Updates the calendar with a day long event when someone applies leave in leave planner

leave-updater.gs

const leaveTag = "label-to-which-the-emails-are-marked";
const calendarId = "new-calendar-id";
const nameRegEx = /Leave plan for (?<name>.*) is as below/;
const leaveTypeRegEx = /Leave Type:\s*(?<type>(.)*)?/;
const startDateRegEx = /Start Date:\s*(?<leave>(?:.*)202.)(?:,\s)*(?:(Half-Day:\s*(.*)))?/;
const endDateRegEx = /End Date:\s*(?<leave>(?:.*)202.)(?:,\s)*(?:(Half-Day:\s*(.*)))?/;

function applyRegEx(regEx, key, messageBody){
  const matches = regEx.exec(messageBody);
  return matches?.groups && matches.groups[key] ? matches.groups[key] : undefined;
}

function parseLeaveDates(gmailMessage){
  const messageBody = gmailMessage.getBody();
  const name = applyRegEx(nameRegEx, 'name', messageBody);
  const leaveType = applyRegEx(leaveTypeRegEx, 'type', messageBody);
  const startDateStr = applyRegEx(startDateRegEx, 'leave', messageBody);
  const endDateStr = applyRegEx(endDateRegEx, 'leave', messageBody);
  return {
    name,
    leaveType,
    startDateStr,
    endDateStr
  }
}

function getLeaveData(){
  const leaveLabel = GmailApp.getUserLabelByName(leaveTag);
  const unReadThreads = leaveLabel.getThreads().filter(thread => thread.isUnread());
  return unReadThreads.reduce((acc, unReadThread) => {
    unReadThread.markRead();
    const gmailMessages = unReadThread.getMessages();
    const leaveData = gmailMessages.map(gmailMessage => parseLeaveDates(gmailMessage));
    return acc.concat(leaveData);
  }, []);
}

function createACalendarEvent({name, leaveType, startDateStr, endDateStr}){
  var calendar = CalendarApp.getCalendarById(calendarId);
  const title = `${name} - ${leaveType}`
  const startDate = new Date(startDateStr);
  const endDate = new Date(endDateStr)
  endDate.setDate(endDate.getDate() + 1)
  calendar.createAllDayEvent(title,startDate,endDate)
}

// This is the main method that's triggered periodically
function leaveUpdater() {
  const leaveData = getLeaveData();
  Logger.log(leaveData);
  leaveData.map(leave => {createACalendarEvent(leave)});
};

Sample metadata with oauth scopes:

{
  "timeZone": "Asia/Kolkata",
  "dependencies": {
  },
  "exceptionLogging": "STACKDRIVER",
  "oauthScopes": ["https://www.googleapis.com/auth/userinfo.email", "https://www.googleapis.com/auth/gmail.labels", "https://www.googleapis.com/auth/gmail.modify", "https://mail.google.com/", "https://www.googleapis.com/auth/calendar", "https://www.googleapis.com/auth/calendar.readonly", "https://www.google.com/calendar/feeds"],
  "runtimeVersion": "V8",
  "gmail": {
    "name": "Leave Planner",
    "logoUrl": "https://www.gstatic.com/images/branding/googleg/1x/googleg_standard_color_64dp.png",
    "contextualTriggers": [{
      "unconditional": {
      },
      "onTriggerFunction": "leaveUpdater"
    }],
    "primaryColor": "#146b2e",
    "openLinkUrlPrefixes": ["https://developers.google.com/gmail"],
    "version": "TRUSTED_TESTER_V2"
  }
}

fixed scheduling leaves for multiple days:

function createACalendarEvent({name, leaveType, startDateStr, endDateStr}){
  var calendar = CalendarApp.getCalendarById(calendarId);
  const title = `${name} - ${leaveType}`
  const startDate = new Date(startDateStr);
  const endDate = new Date(endDateStr)
  endDate.setDate(endDate.getDate() + 1)
  calendar.createAllDayEvent(title,startDate,endDate)
}

endDate is non-inclusive so added +1 to it.

Multiple leaves notifications sent as replies in a single email thread are not getting processed as we are considering only the first message in the thread. Sometimes the leave planner app sends the leaves notifications as replies in the same thread (happens when we submit multiple leave plans within a short period of time I guess).

Fix:

function parseLeaveDates(gmailMessage){
  const messageBody = gmailMessage.getBody();
  const name = applyRegEx(nameRegEx, 'name', messageBody);
  const leaveType = applyRegEx(leaveTypeRegEx, 'type', messageBody);
  const startDateStr = applyRegEx(startDateRegEx, 'leave', messageBody);
  const endDateStr = applyRegEx(endDateRegEx, 'leave', messageBody);
  return {
    name,
    leaveType,
    startDateStr,
    endDateStr
  }
}

function getLeaveData(){
  const leaveLabel = GmailApp.getUserLabelByName(leaveTag);
  const unReadThreads = leaveLabel.getThreads().filter(thread => thread.isUnread());
  return unReadThreads.reduce((acc, unReadThread) => {
    unReadThread.markRead();
    const gmailMessages = unReadThread.getMessages();
    const leaveData = gmailMessages.map(gmailMessage => parseLeaveDates(gmailMessage));
    return acc.concat(leaveData);
  }, []);
}

@arunvelsriram thanks ✌🏼, updated the gist with your snippets 🎉