/*
 * 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.List;
import java.util.Map;

import ch.epfl.data.squall.expressions.ValueExpression;
import ch.epfl.data.squall.storage.BasicStore;
import ch.epfl.data.squall.storage.ValueStore;
import ch.epfl.data.squall.utilities.MyUtilities;
import ch.epfl.data.squall.visitors.OperatorVisitor;

public class DistinctOperator extends OneToOneOperator {

    private final Map _conf;
    private int _numTuplesProcessed;
    private final ProjectOperator _projection;
    private static final long serialVersionUID = 1L;
    private final BasicStore _storage;
    /*
     * Dummy value to associate with a tuple in the backing Storage (Since the
     * backing storage provides a key-value interface)
     */
    private static final String dummyString = new String("dummy");

    public DistinctOperator(Map conf, int[] projectionIndexes) {
	_storage = new ValueStore<String>(conf);
	_projection = new ProjectOperator(projectionIndexes);
	_conf = conf;
    }

    public DistinctOperator(Map conf, List<ValueExpression> veList) {
	_storage = new ValueStore<String>(conf);
	_projection = new ProjectOperator(veList);
	_conf = conf;
    }

    public DistinctOperator(Map conf, ValueExpression... veArray) {
	_storage = new ValueStore<String>(conf);
	_projection = new ProjectOperator(veArray);
	_conf = conf;
    }

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

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

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

    public ProjectOperator getProjection() {
	return _projection;
    }

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

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

    /*
     * If tuple is present in the collection, return null, otherwise, return
     * projected tuple
     */
    @Override
    public List<String> processOne(List<String> tuple, long lineageTimestamp) {
	_numTuplesProcessed++;
	final List<String> projectedTuple = _projection.processOne(tuple,
		lineageTimestamp);
	final String projectedTupleString = MyUtilities.tupleToString(
		projectedTuple, _conf);
	if (_storage.contains(projectedTupleString) == true)
	    return null;
	else {
	    _storage.insert(projectedTupleString, dummyString);
	    return tuple;
	}
    }

    @Override
    public String toString() {
	final StringBuilder sb = new StringBuilder();
	sb.append("DistinctOperator with Projection: ");
	sb.append(_projection.toString());
	return sb.toString();
    }

}