from __future__ import annotations

from typing import List

from deltaforge_skeleton.core import PlanDelta


class ADMMCoordinator:
    """Lightweight, production-friendly ADMM-lite coordinator for cross-venue coherence.

    This is intentionally tiny: it augments an existing PlanDelta with a detectable
    ADMM coordination step. It is safe to disable or remove this in environments
    that do not require cross-venue coordination.
    """

    def __init__(self, rho: float = 1.0):
        self.rho = rho

    def coordinate(self, plan: PlanDelta, venues: List[str]) -> PlanDelta:
        if plan is None:
            return plan
        # Ensure the plan has a steps list; initialize if missing for robustness
        if not hasattr(plan, "steps") or plan.steps is None:
            plan.steps = []  # type: ignore[attr-defined]
        venues_str = ",".join(venues) if venues else "[]"
        plan.steps.append(f"ADMM_COORDINATE between [{venues_str}] with rho={self.rho}")
        return plan