import asyncio
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

app = Flask(__name__)

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


async def _fetch_both(destination: str, travel_date: str, user_agent: str):
    """Fetch GWR trains and Eurostar times simultaneously."""
    gwr, es = await asyncio.gather(
        rtt_scraper.fetch(travel_date, user_agent),
        eurostar_scraper.fetch(destination, travel_date, user_agent),
        return_exceptions=True,
    )
    return gwr, es


@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)

    cache_key = f"{travel_date}_{destination}"
    cached = get_cached(cache_key)

    error = None
    if cached:
        gwr_trains = cached['gwr']
        eurostar_trains = cached['eurostar']
        from_cache = True
    else:
        from_cache = False
        gwr_result, es_result = asyncio.run(_fetch_both(destination, travel_date, user_agent))

        if isinstance(gwr_result, Exception):
            gwr_trains = []
            error = f"Could not fetch GWR trains: {gwr_result}"
        else:
            gwr_trains = gwr_result

        if isinstance(es_result, Exception):
            eurostar_trains = []
            msg = f"Could not fetch Eurostar times: {es_result}"
            error = f"{error}; {msg}" if error else msg
        else:
            eurostar_trains = es_result

        if gwr_trains or eurostar_trains:
            set_cached(cache_key, {'gwr': gwr_trains, 'eurostar': eurostar_trains})

    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')

    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,
    )


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