berziiii / calendar-script

calendar-script

Purpose

The purpose of this calendar script is to take an exisiting Google calendar or iCalendar and create a new calendar from it.

Problem

There was an exisiting Google calendar that had over 200 events associated with it. In order to duplicate the old .ics calendar, you had to copy each individual event to a new date. A second problem was the trivial, and time consuming, process of manually moving each copied calendar event to it's new date.

Solution

Created a Ruby script which takes an exisiting .ics file and copies it to a new .ics calendar file. You can either copy the entire calendar to have it's events appear on the same day or add n number of days to the calendar. This will move the new events dates up by n days while keeping all information (time, summary, description, etc.) the same as the old .ics file.

Usage

Once you have the script.rb file cloned, choose which input calendar file you'd like to copy and create a file for the new .ics calendar file.

To run the script, execute this command in terminal:

ruby script.rb <input_file> <output_file> <interval_weeks>

This script takes the old .ics calendar file, new .ics calendar file and the number of weeks you'd like the event dates to be adjusted.

Below you'll find the parse_event method which loops through the file and parses each event:

def parse_event(line, delimiter)
  d = line.split(/[\:\=](\d{8})/)
  d[1] = Date.parse(d[1])
  return line if d[1].year < 2016
  d[1] = (d[1] + INTERVAL_DAYS).to_s.gsub('-', '')
  if d[2]
    d = d[0] + "#{delimiter}" + d[1] + d[2]
  else
    d = d[0] + "#{delimiter}" + d[1]
  end
end

The INTERVAL_DAYS variable, takes the <interval_weeks> argument value and multiplies it by 7 (days in a week) to get the total days to increase the new calendar events by.

The parse_event method iterates over each line of the input .ics file and checks for these cases:

    if line.include?("RRULE:") && line.include?("UNTIL=")

      line = parse_event(line, "=")

    elsif line.include?("DTSTART:")

      line = parse_event(line, ":")

    elsif line.include?("DTEND:")

      line = parse_event(line, ":")

    elsif line.include?("DTSTART;VALUE=")

      line = parse_event(line, ":")

    elsif line.include?("DTEND;VALUE=")

      line = parse_event(line, ":")

    elsif line.include?("DTSTART;TZID=")

      line = parse_event(line, ":")

    elsif line.include?("DTEND;TZID=")

      line = parse_event(line, ":")

    end

To check to confirm that the changes have taken place between your old and new calendar files, you can run this command in terminal:

diff <input_file> <output_file> |less

You will see the differences between the two calendar files. It should have the same number of lines, the only thing that should have changed is the date of the events. The format of the date is yyyymmdd. You should see the difference between the dates be the INTERVAL_DAYS value. Another way to confirm that the file size is the same run in terminal:

ls -l

Locate your old and new .ics files and you should see the size of the files be identical.