departures.py

#!/usr/bin/python3
# -*- coding: utf-8 -*-
"""
VasttraPi - Your personal departures screen for Västtrafik buses
"""
import pytrafik.client
import json
from datetime import datetime
from pytz import timezone
import os
from datetime import datetime
from collections import defaultdict


class StationOfInterest:
    def __init__(self, station_name, station_id, tracks):
        self.name = station_name
        self.id = station_id
        self.tracks = tracks


class Trip:
    def __init__(self, vehicle_type, line, destination, minutes_left):
        self.vehicle_type = vehicle_type.capitalize()
        self.line = line
        self.destination = destination
        self.minutes_left = int(minutes_left)

    def __repr__(self):
        return self.vehicle_type + " " + self.line + " to " + self.destination + " in " + str(self.minutes_left) + " minutes."


def init_vasttrafik_api_keys(path_to_api_keys):
    """
    Fetches the consumer and secret key from a relative path to a configuration
    file which should not be version controlled. The first line is the key and
    the second is the secret.

    Returns a tuple as (api_key, api_secret)
    """
    # Change working directory to the one that the file is residing in
    abspath = os.path.abspath(__file__)
    dname = os.path.dirname(abspath)
    os.chdir(dname)
    # Parse the keys
    f = open(path_to_api_keys)
    api_key = f.readline().replace('\n', "")
    api_secret = f.readline().replace('\n', "")
    f.close()
    return (api_key, api_secret)


def init_connection(api_key, api_secret):
    """
    Initializes the connection to the Vasttrafik server

    Returns Vasttrafik connection or None if connection failed
    """
    try:
        return pytrafik.client.Client("json", api_key, api_secret)
    except Exception as e:
        print(e)
        print("Authentication failure!")
        return None


def get_time():
    """
    Fetches the local time in Gothenburg

    Returns a tuple with the current date and time
    """
    sweden = timezone('Europe/Stockholm')
    se_time = datetime.now(sweden)

    return (se_time.strftime("%Y-%m-%d"), se_time.strftime("%H:%M"))


def get_next_trips(vasttrafik, stations):
    """
    Fetches the next bus or tram trips for the specified list of
    StationOfInterest and connection to the Vasttrafik servers.

    Returns A list of bus/tram line numbers and minutes to depart for the next
            two trips of each bus or tram line.
    """
    # Get the current time and date from an NTP server as the host might not have an RTC
    (current_date, current_time) = get_time()
    trips = defaultdict(list)  # A dictionary of lists, holding a list of departures for each bus
    for station in stations:
        # Get the departures for each station we are interested in
        try:
            departures = vasttrafik.get_departures(station.id, date=current_date, time=current_time)
        except Exception as e:
            print("Connection failure for station %s" % station.name)
            departures = []  # If something went wrong, empty the departures list so we don't try to iterate through them
        for departure in departures:
            if departure['track'] in station.tracks:
                try:
                    # Sometimes rtTime is not returned, so fall back to normal time instead
                    departure_time = departure['rtTime'] if 'rtTime' in departure else departure['time']
                    trips[(departure['sname'], departure['direction'], departure['type'])].append(departure_time)
                except Exception as e:
                    print("Error while parsing server response")

    nextTrips = []
    for (line, destination, vehicle_type), departure_times in trips.items():
            remaining_departures = 2  # The number of departures that we care to show
            for departure_time in departure_times:
                remaining_departures -= 1
                if remaining_departures < 0:
                    break
                minutes_to_leave = ((datetime.strptime(departure_time, "%H:%M") - datetime.strptime(current_time, "%H:%M")).total_seconds() / 60)
                # If a bus leaves the next day, the above result will be a negative number, therefore we need to completement it
                # with the amount of minutes in a day (1440)
                if minutes_to_leave < 0:  # meaning that the next departure time is on the next day
                    MINUTES_IN_DAY = 1440
                    minutes_to_leave += MINUTES_IN_DAY
                nextTrips.append(Trip(vehicle_type, line, destination, minutes_to_leave))

    return nextTrips


def init():
    """
    Initialize the connection to the server and get a Vasttrafik connection
    object back.

    Returns a Vasttrafik object upon a successful connection, None otherwise
    """
    # Initialize the API keys using the local config file `api-config`
    (api_key, api_secret) = init_vasttrafik_api_keys("api-config")

    return init_connection(api_key, api_secret)