/*
 * Copyright: Dale Stevens 2018
 *
 * About:
 * The script below will pull events from the calendar of your choice, and add them to the
 * primary calendar of the account you employ this script under.
 * There are a couple "knobs" (variables) at the top of the script to assist in tweeking
 * to your liking.
 *
 * Setup:
 * 1. Go to your Google Drive under your desired account (I recommend your "work" account).
 * 2. Create a new Google Apps Script under "more". (you may need to "enable" this service by going to "connect more apps")
 * 3. Paste the code below into 'code.gs'. Save.
 * 4. Click the "clock" icon to setup a new trigger.
 * 5. Choose "Run: sync"
 * 6. Choose "Events: From calendar, Event Updated"
 * 7. Enter your calendar ID (usually your personal email address) in the text box.
 * 8. Save.
 * 9. Run.
 * 10. You may need be prompted to authorize and sign-in to your account. Do this for your primary calendar (the account you're on)
 */

var calendarId="YOUR CALENDAR ID HERE"; // Typically this is your personal gmail address "someone@somewhere.com"
var days_in_advance = 14; // how many days in advance to monitor and block off time
var eventPrefix="BLOCKED"; // update this to the text you'd like to appear in the new events created in primary calendar
var weekdays_only = false;

function copy_event(event, to_calendar) {
  new_event = to_calendar.createEvent(event.getTitle(),event.getStartTime(),event.getEndTime()); // change the Booked text to whatever you would like your merged event titles to be
  new_event.removeAllReminders(); // so you don't get double notifications. Delete this if you want to keep the default reminders for your newly created primary calendar events
  new_event.setTag(calendarId, event.getId());
  return new_event;
}

function update_event(pEvent, sEvent) {
  pEvent.setTitle(eventPrefix+" ("+sEvent.getTitle()+")");
  pEvent.setDescription(sEvent.getDescription());
  pEvent.setTime(sEvent.getStartTime(), sEvent.getEndTime());
  pEvent.setVisibility(CalendarApp.Visibility.PRIVATE); // set blocked time as private appointments in work calendar
}

function is_on_weekday(event) {
  var day = event.getStartTime().getDay();
  return (day > 0 && day < 6);
}

function sync() {

  var today=new Date();
  var enddate=new Date();
  enddate.setDate(today.getDate()+days_in_advance);

  var secondaryCal=CalendarApp.getCalendarById(calendarId);
  var secondaryEvents=secondaryCal.getEvents(today,enddate);

  var primaryCal=CalendarApp.getDefaultCalendar();
  var primaryEvents=primaryCal.getEvents(today,enddate); // all primary calendar events

  var primaryEventsFiltered = {}; // to contain primary calendar events that were previously created from secondary calendar
  var primaryEventsUpdated = []; // to contain primary calendar events that were updated from secondary calendar
  var primaryEventsCreated = []; // to contain primary calendar events that were created from secondary calendar

  Logger.log('Number of primaryEvents: ' + primaryEvents.length);
  Logger.log('Number of secondaryEvents: ' + secondaryEvents.length);

  // create filtered list of existing primary calendar events that were previously created from the secondary calendar
  for each (var pEvent in primaryEvents)
  {
    if ((pid = pEvent.getTag(calendarId)) != null) {
      primaryEventsFiltered[pid] = pEvent;
    }
  }

  // process all events in secondary calendar
  for each (var sEvent in secondaryEvents)
  {
    var pEvent = null;
    var sId = sEvent.getId();
    // if the secondary event has already been blocked in the primary calendar, update it
    if ((pEvent = primaryEventsFiltered[sId]) != null)
    {
      delete primaryEventsFiltered[sId];
      // primaryEventsUpdated.push(pEvent.getId());
    } else {
      if (!weekdays_only || is_on_weekday(sEvent)) {
        pEvent = copy_event(sEvent, primaryCal);
        primaryEventsCreated.push(pEvent.getId());
      }
    }

    update_event(pEvent, sEvent);
    // TODO: Handle All-day events
    // if (evi.isAllDayEvent())
    // {
    //   return; // Do nothing if the event is an all-day or multi-day event. This script only syncs hour-based events
    // }
  }

  // if a primary event previously created no longer exists in the secondary calendar, delete it
  for each (var pEvent in primaryEventsFiltered)
  {
    pEvent.deleteEvent();
  }

}