/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you 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.apache.pig.backend.hadoop.executionengine.physicalLayer.expressionOperators;

import org.apache.pig.backend.executionengine.ExecException;
import org.apache.pig.backend.hadoop.executionengine.physicalLayer.POStatus;
import org.apache.pig.backend.hadoop.executionengine.physicalLayer.Result;
import org.apache.pig.backend.hadoop.executionengine.physicalLayer.plans.PhyPlanVisitor;
import org.apache.pig.data.DataType;
import org.apache.pig.impl.plan.OperatorKey;
import org.apache.pig.impl.plan.NodeIdGenerator;
import org.apache.pig.impl.plan.VisitorException;

/**
 * Boolean and operator.
 */

public class POAnd extends BinaryComparisonOperator {

    /**
     * 
     */
    private static final long serialVersionUID = 1L;

    public POAnd(OperatorKey k) {
        this(k, -1);
    }

    public POAnd(OperatorKey k, int rp) {
        super(k, rp);
        resultType = DataType.BOOLEAN;
    }

    @Override
    public void visit(PhyPlanVisitor v) throws VisitorException {
        v.visitAnd(this);
    }

    @Override
    public String name() {
        return "And" + "[" + DataType.findTypeName(resultType) + "]" +" - " + mKey.toString();
    }

    @Override
    public Result getNextBoolean() throws ExecException {
        Result r = accumChild(null, DataType.BOOLEAN);
        if (r != null) {
            return r;
        }
        
        Result left;
        left = lhs.getNextBoolean();
        // pass on ERROR and EOP 
        if(left.returnStatus != POStatus.STATUS_OK && left.returnStatus != POStatus.STATUS_NULL) {
            return left;
        }
        
        // truth table for AND 
        // t = true, n = null, f = false
        //    AND  t n f
        // 1) t    t n f
        // 2) n    n n f
        // 3) f    f f f
        
        // Short circuit - if lhs is false, return false; ROW 3 above is handled with this
        boolean returnLeft = false;
        if (left.result != null && !(((Boolean)left.result).booleanValue())) {
          if (illustrator == null) {
              return left;
          }
          illustratorMarkup(null, left.result, 1);
          returnLeft = true;
        }
        
        Result right = rhs.getNextBoolean();
        if (returnLeft) {
            return left;
        }
        
        // pass on ERROR and EOP 
        if(right.returnStatus != POStatus.STATUS_OK && right.returnStatus != POStatus.STATUS_NULL) {
            return right;
        }
        
        // if the lhs is null and rhs is true - return null, in all other cases
        // we can just return the rhs - ROW 1 and ROW 2 of table above
        if(left.result == null && right.result != null && ((Boolean)right.result).booleanValue()) {
            return left;
        }
        
        // No matter what, what we get from the right side is what we'll
        // return, null, true, or false.
        if (right.result != null)
            illustratorMarkup(null, right.result, (Boolean) right.result ? 0 : 1);
        return right;
    }

    @Override
    public POAnd clone() throws CloneNotSupportedException {
        POAnd clone = new POAnd(new OperatorKey(mKey.scope, 
            NodeIdGenerator.getGenerator().getNextNodeId(mKey.scope)));
        clone.cloneHelper(this);
        return clone;
    }
}