import requests
from collections import namedtuple
from datetime import datetime, timedelta

class DaisyHandler:
    def __init__(self, config):
        self.auth = (config['daisy']['user'],
                     config['daisy']['password'])
        self.headers = {'Accept': 'application/json'}
        self.url = config['daisy']['url'].rstrip('/')

    def _get(self, path, params={}):
        requestpath = '{}{}'.format(self.url, path)
        r = requests.get(requestpath,
                         params,
                         headers=self.headers,
                         auth=self.auth)
        if not r.status_code == 200:
            raise Exception('Got bad response from Daisy API: {}'
                            .format(r.status_code))
        return r.json()

    def get_booking(self, start_time, end_time, room):
        fmt = '%Y-%m-%d'
        start_day = start_time.strftime(fmt)
        end_day = end_time.strftime(fmt)
        params = {'start': start_day,
                  'end': end_day,
                  'room': room}
        Fit = namedtuple('Fit', ['booking', 'overlap'])
        best = Fit(None, timedelta())
        
        for booking in self._get('/schedule', params=params):
            b_start = datetime.fromtimestamp(int(booking['start'] / 1000))
            b_end = datetime.fromtimestamp(int(booking['end'] / 1000))
            range_start = max(start_time, b_start)
            range_end = min(end_time, b_end)
            overlap = range_end - range_start
            if overlap > best.overlap:
                best = Fit(booking, overlap)

        return best.booking

    def get_person(self, person_id):
        usernames = [name['username']
                     for name in self._get(
                             '/person/{}/usernames'.format(person_id))
                     if name['realm'] == "SU.SE"]
        if len(usernames) != 1:
            raise Exception("More than one SU.SE username: {}"
                            .format(usernames))
        return usernames[0]

    def get_course(self, course_id):
        course = self._get('/courseSegment/{}'.format(course_id))
        return course['designation']

    def get_room_name(self, room_id):
        location = self._get('/location/{}'.format(room_id))
        return location['designation']