session.rb

# frozen_string_literal

require 'google/apis/sheets_v4'
require 'googleauth'
require 'googleauth/stores/file_token_store'
require 'fileutils'

require 'google_sheets/sheet'
require 'google_sheets/spreadsheet'

module GoogleSheets
  class Session
    OOB_URI = 'urn:ietf:wg:oauth:2.0:oob'
    CREDENTIALS_FILENAME = 'token.yaml'
    SCOPE = Google::Apis::SheetsV4::AUTH_SPREADSHEETS

    # Accepts a [Google::Apis::SheetsV4::SheetsService](https://www.rubydoc.info/github/google/google-api-ruby-client/Google/Apis/SheetsV4/SheetsService)
    # through which we can read/write gsheets
    def initialize service
      @service = service
    end

    # instantiates and returns a Spreadsheet object from a key
    # @return [GoogleSheets::Spreadsheet]
    def spreadsheet_from_key key
      Spreadsheet.new @service, key
    end

    # This code is heavily borrowed from https://developers.google.com/sheets/api/quickstart/ruby#step_3_set_up_the_sample
    #
    ##
    # Ensure valid credentials, either by restoring from the saved credentials
    # files or intitiating an OAuth2 authorization. If authorization is required,
    # the user's default browser will be launched to approve the request.
    #
    # @return [Google::Auth::UserRefreshCredentials](https://www.rubydoc.info/gems/googleauth/0.5.0/Google/Auth/UserRefreshCredentials) OAuth2 credentials
    def self.authorize client_id, client_secret, token_path
      credentials_hash = {
        "installed" =>
          {
            "client_id" => client_id,
            "client_secret" => client_secret
          }
      }

      client_id = Google::Auth::ClientId.from_hash(credentials_hash)

      # client_id = Google::Auth::ClientId.from_file(CLIENT_SECRETS_PATH)
      token_store = Google::Auth::Stores::FileTokenStore.new(file: token_path + '/' + CREDENTIALS_FILENAME)
      authorizer = Google::Auth::UserAuthorizer.new(client_id, SCOPE, token_store)
      user_id = 'default'
      credentials = authorizer.get_credentials(user_id)

      if credentials.nil?
        url = authorizer.get_authorization_url(base_url: OOB_URI)
        puts "Open the following URL in the browser and enter the resulting code after authorization:\n #{url} \n"

        code = STDIN.gets

        credentials = authorizer.get_and_store_credentials_from_code(
          user_id: user_id, code: code, base_url: OOB_URI
        )
      end

      credentials
    end

    private_class_method :authorize

    ##
    # Everything starts from this method - authorizes the user and creates a Session object, through which we can read spreadsheets.
    #
    # @return [GoogleSheets::Session]
    def self.start_session client_id:, client_secret:, token_path: '.'
      # Initialize the API
      service = Google::Apis::SheetsV4::SheetsService.new
      # service.client_options.application_name = APPLICATION_NAME
      service.authorization = authorize(client_id, client_secret, token_path)

      Session.new(service)
    end

  end
end