/*
 * 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.collect.HashMultimap;
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.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);
    }
    
    @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);
        }
    }
    
    @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;
    }
}

@@ -703,28 +703,112 @@
 mon.
-collect.HashMultimap
+base.Function;%0Aimport com.google.common.collect.HashMultimap;%0Aimport com.google.common.collect.Iterators
 ;%0Aim
@@ -1128,16 +1128,45 @@
 ashSet;%0A
+import java.util.LinkedList;%0A
 import j
@@ -1774,32 +1774,274 @@
 ts);%0A    %7D%0A    %0A
+    private DistinctQueryResult(final Multimap%3CString, Integer%3E columnLabelAndIndexMap, final Iterator%3CList%3CObject%3E%3E resultData) %7B%0A        this.columnLabelAndIndexMap = columnLabelAndIndexMap;%0A        this.resultData = resultData;%0A    %7D%0A    %0A
     @SneakyThrow
@@ -3188,16 +3188,16 @@
 d(row);%0A
-
         
@@ -3205,24 +3205,366 @@
 %0A    %7D%0A    %0A
+    public List%3CQueryResult%3E divide() %7B%0A        List%3CQueryResult%3E result = new LinkedList%3C%3E();%0A        Iterators.transform(resultData, new Function%3CList%3CObject%3E, DistinctQueryResult%3E() %7B%0A            %0A            @Override%0A            public DistinctQueryResult apply(final List%3CObject%3E row) %7B%0A            %0A            %7D%0A        %7D)%0A    %7D%0A    %0A
     @Overrid

add DistinctQueryResult()