/*
 * Copyright (c) 2011-2015 EPFL DATA Laboratory
 * Copyright (c) 2014-2015 The Squall Collaboration (see NOTICE)
 *
 * All rights reserved.
 *
 * 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 ch.epfl.data.squall.operators;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;

import ch.epfl.data.squall.expressions.ColumnReference;
import ch.epfl.data.squall.expressions.ValueExpression;
import ch.epfl.data.squall.types.StringType;
import ch.epfl.data.squall.visitors.OperatorVisitor;

public class ProjectOperator extends OneToOneOperator implements Operator {
    private static final long serialVersionUID = 1L;

    private List<ValueExpression> _veList = new ArrayList<ValueExpression>();

    private int _numTuplesProcessed = 0;

    public ProjectOperator(int... projectIndexes) {
	for (final int columnNumber : projectIndexes) {
	    final ColumnReference columnReference = new ColumnReference(
		    new StringType(), columnNumber);
	    _veList.add(columnReference);
	}
    }

    public ProjectOperator(List<ValueExpression> veList) {
	_veList = veList;
    }

    public ProjectOperator(ValueExpression... veArray) {
	_veList.addAll(Arrays.asList(veArray));
    }

    @Override
    public void accept(OperatorVisitor ov) {
	ov.visit(this);
    }

    @Override
    public List<String> getContent() {
	throw new RuntimeException(
		"getContent for ProjectionOperator should never be invoked!");
    }

    public List<ValueExpression> getExpressions() {
	return _veList;
    }

    @Override
    public int getNumTuplesProcessed() {
	return _numTuplesProcessed;
    }

    @Override
    public boolean isBlocking() {
	return false;
    }

    @Override
    public String printContent() {
	throw new RuntimeException(
		"printContent for ProjectionOperator should never be invoked!");
    }

    @Override
    public List<String> processOne(List<String> tuple, long lineageTimestamp) {
	_numTuplesProcessed++;
	final List<String> projection = new ArrayList<String>();
	for (final ValueExpression ve : _veList) {
	    final String columnContent = ve.evalString(tuple);
	    projection.add(columnContent);
	}
	return projection;
    }

    @Override
    public String toString() {
	final StringBuilder sb = new StringBuilder();
	sb.append("ProjectOperator ");
	if (!_veList.isEmpty())
	    sb.append("(");
	for (int i = 0; i < _veList.size(); i++) {
	    sb.append(_veList.get(i).toString());
	    if (i == _veList.size() - 1)
		sb.append(")");
	    else
		sb.append(", ");
	}
	return sb.toString();
    }
}