from ipaddress import ip_address
from sanic import Sanic
from sanic.response import text, json
from sanic.views import HTTPMethodView


class GetClientIpMixin:
    def get_client_ip(self, request):
        possible_ip = request.ip

        for header_name in ('x-real-ip', 'x-forwarded-for'):
            candidate_ip = None
            header_value = request.headers.get(header_name)
            if not header_value:
                continue
            for ip in header_value.split(',')[::-1]:
                try:
                    candidate_ip = ip_address(ip.strip())
                except ValueError:
                    continue
                if candidate_ip.is_global:
                    break
            if candidate_ip:
                possible_ip = candidate_ip
                break

        return str(possible_ip)


class MainView(HTTPMethodView, GetClientIpMixin):
    def get(self, request):
        return text(self.get_client_ip(request))


class JsonView(HTTPMethodView, GetClientIpMixin):
    def get(self, request):
        return json({'ip_address': self.get_client_ip(request)})


class Application(object):
    app = Sanic()

    def __init__(self, args):
        self.args = args
        self.app.add_route(MainView.as_view(), '/')
        self.app.add_route(JsonView.as_view(), '/json')

    def run(self):
        self.app.run(host=self.args.interface, port=self.args.port)


if __name__ == '__main__':
    import os
    from argparse import ArgumentParser

    default_host = os.environ.get('APP_HOST', '0.0.0.0')
    default_port = int(os.environ.get('APP_PORT', 8080))
    default_trusted = os.environ.get('TRUSTED_PROXIES') or None

    parser = ArgumentParser('app.py')
    parser.add_argument('--interface', '-i', type=str, help='Interface to listen on', default=default_host)
    parser.add_argument('--port', '-p', type=int, help='Port to listen on', default=default_port)
    parser.add_argument('--proxies', type=str, help='A list of trusted proxies, comma separated. you can use CIDRs.', default=default_trusted)
    args = parser.parse_args()

    zero_if = Application(args)
    zero_if.run()