in-c4/main.py

import re
import time

from fastapi import Depends, FastAPI, Response
from fastapi.staticfiles import StaticFiles
from sqlalchemy import event
from sqlalchemy.engine import Engine
from sqlalchemy.orm import Session

import crud
from database import SessionLocal, engine
from models import Base
from schemas import Item

Base.metadata.create_all(bind=engine)

app = FastAPI()


def get_db():
    db = SessionLocal()
    try:
        yield db
    finally:
        db.close()


@event.listens_for(Engine, "connect")
def _set_sqlite_pragma(conn, _):
    cursor = conn.cursor()
    cursor.execute("PRAGMA foreign_keys=ON;")
    cursor.close()


@app.get("/api/items", response_model=dict[str, Item])
async def list_items(db: Session = Depends(get_db)):
    # natural sort by id
    natsort = lambda item: [
        int(t) if t.isdigit() else t.lower() for t in re.split("(\d+)", item.id)
    ]
    items = crud.get_items(db)
    items = sorted(items, key=natsort)
    return {i.id: i for i in items}


@app.put("/api/items/{id}")
async def put_item(id: str, item: Item, db: Session = Depends(get_db)):
    if item.last_updated is None:
        item.last_updated = rough_timestamp()
    if crud.put_item(db, id, item) == crud.PutItemResult.UPDATED:
        return Response(b"", status_code=204)
    return Response(b"", status_code=201)


@app.delete("/api/items/{id}", status_code=204)
async def delete_item(id: str, db: Session = Depends(get_db)):
    crud.delete_item(db, id)


def rough_timestamp() -> int:
    """Provides an current timestamp with reduced resolution, to improve anonymity."""
    granularity = 2**20  # about 12 days
    return int(time.time()) // granularity * granularity


app.mount("/", StaticFiles(directory="static", html=True), name="static")