"""Effective method contract — primary + composition modifier (AP2.4)."""

from __future__ import annotations

from steering.methods.registry import get_method

PLAN_PHASE_MODIFIER_KEY = "agile_iteration"


def resolve_effective_steering_elements(
    primary_method_key: str,
    *,
    data_slices: list[str],
    active_composition_modifier: str | None,
) -> frozenset[str]:
    """
    Primärmethode + aktiver Modifier; Plan-Phase: agile_iteration wenn work_cycles
    Slice aktiv und Methode komponierbar (Epic-Planung vor aktivem Sprint).
    """
    primary = get_method(primary_method_key)
    elements: set[str] = set(primary.steering_elements if primary else [])

    modifier_keys: list[str] = []
    if active_composition_modifier:
        modifier_keys.append(active_composition_modifier)
    elif "work_cycles" in data_slices:
        agile = get_method(PLAN_PHASE_MODIFIER_KEY)
        if agile and primary_method_key in agile.composes_with:
            modifier_keys.append(PLAN_PHASE_MODIFIER_KEY)

    for modifier_key in modifier_keys:
        modifier = get_method(modifier_key)
        if modifier:
            elements.update(modifier.steering_elements)

    return frozenset(elements)