Scripts/parking

#!/usr/bin/python3
import requests
import sys
import textwrap
import pprint
from pathlib import Path
try:
    from simplejson.errors import JSONDecodeError
except ImportError:
    from json.decoder import JSONDecodeError

api = 'http://parkering.linkoping.se/'
key = Path('key-parking').read_text().strip()

# Fetch JSON from url and run it through transform, pretty printing errors
# and the data worked on as exhaustively as possible.
def json_query(url, transform, params={}):
    try:
        result = requests.get(url, params)
    except requests.exceptions.ConnectionError:
        print("Network connection error.")
        sys.exit(1)
    try:
        data = result.json()
    except JSONDecodeError as err:
        print('Error when decoding JSON:\nFrom endpoint ' + url + ':\n' + str(err) + '\n' + str(result) + '\n')
        sys.exit(1)
    try:
        return transform(data)
    except (IndexError, KeyError) as err:
        print('Error when traversing JSON:\nFrom endpoint ' + url + ':\n' + str(err))
        pprint.PrettyPrinter(indent=2).pprint(data)
        sys.exit(1)

# Get parking lots from the municipal server.
# The timestamp part of this API does not work as expected, if non-zero it will return all computer parking terminal lots
# in ParkingAreaUpdateList regardless of their status, up to a timestamp of less than one hour into the future, after which it will return nothing.
def get_parking_lots():
    return json_query(api + 'Parkeringsdata/ParkeringsdataV1.svc/GetParkeringsytaList/' + key + '/0', lambda data: data['ParkingAreaNewList'], {})

# The key ParkingSpacesAvailable is only present for those lots that are tracked by computer parking terminals.
# All other lots only have static information available.
def computerized(lot):
    return 'ParkingSpacesAvailable' in lot

# The parking type '4' means handicap spots, whoever organized this put handicap spots as separate lots with duplicate names.
def only_has_handicap_spots(lot):
    return lot['ParkingTypes'] == [4]

# The downtown parking lots are equipped with electric charging stations and the API has a parking type for this
# but the lot data has not been updated to reflect this, so this function always returns False.
def electric_car_lot(lot):
    return 3 in lot['ParkingTypes']

def main():
    print('Parking spaces available:')
    for lot in sorted(get_parking_lots(), key=lambda lot: lot['Name']):
        if computerized(lot) and not only_has_handicap_spots(lot):
            print("{Name}: {ParkingSpacesAvailable}/{ParkingSpaces}".format(**lot))

if __name__ == '__main__':
    main()