from __future__ import absolute_import
from functools import wraps, partial
from flask import request, url_for, current_app
from flask import abort as original_flask_abort
from flask import make_response as original_flask_make_response
from flask.views import MethodView
from flask.signals import got_request_exception
from werkzeug.datastructures import Headers
from werkzeug.exceptions import HTTPException, MethodNotAllowed, NotFound, NotAcceptable, InternalServerError
from werkzeug.wrappers import Response as ResponseBase
from flask_restful.utils import http_status_message, unpack, OrderedDict
from flask_restful.representations.json import output_json
import sys
from types import MethodType
import operator
try:
    from collections.abc import Mapping
except ImportError:
    from collections import Mapping


__all__ = ('Api', 'Resource', 'marshal', 'marshal_with', 'marshal_with_field', 'abort')


def abort(http_status_code, **kwargs):
    """Raise a HTTPException for the given http_status_code. Attach any keyword
    arguments to the exception for later processing.
    """
    #noinspection PyUnresolvedReferences
    try:
        original_flask_abort(http_status_code)
    except HTTPException as e:
        if len(kwargs):
            e.data = kwargs
        raise

DEFAULT_REPRESENTATIONS = [('application/json', output_json)]


class Api(object):
    """
    The main entry point for the application.
    You need to initialize it with a Flask Application: ::

    >>> app = Flask(__name__)
    >>> api = restful.Api(app)

    Alternatively, you can use :meth:`init_app` to set the Flask application
    after it has been constructed.

    :param app: the Flask application object
    :type app: flask.Flask or flask.Blueprint
    :param prefix: Prefix all routes with a value, eg v1 or 2010-04-01
    :type prefix: str
    :param default_mediatype: The default media type to return
    :type default_mediatype: str
    :param decorators: Decorators to attach to every resource
    :type decorators: list
    :param catch_all_404s: Use :meth:`handle_error`
        to handle 404 errors throughout your app
    :param serve_challenge_on_401: Whether to serve a challenge response to
        clients on receiving 401. This usually leads to a username/password
        popup in web browsers.
    :param url_part_order: A string that controls the order that the pieces
        of the url are concatenated when the full url is constructed.  'b'
        is the blueprint (or blueprint registration) prefix, 'a' is the api
        prefix, and 'e' is the path component the endpoint is added with
    :type catch_all_404s: bool
    :param errors: A dictionary to define a custom response for each
        exception or error raised during a request
    :type errors: dict

    """

    def __init__(self, app=None, prefix='',
                 default_mediatype='application/json', decorators=None,
                 catch_all_404s=False, serve_challenge_on_401=False,
                 url_part_order='bae', errors=None):
        self.representations = OrderedDict(DEFAULT_REPRESENTATIONS)
        self.urls = {}
        self.prefix = prefix
        self.default_mediatype = default_mediatype
        self.decorators = decorators if decorators else []
        self.catch_all_404s = catch_all_404s
        self.serve_challenge_on_401 = serve_challenge_on_401
        self.url_part_order = url_part_order
        self.errors = errors or {}
        self.blueprint_setup = None
        self.endpoints = set()
        self.resources = []
        self.app = None
        self.blueprint = None

        if app is not None:
            self.app = app
            self.init_app(app)

    def init_app(self, app):
        """Initialize this class with the given :class:`flask.Flask`
        application or :class:`flask.Blueprint` object.

        :param app: the Flask application or blueprint object
        :type app: flask.Flask
        :type app: flask.Blueprint

        Examples::

            api = Api()
            api.add_resource(...)
            api.init_app(app)

        """
        # If app is a blueprint, defer the initialization
        try:
            app.record(self._deferred_blueprint_init)
        # Flask.Blueprint has a 'record' attribute, Flask.Api does not
        except AttributeError:
            self._init_app(app)
        else:
            self.blueprint = app

    def _complete_url(self, url_part, registration_prefix):
        """This method is used to defer the construction of the final url in
        the case that the Api is created with a Blueprint.

        :param url_part: The part of the url the endpoint is registered with
        :param registration_prefix: The part of the url contributed by the
            blueprint.  Generally speaking, BlueprintSetupState.url_prefix
        """
        parts = {
            'b': registration_prefix,
            'a': self.prefix,
            'e': url_part
        }
        return ''.join(parts[key] for key in self.url_part_order if parts[key])

    @staticmethod
    def _blueprint_setup_add_url_rule_patch(blueprint_setup, rule, endpoint=None, view_func=None, **options):
        """Method used to patch BlueprintSetupState.add_url_rule for setup
        state instance corresponding to this Api instance.  Exists primarily
        to enable _complete_url's function.

        :param blueprint_setup: The BlueprintSetupState instance (self)
        :param rule: A string or callable that takes a string and returns a
            string(_complete_url) that is the url rule for the endpoint
            being registered
        :param endpoint: See BlueprintSetupState.add_url_rule
        :param view_func: See BlueprintSetupState.add_url_rule
        :param **options: See BlueprintSetupState.add_url_rule
        """

        if callable(rule):
            rule = rule(blueprint_setup.url_prefix)
        elif blueprint_setup.url_prefix:
            rule = blueprint_setup.url_prefix + rule
        options.setdefault('subdomain', blueprint_setup.subdomain)
        if endpoint is None:
            endpoint = view_func.__name__
        defaults = blueprint_setup.url_defaults
        if 'defaults' in options:
            defaults = dict(defaults, **options.pop('defaults'))
        blueprint_setup.app.add_url_rule(rule, '%s.%s' % (blueprint_setup.blueprint.name, endpoint),
                                         view_func, defaults=defaults, **options)

    def _deferred_blueprint_init(self, setup_state):
        """Synchronize prefix between blueprint/api and registration options, then
        perform initialization with setup_state.app :class:`flask.Flask` object.
        When a :class:`flask_restful.Api` object is initialized with a blueprint,
        this method is recorded on the blueprint to be run when the blueprint is later
        registered to a :class:`flask.Flask` object.  This method also monkeypatches
        BlueprintSetupState.add_url_rule with _blueprint_setup_add_url_rule_patch.

        :param setup_state: The setup state object passed to deferred functions
            during blueprint registration
        :type setup_state: flask.blueprints.BlueprintSetupState

        """

        self.blueprint_setup = setup_state
        if setup_state.add_url_rule.__name__ != '_blueprint_setup_add_url_rule_patch':
            setup_state._original_add_url_rule = setup_state.add_url_rule
            setup_state.add_url_rule = MethodType(Api._blueprint_setup_add_url_rule_patch,
                                                  setup_state)
        if not setup_state.first_registration:
            raise ValueError('flask-restful blueprints can only be registered once.')
        self._init_app(setup_state.app)

    def _init_app(self, app):
        """Perform initialization actions with the given :class:`flask.Flask`
        object.

        :param app: The flask application object
        :type app: flask.Flask
        """
        app.handle_exception = partial(self.error_router, app.handle_exception)
        app.handle_user_exception = partial(self.error_router, app.handle_user_exception)

        if len(self.resources) > 0:
            for resource, urls, kwargs in self.resources:
                self._register_view(app, resource, *urls, **kwargs)

    def owns_endpoint(self, endpoint):
        """Tests if an endpoint name (not path) belongs to this Api.  Takes
        in to account the Blueprint name part of the endpoint name.

        :param endpoint: The name of the endpoint being checked
        :return: bool
        """

        if self.blueprint:
            if endpoint.startswith(self.blueprint.name):
                endpoint = endpoint.split(self.blueprint.name + '.', 1)[-1]
            else:
                return False
        return endpoint in self.endpoints

    def _should_use_fr_error_handler(self):
        """ Determine if error should be handled with FR or default Flask

        The goal is to return Flask error handlers for non-FR-related routes,
        and FR errors (with the correct media type) for FR endpoints. This
        method currently handles 404 and 405 errors.

        :return: bool
        """
        adapter = current_app.create_url_adapter(request)

        try:
            adapter.match()
        except MethodNotAllowed as e:
            # Check if the other HTTP methods at this url would hit the Api
            valid_route_method = e.valid_methods[0]
            rule, _ = adapter.match(method=valid_route_method, return_rule=True)
            return self.owns_endpoint(rule.endpoint)
        except NotFound:
            return self.catch_all_404s
        except:
            # Werkzeug throws other kinds of exceptions, such as Redirect
            pass

    def _has_fr_route(self):
        """Encapsulating the rules for whether the request was to a Flask endpoint"""
        # 404's, 405's, which might not have a url_rule
        if self._should_use_fr_error_handler():
            return True
        # for all other errors, just check if FR dispatched the route
        if not request.url_rule:
            return False
        return self.owns_endpoint(request.url_rule.endpoint)

    def error_router(self, original_handler, e):
        """This function decides whether the error occured in a flask-restful
        endpoint or not. If it happened in a flask-restful endpoint, our
        handler will be dispatched. If it happened in an unrelated view, the
        app's original error handler will be dispatched.
        In the event that the error occurred in a flask-restful endpoint but
        the local handler can't resolve the situation, the router will fall
        back onto the original_handler as last resort.

        :param original_handler: the original Flask error handler for the app
        :type original_handler: function
        :param e: the exception raised while handling the request
        :type e: Exception

        """
        if self._has_fr_route():
            try:
                return self.handle_error(e)
            except Exception:
                pass  # Fall through to original handler