QueryHelper.java

/*
 * 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.cyclop.common;

import java.util.Arrays;
import java.util.Optional;

import org.apache.commons.lang.StringUtils;
import org.cyclop.model.CqlKeySpace;
import org.cyclop.model.CqlKeyword;
import org.cyclop.model.CqlQuery;
import org.cyclop.model.CqlTable;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/** @author Maciej Miklas */
public class QueryHelper {

	private final static Logger LOG = LoggerFactory.getLogger(QueryHelper.class);

	public static Optional<CqlKeySpace> extractSpace(CqlQuery query) {
		String cqlLc = query.partLc.replaceAll("[;]", "");
		if (!cqlLc.startsWith("use")) {
			return Optional.empty();
		}

		String space = cqlLc.substring(3, cqlLc.length()).trim();
		space = StringUtils.trimToNull(space);
		if (space == null) {
			return Optional.empty();
		}
		CqlKeySpace exspace = new CqlKeySpace(space);
		LOG.debug("Extrancted space {} from {}", exspace, query);
		return Optional.of(exspace);
	}

	public static Optional<CqlTable> extractTableName(CqlKeyword cqlKeyword, CqlQuery query) {
		String cqlLc = query.partLc;
		int kwStart = cqlLc.indexOf(cqlKeyword.valueSp);
		if (kwStart == -1) {
			return Optional.empty();
		}
		kwStart += cqlKeyword.valueSp.length();

		int end = cqlLc.indexOf(" ", kwStart + 1);
		if (end == -1) {
			end = cqlLc.length();
		}

		String candidate = cqlLc.substring(kwStart, end);
		candidate = StringUtils.trimToNull(candidate);
		if (candidate == null) {
			return Optional.empty();
		}

		// check whether we have table with keyspace
		CqlTable result = null;
		if (candidate.contains(".") && !candidate.endsWith(".")) {
			String[] talStr = candidate.split("[.]");
			String keyspaceStr = StringUtils.trimToNull(talStr[0]);
			String tableStr = StringUtils.trimToNull(talStr[1]);
			if (tableStr == null) {
				result = null;
			} else {
				if (keyspaceStr == null) {
					result = new CqlTable(candidate);
				} else {
					result = new CqlTable(keyspaceStr, tableStr);
				}
			}

		} else {
			result = new CqlTable(candidate);
		}

		LOG.debug("Extracted table {} from {}, {}", result, cqlKeyword, query);
		return Optional.ofNullable(result);
	}

	public static Optional<CqlKeySpace> extractKeyspace(CqlQuery query, CqlKeyword... cqlKeyword) {
		Optional<CqlKeySpace> foundKeyspace = Arrays.asList(cqlKeyword).stream()
				.map(kw -> extractKeyspaceSingle(query, kw)).filter(f -> f.isPresent()).findFirst()
				.orElse(Optional.empty());
		return foundKeyspace;
	}

	private static Optional<CqlKeySpace> extractKeyspaceSingle(CqlQuery query, CqlKeyword cqlKeyword) {
		String cqlLc = query.partLc;
		int kwStart = cqlLc.indexOf(cqlKeyword.valueSp);
		if (kwStart == -1) {
			return Optional.empty();
		}
		kwStart += cqlKeyword.valueSp.length();

		int end = cqlLc.indexOf(".", kwStart + 1);
		if (end == -1) {
			return Optional.empty();
		}

		String candidate = cqlLc.substring(kwStart, end);
		candidate = StringUtils.trimToNull(candidate);
		if (candidate == null) {
			return Optional.empty();
		}

		CqlKeySpace space = new CqlKeySpace(candidate);
		return Optional.of(space);
	}
}