Google Drive

authenticate.rb

client = Google::APIClient.new(authorization: :oauth_2, application_name: NAME, application_version: VERSION)
client.client_id = CLIENT_ID
client.client_secret = CLIENT_SECRECT
client.authorization.scope = SCOPES

authorizer = Clavem::Authorizer.new do |auth, req, res|
  raise RuntimeError.new if request.query["error"].present? || request.query["code"].blank?
  client.authorization.code = request.query["code"].to_s
  client.authorization.fetch_access_token!
  client.authorization.refresh_token
end

client.authorization.redirect_uri = authorizer.callback_url
authorizer.authorize(client.authorization.authorization_uri)

if authorizer.succeeded? then
  refresh_token = authorizer.token
end

# Now you can store the refresh token somewehere

download.rb

client = Google::APIClient.new(authorization: :oauth_2, application_name: NAME, application_version: VERSION)
client.client_id = CLIENT_ID
client.client_secret = CLIENT_SECRECT
client.authorization.scope = SCOPES
client.authorization.code = REFRESH_TOKEN
client.authorization.fetch_access_token!

api = client.discovered_api('drive', 'v2')
data = client.execute(api_method: api.files.get, parameters: {"fileId" => ID})
raise ArgumentError if result.status == 404

url = result.data.alternate_link

# Now you can download from URL using Faraday, open-uri or whatever.