File manager

#!/opt/cloudlinux/venv/bin/python3 -bb
# coding=utf-8
#
# Copyright © Cloud Linux GmbH & Cloud Linux Software, Inc 2010-2020 All Rights Reserved
#
# Licensed under CLOUD LINUX LICENSE AGREEMENT
# http://cloudlinux.com/docs/LICENCE.TXT
#

import os
import contextlib
import sqlite3

from datetime import datetime, timedelta
from sqlalchemy import (
    Column,
    Boolean,
    DateTime,
    Integer,
    String,
    create_engine,
    event
)
from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy.engine.reflection import Inspector
from sqlalchemy.orm import Session

from wmt.common.const import WMT_DB, RETENTION_TIME_DAYS

Base = declarative_base()


class ScrapeResult(Base):
    """
    created_date is saved in local TZ format
    """
    __tablename__ = 'scrape_result'

    id = Column(Integer, primary_key=True)
    website = Column(String)
    create_date = Column(DateTime, default=lambda: datetime.now(), index=True)

    is_finished = Column(Boolean)

    response_code = Column(Integer, nullable=True)
    response_time_ms = Column(Integer, nullable=True)


class DomainAlerts(Base):
    """
    alert_time is saved in local TZ format
    """
    __tablename__ = 'domain_alerts'

    id = Column(Integer, primary_key=True)
    website = Column(String, index=True)
    alert_time = Column(DateTime, default=lambda: datetime.now(), index=True)

    is_resolved = Column(Boolean, default=False)


def cleanup_old_data(engine):
    n_days_ago = datetime.today() - timedelta(days=RETENTION_TIME_DAYS)
    with session_scope(engine) as session:
        session.query(ScrapeResult)\
            .filter(ScrapeResult.create_date < n_days_ago)\
            .delete()
        session.query(DomainAlerts)\
            .filter(DomainAlerts.alert_time < n_days_ago)\
            .delete()


def create_db_if_not_exist(engine):
    if not is_db_present(engine):
        Base.metadata.create_all(engine)


def is_db_present(engine):
    if not os.path.isfile(WMT_DB):
        return False
    database_inspection = Inspector.from_engine(engine)
    tables = [table for table in database_inspection.get_table_names()]
    return len(tables) > 0


def setup_wal_mode(dbapi_con, con_record):
    dbapi_con.execute('PRAGMA journal_mode = WAL')


def setup_database(readonly=False):
    connection_string = f'file:{WMT_DB}'
    if readonly:
        connection_string = f'{connection_string}?mode=ro'
    creator = lambda: sqlite3.connect(connection_string, uri=True)
    engine = create_engine(
        'sqlite:////', creator=creator, echo=False,
    )
    event.listen(engine, 'connect', setup_wal_mode)
    create_db_if_not_exist(engine)
    return engine


@contextlib.contextmanager
def session_scope(engine) -> Session:
    """Provide a transactional scope around a series of operations."""
    session = Session(bind=engine)
    try:
        yield session
        session.commit()
    except:
        session.rollback()
        raise
    finally:
        session.close()