#!/usr/bin/python

# This script gives client-side access to one Soledad user database.


import sys
import os
import argparse
import re
import tempfile
import getpass
import requests
import json
import srp._pysrp as srp
import binascii
import logging

from leap.common.config import get_path_prefix
from leap.soledad.client import Soledad


# create a logger
logger = logging.getLogger(__name__)
LOG_FORMAT = '%(asctime)s %(message)s'
logging.basicConfig(format=LOG_FORMAT, level=logging.INFO)


safe_unhexlify = lambda x: binascii.unhexlify(x) if (
    len(x) % 2 == 0) else binascii.unhexlify('0' + x)


def fail(reason):
    logger.error('Fail: ' + reason)
    exit(2)


def get_api_info(provider):
    info = requests.get(
        'https://'+provider+'/provider.json', verify=False).json()
    return info['api_uri'], info['api_version']


def login(username, passphrase, provider, api_uri, api_version):
    usr = srp.User(username, passphrase, srp.SHA256, srp.NG_1024)
    auth = None
    try:
        auth = authenticate(api_uri, api_version, usr).json()
    except requests.exceptions.ConnectionError:
        fail('Could not connect to server.')
    if 'errors' in auth:
        fail(str(auth['errors']))
    return api_uri, api_version, auth


def authenticate(api_uri, api_version, usr):
    api_url = "%s/%s" % (api_uri, api_version)
    session = requests.session()
    uname, A = usr.start_authentication()
    params = {'login': uname, 'A': binascii.hexlify(A)}
    init = session.post(
        api_url + '/sessions', data=params, verify=False).json()
    if 'errors' in init:
        fail('test user not found')
    M = usr.process_challenge(
        safe_unhexlify(init['salt']), safe_unhexlify(init['B']))
    return session.put(api_url + '/sessions/' + uname, verify=False,
                       data={'client_auth': binascii.hexlify(M)})


def get_soledad_info(username, provider, passphrase, basedir):
    api_uri, api_version = get_api_info(provider)
    auth = login(username, passphrase, provider, api_uri, api_version)
    # get soledad server url
    service_url = '%s/%s/config/soledad-service.json' % \
                  (api_uri, api_version)
    soledad_hosts = requests.get(service_url, verify=False).json()['hosts']
    hostnames = soledad_hosts.keys()
    # allow for choosing the host
    host = hostnames[0]
    if len(hostnames) > 1:
        i = 1
        print "There are many available hosts:"
        for h in hostnames:
            print "  (%d) %s.%s" % (i, h, provider)
            i += 1
        choice = raw_input("Choose a host to use (default: 1): ")
        if choice != '':
            host = hostnames[int(choice) - 1]
    server_url = 'https://%s:%d/user-%s' % \
              (soledad_hosts[host]['hostname'], soledad_hosts[host]['port'],
               auth[2]['id'])
    # get provider ca certificate
    ca_cert = requests.get('https://%s/ca.crt' % provider, verify=False).text
    cert_file = os.path.join(basedir, 'ca.crt')
    with open(cert_file, 'w') as f:
      f.write(ca_cert)
    return auth[2]['id'], server_url, cert_file, auth[2]['token']


def get_soledad_instance(username, provider, passphrase, basedir):
    # setup soledad info
    uuid, server_url, cert_file, token = \
        get_soledad_info(username, provider, passphrase, basedir)
    logger.info('UUID is %s' % uuid)
    logger.info('Server URL is %s' % server_url)
    secrets_path = os.path.join(
        basedir, '%s.secret' % uuid)
    local_db_path = os.path.join(
        basedir, '%s.db' % uuid)
    # instantiate soledad
    return Soledad(
        uuid,
        unicode(passphrase),
        secrets_path=secrets_path,
        local_db_path=local_db_path,
        server_url=server_url,
        cert_file=cert_file,
        auth_token=token)


# main program

if __name__ == '__main__':

    class ValidateUserHandle(argparse.Action):
        def __call__(self, parser, namespace, values, option_string=None):
            m = re.compile('^([^@]+)@([^@]+\.[^@]+)$')
            res = m.match(values)
            if res == None:
                parser.error('User handle should have the form user@provider.')
            setattr(namespace, 'username', res.groups()[0])
            setattr(namespace, 'provider', res.groups()[1])

    # parse command line
    parser = argparse.ArgumentParser()
    parser.add_argument(
        'user@provider', action=ValidateUserHandle, help='the user handle')
    parser.add_argument(
        '-b', dest='basedir', required=False, default=None, help='the user handle')
    args = parser.parse_args()

    # get the password
    passphrase = getpass.getpass(
        'Password for %s@%s: ' % (args.username, args.provider))

    # get the basedir
    basedir = args.basedir
    if basedir is None:
        basedir = tempfile.mkdtemp()
    logger.info('Using %s as base directory.' % basedir)

    # get the soledad instance
    s = get_soledad_instance(
        args.username, args.provider, passphrase, basedir)