Webhooks

from contextlib import closing
from http import HTTPStatus
from pathlib import Path
import secrets
import sqlite3
from typing import Annotated
from uuid import UUID

from fastapi import FastAPI, Header, HTTPException, Response
from pydantic import BaseModel, Field, JsonValue, SecretStr
from pydantic_settings import BaseSettings


class CallEvent(BaseModel):
    call_id: UUID
    payload: dict[str, JsonValue]


class ReceiverSettings(BaseSettings):
    secret: SecretStr = Field(alias="SARJ_WEBHOOK_SECRET", min_length=1)
    database: Path = Field(alias="SARJ_WEBHOOK_DB_PATH")


def create_app(*, secret: str, database: Path) -> FastAPI:
    if not secret:
        message = "Configure a non-empty webhook credential"
        raise ValueError(message)

    with closing(sqlite3.connect(database, timeout=1)) as connection, connection:
        connection.execute(
            "CREATE TABLE IF NOT EXISTS webhook_inbox (call_id TEXT PRIMARY KEY, body TEXT NOT NULL, processed_at TEXT)"
        )

    app = FastAPI()

    @app.post("/webhooks/sarj", status_code=HTTPStatus.NO_CONTENT)
    def receive(
        event: CallEvent,
        authorization: Annotated[str | None, Header()] = None,
    ) -> Response:
        if authorization is None or not secrets.compare_digest(authorization.encode(), f"Bearer {secret}".encode()):
            raise HTTPException(status_code=HTTPStatus.UNAUTHORIZED, detail="Invalid webhook credential")

        with closing(sqlite3.connect(database, timeout=1)) as connection, connection:
            connection.execute(
                "INSERT INTO webhook_inbox (call_id, body) VALUES (?, ?) ON CONFLICT(call_id) DO NOTHING",
                (str(event.call_id), event.model_dump_json()),
            )
        return Response(status_code=HTTPStatus.NO_CONTENT)

    return app


def configured_app() -> FastAPI:
    settings = ReceiverSettings.model_validate({})
    return create_app(
        secret=settings.secret.get_secret_value(),
        database=settings.database,
    )