iCalendar -- Internet calendaring, Ruby style

require 'icalendar'

# Create a calendar with an event (standard method)
cal = Icalendar::Calendar.new
cal.event do |e|
  e.dtstart     = Icalendar::Values::Date.new('20050428')
  e.dtend       = Icalendar::Values::Date.new('20050429')
  e.summary     = "Meeting with the man."
  e.description = "Have a long lunch meeting and decide nothing..."
  e.ip_class    = "PRIVATE"
end

cal.publish

event = Icalendar::Event.new
event.dtstart = DateTime.civil(2006, 6, 23, 8, 30)
event.summary = "A great event!"
cal.add_event(event)

event2 = cal.event  # This automatically adds the event to the calendar
event2.dtstart = DateTime.civil(2006, 6, 24, 8, 30)
event2.summary = "Another great event!"

params = {"altrep" => "http://my.language.net", "language" => "SPANISH"}

event = cal.event do |e|
  e.dtstart = Icalendar::Values::Date.new('20050428')
  e.dtend   = Icalendar::Values::Date.new('20050429')
  e.summary = Icalendar::Values::Text.new "This is a summary with params.", params
end
event.summary.ical_params #=> {'altrep' => 'http://my.language.net', 'language' => 'SPANISH'}

# or

event = cal.event do |e|
  e.dtstart = Icalendar::Values::Date.new('20050428')
  e.dtend   = Icalendar::Values::Date.new('20050429')
  e.summary = "This is a summary with params."
  e.summary.ical_params = params
end
event.summary.ical_params #=> {'altrep' => 'http://my.language.net', 'language' => 'SPANISH'}

event = cal.event do |e|
  e.dtstart = Icalendar::Values::DateOrDateTime.new('20140924')
  e.dtend   = Icalendar::Values::DateOrDateTime.new('20140925').call
  e.summary = 'This is an all-day event, because DateOrDateTime will return Dates'
end

event = cal.event do |e|
  e.url = 'https://example.com'
end

cal.event do |e|
  # ...other event properties
  e.alarm do |a|
    a.action          = "EMAIL"
    a.description     = "This is an event reminder" # email body (required)
    a.summary         = "Alarm notification"        # email subject (required)
    a.attendee        = %w(mailto:me@my-domain.com mailto:me-too@my-domain.com) # one or more email recipients (required)
    a.append_attendee "mailto:me-three@my-domain.com"
    a.trigger         = "-PT15M" # 15 minutes before
    a.append_attach   Icalendar::Values::Uri.new("ftp://host.com/novo-procs/felizano.exe", "fmttype" => "application/binary") # email attachments (optional)
  end

  e.alarm do |a|
    a.action  = "DISPLAY" # This line isn't necessary, it's the default
    a.summary = "Alarm notification"
    a.trigger = "-P1DT0H0M0S" # 1 day before
  end

  e.alarm do |a|
    a.action        = "AUDIO"
    a.trigger       = "-PT15M"
    a.append_attach "Basso"
  end
end

event.has_alarm?
# => false

event.alarm
# => #<Icalendar::Alarm ... >

event.has_alarm?
#=> true

cal = Icalendar::Calendar.new
cal.timezone do |t|
  t.tzid = "America/Chicago"

  t.daylight do |d|
    d.tzoffsetfrom = "-0600"
    d.tzoffsetto   = "-0500"
    d.tzname       = "CDT"
    d.dtstart      = "19700308T020000"
    d.rrule        = "FREQ=YEARLY;BYMONTH=3;BYDAY=2SU"
  end

  t.standard do |s|
    s.tzoffsetfrom = "-0500"
    s.tzoffsetto   = "-0600"
    s.tzname       = "CST"
    s.dtstart      = "19701101T020000"
    s.rrule        = "FREQ=YEARLY;BYMONTH=11;BYDAY=1SU"
  end
end

require 'icalendar/tzinfo'

cal = Icalendar::Calendar.new

event_start = DateTime.new 2008, 12, 29, 8, 0, 0
event_end = DateTime.new 2008, 12, 29, 11, 0, 0

tzid = "America/Chicago"
tz = TZInfo::Timezone.get tzid
timezone = tz.ical_timezone event_start
cal.add_timezone timezone

cal.event do |e|
  e.dtstart = Icalendar::Values::DateTime.new event_start, 'tzid' => tzid
  e.dtend   = Icalendar::Values::DateTime.new event_end, 'tzid' => tzid
  e.summary = "Meeting with the man."
  e.description = "Have a long lunch meeting and decide nothing..."
  e.organizer = "mailto:jsmith@example.com"
  e.organizer = Icalendar::Values::CalAddress.new("mailto:jsmith@example.com", cn: 'John Smith')
end

# Open a file or pass a string to the parser
cal_file = File.open("single_event.ics")

# Parser returns an array of calendars because a single file
# can have multiple calendars.
cals = Icalendar::Calendar.parse(cal_file)
cal = cals.first

# Now you can access the cal object in just the same way I created it
event = cal.events.first

puts "start date-time: #{event.dtstart}"
puts "start date-time timezone: #{event.dtstart.ical_params['tzid']}"
puts "summary: #{event.summary}"

# Sometimes you want to strongly verify only rfc-approved properties are
# used
strict_parser = Icalendar::Parser.new(cal_file, true)
cal = strict_parser.parse

# Open a file or pass a string to the parser
event_file = File.open("event.ics")

# Parser returns an array of events because a single file
# can have multiple events.
events = Icalendar::Event.parse(event_file)
event = events.first

puts "start date-time: #{event.dtstart}"
puts "start date-time timezone: #{event.dtstart.ical_params['tzid']}"
puts "summary: #{event.summary}"

cal = Calendar.new
10.times { cal.event } # Create 10 events with only default data.
some_event = cal.events[5] # Grab it from the array of events

# Use the uid as the key in your app
key = some_event.uid

# so later you can find it.
same_event = cal.find_event(key)