#!/usr/bin/env python3
#
# Copyright 2019  Lars Wirzenius
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.


import argparse
import base64
import configparser
import http
import json
import os
import sys
import urllib.request


CONFIG_FILENAME = os.path.expanduser('~/.config/effitool/credentials.conf')
JSON = 'application/json'
URLENC = 'application/x-www-form-urlencoded'


class Config:

    def __init__(self):
        self._cp = configparser.ConfigParser()

    def read(self, filename):
        with open(filename) as f:
            self._cp.read_file(f)

    def dump(self, f):
        self._cp.write(f)

    def servers(self):
        return [k for k in self._cp.keys() if k != 'DEFAULT']

    def get_default_server(self):
        sections = self._cp.sections()
        if len(sections) != 1:
            raise Exception('Config must have exactly one server')
        return sections[0]

    def get(self, name):
        server = self._cp[name]
        return {
            'url': server['url'],
            'client_id': server['client_id'],
            'client_secret': server['client_secret'],
        }


class HTTPAPI:

    def __init__(self, url):
        self._url = url

    def url(self, path):
        return '{}{}'.format(self._url, path)

    def get_json(self, r):
        ok = (http.HTTPStatus.OK, http.HTTPStatus.CREATED)

        status = r.getcode()
        if status not in ok:
            raise Exception('Got HTTP status {}'.format(status))

        info = r.info()
        ct = info.get_content_type()
        if ct != JSON:
            raise Exception('Response is not JSON: {}'.ct)

        body = r.read()
        return json.loads(body)

    def get(self, path):
        url = self.url(path)
        with urllib.request.urlopen(url) as r:
            return self.get_json(r)

    def get_access_token(self, client_id, client_secret, scopes):
        obj = self.post_form(
            '/token', client_id, client_secret, 
            grant_type='client_credentials', scope=' '.join(scopes))
        return obj['access_token']

    def post_form(self, path, user, password, **kwargs):
        url = self.url(path)
        host, port, path = self.parse_url(url)

        data = urllib.parse.urlencode(kwargs).encode('UTF-8')
        headers = {
            'Content-type': URLENC,
            'Authorization': self.get_authorization(user, password),
        }

        req = urllib.request.Request(
            url, data=data, headers=headers, method='POST')
        r = urllib.request.urlopen(req)
        return self.get_json(r)

    def parse_url(self, url):
        parse = urllib.parse.urlparse(url)
        if parse.scheme != 'https':
            raise Exception(
                'URL scheme must be https, not {}'.format(parse.scheme))

        if ':' in parse.netloc:
            host, port = parse.netloc.split(':', 1)
            port = int(port)
        else:
            host = parse.netloc
            port = None

        return host, port, parse.path

    def get_authorization(self, user, password):
        clear = '{}:{}'.format(user, password)
        basic = base64.b64encode(clear.encode('UTF-8'))
        return 'Basic {}'.format(basic.decode('UTF-8'))


def list_servers(args, config):
    for name in config.servers():
        print('server', name)
        server = config.get(name)
        for key in sorted(server):
            print('  ', key, server[key])


def status(args, config):
    for name in config.servers():
        server = config.get(name)
        url = server['url']
        api = HTTPAPI(url)
        obj = api.get('/status')
        print('server', name, obj['resources'])


def register_client(args, config):
    new_client_id = args['client_id']
    new_client_secret = args['client_secret']
    name = config.get_default_server()
    server = config.get(name)
    url = server['url']
    client_id = server['client_id']
    client_secret = server['client_secret']
    api = HTTPAPI(url)
    token = api.get_access_token(client_id, client_secret, ['xxx'])
    print(token)
    print('NEED TO ACTUALLY CREATE CLIENT HERE')
    assert 0


def process_args(config):
    subcommands = [
        ('list-servers', list_servers, []),
        ('status', status, []),
        ('register-client', register_client, [
            ('--client-id', {'required':True}),
            ('--client-secret', {'required':True}),
        ]),
    ]

    p = argparse.ArgumentParser()
    factory = p.add_subparsers()

    for name, func, args in subcommands:
        pp = factory.add_parser(name)
        for name, kwargs in args:
            pp.add_argument(name, **kwargs)
        pp.set_defaults(func=func)

    args = vars(p.parse_args())
    func = args['func']
    func(args, config)


def main():
    config = Config()
    config.read(CONFIG_FILENAME)
    args = process_args(config)


if __name__ == '__main__':
    main()