"""브라우저용 세션 projection이 공유하는 순수 도우미."""

from __future__ import annotations

from datetime import datetime, timezone
from typing import cast

from .services import state_machine
from .stage_contract import StageLabel, stage_label as _normalize_stage_label
from .store import InProcSession, TurnRecord

LEARNER_VISIBLE_AI_ROLE = "counselor"

# 전 주기(라포→정리) 기준 라포 만점: 마지막 전이 임계(개입→정리)를 100으로 본다.
_FULL_CYCLE_RAPPORT = max(state_machine.STAGE_ADVANCE_RAPPORT.values())


def stage_label(stage: object) -> StageLabel:
    return cast(StageLabel, _normalize_stage_label(stage))


def iso(ts: float | None) -> str | None:
    if ts is None:
        return None
    return datetime.fromtimestamp(ts, tz=timezone.utc).isoformat(timespec="seconds")


def learner_visible_turns(sess: InProcSession) -> list[TurnRecord]:
    return sess.turns_visible_to(LEARNER_VISIBLE_AI_ROLE)


def _rapport_percent(credit: float) -> int:
    if _FULL_CYCLE_RAPPORT <= 0:
        return 0
    return max(0, min(100, int(round(float(credit or 0.0) / _FULL_CYCLE_RAPPORT * 100))))