"""
Combine GWR Bristol→Paddington trains with Eurostar St Pancras→destination trains.
"""
from flask import Flask, render_template, redirect, url_for, request
from datetime import date, timedelta

from cache import get_cached, set_cached
import scraper.eurostar as eurostar_scraper
import scraper.realtime_trains as rtt_scraper
from trip_planner import combine_trips

RTT_PADDINGTON_URL = (
    "https://www.realtimetrains.co.uk/search/detailed/"
    "gb-nr:PAD/from/gb-nr:BRI/{date}/0000-2359"
    "?stp=WVS&show=pax-calls&order=wtt"
)

app = Flask(__name__)

DESTINATIONS = {
    'paris':      'Paris Gare du Nord',
    'brussels':   'Brussels Midi',
    'lille':      'Lille Europe',
    'amsterdam':  'Amsterdam Centraal',
}


@app.route('/')
def index():
    today = date.today().isoformat()
    return render_template('index.html', destinations=DESTINATIONS, today=today)


@app.route('/search')
def search():
    slug = request.args.get('destination', '')
    travel_date = request.args.get('travel_date', '')
    if slug in DESTINATIONS and travel_date:
        return redirect(url_for('results', slug=slug, travel_date=travel_date))
    return redirect(url_for('index'))


@app.route('/results/<slug>/<travel_date>')
def results(slug, travel_date):
    destination = DESTINATIONS.get(slug)
    if not destination or not travel_date:
        return redirect(url_for('index'))

    user_agent = request.headers.get('User-Agent', rtt_scraper.DEFAULT_UA)

    rtt_cache_key = f"rtt_{travel_date}"
    es_cache_key = f"eurostar_{travel_date}_{destination}"

    cached_rtt = get_cached(rtt_cache_key)
    cached_es = get_cached(es_cache_key)
    from_cache = bool(cached_rtt and cached_es)

    error = None

    if cached_rtt:
        gwr_trains = cached_rtt
    else:
        try:
            gwr_trains = rtt_scraper.fetch(travel_date, user_agent)
            set_cached(rtt_cache_key, gwr_trains)
        except Exception as e:
            gwr_trains = []
            error = f"Could not fetch GWR trains: {e}"

    if cached_es:
        eurostar_trains = cached_es
    else:
        try:
            eurostar_trains = eurostar_scraper.fetch(destination, travel_date, user_agent)
            set_cached(es_cache_key, eurostar_trains)
        except Exception as e:
            eurostar_trains = []
            msg = f"Could not fetch Eurostar times: {e}"
            error = f"{error}; {msg}" if error else msg

    trips = combine_trips(gwr_trains, eurostar_trains, travel_date)

    dt = date.fromisoformat(travel_date)
    prev_date = (dt - timedelta(days=1)).isoformat()
    next_date = (dt + timedelta(days=1)).isoformat()
    travel_date_display = dt.strftime('%A %-d %B %Y')

    eurostar_url = eurostar_scraper.ROUTE_URLS[destination] + f"?date={travel_date}"
    rtt_url = RTT_PADDINGTON_URL.format(date=travel_date)

    return render_template(
        'results.html',
        trips=trips,
        destination=destination,
        travel_date=travel_date,
        slug=slug,
        prev_date=prev_date,
        next_date=next_date,
        travel_date_display=travel_date_display,
        gwr_count=len(gwr_trains),
        eurostar_count=len(eurostar_trains),
        from_cache=from_cache,
        error=error,
        eurostar_url=eurostar_url,
        rtt_url=rtt_url,
    )


if __name__ == '__main__':
    app.run(debug=True)