"""The Fluksio engine, and the decorators that declare flows in your own code.

Two audiences, one import name. In a research repository, ``from fluksio
import Port, node, Flow`` is the authoring API: it says which of your existing
functions are nodes and which nodes make up a flow, and ``fluksio sync``
uploads what it finds. Those names come from :mod:`fluksio.sdk`, which imports
nothing but the standard library.

Inside a node, ``import fluksio`` is not this package at all: the worker
installs a reporter of its own under that name before any node code runs, so
what a node gets is :mod:`fluksio_worker.worker_main`'s ``emit`` and
``save_artifact`` — and inert copies of the decorators, since a module the
node imports may well declare them at its top. The stubs below stand in the
same place everywhere else, and say so rather than failing as a missing
attribute.

Nothing is imported from the rest of the package here. Every ``from fluksio.x
import y`` in the engine passes through this module, and an import cycle or a
second of start-up cost would both begin here.
"""

import logging
from importlib.metadata import PackageNotFoundError
from importlib.metadata import version as _version
from typing import Any

from fluksio.sdk import Flow, Port, node, use

try:
    __version__ = _version("fluksio")
except PackageNotFoundError:  # pragma: no cover - a checkout that was never installed
    __version__ = "0.0.0+unknown"

__all__ = [
    "Flow",
    "Port",
    "emit",
    "load_artifact",
    "node",
    "save_artifact",
    "use",
]

logger = logging.getLogger(__name__)

_OUTSIDE = (
    "fluksio.{name}() only works inside a node: the worker running it installs "
    "the real one. There is nothing to {verb} out here."
)


def emit(**ports: Any) -> None:
    """Publish values on a node's declared output ports, mid-run.

    Outside a node there is nowhere to publish to, and this does nothing on
    purpose: a node function called directly — in a test, in a notebook, under
    a debugger — is ordinary Python, and having it die on a progress report
    would defeat the point of the code staying yours.
    """
    logger.debug("fluksio.emit(%s) outside a node", ", ".join(ports))


def save_artifact(
    source: Any,
    name: str = "",
    media_type: str = "application/octet-stream",
    volatile: bool = False,
) -> dict[str, Any]:
    """Put bytes in the artifact store and return a reference to them."""
    raise RuntimeError(_OUTSIDE.format(name="save_artifact", verb="save to"))


def load_artifact(ref: dict[str, Any]) -> str:
    """Fetch what an artifact reference points at, and return a path to it."""
    raise RuntimeError(_OUTSIDE.format(name="load_artifact", verb="load from"))