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/*
 * Copyright 2016-2018 shardingsphere.io.
 * 
 * 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.
 * 
 */

package io.shardingsphere.core.metadata;

import io.shardingsphere.core.exception.ShardingException;
import io.shardingsphere.core.rule.DataNode;
import io.shardingsphere.core.rule.ShardingDataSourceNames;
import io.shardingsphere.core.rule.ShardingRule;
import io.shardingsphere.core.rule.TableRule;
import lombok.Getter;
import lombok.Setter;

import java.sql.Connection;
import java.sql.SQLException;
import java.util.Collection;
import java.util.Collections;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

/**
 * Abstract Sharding metadata.
 *
 * @author panjuan
 * @author zhaojun
 */
@Getter
@Setter
public abstract class ShardingMetaData {

    private Map tableMetaDataMap;

    /**
     * Initialize sharding metadata.
     *
     * @param shardingRule sharding rule
     * @throws SQLException SQL exception
     */
    public void init(final ShardingRule shardingRule) throws SQLException {
        tableMetaDataMap = new HashMap<>(shardingRule.getTableRules().size(), 1);
        for (TableRule each : shardingRule.getTableRules()) {
            refresh(each, shardingRule);
        }
    }

    /**
     * refresh each tableMetaData by TableRule.
     *
     * @param each table rule
     * @param shardingRule sharding rule
     * @throws SQLException SQL Exception
     */
    public void refresh(final TableRule each, final ShardingRule shardingRule) throws SQLException {
        refresh(each, shardingRule, Collections.emptyMap());
    }

    /**
     * refresh each tableMetaData by TableRule.
     *
     * @param each table rule
     * @param shardingRule sharding rule
     * @param connectionMap connection map passing from sharding connection
     * @throws SQLException SQL exception
     */
    public void refresh(final TableRule each, final ShardingRule shardingRule, final Map connectionMap) throws SQLException {
        tableMetaDataMap.put(each.getLogicTable(), getTableMetaData(each.getLogicTable(), each.getActualDataNodes(), shardingRule.getShardingDataSourceNames(), connectionMap));
    }

    private TableMetaData getTableMetaData(final String logicTableName, final List actualDataNodes,
                                           final ShardingDataSourceNames shardingDataSourceNames, final Map connectionMap) throws SQLException {
        Collection result = null;
        for (DataNode each : actualDataNodes) {
            Collection columnMetaDataList = getColumnMetaDataList(each, shardingDataSourceNames, connectionMap);
            if (null == result) {
                result = columnMetaDataList;
            }
            if (!result.equals(columnMetaDataList)) {
                throw new ShardingException(getErrorMsgOfTableMetaData(logicTableName, result, columnMetaDataList));
            }
        }
        return new TableMetaData(result);
    }

    /**
     * Get column metadata implementing by concrete handler.
     *
     * @param dataNode DataNode
     * @param shardingDataSourceNames ShardingDataSourceNames
     * @param connectionMap connection map from sharding connection
     * @return ColumnMetaData
     * @throws SQLException SQL exception
     */
    public abstract Collection getColumnMetaDataList(DataNode dataNode, ShardingDataSourceNames shardingDataSourceNames, Map connectionMap) throws SQLException;

    private String getErrorMsgOfTableMetaData(final String logicTableName, final Collection oldColumnMetaDataList, final Collection newColumnMetaDataList) {
        StringBuilder stringBuilder = new StringBuilder();
        stringBuilder.append(" Cannot get uniformed table structure for ").append(logicTableName).append(".");
        stringBuilder.append(" The different column metadata of actual tables is as follows: ");
        for (ColumnMetaData each : oldColumnMetaDataList) {
            stringBuilder.append(each.toString()).append(" ");
        }
        stringBuilder.append("\n");
        for (ColumnMetaData each : newColumnMetaDataList) {
            stringBuilder.append(each.toString()).append(" ");
        }
        return stringBuilder.toString();
    }
}