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)});
};

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