/*
 * Copyright 2016-2018 shardingsphere.io.
 * <p>
 * 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.
 * </p>
 */

package io.shardingsphere.core.parsing.antlr.extractor.statement.handler;

import org.antlr.v4.runtime.ParserRuleContext;
import org.antlr.v4.runtime.tree.ParseTree;

import com.google.common.base.Optional;

import io.shardingsphere.core.parsing.antlr.extractor.statement.handler.result.ExtractResult;
import io.shardingsphere.core.parsing.antlr.extractor.statement.handler.result.SQLTokenExtractResult;
import io.shardingsphere.core.parsing.antlr.extractor.statement.util.ASTUtils;
import io.shardingsphere.core.parsing.parser.token.IndexToken;
import io.shardingsphere.core.util.SQLUtil;

/**
 * Rename index extract handler.
 * 
 * @author duhongjun
 */
public final class RenameIndexExtractHandler implements ASTExtractHandler {

    @Override
    public ExtractResult extract(final ParserRuleContext ancestorNode) {
        Optional<ParserRuleContext> renameIndexNode = ASTUtils.findFirstChildNode(ancestorNode, RuleName.RENAME_INDEX);
        if (!renameIndexNode.isPresent() || 4 > renameIndexNode.get().getChildCount()) {
            return null;
        }
        ParseTree oldIndexNode = renameIndexNode.get().getChild(2);
        if (!(oldIndexNode instanceof ParserRuleContext)) {
            return null;
        }
        ParseTree newIndexNode = renameIndexNode.get().getChild(4);
        if (!(newIndexNode instanceof ParserRuleContext)) {
            return null;
        }
        SQLTokenExtractResult extractResult = new SQLTokenExtractResult();
        extractResult.getSqlTokens().add(getIndexToken((ParserRuleContext) oldIndexNode));
        extractResult.getSqlTokens().add(getIndexToken((ParserRuleContext) newIndexNode));
        return extractResult;
    }
    
    private IndexToken getIndexToken(final ParserRuleContext indexNode) {
        return new IndexToken(indexNode.getStop().getStartIndex(), SQLUtil.getNameWithoutSchema(indexNode.getText()), null);
    }
}

@@ -1346,16 +1346,20 @@
 ndler %7B%0A
+    
 %0A    @Ov
@@ -1376,16 +1376,25 @@
  public 
+Optional%3C
 ExtractR
@@ -1390,32 +1390,33 @@
 al%3CExtractResult
+%3E
  extract(final P
@@ -1668,36 +1668,49 @@
          return 
-null
+Optional.absent()
 ;%0A        %7D%0A    
@@ -1844,36 +1844,49 @@
          return 
-null
+Optional.absent()
 ;%0A        %7D%0A    
@@ -2028,20 +2028,33 @@
  return 
-null
+Optional.absent()
 ;%0A      
@@ -2087,24 +2087,17 @@
 tResult 
-extractR
+r
 esult = 
@@ -2129,32 +2129,25 @@
 ();%0A        
-extractR
+r
 esult.getSql
@@ -2217,24 +2217,17 @@
         
-extractR
+r
 esult.ge
@@ -2308,17 +2308,27 @@
  return 
-e
+Optional.%3CE
 xtractRe
@@ -2331,16 +2331,27 @@
 ctResult
+%3Eof(result)
 ;%0A    %7D%0A

use optional for checkstyle