scrap-is-not-scrap/sins/orm.py

#!/usr/bin/env python3
from datetime import datetime
from hashlib import sha1
from pathlib import Path
from sqlalchemy import LargeBinary, Column, ForeignKey, Integer, String, DateTime, create_engine
from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy.orm import Session, relationship, backref
from sqlalchemy.orm.collections import attribute_mapped_collection

now = '{0:%Y%m%dT%H%M%S}'.format(datetime.utcnow())
Base = declarative_base()


def db_config(path: Path) -> Session:
    engine = create_engine(f'sqlite:///{path.resolve()}', native_datetime=True)
    Base.metadata.create_all(engine)
    session = Session(engine)
    return session


class ScrapNode(Base):
    __tablename__ = 'scrap_node'
    ctime = Column(DateTime, default=datetime.utcnow)
    id = Column(Integer, primary_key=True)
    length = Column(Integer, default=0)
    mtime = Column(DateTime, onupdate=datetime.utcnow)
    parent_id = Column(Integer, ForeignKey(id))
    checksum = Column(String)
    objdump = Column(String)
    image = Column(LargeBinary)

    children = relationship(
        "ScrapNode",
        cascade="all, delete-orphan",
        backref=backref("parent", remote_side=id),
        collection_class=attribute_mapped_collection('name'))

    def __init__(self, *, child: bytes, parent_id: int = None):
        self.parent_id = parent_id
        self.image = child
        self.length = len(child)
        self.sha1sum

    def __repr__(self):
        values = {
            'checksum': self.checksum,
            'length': self.length,
            'parent_id': self.parent_id,
            'id': self.id,
        }

        return f'{values}\n{self.objdump}'

    @property
    def sha1sum(self):
        if self.checksum:
            return self.checksum

        checksum = sha1()
        checksum.update(self.image)
        self.checksum = checksum.hexdigest()

        return self.checksum