package foundation.io.engine;

import java.sql.ResultSet;
import java.sql.ResultSetMetaData;

import org.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.Logger;

import foundation.data.entity.Entity;
import foundation.data.entity.EntitySet;
import foundation.data.meta.field.FieldRuntimeCreator;
import foundation.data.meta.field.FieldsRuntime;
import foundation.data.meta.field.ResultMetaFieldReader;
import foundation.io.define.IOSQLContext;
import foundation.persist.ILoadable;
import foundation.persist.NamedSQL;
import foundation.persist.SQLRunner;

public class BatchEntityLoader implements ILoadable {

	private static Logger logger;
	private IOSQLContext ioContext;
	private FieldsRuntime fieldsMeta;
	private EntitySet entitySet;
	private int batchCount;
	
	
	static {
		logger = LogManager.getLogger(BatchEntityLoader.class);
	}
	
	public BatchEntityLoader(IOSQLContext ioContext) throws Exception {
		this.ioContext = ioContext;
	}

	public EntitySet load(int batchCount) throws Exception {
		this.batchCount = batchCount;
		NamedSQL namedSQL = NamedSQL.getInstance("batchSelectFromTable");
		
		try {
			ioContext.setParametersTo(namedSQL);
			SQLRunner.getData(namedSQL, this);			
		}
		catch(Exception e) {
			printError(namedSQL, e);
			throw e;
		}

		return entitySet;
	}

	@Override
	public void load(ResultSet rslt, Object... args) throws Exception {
		if (fieldsMeta == null) {
			loadMeta(rslt.getMetaData());
		}
		
		entitySet = new EntitySet(fieldsMeta, batchCount);
		
		int lineNo = 1;
		try {
			int fieldCount = fieldsMeta.getFieldCount();
			
			while (rslt.next()) {
				Entity entity = entitySet.append();

				//1. set value
				for (int j = 0; j < fieldCount; j++) {
					Object object = rslt.getObject(j + 1);
					entity.set(j, object);
				}
				
				lineNo++;
			}
		}
		catch (Exception e) {
			String error = "获取第" + lineNo + "行数据时发生错误：" + e.getMessage();
			throw new Exception(error);
		}		
	}
	
	private void loadMeta(ResultSetMetaData metaData) throws Exception {
		ResultMetaFieldReader fieldReader = new ResultMetaFieldReader(metaData);
		fieldsMeta = FieldRuntimeCreator.create(fieldReader);
	}

	private void printError(NamedSQL namedSQL, Exception e) {
		logger.error("load data error:");
		
		try {
			logger.error("sql:" + namedSQL.toString());
			
			if (entitySet != null) {
				int i = 1;
				
				for (Entity entity: entitySet) {
					logger.error("line" + i + ":" + entity.toString());
					i++;
					
					if (i > 5) {
						break;
					}
				}
			}
		} 
		catch (Exception e1) {
			logger.error(e1);
		}		
	}
	
}