org.apache.lens.server.api.query.save.param.ParameterResolver.java Source code

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Here is the source code for org.apache.lens.server.api.query.save.param.ParameterResolver.java

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/**
 * 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
 * <p/>
 * http://www.apache.org/licenses/LICENSE-2.0
 * <p/>
 * 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.lens.server.api.query.save.param;

import java.util.List;
import java.util.Map;
import java.util.regex.MatchResult;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

import javax.ws.rs.core.MultivaluedMap;

import org.apache.lens.api.query.save.Parameter;
import org.apache.lens.api.query.save.SavedQuery;
import org.apache.lens.server.api.query.save.SavedQueryHelper;
import org.apache.lens.server.api.query.save.exception.MissingParameterException;
import org.apache.lens.server.api.query.save.exception.ParameterCollectionException;
import org.apache.lens.server.api.query.save.exception.ParameterValueException;
import org.apache.lens.server.api.query.save.exception.ValueEncodeException;

import com.google.common.collect.ImmutableMap;
import com.google.common.collect.Sets;

/**
 * The class ParameterResolver.
 * Takes care of resolving the parameter with values specified for the given query
 *
 */
public class ParameterResolver {

    private final ImmutableMap<String, Parameter> parameterMap;
    private final SavedQuery savedQuery;
    private final MultivaluedMap<String, String> queryParameters;

    private ParameterResolver(SavedQuery savedQuery, MultivaluedMap<String, String> queryParameters) {
        final ImmutableMap.Builder<String, Parameter> builder = ImmutableMap.builder();
        for (Parameter parameter : savedQuery.getParameters()) {
            builder.put(parameter.getName(), parameter);
        }
        parameterMap = builder.build();
        this.savedQuery = savedQuery;
        this.queryParameters = SavedQueryHelper.getDefaultParameterValues(savedQuery);
        this.queryParameters.putAll(queryParameters);
    }

    /**
     *
     * @return resolved query
     * @throws ParameterValueException, IllegalArgumentException
     *
     * The function resolves the provided values for the bind params.
     * A MissingParameterException is thrown if a value is not provided for one of the params
     *
     */
    private String resolve() throws ParameterValueException, MissingParameterException {
        final Sets.SetView<String> unProvidedParameters = Sets.difference(parameterMap.keySet(),
                queryParameters.keySet());
        if (unProvidedParameters.size() > 0) {
            throw new MissingParameterException(unProvidedParameters);
        }
        final StringBuilder query = new StringBuilder(savedQuery.getQuery());
        for (Map.Entry<String, List<String>> parameter : queryParameters.entrySet()) {
            final String parameterName = parameter.getKey();
            final List<String> values = parameter.getValue();
            final Parameter parameterDetail = parameterMap.get(parameterName);
            final String encodedValue;
            try {
                encodedValue = ParameterCollectionTypeEncoder
                        .valueOf(parameterDetail.getCollectionType().toString())
                        .encode(parameterDetail.getDataType(), values);
            } catch (ValueEncodeException | ParameterCollectionException e) {
                throw new ParameterValueException(parameterName, values, e);
            }
            resolveParameter(query, parameterName, encodedValue);
        }
        return query.toString();
    }

    /**
     * The function replaces all the occurrences of the specified bind parameter with the resolved value.
     * There could be more than one occurrence of a particular bind param
     *
     * For eg. select * from table where col1 = :p1 and col2 = :p1. In this case all the valid occurrences
     * of the bind param p1 will be replaced by the resolved value.
     *
     * @param query (gets mutated)
     * @param parameter, the bind param
     * @param resolvedValue, the value to be resolved
     */
    private static void resolveParameter(StringBuilder query, String parameter, String resolvedValue) {
        final Pattern pattern = Pattern.compile(ParameterParser.getPatternStringFor(parameter));
        Matcher matcher = pattern.matcher(query);
        while (matcher.find()) {
            if (matcher.group(1) != null) {
                final MatchResult result = matcher.toMatchResult();
                query.replace(result.start(1) - ParameterParser.getParameterPrefixLength(), result.end(1),
                        resolvedValue);
                matcher = pattern.matcher(query);
            }
        }
    }

    public static String resolve(SavedQuery savedQuery, MultivaluedMap<String, String> queryParameters)
            throws ParameterValueException, MissingParameterException {
        return new ParameterResolver(savedQuery, queryParameters).resolve();
    }
}