import os
from jinja2 import Environment, FileSystemLoader
import inspect
from parse import parse
from webob import Request, Response
from requests import Session as RequestsSession
from wsgiadapter import WSGIAdapter as RequestsWSGIAdapter
from whitenoise import WhiteNoise
from .middleware import Middleware


class API:
    def __init__(self, templates_dir="templates", static_dir="static"):
        self.routes = {}

        self.templates_env = Environment(loader=FileSystemLoader(os.path.abspath(templates_dir)))
        self.exception_handler = None
        self.whitenoise = WhiteNoise(self.wsgi_app, root=static_dir)
        self.middleware = Middleware(self)

    def add_exception_handler(self, exception_handler):
        self.exception_handler = exception_handler

    def route(self, path):
        def wrapper(handler):
            self.add_route(path, handler)
            return handler

        return wrapper

    def add_middleware(self, middleware_cls):
        self.middleware.add(middleware_cls)

    def add_route(self, path, handler):
        assert path not in self.routes, "Such route already exists."

        self.routes[path] = handler

    def template(self, template_name, context=None):
        if context is None:
            context = {}

        return self.templates_env.get_template(template_name).render(**context)

    def wsgi_app(self, environ, start_response):
        request = Request(environ)

        response = self.handle_request(request)

        return response(environ, start_response)

    def __call__(self, environ, start_response):
        path_info = environ["PATH_INFO"]

        if path_info.startswith("/static"):
            environ["PATH_INFO"] = path_info[len("/static"):]
            return self.whitenoise(environ, start_response)

        return self.middleware(environ, start_response)

    def find_handler(self, request_path):
        for path, handler in self.routes.items():
            parse_result = parse(path, request_path)
            if parse_result is not None:
                return handler, parse_result.named

        return None, None

    def handle_request(self, request):
        response = Response()

        handler, kwargs = self.find_handler(request_path=request.path)

        try:
            if handler is not None:
                if inspect.isclass(handler):
                    handler = getattr(handler(), request.method.lower(), None)
                    if handler is None:
                        raise AttributeError("Method now allowed", request.method)

                handler(request, response, **kwargs)
            else:
                self.default_response(response)
        except Exception as e:
            if self.exception_handler is None:
                raise e
            else:
                self.exception_handler(request, response, e)

        return response

    def default_response(self, response):
        response.status_code = 404
        response.text = "Not found."

    def test_session(self, base_url="http://testserver"):
        session = RequestsSession()
        session.mount(prefix=base_url, adapter=RequestsWSGIAdapter(self))
        return session

