/*
 * 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.executor.sql.execute.result;

import com.google.common.base.Function;
import com.google.common.collect.HashMultimap;
import com.google.common.collect.Iterators;
import com.google.common.collect.Multimap;
import io.shardingsphere.core.merger.QueryResult;
import lombok.SneakyThrows;

import java.io.InputStream;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.Calendar;
import java.util.Collection;
import java.util.Iterator;
import java.util.LinkedHashSet;
import java.util.LinkedList;
import java.util.List;
import java.util.Map.Entry;
import java.util.Set;

/**
 * Distinct query result.
 *
 * @author panjuan
 */
public final class DistinctQueryResult implements QueryResult {
    
    private final Multimap<String, Integer> columnLabelAndIndexMap;
    
    private final Iterator<List<Object>> resultData;
    
    private List<Object> currentRow;
    
    @SneakyThrows
    public DistinctQueryResult(final Collection<QueryResult> queryResults) {
        this.columnLabelAndIndexMap = getColumnLabelAndIndexMap(queryResults.iterator().next());
        resultData = getResultData(queryResults);
    }
    
    private DistinctQueryResult(final Multimap<String, Integer> columnLabelAndIndexMap, final Iterator<List<Object>> resultData) {
        this.columnLabelAndIndexMap = columnLabelAndIndexMap;
        this.resultData = resultData;
    }
    
    @SneakyThrows
    private Multimap<String, Integer> getColumnLabelAndIndexMap(final QueryResult queryResult) {
        Multimap<String, Integer> result = HashMultimap.create();
        for (int columnIndex = 1; columnIndex <= queryResult.getColumnCount(); columnIndex++) {
            result.put(queryResult.getColumnLabel(columnIndex), columnIndex);
        }
        return result;
    }
    
    @SneakyThrows
    private Iterator<List<Object>> getResultData(final Collection<QueryResult> queryResults) {
        Set<List<Object>> resultData = new LinkedHashSet<>();
        for (QueryResult each : queryResults) {
            fill(resultData, each);
        }
        return resultData.iterator();
    }
    
    private void fill(final Set<List<Object>> resultData, final QueryResult queryResult) throws SQLException {
        while (queryResult.next()) {
            List<Object> row = new ArrayList<>(queryResult.getColumnCount());
            for (int columnIndex = 1; columnIndex <= queryResult.getColumnCount(); columnIndex++) {
                row.add(queryResult.getValue(columnIndex, Object.class));
            }
            resultData.add(row);
        }
    }
    
    public List<QueryResult> divide() {
        List<QueryResult> result = new LinkedList<>();
        Iterators.transform(resultData, new Function<List<Object>, DistinctQueryResult>() {
            
            @Override
            public DistinctQueryResult apply(final List<Object> row) {
            
            }
        })
    }
    
    @Override
    public boolean next() {
        if (resultData.hasNext()) {
            currentRow = resultData.next();
            return true;
        }
        currentRow = null;
        return false;
    }

    @Override
    public Object getValue(final int columnIndex, final Class<?> type) {
        return currentRow.get(columnIndex - 1);
    }

    @Override
    public Object getValue(final String columnLabel, final Class<?> type) {
        return currentRow.get(getIndexByColumnLabel(columnLabel));
    }

    @Override
    public Object getCalendarValue(final int columnIndex, final Class<?> type, final Calendar calendar) {
        return currentRow.get(columnIndex - 1);
    }

    @Override
    public Object getCalendarValue(final String columnLabel, final Class<?> type, final Calendar calendar) {
        return currentRow.get(getIndexByColumnLabel(columnLabel));
    }

    @Override
    public InputStream getInputStream(final int columnIndex, final String type) {
        return (InputStream) currentRow.get(columnIndex - 1);
    }

    @Override
    public InputStream getInputStream(final String columnLabel, final String type) {
        return (InputStream) currentRow.get(getIndexByColumnLabel(columnLabel));
    }

    @Override
    public boolean wasNull() {
        return null == currentRow;
    }

    @Override
    public int getColumnCount() {
        return columnLabelAndIndexMap.size();
    }

    @Override
    public String getColumnLabel(final int columnIndex) throws SQLException {
        for (Entry<String, Integer> entry : columnLabelAndIndexMap.entries()) {
            if (columnIndex == entry.getValue()) {
                return entry.getKey();
            }
        }
        throw new SQLException("Column index out of range", "9999");
    }
    
    private Integer getIndexByColumnLabel(final String columnLabel) {
        return new ArrayList<>(columnLabelAndIndexMap.get(columnLabel)).get(0) - 1;
    }
}

@@ -805,16 +805,56 @@
 rators;%0A
+import com.google.common.collect.Lists;%0A
 import c
@@ -1172,37 +1172,8 @@
 et;%0A
-import java.util.LinkedList;%0A
 impo
@@ -3232,24 +3232,32 @@
 public List%3C
+Distinct
 QueryResult%3E
@@ -3280,63 +3280,34 @@
     
-List%3CQueryResult%3E result = new LinkedList%3C%3E();%0A        
+return Lists.newArrayList(
 Iter
@@ -3386,32 +3386,24 @@
 lt%3E() %7B%0A    
-        
 %0A           
@@ -3492,24 +3492,213 @@
             
+    Set%3CList%3CObject%3E%3E resultData = new LinkedHashSet%3C%3E();%0A                resultData.add(row);%0A                return new DistinctQueryResult(columnLabelAndIndexMap, resultData.iterator());
 %0A           
@@ -3710,16 +3710,18 @@
       %7D)
+);
 %0A    %7D%0A 

use Lists.newArrayList