/*
 * 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.core.rewrite.token.generator;

import com.google.common.base.Optional;
import org.apache.shardingsphere.core.parse.sql.segment.dml.assignment.AssignmentSegment;
import org.apache.shardingsphere.core.parse.sql.segment.dml.assignment.SetAssignmentsSegment;
import org.apache.shardingsphere.core.parse.sql.statement.SQLStatement;
import org.apache.shardingsphere.core.parse.sql.statement.dml.InsertStatement;
import org.apache.shardingsphere.core.parse.sql.token.impl.InsertSetAddItemsToken;
import org.apache.shardingsphere.core.rule.EncryptRule;

import java.util.ArrayList;
import java.util.Collection;
import java.util.LinkedList;
import java.util.List;

/**
 * Insert set add items token generator.
 *
 * @author panjuan
 */
public final class InsertSetAddItemsTokenGenerator implements OptionalSQLTokenGenerator<EncryptRule> {
    
    @Override
    public Optional<InsertSetAddItemsToken> generateSQLToken(final SQLStatement sqlStatement, final EncryptRule encryptRule) {
        Optional<SetAssignmentsSegment> setAssignmentsSegment = sqlStatement.findSQLSegment(SetAssignmentsSegment.class);
        if (!(sqlStatement instanceof InsertStatement && setAssignmentsSegment.isPresent())) {
            return Optional.absent();
        }
        return createInsertSetAddItemsToken((InsertStatement) sqlStatement, encryptRule, setAssignmentsSegment.get());
    }
    
    private Optional<InsertSetAddItemsToken> createInsertSetAddItemsToken(final InsertStatement insertStatement, final EncryptRule encryptRule, final SetAssignmentsSegment segment) {
        Collection<String> columnNames = getQueryAssistedColumn(insertStatement, encryptRule);
        if (columnNames.isEmpty()) {
            return Optional.absent();
        }
        List<AssignmentSegment> assignments = new ArrayList<>(segment.getAssignments());
        return Optional.of(new InsertSetAddItemsToken(assignments.get(assignments.size() - 1).getStopIndex() + 1, columnNames));
    }
    
    private Collection<String> getQueryAssistedColumn(final InsertStatement insertStatement, final EncryptRule encryptRule) {
        Collection<String> result = new LinkedList<>();
        for (String each : insertStatement.getColumnNames()) {
            Optional<String> assistedColumnName = encryptRule.getEncryptorEngine().getAssistedQueryColumn(insertStatement.getTables().getSingleTableName(), each);
            if (assistedColumnName.isPresent()) {
                result.add(assistedColumnName.get());
            }
        }
        return result;
    }
}

add InsertSetAddItemsTokenGenerator