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package com.github.antelopeframework.mybatis.shard.converter;

import java.util.Map;

import com.github.antelopeframework.mybatis.shard.ShardTable;
import com.github.antelopeframework.mybatis.shard.ShardTableHolder;
import com.github.antelopeframework.mybatis.shard.ShardContext.ShardOnPair;

import net.sf.jsqlparser.statement.Statement;
import net.sf.jsqlparser.util.deparser.StatementDeParser;

/**
 * SQL 语句转换接口的抽象实现.
 * 
 * @author yangzhi.yzh
 *
 */
public abstract class AbstractSqlConverter implements SqlConverter {
	
	@Override
	public String convert(String sqlMapperId, Statement statement, Map shardOns) {
		return doDeParse(doConvert(sqlMapperId, statement, shardOns));
	}
	
	/**
	 * 使用 jsqlparser, 生成 SQL 语句.
	 * 
	 * @param statement
	 * @return
	 */
	protected String doDeParse(Statement statement) {
		StatementDeParser deParser = new StatementDeParser(new StringBuilder());
		statement.accept(deParser);
		
		return deParser.getBuffer().toString();
	}

	/**
	 * 
	 * @param sqlMapperId
	 * @param tableName
	 * @param shardOns
	 * @return
	 */
	protected String convertTableName(String sqlMapperId, String tableName, Map shardOns) {
		ShardTable shardTable = ShardTableHolder.getInstance().getShardTable(tableName);
		
		if (shardTable == null) {
			return tableName;
		}
		
		ShardOnPair pair = shardOns.get(tableName);
		if (pair == null) {
			return tableName;
		}
		
		return shardTable.getStrategy().getTargetTableName(sqlMapperId, shardTable, pair.getShardOn(), pair.getShardValue());
	}

	/**
	 * 
	 * @param paramString
	 * @param paramStatement
	 * @param paramObject
	 * @return
	 */
	protected abstract Statement doConvert(String sqlMapperId, Statement statement, Map shardOns);
}