google_calendar_api.rb

require 'google/apis/calendar_v3'

class GoogleCalendarController < ApplicationController

  def redirect
    client = Signet::OAuth2::Client.new(client_options)

    redirect_to client.authorization_uri.to_s
  end

  def callback
    client = Signet::OAuth2::Client.new(client_options)
    client.code = params[:code]

    response = client.fetch_access_token!

    session[:authorization] = response

    redirect_to calendars_url
  end

  def index
    client = Signet::OAuth2::Client.new(client_options)
    client.update!(session[:authorization])

    service = Google::Apis::CalendarV3::CalendarService.new
    service.authorization = client

    @calendar_list = service.list_calendar_lists
  end

  def events
    client = Signet::OAuth2::Client.new(client_options)
    client.update!(session[:authorization])

    service = Google::Apis::CalendarV3::CalendarService.new
    service.authorization = client


    existing_event = service.get_event(params[:calendar_id], "f2cep271crog3if11tg58adnns_20180829T160000Z")
    existing_event.summary = "Google Calendar IO 2018"
    service.update_event(params[:calendar_id], "f2cep271crog3if11tg58adnns_20180829T160000Z", existing_event)

    @event_list = service.list_events(
      params[:calendar_id],
      max_results: 120,
      single_events: true,
      order_by: 'startTime',
      time_min: 10.days.from_now.iso8601,
    )
  end


  def update_event
    service.update_event("f2cep271crog3if11tg58adnns_20180829T160000Z", event)
  end

  def create_event
    service.insert_event(params[:calendar_id], event)
  end

  def event
    Google::Apis::CalendarV3::Event.new({
      summary: 'Google I/O 2018',
      location: '800 Howard St., San Francisco, CA 94103',
      description: 'A chance to hear more about Google\'s developer products.',
      start: {
        date_time: '2018-08-10T09:00:00-07:00',
        time_zone: 'America/Los_Angeles',
      },
      end: {
        date_time: '2018-08-10T17:00:00-07:00',
        time_zone: 'America/Los_Angeles',
      },
      recurrence: [
        'RRULE:FREQ=DAILY;COUNT=2'
      ],
      attendees: [
        { email: 'lpage@example.com' },
        { email: 'sbrin@example.com' },
      ],
      reminders: {
        use_default: true,
      },
    })
  end

  private

  def client_options
    {
      client_id: ENV.fetch("LC_GOOGLEOAUTH_CLIENT_ID"),
      client_secret: ENV.fetch("LC_GOOGLEOAUTH_CLIENT_SECRET"),
      authorization_uri: 'https://accounts.google.com/o/oauth2/auth',
      token_credential_uri: 'https://accounts.google.com/o/oauth2/token',
      scope: Google::Apis::CalendarV3::AUTH_CALENDAR,
      redirect_uri: calendar_callback_url,
    }
  end
end