#!/usr/bin/env python3

from contextlib import nullcontext
import csv
from datetime import date, datetime, time, timedelta
import os
import json
from pytz import timezone
import requests

import click
from flask import Flask, render_template
from flask.cli import AppGroup
from flask_migrate import Migrate
from flask_sqlalchemy import SQLAlchemy
from sqlalchemy import Boolean, Column, Date, DateTime, Integer, String, Time
from sqlalchemy.sql import func
from tqdm import tqdm

import config

app = Flask(__name__)

cli = AppGroup('tgvmax', help="Manage the TGVMax dataset.")
app.cli.add_command(cli)

app.config |= config.FLASK_CONFIG

db = SQLAlchemy(app)
Migrate(app, db)


class Train(db.Model):
    __tablename__ = 'train'
    id = Column(String, primary_key=True)
    day = Column(Date, index=True)
    number = Column(Integer, index=True)
    entity = Column(String(16))
    axe = Column(String(32), index=True)
    orig_iata = Column(String(5), index=True)
    dest_iata = Column(String(5), index=True)
    orig = Column(String(32))
    dest = Column(String(32))
    dep = Column(Time)
    arr = Column(Time)
    tgvmax = Column(Boolean, index=True)
    remaining_seats = Column(Integer, default=-1)
    last_modification = Column(DateTime)
    expiration_time = Column(DateTime)


class RouteQueue(db.Model):
    id = Column(Integer, autoincrement=True, primary_key=True)
    queue_time = Column(DateTime(timezone=True), server_default=func.now())
    day = Column(Date)
    origin = Column(String(5))
    destination = Column(String(5))
    response_time = Column(DateTime(timezone=True), nullable=True, default=None)
    expiration_time = Column(DateTime(timezone=True), nullable=True, default=None)


@cli.command("update-dataset")
@click.option('--verbose', '-v', is_flag=True, help="Display errors.")
def update_dataset(verbose: bool = False):
    """
    Query the latest version of the SNCF OpenData dataset, as a CSV file.
    """
    resp = requests.get('https://ressources.data.sncf.com/explore/dataset/tgvmax/information/')
    content = resp.content.decode().split('<script type="application/ld+json">')[1].split('</script>')[0].strip()
    content = content.replace('\r', '')
    content = content.replace('" \n', '" \\n')
    content = content.replace('.\n', '.\\n')
    content = content.replace('\n\n \nLa', '\\n\\n \\nLa')
    content = content.replace('\n"', '\\n"')

    info = json.loads(content)
    modified_date = datetime.fromisoformat(info['dateModified'])

    utc = timezone('UTC')
    last_modified = datetime.utcfromtimestamp(os.path.getmtime('tgvmax.csv')).replace(tzinfo=utc) if os.path.isfile(
        'tgvmax.csv') else datetime(1, 1, 1, tzinfo=utc)

    if last_modified < modified_date:
        if verbose:
            print("Updating tgvmax.csv…")
        with requests.get(info['distribution'][0]['contentUrl'], stream=True) as resp:
            resp.raise_for_status()
            with open('tgvmax.csv', 'wb') as f:
                with tqdm(unit='io', unit_scale=True) if verbose else nullcontext() as t:
                    for chunk in resp.iter_content(chunk_size=512 * 1024):
                        if chunk:
                            f.write(chunk)
                            if verbose:
                                t.update(len(chunk))
        os.utime('tgvmax.csv', (modified_date.timestamp(), modified_date.timestamp()))
        if verbose:
            print("Done")
    else:
        if verbose:
            print("Last modification:", modified_date)
        exit(2)


@cli.command("parse-csv")
@click.option('-F', '--flush', type=bool, is_flag=True, help="Flush the database before filling it.")
@click.option('--verbose', '-v', is_flag=True, help="Display errors.")
def parse_trains(flush: bool = False, verbose: bool = False):
    """
    Parse the CSV file and store it to the database.
    """

    if flush:
        if verbose:
            print("Flush database…")
        db.session.query(Train).delete()

    last_modification = datetime.utcfromtimestamp(os.path.getmtime('tgvmax.csv')).replace(tzinfo=timezone('UTC'))

    with open('tgvmax.csv') as f:
        first_line = True
        already_seen = set()
        for line in (tqdm if verbose else lambda x: x)(csv.reader(f, delimiter=';')):
            if first_line:
                first_line = False
                continue

            train_id = f"{line[1]}-{line[0]}-{line[4]}-{line[5]}"
            if train_id in already_seen:
                # Some trains are mysteriously duplicated, concerns only some « Intercités de nuit »
                # and the Brive-la-Gaillarde -- Paris
                # and, maybe, for Roubaix-Tourcoing
                if line[3] != "IC NUIT" and line[1] != '3614' and not (line[4] == 'FRADP' and line[5] == 'FRADM'):
                    print("Duplicate:", train_id)
                continue

            train = Train(
                id=train_id,
                day=date.fromisoformat(line[0]),
                number=int(line[1]),
                entity=line[2],
                axe=line[3],
                orig_iata=line[4],
                dest_iata=line[5],
                orig=line[6],
                dest=line[7],
                dep=time.fromisoformat(line[8]),
                arr=time.fromisoformat(line[9]),
                tgvmax=line[10] == 'OUI',
                last_modification=last_modification,
                expiration_time=last_modification,
            )
            if flush:
                db.session.add(train)
            else:
                db.session.merge(train)

            if line[3] == "IC NUIT" or line[1] == '3614' or (line[4] == 'FRADP' and line[5] == 'FRADM'):
                already_seen.add(train_id)

    db.session.commit()


def find_routes(day: date, origin: str, destination: str | None):
    trains = db.session.query(Train).filter_by(day=day, tgvmax=True).all()

    trains.sort(key=lambda train: train.dep)

    # For better results later, fetch all trains from the origin or to the destination
    # This is not exhaustive, but can be a good approximation
    queue_routes(day, origin=origin)
    if destination:
        queue_routes(day, destination=destination)

    per_arr_explore = {}
    valid_routes = []

    for train in tqdm(trains):
        if train.orig == origin:
            # Update from the TGVMax simulator
            queue_route(day, train.orig_iata, train.dest_iata)

            it = [train]
            if train.dest == destination:
                # We hope that we have a direct train
                valid_routes.append(it)
            else:
                per_arr_explore.setdefault(train.dest, [])
                per_arr_explore[train.dest].append(it)
            continue

        for it in list(per_arr_explore.get(train.orig, [])):
            if any(train.dest == tr.dest or train.dest == origin for tr in it):
                # Avoid loops
                continue

            last_train = it[-1]

            if last_train.arr <= train.dep:
                # Update from the TGVMax simulator, this line can be useful later
                queue_route(day, train.orig_iata, train.dest_iata)

                new_it = it + [train]
                if train.dest == destination:
                    # Goal is achieved
                    valid_routes.append(new_it)
                else:
                    per_arr_explore.setdefault(train.dest, [])
                    per_arr_explore[train.dest].append(new_it)

    return {destination: valid_routes} if destination else per_arr_explore


def queue_route(day: date | datetime, origin: str, destination: str, verbose: bool = False):
    """
    Fetch the TGVMax simulator to refresh data.

    DAY: The day to query, in format YYYY-MM-DD.

    ORIGIN: The origin of the route.

    DESTINATION: The destination of the route.
    """
    if isinstance(day, datetime):
        day = day.date()

    query = db.session.query(RouteQueue).filter_by(day=day, origin=origin, destination=destination, response_time=None)
    if query.count():
        if verbose:
            print("Already queued")
        return

    query = db.session.query(RouteQueue).filter(RouteQueue.day == day,
                                                RouteQueue.origin == origin,
                                                RouteQueue.destination == destination,
                                                RouteQueue.expiration_time >= datetime.now(timezone('UTC')))
    if query.count():
        if verbose:
            print("Using recent value")
        return

    db.session.add(RouteQueue(day=day, origin=origin, destination=destination))
    db.session.commit()


# Don't use the decorator to keep the function callable
cli.command('queue-route')(click.argument('day', type=click.DateTime(formats=['%Y-%m-%d']))
                           (click.argument('origin', type=str)
                            (click.argument('destination', type=str)
                             (click.option('--verbose', '-v', type=bool, is_flag=True, help="Display errors.")
                              (queue_route)))))


def queue_routes(day: date | datetime, origin: str | None = None,
                 destination: str | None = None, verbose: bool = False):
    if isinstance(day, datetime):
        day = day.date()

    query = db.session.query(Train).filter((Train.day == day))
    if origin:
        query = query.filter((Train.orig_iata == origin) | (Train.orig == origin))
    if destination:
        query = query.filter((Train.dest_iata == destination) | (Train.dest == destination))
    for train in query.all():
        queue_route(day, train.orig_iata, train.dest_iata, verbose)


# Same as above
cli.command('queue-routes')(click.argument('day', type=click.DateTime(formats=['%Y-%m-%d']))
                            (click.option('--origin', '-o', default=None)
                             (click.option('--destination', '-d', default=None)
                              (click.option('--verbose', '-v', type=bool, is_flag=True, help="Display errors.")
                               (queue_routes)))))


@cli.command('process-queue', help="Process the waiting list to refresh from the simulator.")
@click.argument('number', default=30, type=int)
def process_queue(number: int):
    queue = db.session.query(RouteQueue).filter_by(response_time=None).order_by(RouteQueue.queue_time)
    if number > 0:
        queue = queue[:number]

    URL = "https://www.maxjeune-tgvinoui.sncf/api/public/refdata/search-freeplaces-proposals"

    for req in queue:
        req: RouteQueue
        resp = requests.post(URL, json={
            'departureDateTime': req.day.isoformat(),
            'origin': req.origin,
            'destination': req.destination,
        })

        if resp.status_code == 404:
            # No travel found
            req.response_time = datetime.now()
            req.expiration_time = datetime.now() + timedelta(hours=1)
            db.session.add(req)
            db.session.commit()
            continue

        resp.raise_for_status()

        data = resp.json()
        req.response_time = datetime.utcfromtimestamp(data['updatedAt'] // 1000).replace(tzinfo=timezone('UTC'))
        req.expiration_time = datetime.utcfromtimestamp(data['expiresAt'] // 1000).replace(tzinfo=timezone('UTC'))
        req.expiration_time += timedelta(hours=3)  # By default 5 minutes, extend it to 3 hours to be safe
        db.session.add(req)

        db.session.query(Train).filter_by(day=req.day, orig_iata=req.origin, dest_iata=req.destination) \
            .update(dict(tgvmax=False, remaining_seats=-1))

        for proposal in data['proposals']:
            train = db.session.query(Train).filter_by(day=req.day, number=int(proposal['trainNumber']),
                                                      orig_iata=req.origin, dest_iata=req.destination).first()
            if train is None:
                # In a city with multiple stations
                print(proposal)
                continue
            train.tgvmax = True
            train.remaining_seats = proposal['freePlaces']
            train.last_modification = req.response_time
            train.expiration_time = req.expiration_time
            db.session.add(train)

        db.session.commit()


@app.get('/')
def index():
    return render_template('index.html', today=date.today(), max_day=date.today() + timedelta(days=30))


@app.get('/api/iata-codes/')
def iata_codes():
    query = db.session.query(Train).with_entities(Train.orig_iata, Train.orig).distinct()
    return {
        'iata2name': {
            k: v for (k, v) in query.all()
        },
        'name2iata': {
            v: k for (k, v) in query.all()
        }
    }


@app.get('/api/routes/<day>/<origin>/<destination>/')
def get_routes(day: date | str, origin: str, destination: str):
    if isinstance(day, str):
        day = date.fromisoformat(day)

    if destination == 'undefined':
        destination = None

    routes = find_routes(day, origin, destination)

    return {
            city: [
                [{
                    'origin': tr.orig,
                    'origin_iata': tr.orig_iata,
                    'destination': tr.dest,
                    'destination_iata': tr.dest_iata,
                    'departure': tr.dep.isoformat(),
                    'arrival': tr.arr.isoformat(),
                    'number': tr.number,
                    'free_seats': tr.remaining_seats,
                } for tr in route] for route in city_routes
            ] for city, city_routes in routes.items()
        }


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