package com.comerica.zk.fn;

import java.lang.reflect.Method;
import java.util.Properties;

import org.apache.log4j.Logger;
import org.zkoss.poi.ss.formula.eval.ErrorEval;
import org.zkoss.poi.ss.formula.eval.NumberEval;
import org.zkoss.poi.ss.formula.eval.StringEval;
import org.zkoss.poi.ss.formula.eval.ValueEval;
import org.zkoss.xel.Function;

import com.comerica.zk.COSheet;
import com.comerica.zk.datasource.Datasource;
import com.comerica.zk.datasource.DatasourceException;
import com.comerica.zk.datasource.DatasourceProvider;

public class Ds implements Function {

	private static final Logger LOGGER = Logger.getLogger(Ds.class);
	
	private DatasourceProvider datasourceProvider;
	
	private COSheet cosheet;

	public Ds(COSheet cosheet) throws DatasourceException{
		datasourceProvider = instantiateDatasourceProvider();
		this.cosheet = cosheet;
	}

	@Override
	public Object invoke(Object obj, Object... args) throws Exception {
		LOGGER.info("invoke(Object paramObject, Object... paramArrayOfObject)");
		if (getCosheet().isCanRetrieveData()) {
			
			String dsName = (String)args[0];
			try {
				return new NumberEval(getDs(dsName));
			} catch (DatasourceException e) {
				return ErrorEval.VALUE_INVALID;
			}
		} else {
			return ErrorEval.NA;
		}
	}

	public double getDs(String datasourceName) throws DatasourceException {
		LOGGER.info("getDS has been called with datasource: " + datasourceName);
		
		Datasource datasource = datasourceProvider.getNamedDatasourceForCurrentUser(datasourceName);
		double total = datasource.getTotal();
		return total;
	}
	
	private DatasourceProvider instantiateDatasourceProvider() throws DatasourceException {
		LOGGER.info("instantiateDatasourceProvider()");
		DatasourceProvider provider = null;
		try{
			Properties properties = new Properties();
			properties.load(Ds.class.getClassLoader().getResourceAsStream("datasource.properties"));
			String className = properties.getProperty("provider.implementation");
			provider = (DatasourceProvider) Class.forName(className).newInstance();
		}catch(Exception e){
			LOGGER.error("Error instantiating DatasourceProvider : " + e.toString());
			throw new DatasourceException("Error instantiating DatasourceProvider", e);
		}
		return provider;
	}	
	
	public COSheet getCosheet() {
		return cosheet;
	}

	public void setCosheet(COSheet cosheet) {
		this.cosheet = cosheet;
	}


	@Override
	public Class<?>[] getParameterTypes() {
		LOGGER.info("getParameterTypes()");
		return new Class[]{String.class};
	}


	@Override
	public Class<?> getReturnType() {
		return ValueEval.class;
	}


	@Override
	public Method toMethod() {
		return null;
	}
}