o2web/graphql-auth

require 'jwt'
require 'graphql-auth'

module GraphQL
  module Auth
    class JwtManager
      ALGORITHM = 'HS256'
      TYPE = 'Bearer'

      class << self
        def issue_with_expiration(payload, custom_expiration = nil)
          if custom_expiration.present? && custom_expiration.is_a?(ActiveSupport::Duration)
            payload[:exp] = custom_expiration
          else
            payload.merge!(expiration)
          end

          issue payload
        end

        def issue(payload)
          token = JWT.encode payload,
                             auth_secret,
                             ALGORITHM
          set_type token
        end

        def token_expiration(token)
          decrypted_token = decode(token)
          decrypted_token.try(:[], 'exp')
        end

        def decode(token)
          token = extract_token token
          decrypted_token = JWT.decode token,
                                       auth_secret,
                                       true,
                                       { algorithm: ALGORITHM }
          decrypted_token.first
        end

        private

        def auth_secret
          GraphQL::Auth.configuration.jwt_secret_key
        end

        def set_type(token)
          "#{TYPE} #{token}"
        end

        def extract_token(token)
          token.gsub "#{TYPE} ", ''
        end

        def expiration
          exp = Time.now.to_i + GraphQL::Auth.configuration.token_lifespan
          { exp: exp }
        end

        alias_method :issue_without_expiration, :issue
      end
    end
  end
end