gem 'timetree'

# set token by TimeTree.configure methods.
TimeTree.configure do |config|
  config.calendar_app_application_id = '<YOUR_APPLICATION_ID>'
  config.calendar_app_private_key = File.read('<YOUR_PATH_TO_PEM>')
end
client = TimeTree::CalendarApp::Client.new('<INSTALLATION_ID>')

# set token by TimeTree::CalendarApp::Client initializer.
client = TimeTree::CalendarApp::Client.new('<INSTALLATION_ID>', '<YOUR_APPLICATION_ID>', '<YOUR_PRIVATE_KEY_CONTENT>')

# get connected calendar's information.
cal = client.calendar
# => #<TimeTree::Calendar id:xxx_cal001>

# get upcoming events on the calendar.
evs = cal.upcoming_events
# => [#<TimeTree::Event id:xxx_ev001>, #<TimeTree::Event id:xxx_ev002>, ...]
ev = evs.first.title
# => "Event Title"

# set token by TimeTree.configure methods.
TimeTree.configure do |config|
  config.oauth_app_token = '<YOUR_ACCESS_TOKEN>'
end
client = TimeTree::OAuthApp::Client.new

# set token by TimeTree::OAuthApp::Client initializer.
client = TimeTree::OAuthApp::Client.new('<YOUR_ACCESS_TOKEN>')

# get a current user's information.
user = client.current_user
# => #<TimeTree::User id:xxx_u001>
user.name
# => "USER Name"

# get current user's calendars.
cals = client.calendars
# => [#<TimeTree::Calendar id:xxx_cal001>, #<TimeTree::Calendar id:xxx_cal002>, ...]
cal = cals.first
cal.name
# => "Calendar Name"

# get upcoming events on the calendar.
evs = cal.upcoming_events
# => [#<TimeTree::Event id:xxx_ev001>, #<TimeTree::Event id:xxx_ev002>, ...]
ev = evs.first
ev.title
# => "Event Title"

# updates an event.
ev.title += ' Updated'
ev.start_at = Time.parse('2020-06-20 09:00 +09:00')
ev.end_at = Time.parse('2020-06-20 10:00 +09:00')
ev.update
# => #<TimeTree::Event id:xxx_ev001>

# creates an event.
copy_ev = ev.dup
new_ev = copy_ev.create
# => #<TimeTree::Event id:xxx_new_ev001>

# deletes an event.
ev.delete
# => true

# creates a comment to an event.
ev.create_comment 'Hi there!'
# => #<TimeTree::Activity id:xxx_act001>

# handles APIs error.
begin
  ev.delete
  ev.delete # 404 Error occured.
rescue TimeTree::ApiError => e
  e
  => #<TimeTree::ApiError title:Not Found, status:404>
  e.response
  => #<Faraday::Response>
end

# if the log level set :debug, you can get the request/response information.
TimeTree.configuration.logger.level = :debug
=> #<TimeTree::Event id:event_id_001_not_found>
>> client.event 'cal_id_001', 'event_id_001_not_found'
I, [2020-06-24T10:05:07.294807]  INFO -- : GET https://timetreeapis.com/calendars/cal_id_001/events/event_id_001_not_found?include=creator%2Clabel%2Cattendees
D, [2020-06-24T10:05:07.562038] DEBUG -- : Response status:404, body:{:type=>"https://developers.timetreeapp.com/en/docs/api#client-failure", :title=>"Not Found", :status=>404, :errors=>"Event not found"}