import json
import inspect
from django.contrib.admindocs.views import simplify_regex
from django.utils.encoding import force_str


class ApiEndpoint(object):

    def __init__(self, pattern, parent_pattern=None):
        self.pattern = pattern
        self.callback = pattern.callback
        # self.name = pattern.name
        self.docstring = self.__get_docstring__()
        self.name_parent = simplify_regex(parent_pattern.regex.pattern).strip('/') if parent_pattern else None
        self.path = self.__get_path__(parent_pattern)
        self.allowed_methods = self.__get_allowed_methods__()
        # self.view_name = pattern.callback.__name__
        self.errors = None
        self.fields = self.__get_serializer_fields__()
        self.fields_json = self.__get_serializer_fields_json__()
        self.permissions = self.__get_permissions_class__()

    def __get_path__(self, parent_pattern):
        if parent_pattern:
            return "/{0}{1}".format(self.name_parent, simplify_regex(self.pattern.regex.pattern))
        return simplify_regex(self.pattern.regex.pattern)

    def __get_allowed_methods__(self):
        return [force_str(m).upper() for m in self.callback.cls.http_method_names if hasattr(self.callback.cls, m)]

    def __get_docstring__(self):
        return inspect.getdoc(self.callback)

    def __get_permissions_class__(self):
        for perm_class in self.pattern.callback.cls.permission_classes:
            return perm_class.__name__

    def __get_serializer_fields__(self):
        fields = []
        serializer = None

        if hasattr(self.callback.cls, 'serializer_class'):
            serializer = self.callback.cls.serializer_class

        elif hasattr(self.callback.cls, 'get_serializer_class'):
            serializer = self.callback.cls.get_serializer_class(self.pattern.callback.cls())

        if hasattr(serializer, 'get_fields'):
            try:
                fields = [{
                    "name": key,
                    "type": str(field.__class__.__name__),
                    "required": field.required
                } for key, field in serializer().get_fields().items()]
            except KeyError as e:
                self.errors = e
                fields = []

            # FIXME:
            # Show more attibutes of `field`?

        return fields

    def __get_serializer_fields_json__(self):
        # FIXME:
        # Return JSON or not?
        return json.dumps(self.fields)