/*
 * 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.apache.shardingsphere.encrypt.distsql.handler.update;

import lombok.AccessLevel;
import lombok.NoArgsConstructor;
import org.apache.shardingsphere.encrypt.config.EncryptRuleConfiguration;
import org.apache.shardingsphere.encrypt.config.rule.EncryptColumnItemRuleConfiguration;

import java.util.Collection;
import java.util.stream.Collectors;

/**
 * Unused algorithm finder.
 */
@NoArgsConstructor(access = AccessLevel.PRIVATE)
public final class UnusedAlgorithmFinder {
    
    /**
     * Find unused encryptor.
     *
     * @param ruleConfig encrypt rule configuration
     * @return found unused encryptor
     */
    public static Collection<String> findUnusedEncryptor(final EncryptRuleConfiguration ruleConfig) {
        Collection<String> inUsedEncryptors = ruleConfig.getTables().stream().flatMap(each -> each.getColumns().stream()).map(optional -> optional.getCipher().getEncryptorName())
                .collect(Collectors.toSet());
        inUsedEncryptors.addAll(ruleConfig.getTables().stream().flatMap(each -> each.getColumns().stream())
                .map(optional -> optional.getAssistedQuery().map(EncryptColumnItemRuleConfiguration::getEncryptorName).orElse(""))
                .collect(Collectors.toSet()));
        inUsedEncryptors.addAll(ruleConfig.getTables().stream().flatMap(each -> each.getColumns().stream())
                .map(optional -> optional.getLikeQuery().map(EncryptColumnItemRuleConfiguration::getEncryptorName).orElse(""))
                .collect(Collectors.toSet()));
        return ruleConfig.getEncryptors().keySet().stream().filter(each -> !inUsedEncryptors.contains(each)).collect(Collectors.toSet());
    }
}
