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/**
 * Copyright (c) 2011-2017, James Zhan 詹波 ([email protected]).
 *
 * 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 com.jfinal.template.ext.directive;

import java.io.IOException;
import java.util.Date;

import com.jfinal.template.Directive;
import com.jfinal.template.Env;
import com.jfinal.template.TemplateException;
import com.jfinal.template.expr.ast.Expr;
import com.jfinal.template.expr.ast.ExprList;
import com.jfinal.template.io.Writer;
import com.jfinal.template.stat.ParseException;
import com.jfinal.template.stat.Scope;

/**
 * #date 日期格式化输出指令
 * 
 * 三种用法：
 * 1：#date(createAt) 用默认 datePattern 配置，输出 createAt 变量中的日期值
 * 2：#date(createAt, "yyyy-MM-dd HH:mm:ss") 用第二个参数指定的 datePattern，输出 createAt 变量中的日期值
 * 3：#date() 用默认 datePattern 配置，输出 “当前” 日期值
 * 
 * 注意：
 * 1：#date 指令中的参数可以是变量，例如：#date(d, p) 中的 d 与 p 可以全都是变量
 * 2：默认 datePattern 可通过 Engine.setDatePattern(...) 进行配置
 */
public class DateDirective extends Directive {
	
	private Expr valueExpr;
	private Expr datePatternExpr;
	private int paraNum;
	
	public void setExprList(ExprList exprList) {
		this.paraNum = exprList.length();
		if (paraNum > 2) {
			throw new ParseException("Wrong number parameter of #date directive, two parameters allowed at most", location);
		}
		
		if (paraNum == 0) {
			this.valueExpr = null;
			this.datePatternExpr = null;
		} else if (paraNum == 1) {
			this.valueExpr = exprList.getExpr(0);
			this.datePatternExpr = null;
		} else if (paraNum == 2) {
			this.valueExpr = exprList.getExpr(0);
			this.datePatternExpr = exprList.getExpr(1);
		}
	}
	
	public void exec(Env env, Scope scope, Writer writer) {
		if (paraNum == 1) {
			outputWithoutDatePattern(env, scope, writer);
		} else if (paraNum == 2) {
			outputWithDatePattern(env, scope, writer);
		} else {
			outputToday(env, writer);
		}
	}
	
	private void outputToday(Env env, Writer writer) {
		write(writer, new Date(), env.getEngineConfig().getDatePattern());
	}
	
	private void outputWithoutDatePattern(Env env, Scope scope, Writer writer) {
		Object value = valueExpr.eval(scope);
		if (value != null) {
			write(writer, (Date)value, env.getEngineConfig().getDatePattern());
		}
	}
	
	private void outputWithDatePattern(Env env, Scope scope, Writer writer) {
		Object value = valueExpr.eval(scope);
		if (value == null) {
			return ;
		}
		
		Object datePattern = this.datePatternExpr.eval(scope);
		if ( !(datePattern instanceof String) ) {
			throw new TemplateException("The sencond parameter datePattern of #date directive must be String", location);
		}
		
		write(writer, (Date)value, (String)datePattern);
	}
	
	private void write(Writer writer, Date date, String datePattern) {
		try {
			writer.write(date, datePattern);
		} catch (IOException e) {
			throw new TemplateException(e.getMessage(), location, e);
		}
	}
}