import json
import os
import re
import sys
import time

import requests


API_URL = 'https://allocate.timetable.monash.edu/aplus-2016/rest/student/'
HOMEPAGE_URL = 'https://allocate.timetable.monash.edu/aplus-2016/student/'

USERNAME = 'jccam5'
PASSWORD = 'PASSWORD'

PREFERENCES = {
    'FIT1047_CL_S1_DAY': {
        'Laboratory': 22,
    },
}

class AllocatePlus:
    def __init__(self, session, data):
        self.session = session
        self.data = data

    def update_data(self):
        self.data = self.session.get(self.get_api_url('{student[student_code]}/')).json()

    def get_api_url(self, url, *args, **kwargs):
        return API_URL + url.format(*args, **kwargs, **self.data)

    def send_preference(self, subject_code, activity_group_code, activity_code):
        return self.session.post(self.get_api_url('changeActivity/'), data={
            'token': 'a',
            'student_code': self.data['student']['student_code'],
            'subject_code': subject_code,
            'activity_group_code': activity_group_code,
            'activity_code': activity_code
        }).json()

    def get_preference(self, subject_code, activity_group_code):
        raise NotImplementedError("get_preference")

    @classmethod
    def login(cls, username, password):
        s = requests.Session()
        login = s.post(API_URL + 'login', data={'username': username, 'password': password})
        s.params.update({'ss': login.json()['token']})
        homepage = s.get(HOMEPAGE_URL)
        data = json.loads(re.search(r'^data=([^;]+);$', homepage.text, re.M).group(1))
        return cls(s, data)

if __name__ == '__main__':
    if not USERNAME or not PASSWORD:
        print("Set USERNAME and PASSWORD in the file")
        sys.exit(1)

    exists = os.path.exists('already_set.json')

    if exists:
        with open('already_set.json') as f:
            already_set = json.load(f)
    else:
        already_set = {}

    ap = AllocatePlus.login(USERNAME, PASSWORD)

    for unit in PREFERENCES:
        for activity in PREFERENCES[unit]:
            if exists:
                set_yet = unit in already_set and activity in already_set[unit]
            else:
                set_yet = ap.get_preference(unit, activity) == PREFERENCES[unit][activity]

            if not set_yet:
                if unit not in not_set:
                    not_set[unit] = {}

                not_set[unit][activity] = PREFERENCES[unit][activity]

    i = 0

    while not_set:
        i += 1
        for unit in not_set:
            for activity in not_set[unit]:
                try:
                    print(unit, activity, i)
                    result = ap.send_preference(unit, activity, not_set[unit][activity])

                    if result['success']:
                        if unit not in already_set:
                            already_set[unit] = {}

                        already_set[unit][activity] = not_set[unit][activity]

                        del not_set[unit][activity]

                        if not not_set[unit]:
                            del not_set[unit]

                        with open('already_set.json', 'w') as f:
                            json.dump(already_set, f)
                except Exception as e:
                    print("Found exception", e)
                time.sleep(sleep_time)