/**
 * A script to install into google app scripts
 * https://www.google.com/script/start/
 * That will email your agenda for the next day whenever
 * you specify a trigger. (I set it daily at 8-9pm)
 *
 * Why? I use this to remind me via personal email what I'm
 * going to be doing the next day at work without having to
 * scan my work email / calendar
 */

function getMinutesBetweenDates(startDate, endDate) {
    var diff = endDate.getTime() - startDate.getTime();
    return (diff / 60000);
}

function willAttendMeeting(status) {
  return (status === CalendarApp.GuestStatus.OWNER || status === CalendarApp.GuestStatus.YES || status === CalendarApp.GuestStatus.MAYBE);
}

function getEventsAndMail() {
  // message defaults - set to address in the script properties
  // File -> Project Properties -> Script properties tab
  var scriptProps = PropertiesService.getScriptProperties();
  var mailTo = scriptProps.getProperty('MAILTO');
  var subject = "Tomorrow's Meetings"
  var message = '';
  var timeSplit;
  var startSplit;
  var endSplit;
  var niceTime;
  var niceStart;
  var niceEnd;
  var eventLoc;
  var locSplit;
  var niceLoc = '';

  // event data
  var messageEvents = [];
  var events;
  var eventTime;
  var eventTitle;
  var eventStartDate;
  var eventEndDate;
  var dayFreeMin = 8 * 60; //an eight hour day

  // Get Date objects for tomorrow morning and night
  var d = new Date();
  d.setHours(0,0,0,0);
  d.setDate(d.getDate() + 1);
  var tomorrowAm = new Date(d);
  d.setDate(d.getDate() + 1);
  var tomorrowPm = new Date(d)

  // not a weekend
  if (tomorrowAm.getDay() !== 6 && tomorrowAm.getDay() !== 0) {
    // get the events
    events = CalendarApp.getDefaultCalendar().getEvents(tomorrowAm, tomorrowPm);

    if (!events.length) {
      subject = 'NO MEETINGS?';
      message = "Probably a bug, check your calendar";
    } else {
      // create the list
      for (var i = 0; i < events.length; i++) {
        if (willAttendMeeting(events[i].getMyStatus())) { //otherwise shows _everything_
          eventStartDate = events[i].getStartTime();
          eventEndDate = events[i].getEndTime();
          eventTitle = events[i].getTitle().trim();
          
          //logic to ignore time blocked shield meetings indicated by a trailing sheild emoji 🛡
          // TODO: Notice when you're double booked, currently subtracts everything
          if (!/🛡$/.test(eventTitle)) {
            dayFreeMin = dayFreeMin - getMinutesBetweenDates(eventStartDate, eventEndDate);
          }
          
          startSplit = eventStartDate.toTimeString().split(':');
          niceStart = startSplit[0] + ':' + startSplit[1]
          endSplit = eventEndDate.toTimeString().split(':');
          niceEnd = endSplit[0] + ':' + endSplit[1];
          eventLoc = events[i].getLocation();
          niceLoc = '';
          if (eventLoc) {
            locSplit = eventLoc.split('(');
            niceLoc = ' in ' + locSplit[0].trim();
          }
          message += niceStart + ' - ' + niceEnd + niceLoc + "\n\t"
          + eventTitle + "\n";
        }
      }
    }
    
    message = "You have " + Math.floor(dayFreeMin/60) + " free hours tomorrow \n\n" + message;

    MailApp.sendEmail(mailTo, subject, message);
  }
}