from celery import Celery, Task
from app import app as flaskapp
from app import db
from model import Session, Account, TwitterArchive, Post, OAuthToken,\
                  MastodonInstance
import lib.twitter
import lib.mastodon
from mastodon.Mastodon import MastodonRatelimitError
from twitter import TwitterError
from urllib.error import URLError
from datetime import timedelta
from zipfile import ZipFile
from io import BytesIO, TextIOWrapper
import json
from kombu import Queue
import random
import version


app = Celery('tasks', broker=flaskapp.config['CELERY_BROKER'],
             task_serializer='pickle')
app.conf.task_queues = (
        Queue('default', routing_key='celery'),
        Queue('high_prio', routing_key='high'),
        Queue('higher_prio', routing_key='higher'),
)
app.conf.task_default_queue = 'default'
app.conf.task_default_exchange = 'celery'
app.conf.task_default_exchange_type = 'direct'

if 'SENTRY_DSN' in flaskapp.config:
    from raven import Client
    from raven.contrib.celery import register_signal, register_logger_signal
    sentry = Client(flaskapp.config['SENTRY_DSN'], release=version.version)
    register_logger_signal(sentry)
    register_signal(sentry)


class DBTask(Task):
    def __call__(self, *args, **kwargs):
        try:
            super().__call__(*args, **kwargs)
        finally:
            db.session.close()


app.Task = DBTask


def noop(*args, **kwargs):
    pass


@app.task(autoretry_for=(TwitterError, URLError, MastodonRatelimitError))
def fetch_acc(id_, cursor=None):
    acc = Account.query.get(id_)
    print(f'fetching {acc}')
    try:
        action = noop
        if(acc.service == 'twitter'):
            action = lib.twitter.fetch_acc
        elif(acc.service == 'mastodon'):
            action = lib.mastodon.fetch_acc
        cursor = action(acc, cursor)
        if cursor:
            fetch_acc.si(id_, cursor).apply_async()
    finally:
        db.session.rollback()
        acc.touch_fetch()
        db.session.commit()


@app.task
def queue_fetch_for_most_stale_accounts(
        min_staleness=timedelta(minutes=2), limit=20):
    accs = Account.query\
            .join(Account.tokens).group_by(Account)\
            .filter(Account.last_fetch < db.func.now() - min_staleness)\
            .order_by(db.asc(Account.last_fetch))\
            .limit(limit)
    for acc in accs:
        fetch_acc.s(acc.id).delay()
    db.session.commit()


@app.task(autoretry_for=(TwitterError, URLError))
def import_twitter_archive_month(archive_id, month_path):
    ta = TwitterArchive.query.get(archive_id)

    try:

        with ZipFile(BytesIO(ta.body), 'r') as zipfile:
            with TextIOWrapper(zipfile.open(month_path, 'r')) as f:

                # seek past header
                f.readline()

                tweets = json.load(f)

        for tweet in tweets:
            post = lib.twitter.post_from_api_tweet_object(tweet)
            existing_post = db.session.query(Post).get(post.id)

            if post.author_id != ta.account_id or\
               existing_post and existing_post.author_id != ta.account_id:
                raise Exception("Shenanigans!")

            post = db.session.merge(post)

        ta.chunks_successful = TwitterArchive.chunks_successful + 1
        db.session.commit()

    except Exception as e:
        db.session.rollback()
        ta.chunks_failed = TwitterArchive.chunks_failed + 1
        db.session.commit()
        raise e


@app.task
def periodic_cleanup():
    # delete sessions after 48 hours
    (Session.query
     .filter(Session.updated_at < (db.func.now() - timedelta(hours=48)))
     .delete(synchronize_session=False))

    # delete twitter archives after 3 days
    (TwitterArchive.query
     .filter(TwitterArchive.updated_at < (db.func.now() - timedelta(days=3)))
     .delete(synchronize_session=False))

    # delete anonymous oauth tokens after 1 day
    (OAuthToken.query
     .filter(OAuthToken.updated_at < (db.func.now() - timedelta(days=1)))
     .filter(OAuthToken.account_id == None)  # noqa: E711
     .delete(synchronize_session=False))

    # disable users with no tokens
    unreachable = (
            Account.query
            .outerjoin(Account.tokens)
            .group_by(Account).having(db.func.count(OAuthToken.token) == 0)
            .filter(Account.policy_enabled == True))  # noqa: E712
    for account in unreachable:
        account.policy_enabled = False

    # normalise mastodon instance popularity scores
    biggest_instance = (
            MastodonInstance.query
            .order_by(db.desc(MastodonInstance.popularity)).first())
    if biggest_instance.popularity > 40:
        MastodonInstance.query.update({
            MastodonInstance.popularity:
                MastodonInstance.popularity * 40 / biggest_instance.popularity
        })

    db.session.commit()


@app.task
def queue_deletes():
    eligible_accounts = (
            Account.query.filter(Account.policy_enabled == True)  # noqa: E712
            .filter(Account.next_delete < db.func.now()))
    for account in eligible_accounts:
        delete_from_account.s(account.id).apply_async()


@app.task(autoretry_for=(TwitterError, URLError, MastodonRatelimitError))
def delete_from_account(account_id):
    account = Account.query.get(account_id)
    latest_n_posts = (Post.query.with_parent(account)
                      .order_by(db.desc(Post.created_at))
                      .limit(account.policy_keep_latest)
                      .cte(name='latest'))
    posts = (
        Post.query.with_parent(account)
        .filter(
            Post.created_at + account.policy_keep_younger <= db.func.now())
        .filter(~Post.id.in_(db.select((latest_n_posts.c.id,))))
        .order_by(db.func.random())
        .limit(100).with_for_update().all())

    to_delete = None

    action = noop
    if account.service == 'twitter':
        action = lib.twitter.delete
        posts = refresh_posts(posts)
        if posts:
            eligible = list((  # nosec
                post for post in posts if
                (not account.policy_keep_favourites or not post.favourite)
                and (not account.policy_keep_media or not post.has_media)
                ))
            if eligible:
                to_delete = random.choice(eligible)
    elif account.service == 'mastodon':
        action = lib.mastodon.delete
        for post in posts:
            refreshed = refresh_posts((post,))
            if refreshed and \
               (not account.policy_keep_favourites or not post.favourite) \
               and (not account.policy_keep_media or not post.has_media)\
               and (not account.policy_keep_direct or not post.direct):
                to_delete = refreshed[0]
                break

    if to_delete:
        print("deleting {}".format(to_delete))
        account.touch_delete()
        action(to_delete)

    db.session.commit()


def refresh_posts(posts):
    posts = list(posts)
    if len(posts) == 0:
        return []

    if posts[0].service == 'twitter':
        return lib.twitter.refresh_posts(posts)
    elif posts[0].service == 'mastodon':
        return lib.mastodon.refresh_posts(posts)


@app.task(autoretry_for=(TwitterError, URLError),
          throws=(MastodonRatelimitError))
def refresh_account(account_id):
    account = Account.query.get(account_id)

    limit = 100
    if account.service == 'mastodon':
        limit = 5
    posts = (Post.query.with_parent(account)
             .order_by(db.asc(Post.updated_at)).limit(limit).all())

    posts = refresh_posts(posts)
    account.touch_refresh()
    db.session.commit()


@app.task(autoretry_for=(TwitterError, URLError),
          throws=(MastodonRatelimitError))
def refresh_account_with_oldest_post():
    post = (Post.query.outerjoin(Post.author).join(Account.tokens)
            .group_by(Post).order_by(db.asc(Post.updated_at)).first())
    refresh_account(post.author_id)


@app.task(autoretry_for=(TwitterError, URLError),
          throws=(MastodonRatelimitError))
def refresh_account_with_longest_time_since_refresh():
    acc = (Account.query.join(Account.tokens).group_by(Account)
           .order_by(db.asc(Account.last_refresh)).first())
    refresh_account(acc.id)


app.add_periodic_task(6*60, periodic_cleanup)
app.add_periodic_task(45, queue_fetch_for_most_stale_accounts)
app.add_periodic_task(45, queue_deletes)
app.add_periodic_task(90, refresh_account_with_oldest_post)
app.add_periodic_task(90, refresh_account_with_longest_time_since_refresh)

if __name__ == '__main__':
    app.worker_main()