from datetime import datetime, timedelta
from hashlib import sha1
import hmac
import httpx
import json
import os

dev_id = os.environ['PTV_USER_ID']
api_key = os.environ['PTV_API_KEY']

def sign(request):
    request += '&' if '?' in request else '?'
    request += 'devid='
    request += dev_id
    hashed = hmac.new(api_key.encode(), request.encode(), sha1)
    return f'https://timetableapi.ptv.vic.gov.au{request}&signature={hashed.hexdigest().upper()}'

def fetch(path, cache, ttl=timedelta(minutes=5)):
    def do():
        res = httpx.get(sign(path))
        res.raise_for_status()
        return res.text
    return json.loads(cache.get(path, ttl, do))

# Lilydale route 9 (type 0) (dir 1 in, 8 out) (stop 1229)
# Belgrave route 2 (type 0) (dir 1 in, 2 out) (stop 1229)
# 109 route 722 (type 1) (dir 2 E, 3 W) (stop 2415 E, 2460 W)
# 70 route 940 (type 1) (dir 28 E, 29 W) (stop 2161 E, 2162 W)
# 766 route 15800 (type 2) (dir 13 N, 207 S) (stop 17861)
# 612 route 13024 (type 2) (dir 13 N, 158 S) (stop 17861)

def fetch_departures(stop_id, route_type_id, cache):
    # TODO: Expand runs
    return fetch(f'/v3/departures/route_type/{route_type_id}/stop/{stop_id}', cache)['departures']

def fetch_run(run_ref, cache):
    return fetch(f'/v3/runs/{run_ref}', cache, timedelta(hours=8))['runs']

def departure_time(dep):
    return datetime.fromisoformat(dep['estimated_departure_utc'] or dep['scheduled_departure_utc'])

def get_departure_data(now, cache):
    bus = fetch_departures(17861, 2, cache)
    train = fetch_departures(1229, 0, cache)
    tram_109w = fetch_departures(2460, 1, cache)
    tram_70w = fetch_departures(2161, 1, cache)

    next_express_dep = None
    train.sort(key=departure_time)
    for dep in train:
        if dep['direction_id'] == 1 and departure_time(dep) > now:
            match fetch_run(dep['run_ref'], cache):
                case [run]:
                    if run['express_stop_count'] > 1: # Ignore East Richmond
                        next_express_dep = dep
                        break

    def earliest(deps):
        return min((departure_time(dep) for dep in deps if departure_time(dep) > now), default=None)

    return {
        '612 S': earliest(dep for dep in bus if dep['route_id'] == 13024 and dep['direction_id'] == 139),
        '612 N': earliest(dep for dep in bus if dep['route_id'] == 13024 and dep['direction_id'] == 13),
        '766 N': earliest(dep for dep in bus if dep['route_id'] == 15800 and dep['direction_id'] == 13),

        'Union W': earliest(dep for dep in train if dep['direction_id'] == 1 and dep is not next_express_dep),
        'Union W Express': departure_time(next_express_dep) if next_express_dep else None,
        'Union E': earliest(dep for dep in train if dep['direction_id'] in {2, 8}),

        '109 W': earliest(tram_109w),
        '70 W': earliest(tram_70w),
    }