementSymbols(new LinkedList<ElementSymbol>());
		}
		getElementSymbols().add(symbol);
    }
	
    public void acceptVisitor(LanguageVisitor visitor) {
        visitor.visit(this);
    }

	/**
	 * Return a deep copy of this object
	 * @return Deep copy of this object
	 */
	public Object clone() {
		MultipleElementSymbol copy = new MultipleElementSymbol();
		if (group != null) {
			copy.group = group.clone();
		}

		List<ElementSymbol> elements = getElementSymbols();
		if(elements != null && elements.size() > 0) {
			copy.setElementSymbols(LanguageObject.Util.deepClone(elements, ElementSymbol.class));				
		}	

		return copy;
	}
	
	/**
	 * @return null if selecting all groups, otherwise the specific group
	 */
	public GroupSymbol getGroup() {
		return group;
	}
	
	public void setGroup(GroupSymbol group) {
		this.group = group;
	}
	
	@Override
	public String toString() {
		return SQLStringVisitor.getSQLString(this);
	}
	
	@Override
	public int hashCode() {
		return HashCodeUtil.hashCode(0, group);
	}
	
	@Override
	public boolean equals(Object obj) {
		if (obj == this) {
			return true;
		}
		if (!(obj instanceof MultipleElementSymbol)) {
			return false;
		}
		MultipleElementSymbol other = (MultipleElementSymbol)obj;
		return EquivalenceUtil.areEqual(this.group, other.group);
	}

}
