app/backend/fluksio/api/routes/cloud.py

"""Connecting this instance to a Fluksio portal, and cutting it loose.

Entirely optional, and superuser-only to change: enrolling grants a remote
party the rights of the account that performed it, which is not a decision an
ordinary user of this instance gets to make on everyone else's behalf.

Admitting further portal accounts is the same decision made again, so it is
guarded the same way. A person let in this way gets an ordinary local account
of their own — never a superuser, so they cannot admit anyone else, and the
chain stops with whoever a superuser here typed a code for.
"""

from __future__ import annotations

import logging
import secrets
from typing import Any

import httpx
from fastapi import APIRouter, Depends, HTTPException, Request
from fastapi.concurrency import run_in_threadpool
from pydantic import BaseModel, Field
from sqlmodel import select

from fluksio import crud
from fluksio.api.deps import (
    CurrentUser,
    SessionDep,
    get_current_active_superuser,
    get_current_user,
)
from fluksio.cloud import config as cloud_config
from fluksio.cloud import enroll as enroll_mod
from fluksio.core.security import get_password_hash
from fluksio.models import Message, User, UserPublic

logger = logging.getLogger(__name__)

router = APIRouter(prefix="/cloud", tags=["cloud"])


class EnrollBody(BaseModel):
    #: Where the portal's API lives, e.g. https://hub.fluksio.com
    portal_url: str = Field(min_length=1, max_length=255)
    claim_code: str = Field(min_length=1, max_length=32)


@router.get("/status", dependencies=[Depends(get_current_user)])
def read_status(request: Request) -> dict[str, Any]:
    """Whether this instance is enrolled, and whether the link is up.

    Readable by any signed-in user: everyone here has a right to know whether
    the machine they are using can be reached from outside.
    """
    connector = getattr(request.app.state, "cloud_connector", None)
    if connector is None:
        config = cloud_config.load()
        return {
            "enrolled": config is not None,
            "connected": False,
            "portal_url": config.portal_url if config else None,
            "issuer": config.issuer if config else None,
            "portal_account": config.portal_account if config else None,
            "instance_id": config.instance_id if config else None,
            "last_error": None,
            "connected_since": None,
        }
    status: dict[str, Any] = connector.status()
    return status


@router.post(
    "/enroll",
    dependencies=[Depends(get_current_active_superuser)],
    response_model=Message,
)
async def enroll(
    request: Request, session: SessionDep, current_user: CurrentUser, body: EnrollBody
) -> Message:
    """Redeem a claim code and start dialling the portal.

    The account performing this is mapped to the portal account that owns the
    instance, so the owner's portal sessions arrive here as them. Widening
    that to anyone else is a local decision made one person at a time, below —
    never something the portal can do from its side.

    The same work as `fluksio enroll` on the command line, which is how a
    machine with no browser pointed at it does this.
    """
    try:
        await run_in_threadpool(
            enroll_mod.enroll, session, current_user, body.portal_url, body.claim_code
        )
    except enroll_mod.EnrollError as exc:
        raise HTTPException(status_code=exc.status, detail=exc.detail) from exc

    _start_connector(request.app)
    return Message(message="Connected to the portal")


class RemoteUserBody(BaseModel):
    #: The code the person wanting in minted on their portal account.
    code: str = Field(min_length=1, max_length=32)


@router.post(
    "/users",
    dependencies=[Depends(get_current_active_superuser)],
    response_model=UserPublic,
)
def add_remote_user(session: SessionDep, body: RemoteUserBody) -> Any:
    """Admit a portal account, and give it a local user of its own.

    The point of the local user is that it is ordinary: a remote person shows
    up in Admin → Users like everyone else, holds no superuser flag, and is
    removed by deleting them there. They have no password because they never
    sign in here — the portal vouches for them, and this row is what says which
    of our accounts that vouching amounts to.
    """
    config = cloud_config.load()
    if config is None:
        raise HTTPException(
            status_code=409,
            detail="This instance is not connected to a portal",
        )
    try:
        response = httpx.post(
            f"{config.portal_url.rstrip('/')}/api/v1/instance-members/",
            headers={"Authorization": f"Bearer {config.token}"},
            json={"code": body.code.strip()},
            timeout=15.0,
        )
    except httpx.HTTPError as exc:
        raise HTTPException(
            status_code=502, detail=f"Could not reach the portal: {exc}"
        ) from exc
    if response.status_code == 404:
        raise HTTPException(
            status_code=400, detail="That code is unknown or has expired"
        )
    if response.status_code == 409:
        raise HTTPException(
            status_code=409, detail="That code belongs to this instance's owner"
        )
    if response.status_code != 200:
        raise HTTPException(
            status_code=502,
            detail=f"The portal refused the code ({response.status_code})",
        )

    data = response.json()
    portal_sub = str(data["user_id"])
    email = str(data["email"])
    existing = session.exec(select(User).where(User.portal_sub == portal_sub)).first()
    if existing is not None:
        raise HTTPException(
            status_code=409, detail=f"{existing.email} already has access"
        )
    if crud.get_user_by_email(session=session, email=email) is not None:
        # Never quietly hand an existing local account — possibly a superuser's
        # — to whoever holds that address on the portal.
        raise HTTPException(
            status_code=409, detail="A local user with this email already exists"
        )
    user = User(
        email=email,
        # Unusable by construction: this account is reached through the portal
        # or not at all. Password recovery would issue one, which is a gap
        # worth closing the day local sign-in for these accounts is wanted.
        hashed_password=get_password_hash(secrets.token_urlsafe(32)),
        is_superuser=False,
        is_active=True,
        portal_sub=portal_sub,
    )
    session.add(user)
    session.commit()
    session.refresh(user)
    return user


def forget_remote_user(portal_sub: str) -> None:
    """Tell the portal a remote user is gone from here.

    Best effort on purpose: the local account is what grants access, so it is
    already over by the time this runs. A portal that cannot be reached keeps a
    row that opens nothing — the instance refuses the session either way.
    """
    config = cloud_config.load()
    if config is None:
        return
    try:
        response = httpx.delete(
            f"{config.portal_url.rstrip('/')}/api/v1/instance-members/{portal_sub}",
            headers={"Authorization": f"Bearer {config.token}"},
            timeout=15.0,
        )
    except httpx.HTTPError as exc:
        logger.warning("Could not drop %s at the portal: %s", portal_sub, exc)
        return
    if response.status_code != 200:
        logger.warning(
            "The portal refused to drop %s (%s)", portal_sub, response.status_code
        )


@router.delete(
    "", dependencies=[Depends(get_current_active_superuser)], response_model=Message
)
def disconnect(request: Request) -> Message:
    """Sever the connection from this side.

    Unilateral and immediate: the config is the only reason portal tokens
    verify here, so deleting it ends remote access whatever the portal still
    has on file.
    """
    task = getattr(request.app.state, "cloud_task", None)
    if task is not None:
        task.cancel()
        request.app.state.cloud_task = None
    request.app.state.cloud_connector = None
    cloud_config.delete()
    return Message(message="Disconnected from the portal")


def _start_connector(app: Any) -> None:
    from fluksio.cloud.connector import start

    start(app)