from enum import Enum

from flask import url_for
from werkzeug.exceptions import HTTPException


class ApiErrorType(Enum):
  invalid_request = 'invalid_request'


class ApiException(HTTPException):
  """
  Represents an error in the application/problem+json format.

  See: https://tools.ietf.org/html/rfc7807

   -  "type" (string) - A URI reference that identifies the
      problem type.

   -  "title" (string) - A short, human-readable summary of the problem
      type.  It SHOULD NOT change from occurrence to occurrence of the
      problem, except for purposes of localization

   -  "status" (number) - The HTTP status code

   -  "detail" (string) - A human-readable explanation specific to this
      occurrence of the problem.

   -  "instance" (string) - A URI reference that identifies the specific
      occurrence of the problem.  It may or may not yield further
      information if dereferenced.
  """

  def __init__(self, error_type, status_code, error_description, payload=None):
    Exception.__init__(self)
    self.error_description = error_description
    self.code = status_code
    self.payload = payload
    self.error_type = error_type
    self.data = self.to_dict()

    super(ApiException, self).__init__(error_description, None)

  def to_dict(self):
    rv = dict(self.payload or ())

    if self.error_description is not None:
      rv['detail'] = self.error_description
      rv['error_message'] = self.error_description  # TODO: deprecate

    rv['error_type'] = self.error_type.value  # TODO: deprecate
    rv['title'] = self.error_type.value
    rv['type'] = url_for('api.error', error_type=self.error_type.value, _external=True)
    rv['status'] = self.code

    return rv


class InvalidRequest(ApiException):
  def __init__(self, error_description, payload=None):
    ApiException.__init__(self, ApiErrorType.invalid_request, 400, error_description, payload)


class InvalidResponse(ApiException):
  def __init__(self, error_description, payload=None):
    ApiException.__init__(self, ApiErrorType.invalid_response, 400, error_description, payload)