package com.bt.common.directive;

import java.io.IOException;
import java.time.LocalDateTime;
import java.time.format.DateTimeFormatter;
import java.time.temporal.TemporalAccessor;
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：<br>
 * 1：#date(createAt) 用默认 datePattern 配置，输出 createAt 变量中的日期值<br>
 * 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<br>
 * 3：#date() 用默认 datePattern 配置，输出 “当前” 日期值
 *
 * 注意：<br>
 * 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<br>
 * 2：默认 datePattern 可通过 Engine.setDatePattern(...) 进行配置
 *
 * @author Max_Qiu
 */
public class MyDateDirective extends Directive {
  private Expr valueExpr;
  private Expr datePatternExpr;
  private int paraNum;
  @Override
  public void setExprList(ExprList exprList) {
    this.paraNum = exprList.length();
    if (paraNum > 2) {
      throw new ParseException("#date 指令最多两个参数", 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);
    }
  }
  @Override
  public void exec(Env env, Scope scope, Writer writer) {
    if (paraNum == 1) {
      outputWithDatePattern(scope, env.getEngineConfig().getDatePattern(), writer);
    } else if (paraNum == 2) {
      Object datePattern = this.datePatternExpr.eval(scope);
      if (!(datePattern instanceof String)) {
        throw new TemplateException("#date 指令的第二个参数类型必须是 String", location);
      }
      outputWithDatePattern(scope, (String)datePattern, writer);
    } else {
      write(writer, LocalDateTime.now(), env.getEngineConfig().getDatePattern());
    }
  }
  private void outputWithDatePattern(Scope scope, String datePattern, Writer writer) {
    Object value = valueExpr.eval(scope);
    if (value instanceof TemporalAccessor) {
      write(writer, (TemporalAccessor)value, datePattern);
    } else if (value instanceof Date) {
      write(writer, (Date)value, datePattern);
    } else if (value != null) {
      throw new TemplateException("#date 指令的第一个参数必须是实现TemporalAccessor接口的时间类型或者是Date类型", location);
    }
  }
  private void write(Writer writer, TemporalAccessor temporal, String datePattern) {
    String s;
    try {
      s = DateTimeFormatter.ofPattern(datePattern).format(temporal);
    } catch (Exception e) {
      throw new TemplateException("格式化出错，请检查第二个参数：" + datePattern, location, e);
    }
    try {
      writer.write(s, 0, s.length());
    } catch (IOException e) {
      throw new TemplateException(e.getMessage(), location, e);
    }
  }
  private void write(Writer writer, Date date, String datePattern) {
    try {
      writer.write(date, datePattern);
    } catch (IOException e) {
      throw new TemplateException(e.getMessage(), location, e);
    }
  }
}