site/backend/app/models.py

import os
from datetime import datetime, timezone
from typing import Optional
import sqlalchemy as sa
import sqlalchemy.orm as so
from werkzeug.security import generate_password_hash, check_password_hash
import pydenticon, hashlib, base64

from app import db, login
from flask_login import UserMixin

followers = sa.Table(
        'followers',
        db.metadata,
        sa.Column('follower_id', sa.Integer, sa.ForeignKey('user.id'), primary_key=True),
        sa.Column('followed_id', sa.Integer, sa.ForeignKey('user.id'), primary_key=True)
)

class User(UserMixin, db.Model):
    id: so.Mapped[int] = so.mapped_column(primary_key=True)
    username: so.Mapped[str] = so.mapped_column(sa.String(64), index=True, unique=True)
    email: so.Mapped[str] = so.mapped_column(sa.String(120), index=True, unique=True)
    password_hash: so.Mapped[Optional[str]] = so.mapped_column(sa.String(256))
    posts: so.WriteOnlyMapped['Post'] = so.relationship(back_populates='author')
    about_me: so.Mapped[Optional[str]] = so.mapped_column(sa.String(140))
    last_seen: so.Mapped[Optional[datetime]] = so.mapped_column(default=lambda: datetime.now(timezone.utc))
    following: so.WriteOnlyMapped['User'] = so.relationship(
            secondary=followers,
            primaryjoin=(followers.c.follower_id == id),
            secondaryjoin=(followers.c.followed_id == id),
            back_populates='followers')
    followers: so.WriteOnlyMapped['User'] = so.relationship(
            secondary=followers,
            primaryjoin=(followers.c.followed_id == id),
            secondaryjoin=(followers.c.follower_id == id),
            back_populates='following')

    def set_password(self, password):
        self.password_hash = generate_password_hash(password)
    def check_password(self, password):
        return check_password_hash(self.password_hash, password)
    def gen_avatar(self, write_png=True):
        foreground = [ "rgb(45,79,255)",
               "rgb(254,180,44)",
               "rgb(226,121,234)",
               "rgb(30,179,253)",
               "rgb(232,77,65)",
               "rgb(49,203,115)",
               "rgb(141,69,170)" ]
        background = "rgb(22,22,22)"

        digest = hashlib.md5(self.email.lower().encode('utf-8')).hexdigest()
        basedir = os.path.abspath(os.path.dirname(__file__))
        pngloc = os.path.join(basedir, 'usercontent', 'identicon', str(digest) + '.png')
        icongen = pydenticon.Generator(5, 5, digest=hashlib.md5, foreground=foreground, background=background)
        pngicon = icongen.generate(self.email, 120, 120, padding=(10, 10, 10, 10), inverted=False, output_format="png")
        if write_png:
            pngfile = open(pngloc, "wb")
            pngfile.write(pngicon)
            pngfile.close()
        else:
            return str(base64.b64encode(pngicon))[2:-1]
    def avatar_path(self):
        digest = hashlib.md5(self.email.lower().encode('utf-8')).hexdigest()
        basedir = os.path.abspath(os.path.dirname(__file__))
        pngloc = os.path.join(basedir, 'usercontent', 'identicon', digest + '.png')
        return pngloc

    def follow(self, user):
        if not self.is_following(user):
            self.following.add(user)
    def unfollow(self, user):
        if self.is_following(user):
            self.following.remove(user)
    def is_following(self, user):
        query = self.following.select().where(User.id == user.id)
        return db.session.scalar(query) is not None
    def followers_count(self):
        query = sa.select(sa.func.count()).select_from(self.followers.select().subquery())
        return db.session.scalar(query)
    def following_count(self):
        query = sa.select(sa.func.count()).select_from(self.following.select().subquery())
        return db.session.scalar(query)
    def following_posts(self):
        Author = so.aliased(User)
        Follower = so.aliased(User)
        return (
                sa.select(Post)
                .join(Post.author.of_type(Author))
                .join(Author.followers.of_type(Follower), isouter=True)
                .where(sa.or_(
                    Follower.id == self.id
                    Author.id == self.id
                ))
                .group_by(Post)
                .order_by(Post.timestamp.desc())
        )

    def __repr__(self):
        return '<User {}>'.format(self.username)

class Post(db.Model):
    id: so.Mapped[int] = so.mapped_column(primary_key=True)
    body: so.Mapped[str] = so.mapped_column(sa.String(140))
    timestamp: so.Mapped[datetime] = so.mapped_column(index=True, default=lambda: datetime.now(timezone.utc))
    user_id: so.Mapped[int] = so.mapped_column(sa.ForeignKey(User.id), index=True)
    author: so.Mapped[User] = so.relationship(back_populates='posts')

    def __repr__(self):
        return '<Post {}>'.format(self.body)


@login.user_loader
def load_user(id):
    return db.session.get(User, int(id))