"""The python packages node code may import.

A manifest in the flow store, a venv on the data volume, and one button that
brings the second in line with the first. Nothing here restarts the engine:
the worker pool retires its processes, and the next node call picks up the new
packages.
"""

import time
from typing import Any

from fastapi import APIRouter, Depends, HTTPException
from fastapi.concurrency import run_in_threadpool

from fluksio.api.deps import (
    CurrentUser,
    FlowControllerDep,
    WorkerPoolDep,
    get_current_user,
)
from fluksio.flow import modules
from fluksio.flow.events import event_bus
from fluksio.flow.schemas import ApplyRequest, ApplyResult, ModulesInfo
from fluksio.models import Message

router = APIRouter(
    prefix="/modules", tags=["modules"], dependencies=[Depends(get_current_user)]
)


@router.get("/", response_model=ModulesInfo)
async def read_modules(controller: FlowControllerDep) -> Any:
    """What node code can import, and whether it matches the manifest."""
    return await run_in_threadpool(modules.info, controller.store)


@router.post("/apply", response_model=ApplyResult)
async def apply_modules(
    body: ApplyRequest,
    controller: FlowControllerDep,
    pool: WorkerPoolDep,
    user: CurrentUser,
) -> Any:
    """Install exactly these requirements, then hand them to the workers.

    A manifest that does not resolve changes nothing: the venv is left as it
    was and the stored manifest is only written once the install succeeded.

    Only the flows already holding a node that would not load are rebuilt,
    because those are the ones an install is called to fix. A flow that this
    install *breaks* — a package taken back out from under it — is still green
    and fails at call time with the node author's own import error, until
    something rebuilds it.
    """
    ok, output = await run_in_threadpool(modules.sync, body.requirements)
    if not ok:
        raise HTTPException(
            status_code=400,
            detail=output or "These requirements could not be installed",
        )
    await run_in_threadpool(controller.store.write_requirements, body.requirements)
    event_bus.publish(
        {
            "type": "audit",
            "action": "installed modules",
            "flow": "",
            "user": user.email,
            "ts": time.time(),
        }
    )
    # Retire the workers first, so the rebuild compiles every node against the
    # packages that were just installed — a node that could not import one is
    # the reason this was called, and it stays red until it is built again.
    await _retire(controller, pool)
    return ApplyResult(ok=True, output=output)


@router.post("/refresh", response_model=Message)
async def refresh_modules(
    controller: FlowControllerDep,
    pool: WorkerPoolDep,
    user: CurrentUser,
) -> Any:
    """Retire the workers without installing anything.

    A node that imports the caller's own package holds it in `sys.modules` for
    as long as the process lives, so editing that package changes nothing a
    running worker can see — recompiling the node would not help either, since
    the import returns the module already there. Retiring the processes is the
    whole of it, and `fluksio sync` asks for it after every upload.
    """
    event_bus.publish(
        {
            "type": "audit",
            "action": "refreshed workers",
            "flow": "",
            "user": user.email,
            "ts": time.time(),
        }
    )
    await _retire(controller, pool)
    return Message(message="Workers retired; the next call imports afresh")


async def _retire(controller: Any, pool: Any) -> None:
    """Send the worker processes away and rebuild whatever was broken."""
    pool.respawn_all()
    await controller.reload_failed_flows()