FHG-IMW/epo-ops

module EpoOps
  class Error < StandardError
    # @return [Integer]
    attr_reader :code, :rate_limit

    # Raised when EPO returns a 4xx HTTP status code
    ClientError = Class.new(self)
    # Raised when EPO returns the HTTP status code 400
    BadRequest = Class.new(ClientError)
    # Raised when EPO returns the HTTP status code 401
    Unauthorized = Class.new(ClientError)
    # Raised when EPO returns the HTTP status code 403
    Forbidden = Class.new(ClientError)
    # Raised when EPO returns the HTTP status code 404
    NotFound = Class.new(ClientError)
    # Raised when EPO returns the HTTP status code 406
    NotAcceptable = Class.new(ClientError)
    # Raised when EPO returns the HTTP status code 422
    UnprocessableEntity = Class.new(ClientError)
    # Raised when EPO returns the HTTP status code 429
    TooManyRequests = Class.new(ClientError)
    # Raised when EPO returns a 5xx HTTP status code
    ServerError = Class.new(self)
    # Raised when EPO returns the HTTP status code 500
    InternalServerError = Class.new(ServerError)
    # Raised when EPO returns the HTTP status code 502
    BadGateway = Class.new(ServerError)
    # Raised when EPO returns the HTTP status code 503
    ServiceUnavailable = Class.new(ServerError)
    # Raised when EPO returns the HTTP status code 504
    GatewayTimeout = Class.new(ServerError)
    # AccessToken has expired
    AccessTokenExpired = Class.new(ClientError)

    ERRORS = {
      400 => EpoOps::Error::BadRequest,
      401 => EpoOps::Error::Unauthorized,
      403 => EpoOps::Error::Forbidden,
      404 => EpoOps::Error::NotFound,
      406 => EpoOps::Error::NotAcceptable,
      422 => EpoOps::Error::UnprocessableEntity,
      429 => EpoOps::Error::TooManyRequests,
      500 => EpoOps::Error::InternalServerError,
      502 => EpoOps::Error::BadGateway,
      503 => EpoOps::Error::ServiceUnavailable,
      504 => EpoOps::Error::GatewayTimeout
    }.freeze
    FORBIDDEN_MESSAGES = {
      'This request has been rejected due to the violation of Fair Use policy' => EpoOps::Error::TooManyRequests
    }.freeze

    class << self
      # Parses an error from the given response
      # @return [Error]
      def from_response(response)
        code = response.status
        message = parse_error(response.parsed)

        if code == 403 && FORBIDDEN_MESSAGES[message]
          FORBIDDEN_MESSAGES[message].new(message, response.headers, code)
        elsif code == 400 && response.headers['www-authenticate'] && response.headers['www-authenticate'].include?('Access Token expired')
          Error::AccessTokenExpired.new('Access Token expired', response.headers, code)
        else
          ERRORS[code].new(message, response.headers, code)
        end
      end

      private

      def parse_error(body)
        if body.nil? || body.empty?
          nil
        elsif body['error'] && body['error']['message']
          body['error']['message']
        end
      end
    end

    def initialize(message = '', rate_limit = {}, code = nil)
      super(message)
      @code = code
      @rate_limit = RateLimit.new(rate_limit)
    end
  end
end