from celery import Celery

from app import app as flaskapp
from app import db
from model import Session, Account, TwitterArchive, Post
import lib.twitter
from twitter import TwitterError
from urllib.error import URLError
from datetime import timedelta, datetime
from zipfile import ZipFile
from io import BytesIO, TextIOWrapper
import json
from kombu import Queue
import random

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'

@app.task(autoretry_for=(TwitterError, URLError))
def fetch_acc(id, cursor=None):
    acc = Account.query.get(id)
    print(f'fetching {acc}')
    try:
        if(acc.service == 'twitter'):
            cursor = lib.twitter.fetch_acc(acc, cursor, **flaskapp.config.get_namespace("TWITTER_"))
            if cursor:
                fetch_acc.si(id, cursor).apply_async()
    finally:
        db.session.rollback()
        acc.last_fetch = db.func.now()
        db.session.commit()

@app.task
def queue_fetch_for_most_stale_accounts(min_staleness=timedelta(minutes=5), limit=20):
    accs = Account.query\
            .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()
        acc.touch_fetch()
    db.session.commit()

@app.task
def chunk_twitter_archive(archive_id):
    ta = TwitterArchive.query.get(archive_id)

    with ZipFile(BytesIO(ta.body), 'r') as zipfile:
        files = [filename for filename in zipfile.namelist() if filename.startswith('data/js/tweets/') and filename.endswith('.js')]

    files.sort()

    ta.chunks = len(files)
    db.session.commit()

    for filename in files:
        import_twitter_archive_month.s(archive_id, filename).apply_async()


@app.task
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():
    Session.query.filter(Session.updated_at < (db.func.now() - timedelta(hours=48))).\
            delete(synchronize_session=False)
    TwitterArchive.query.filter(TwitterArchive.updated_at < (db.func.now() - timedelta(days=7))).\
            delete(synchronize_session=False)
    db.session.commit()


@app.task
def queue_deletes():
    eligible_accounts = Account.query.filter(Account.policy_enabled == True).\
            filter(Account.last_delete + Account.policy_delete_every < db.func.now())
    for account in eligible_accounts:
        delete_from_account.s(account.id).apply_async()

@app.task
def delete_from_account(account_id):
    account = Account.query.get(account_id)
    latest_n_posts = db.session.query(Post.id).with_parent(account).order_by(db.desc(Post.created_at)).limit(account.policy_keep_latest)
    posts = Post.query.with_parent(account).\
        filter(Post.created_at + account.policy_keep_younger <= db.func.now()).\
        filter(~Post.id.in_(latest_n_posts)).\
        order_by(db.func.random()).limit(100).all()

    posts = refresh_account(account_id)
    if account.service == 'twitter':
        eligible = list((post for post in posts if not account.policy_keep_favourites or not post.favourite))
        if eligible:
            if account.policy_delete_every == timedelta(0):
                print("deleting all {} eligible posts for {}".format(len(eligible), account))
                for post in eligible:
                    lib.twitter.delete(post)
            else:
                post = random.choice(list((post for post in posts if not account.policy_keep_favourites or not post.favourite)))
                print("deleting {}".format(post))
                lib.twitter.delete(post)
                account.touch_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)

@app.task
def refresh_account(account_id):
    account = Account.query.get(account_id)

    oldest_post = Post.query.with_parent(account).order_by(db.asc(Post.updated_at)).first()

    if not oldest_post:
        return []

    posts = Post.query.with_parent(account).filter(Post.id != oldest_post.id).order_by(db.func.random()).limit(99).all()
    posts.append(oldest_post)

    posts = refresh_posts(posts)
    db.session.commit()
    return posts

@app.task
def refresh_account_with_oldest_post():
    post = Post.query.options(db.joinedload(Post.author)).order_by(db.asc(Post.updated_at)).first()
    return refresh_account(post.author_id)

app.add_periodic_task(6*60*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(30*60, refresh_account_with_oldest_post)

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