/*
 * 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.translator.mongodb;

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

import org.teiid.language.QueryExpression;
import org.teiid.language.Select;
import org.teiid.logging.LogConstants;
import org.teiid.logging.LogManager;
import org.teiid.metadata.RuntimeMetadata;
import org.teiid.mongodb.MongoDBConnection;
import org.teiid.translator.DataNotAvailableException;
import org.teiid.translator.ExecutionContext;
import org.teiid.translator.ResultSetExecution;
import org.teiid.translator.TranslatorException;

import com.mongodb.*;

public class MongoDBQueryExecution extends MongoDBBaseExecution implements ResultSetExecution {
	private Select command;
	private MongoDBExecutionFactory executionFactory;
	private Cursor results;
	private MongoDBSelectVisitor visitor;
	private Class<?>[] expectedTypes;

	public MongoDBQueryExecution(
			MongoDBExecutionFactory executionFactory,
			QueryExpression command, ExecutionContext executionContext,
			RuntimeMetadata metadata, MongoDBConnection connection) {
		super(executionContext, metadata, connection);
		this.command = (Select)command;
		this.executionFactory = executionFactory;
		this.expectedTypes = command.getColumnTypes();
	}

	@Override
	public void execute() throws TranslatorException {
		this.visitor = new MongoDBSelectVisitor(this.executionFactory, this.metadata);
		this.visitor.visitNode(this.command);

		if (!this.visitor.exceptions.isEmpty()) {
    		throw this.visitor.exceptions.get(0);
    	}

		LogManager.logInfo(LogConstants.CTX_CONNECTOR, this.command);

		DBCollection collection = this.mongoDB.getCollection(this.visitor.mongoDoc.getTargetTable().getName());
		if (collection != null) {
			// TODO: check to see how to pass the hint
			ArrayList<DBObject> ops = new ArrayList<DBObject>();

			for (ProcessingNode ref:this.visitor.mergePlanner.getNodes()) {
                buildAggregate(ops, ref.getInstruction()); 
            }
			
			if (this.visitor.project.isEmpty()) {
			    throw new TranslatorException(MongoDBPlugin.Event.TEIID18025, MongoDBPlugin.Util.gs(MongoDBPlugin.Event.TEIID18025));
			}
			
			assert visitor.selectColumns.size() == visitor.selectColumnReferences.size();
			
			if (this.visitor.projectBeforeMatch) {
				buildAggregate(ops, "$project", this.visitor.project); //$NON-NLS-1$
			}

			
			buildAggregate(ops, "$match", this.visitor.match); //$NON-NLS-1$

			buildAggregate(ops, "$group", this.visitor.group); //$NON-NLS-1$
			buildAggregate(ops, "$match", this.visitor.having); //$NON-NLS-1$

			if (!this.visitor.projectBeforeMatch) {
				buildAggregate(ops, "$project", this.visitor.project); //$NON-NLS-1$
			}
			
			buildAggregate(ops, "$sort", this.visitor.sort); //$NON-NLS-1$
			buildAggregate(ops, "$skip", this.visitor.skip); //$NON-NLS-1$
			buildAggregate(ops, "$limit", this.visitor.limit); //$NON-NLS-1$

			try {
                this.results = collection.aggregate(ops, this.executionFactory.getOptions(this.executionContext.getBatchSize()));
			} catch (MongoException e) {
				throw new TranslatorException(e);
			}
		}
	}

	private void buildAggregate(List<DBObject> query, String type, Object object) {
		if (object != null) {
			LogManager.logDetail(LogConstants.CTX_CONNECTOR, "{\""+type+"\": {"+object.toString()+"}}"); //$NON-NLS-1$ //$NON-NLS-2$ //$NON-NLS-3$ 
			query.add(new BasicDBObject(type, object));
		}
	}
	
    private void buildAggregate(List<DBObject> query, DBObject dbObject) {
        if (dbObject != null) {
            query.add(dbObject);
        }
    }	

	@Override
	public List<?> next() throws TranslatorException, DataNotAvailableException {
		if (this.results != null && this.results.hasNext()) {
			DBObject result = this.results.next();
			if (result != null) {
				ArrayList row = new ArrayList();
				for (int i = 0; i < this.visitor.selectColumns.size();i++) {
					row.add(this.executionFactory.retrieveValue(result.get(this.visitor.selectColumns.get(i)), this.expectedTypes[i], this.mongoDB, this.visitor.selectColumns.get(i), this.visitor.selectColumnReferences.get(i)));
				}
				return row;
			}
		}
		return null;
	}

	@Override
	public void close() {
	    if (this.results != null) {
    		this.results.close();
    		this.results = null;
	    }
	}

	@Override
	public void cancel() throws TranslatorException {
		close();
	}
}
