"""Egress apply for the smolmachines backend.

The smolmachines sidecar bundle runs as a sidecar smolVM. Route-file
inspection and reload signalling therefore go through ``smolvm machine
exec`` instead of Docker.
"""

from __future__ import annotations

from pathlib import Path

from ...bottle_state import egress_state_dir
from ...log import warn
from ..egress_apply import EgressApplicator, EgressApplyError
from . import sidecar_bundle as _bundle
from . import smolvm as _smolvm

# Routes file path inside the sidecar VM. Set via EGRESS_ROUTES env var
# at launch so the addon reads from the virtiofs-mounted confdir instead
# of the default /etc/egress/routes.yaml.
_EGRESS_ROUTES_IN_SIDECAR_VM = "/bot-bottle-data/egress/routes.yaml"


def fetch_current_routes(slug: str) -> str:
    machine = _bundle.bundle_machine_name(slug)
    result = _smolvm.machine_exec(machine, ["cat", _EGRESS_ROUTES_IN_SIDECAR_VM])
    if result.returncode != 0:
        raise EgressApplyError(
            f"could not read routes.yaml from {machine}: "
            f"{(result.stderr or '').strip() or 'sidecar VM not running?'}"
        )
    return result.stdout


class SmolmachinesEgressApplicator(EgressApplicator):
    @staticmethod
    def _routes_path(slug: str) -> Path:
        # Routes live in the smolvm-sidecar-data staging dir, which is
        # virtiofs-mounted at /bot-bottle-data/ in the sidecar VM. Writes
        # here are visible inside the VM immediately; a SIGHUP causes the
        # addon to reload from _EGRESS_ROUTES_IN_SIDECAR_VM.
        return egress_state_dir(slug) / "smolvm-sidecar-data" / "egress" / "routes.yaml"

    def _signal_bundle_reload(self, slug: str) -> None:
        machine = _bundle.bundle_machine_name(slug)
        result = _smolvm.machine_exec(machine, ["sh", "-c", "kill -HUP 1"])
        if result.returncode != 0:
            last_error = (result.stderr or "").strip() or (result.stdout or "").strip()
            warn(
                f"egress: routes updated on disk for {slug}, but bundle reload failed: "
                f"{last_error or 'smolvm exec failed'}"
            )
            raise EgressApplyError(
                f"could not reload egress bundle {machine}: "
                f"{last_error or 'smolvm exec failed'}"
            )


applicator = SmolmachinesEgressApplicator()


__all__ = [
    "SmolmachinesEgressApplicator",
    "EgressApplyError",
    "applicator",
    "fetch_current_routes",
]