#!/usr/bin/env python3

import flask
app = flask.Flask(__name__)

from . import config

import hashlib
import hmac
import json
import pytz
import traceback
from binascii import hexlify
from datetime import datetime, timedelta
from urllib.parse import urlencode
from urllib.request import Request, urlopen

request_cache = {}
def do_request(endpoint, args=None):
	url = endpoint + '?devid=' + config.PTV_USER_ID
	if args:
		url += '&' + urlencode(args)
	
	# Check cache
	timenow = pytz.utc.localize(datetime.utcnow()).astimezone(timezone)
	cachexp = timenow - timedelta(seconds=60)
	if url in request_cache:
		if request_cache[url][0] >= cachexp:
			# Use cached response
			return request_cache[url][1]
	
	# Generate signature
	signature = hexlify(hmac.digest(config.PTV_API_KEY.encode('ascii'), url.encode('ascii'), 'sha1')).decode('ascii')
	
	req = Request('https://timetableapi.ptv.vic.gov.au' + url + '&signature=' + signature, headers={'User-Agent': 'virtual-metro/0.1'})
	try:
		resp = urlopen(req)
	except Exception as ex:
		print('Unable to refresh cache')
		traceback.print_exc()
		
		if url in request_cache:
			return request_cache[url][1]
		else:
			return None
	data = json.load(resp)
	
	# Cache the response
	request_cache[url] = (timenow, data)
	
	return data

def parse_date(dtstring):
	return pytz.utc.localize(datetime.strptime(dtstring, '%Y-%m-%dT%H:%M:%SZ')).astimezone(timezone)

ROUTE_TYPE = 0
LOOP_STATIONS = ['Parliament', 'Melbourne Central', 'Flagstaff', 'Southern Cross', 'Flinders Street']

timezone = pytz.timezone('Australia/Melbourne')

@app.route('/')
@app.route('/index')
def index():
	return flask.render_template('index.html')

def stop_to_name(stop, route_id):
	name = stop['stop_name']
	if name.endswith(' Station'):
		name = name[:-8]
	if name == 'Flemington Racecourse' and route_id and route_id != 16 and route_id != 17 and route_id != 1482:
		# PTV bug??
		name = 'South Kensington'
	return name

route_stops = {} # Cache lookup
def parse_departure(departure, departures, timenow):
	result = {}
	result['dest'] = departures['runs'][str(departure['run_id'])]['destination_name']
	result['sch'] = parse_date(departure['scheduled_departure_utc']).strftime('%I:%M').lstrip('0')
	mins = (parse_date(departure['estimated_departure_utc'] or departure['scheduled_departure_utc']) - timenow).total_seconds() / 60
	if mins < 0.5:
		result['now'] = 'NOW'
	else:
		result['min'] = round(mins)
	
	# Get stopping pattern
	result['stops'] = []
	pattern = do_request('/v3/pattern/run/{}/route_type/{}'.format(departure['run_id'], ROUTE_TYPE), {'expand': 'all'})
	pattern_stops = [(x['stop_id'], stop_to_name(pattern['stops'][str(x['stop_id'])], departure['route_id']), False) for x in pattern['departures']]
	
	# Get all stops on route
	if (departure['route_id'], departure['direction_id']) not in route_stops:
		stops = do_request('/v3/stops/route/{}/route_type/{}'.format(departure['route_id'], ROUTE_TYPE), {'direction_id': departure['direction_id']})
		stops['stops'].sort(key=lambda x: x['stop_sequence'])
		route_stops[(departure['route_id'], departure['direction_id'])] = stops['stops']
	
	route_stops_dir = []
	for stop in route_stops[(departure['route_id'], departure['direction_id'])]:
		# Cut off at Flinders Street
		route_stops_dir.append(stop)
		if stop_to_name(stop, departure['route_id']) == 'Flinders Street':
			break
	
	# Calculate stopping pattern
	result['stops'] = []
	
	# Find this run along pattern_stops
	ps_route_start = next((k for k, stop in enumerate(pattern_stops) if stop[0] == int(flask.request.args['stop_id'])), 0)
	ps_route_end = next((k for k, stop in enumerate(pattern_stops) if stop[0] == pattern['runs'][str(departure['run_id'])]['final_stop_id']), len(pattern_stops)-1)
	
	ps_route_flinders = next((k for k, stop in enumerate(pattern_stops) if stop[0] == 1071), len(pattern_stops)-1)
	if ps_route_flinders > ps_route_start:
		ps_route_end = min(ps_route_end, ps_route_flinders) # Cut off at Flinders Street
	
	# Find this run along route_stops_dir
	rsd_route_start = next((k for k, stop in enumerate(route_stops_dir) if stop['stop_id'] == int(flask.request.args['stop_id'])), 0)
	rsd_route_end = next((k for k, stop in enumerate(route_stops_dir) if stop['stop_id'] == pattern['runs'][str(departure['run_id'])]['final_stop_id']), len(route_stops_dir)-1)
	
	rsd_route_flinders = next((k for k, stop in enumerate(route_stops_dir) if stop['stop_id'] == 1071), len(route_stops_dir)-1)
	if rsd_route_flinders > rsd_route_start:
		rsd_route_end = min(rsd_route_end, rsd_route_flinders)
	
	# Add express stops
	for k, stop in enumerate(route_stops_dir[rsd_route_start:rsd_route_end+1]):
		if any(x[0] == stop['stop_id'] for x in pattern_stops):
			continue
		if stop_to_name(stop, departure['route_id']) in LOOP_STATIONS:
			continue
		# Express stop
		# Identify location based on previous stop
		if rsd_route_start+k == 0:
			ps_index = 0
		else:
			ps_index = next((l+1 for l, stop in enumerate(pattern_stops) if stop[0] == route_stops_dir[rsd_route_start+k-1]['stop_id']), None)
		if ps_index is None:
			continue
		pattern_stops.insert(ps_index, (stop['stop_id'], stop_to_name(stop, departure['route_id']), True))
		ps_route_end += 1
	
	# Convert to string
	express_stops = []
	num_city_loop = 0
	for _, stop_name, is_express in pattern_stops[ps_route_start+1:ps_route_end+1]:
		if is_express:
			result['stops'].append('   ---')
			express_stops.append(stop_name)
		else:
			result['stops'].append(stop_name)
			if stop_name in LOOP_STATIONS:
				num_city_loop += 1
	
	# Impute remainder of journey
	if result['stops'] and result['stops'][-1] == 'Parliament':
		result['stops'].append('Melbourne Central')
		result['stops'].append('Flagstaff')
		result['stops'].append('Southern Cross')
		result['stops'].append('Flinders Street')
		num_city_loop += 4
	
	result['dest'] = result['stops'][-1] if result['stops'] else None
	if result['dest'] is None:
		result['dest'] = 'Arrival'
		result['desc'] = ''
	elif result['dest'] in LOOP_STATIONS:
		# Up train
		# Is this a City Loop train?
		if num_city_loop >= 3:
			result['dest'] = 'City Loop'
		result['desc'] = 'All Except {}'.format(express_stops[0]) if len(express_stops) == 1 else 'Limited Express' if len(express_stops) > 1 else 'Stops All Stations'
	else:
		# Down train
		# Is this a via City Loop train?
		if num_city_loop >= 3:
			result['desc'] = 'Ltd Express via City Loop' if len(express_stops) > 1 else 'Stops All via City Loop'
		else:
			result['desc'] = 'All Except {}'.format(express_stops[0]) if len(express_stops) == 1 else 'Limited Express' if len(express_stops) > 1 else 'Stops All Stations'
	
	return result

@app.route('/latest')
def latest():
	timenow = pytz.utc.localize(datetime.utcnow()).astimezone(timezone)
	result = {}
	result['time_offset'] = timenow.utcoffset().total_seconds()
	
	departures = do_request('/v3/departures/route_type/{}/stop/{}'.format(ROUTE_TYPE, flask.request.args['stop_id']), {'platform_numbers': flask.request.args['plat_id'], 'max_results': '5', 'expand': 'all'})
	departures['departures'].sort(key=lambda x: x['scheduled_departure_utc'])
	
	if len(departures['departures']) == 0:
		# Invalid stop ID, platform ID, no departures, etc.
		return flask.jsonify(result)
	
	result['stop_name'] = stop_to_name(departures['stops'][flask.request.args['stop_id']], None)
	
	# Next train
	
	for i, departure in enumerate(departures['departures']):
		if parse_date(departure['estimated_departure_utc'] or departure['scheduled_departure_utc']) < timenow:
			continue
		
		# This is the next train
		result.update(parse_departure(departure, departures, timenow))
		
		break
	
	# Next trains
	
	result['next'] = []
	for departure in departures['departures'][i+1:i+3]:
		result['next'].append(parse_departure(departure, departures, timenow))
	
	return flask.jsonify(result)

# Cache list of stations
stns = None

def get_station_list():
	global stns
	if not stns:
		stn_list = {}
		
		routes = do_request('/v3/routes', {'route_types': ROUTE_TYPE})
		for route in routes['routes']:
			stops = do_request('/v3/stops/route/{}/route_type/{}'.format(route['route_id'], ROUTE_TYPE), {})
			for stop in stops['stops']:
				stn_list[stop['stop_id']] = stop['stop_name'].replace(' Station', '')
		
		stns = [(k, v) for k, v in stn_list.items()]
		stns.sort(key=lambda x: x[1])

if not app.debug:
	get_station_list()

@app.route('/stations')
def stations():
	get_station_list()
	return flask.render_template('stations.html', stations=stns)