"""Phase Z-2 retry_failure_classifier + next_action_router (A4 — 분류 / 매핑만).

A3 (zone_ratio_retry) 의 결과 (retry_trace) 를 받아 :
  1. **retry_failure_classifier** : 실패 type 을 4 종 중 하나로 분류
  2. **next_action_router**       : failure_type → next_proposed_action 매핑

본 module 은 ***분류 + 매핑까지만***. layout_adjust / frame_reselect / details_popup
실행 X. retry_trace 에 `failure_classification` + `next_action_proposal` 두 필드 추가.

**잠근 매핑** (사용자 잠금 — 2026-05-17, IMP-12 u3 cascade) :

| failure_type                            | next_proposed_action      |
|---|---|
| donor_slack_insufficient                | cross_zone_redistribute    |
| no_donor_candidates                     | cross_zone_redistribute    |
| cross_zone_redistribute_insufficient    | glue_compression           |
| glue_absorption_insufficient            | font_step_compression      |
| font_step_insufficient                  | layout_adjust              |
| rerender_still_fails                    | frame_reselect             |
| not_attempted                           | none                       |

**escalation 단계 hierarchy** (Step 17 deterministic salvage cascade → layout/frame) :
```
cross_zone_redistribute    (fit_verifier.redistribute — role-height adjustment)
  ↓ 그래도 안 되면
glue_compression           (SPACING_GLUE envelope, frame-scoped)
  ↓ 그래도 안 되면
font_step_compression      (FONT_SIZE_STEPS, zone-scoped)
  ↓ 그래도 안 되면
layout_adjust              (zone topology 변경)
  ↓ 그래도 안 되면
frame_reselect             (V4 top-k 의 다른 frame)
  ↓ 그래도 안 되면
details_popup_escalation   (가장 invasive — content popup, 마지막 resort)
```

`details_popup_escalation` 은 본 매핑에 *없음* — tabular_overflow / structural_major_overflow /
frame_reselect 실패 이후 단계에서 다룸 (별 step).
"""

from __future__ import annotations

from typing import Optional


# ─── §A4-1 failure_type registry ──────────────────────────────────

FAILURE_TYPE_DESCRIPTIONS: dict[str, str] = {
    "not_attempted": (
        "retry was not attempted (router_active=False or zone_ratio_retry "
        "not in proposed actions). 정상 path 의 일부 — 실패 X"
    ),
    "donor_slack_insufficient": (
        "primary donor 의 slack 이 target_added_px 보다 작음. 현재 layout 안 "
        "redistribution 한도 도달"
    ),
    "no_donor_candidates": (
        "donor 후보 자체 없음 — single layout / sibling visual fail / capacity "
        "mismatch / slack 0 등의 이유로 zone redistribution 불가"
    ),
    "rerender_still_fails": (
        "redistribution 실행 + rerender 까지 했는데도 visual_check 실패. "
        "현재 frame/zone 조합이 content 와 맞지 않음"
    ),
    "cross_zone_redistribute_insufficient": (
        "cross_zone_redistribute salvage step failed — fit_verifier.redistribute "
        "could not find a feasible role-height adjustment within the frame envelope"
    ),
    "glue_absorption_insufficient": (
        "glue_compression salvage step failed — frame envelope cannot absorb "
        "remaining overflow via SPACING_GLUE overrides (no global spacing shrink)"
    ),
    "font_step_insufficient": (
        "font_step_compression salvage step failed — FONT_SIZE_STEPS exhausted "
        "down to the floor without resolving overflow (or text_metrics missing)"
    ),
}


# ─── §A4-1b salvage_steps[-1].action → failure_type table ──────────
# u2 (IMP-12): _attempt_salvage_chain (u8) writes per-step records into
# retry_trace["salvage_steps"] with {action, passed, failure_reason}. classifier
# inspects salvage_steps[-1] so u3 can route 3 new types onto the cascade.

SALVAGE_FAILURE_TYPE_BY_ACTION: dict[str, str] = {
    "cross_zone_redistribute": "cross_zone_redistribute_insufficient",
    "glue_compression":        "glue_absorption_insufficient",
    "font_step_compression":   "font_step_insufficient",
}


# ─── §A4-2 next_action mapping (사용자 잠금) ──────────────────────

NEXT_ACTION_BY_FAILURE: dict[str, str] = {
    "donor_slack_insufficient":             "cross_zone_redistribute",
    "no_donor_candidates":                  "cross_zone_redistribute",
    "cross_zone_redistribute_insufficient": "glue_compression",
    "glue_absorption_insufficient":         "font_step_compression",
    "font_step_insufficient":               "layout_adjust",
    "rerender_still_fails":                 "frame_reselect",
    "not_attempted":                        "none",
}

NEXT_ACTION_RATIONALE: dict[str, str] = {
    "donor_slack_insufficient": (
        "primary donor slack 한도 도달 → cross_zone_redistribute 로 sibling zone "
        "전체 role-height 재분배 (fit_verifier.redistribute). layout 변경은 cascade 끝"
    ),
    "no_donor_candidates": (
        "단일 donor 후보 없음 → cross_zone_redistribute 로 role-height 전체 "
        "재할당 시도 (fit_verifier.redistribute). layout 변경은 cascade 끝"
    ),
    "cross_zone_redistribute_insufficient": (
        "role-height 재분배도 frame envelope 못 맞춤 → glue_compression "
        "(SPACING_GLUE frame-scoped) 으로 frame 내부 여백 축소"
    ),
    "glue_absorption_insufficient": (
        "frame 여백 envelope 도 부족 → font_step_compression "
        "(FONT_SIZE_STEPS zone-scoped) 으로 폰트 한 단계 축소"
    ),
    "font_step_insufficient": (
        "deterministic salvage cascade 모두 소진 → layout_adjust 로 zone "
        "topology 부터 재구성. frame_reselect 는 그 다음 단계"
    ),
    "rerender_still_fails": (
        "redistribution + rerender 까지 했는데도 visual fail → 현재 "
        "frame/zone 조합 자체 부적합, V4 top-k 의 다른 frame 평가 (frame_reselect). "
        "popup 직행은 아직 빠름 (tabular / structural_major 가 아닌 한)"
    ),
    "not_attempted": (
        "retry 시도 자체가 없었음 (visual ok 등) — escalation 불필요"
    ),
}

# 본 매핑이 가리키는 next action 들의 *현재 코드* 구현 상태
# IMP-12 u7 (2026-05-18): 3 cascade salvage actions registered as IMPLEMENTED.
# plan/apply pairs live in phase_z2_retry (u4/u5/u6); pipeline orchestrator wiring
# (_attempt_salvage_chain) lands in u8/u9. router-level mapping is decoupled from
# orchestrator wiring on purpose so route_retry_failure → impl_status reflects
# the deterministic surface availability, not whether a given pipeline run has
# already invoked it.
NEXT_ACTION_IMPLEMENTATION_STATUS: dict[str, str] = {
    "cross_zone_redistribute": "IMPLEMENTED",  # u4 plan_cross_zone_redistribute + apply_cross_zone_redistribute_css
    "glue_compression":        "IMPLEMENTED",  # u5 plan_glue_compression + apply_glue_compression_css
    "font_step_compression":   "IMPLEMENTED",  # u6 plan_font_step_compression + apply_font_step_compression_css
    "layout_adjust":           "MISSING",
    "frame_reselect":          "MISSING",
    "none":                    "n/a",
}


# ─── classifier ──────────────────────────────────────────────────


def classify_retry_failure(retry_trace: dict) -> Optional[dict]:
    """retry_trace → failure classification.

    Returns:
        None    : retry 가 *성공* 한 case (retry_passed=True). 분류할 failure 없음.
        dict    : {failure_type, classification_rule}
    """
    # case 0 : retry 성공 — failure 없음
    if retry_trace.get("retry_passed"):
        return None

    # case 0.5 : salvage chain 자체 성공 — failure 없음 (u8/u9 wiring)
    if retry_trace.get("salvage_passed"):
        return None

    # case 0.7 : salvage chain attempted and ended in a salvage-level failure.
    # zone_ratio_retry 가 먼저 실패한 뒤 _attempt_salvage_chain 이 가동된 path —
    # 마지막 salvage step 의 action 으로 failure_type 을 분류한다. u3 가 routing.
    salvage_steps = retry_trace.get("salvage_steps") or []
    if salvage_steps:
        last = salvage_steps[-1] or {}
        if not last.get("passed"):
            action = (last.get("action") or "").lower()
            ftype = SALVAGE_FAILURE_TYPE_BY_ACTION.get(action)
            if ftype is not None:
                reason = last.get("failure_reason") or ""
                return {
                    "failure_type": ftype,
                    "classification_rule": (
                        f"salvage_steps[-1].action == {action!r} "
                        f"AND passed=False. raw failure_reason: {reason!r}"
                    ),
                }

    # case 1 : retry 시도 자체 안 됨 (router_active=False 또는 다른 action)
    if not retry_trace.get("retry_attempted"):
        return {
            "failure_type": "not_attempted",
            "classification_rule": (
                "retry_attempted=False — router_active=False or zone_ratio_retry "
                "not in proposed_actions"
            ),
        }

    # case 2 : plan 단계 실패 (rerender 안 일어남)
    plan = retry_trace.get("plan") or {}
    if plan and not plan.get("feasible"):
        reason = (plan.get("failure_reason") or "")
        reason_lower = reason.lower()

        # donor slack insufficient — primary donor 가 있으나 slack 부족
        if (
            "primary donor" in reason_lower
            and "slack" in reason_lower
            and "target_added_px" in reason_lower
        ):
            return {
                "failure_type": "donor_slack_insufficient",
                "classification_rule": (
                    "plan.feasible=False AND failure_reason matches "
                    "'primary donor ... slack ... target_added_px ...'"
                ),
            }

        # no donor candidates — sibling 자체 없거나 모두 자격 미달
        if "no donor candidates" in reason_lower:
            return {
                "failure_type": "no_donor_candidates",
                "classification_rule": (
                    "plan.feasible=False AND failure_reason matches "
                    "'no donor candidates'"
                ),
            }

        # 위 두 패턴 미매칭 — 보수적으로 no_donor_candidates 로 분류
        # (donor 가 거의 모두 막힌 경우 와 구조적으로 비슷)
        return {
            "failure_type": "no_donor_candidates",
            "classification_rule": (
                f"plan.feasible=False, failure_reason did not match known patterns. "
                f"defaulting to 'no_donor_candidates'. raw failure_reason: {reason!r}"
            ),
        }

    # case 3 : plan feasible AND rerender 했는데 visual fail
    if retry_trace.get("rerender_attempted") and not retry_trace.get("retry_passed"):
        return {
            "failure_type": "rerender_still_fails",
            "classification_rule": (
                "plan.feasible=True AND rerender_attempted=True AND retry_passed=False"
            ),
        }

    # case 4 (defensive) : 어떤 case 에도 안 잡힘 — 보수적 fallback
    return {
        "failure_type": "not_attempted",
        "classification_rule": (
            "no failure pattern matched (defensive fallback). retry_trace 구조 "
            "예상과 다름 — 검토 필요"
        ),
    }


# ─── router ──────────────────────────────────────────────────────


def route_retry_failure(failure_type: str) -> dict:
    """failure_type → next_proposed_action mapping.

    Returns:
        dict :
          next_proposed_action
          next_action_rationale
          next_action_implementation_status
          mapping_source
    """
    next_action = NEXT_ACTION_BY_FAILURE.get(failure_type)
    if next_action is None:
        return {
            "next_proposed_action": None,
            "next_action_rationale": (
                f"failure_type '{failure_type}' has no mapping in NEXT_ACTION_BY_FAILURE"
            ),
            "next_action_implementation_status": "unknown",
            "mapping_source": "no mapping (unknown failure_type)",
        }
    return {
        "next_proposed_action": next_action,
        "next_action_rationale": NEXT_ACTION_RATIONALE.get(failure_type, ""),
        "next_action_implementation_status": NEXT_ACTION_IMPLEMENTATION_STATUS.get(
            next_action, "unknown"
        ),
        "mapping_source": "A4 NEXT_ACTION_BY_FAILURE (사용자 잠금 2026-05-17, IMP-12 u3 cascade)",
    }


# ─── enrichment wrapper ──────────────────────────────────────────


def enrich_retry_trace_with_failure_classification(retry_trace: dict) -> dict:
    """retry_trace 에 `failure_classification` + `next_action_proposal` 두 필드 추가.

    Mutates retry_trace in place AND returns it.

    retry_passed=True 인 경우 → 두 필드 모두 None (failure 없음, escalation 없음).
    """
    fc = classify_retry_failure(retry_trace)
    if fc is None:
        # retry succeeded — no failure to classify
        retry_trace["failure_classification"] = None
        retry_trace["next_action_proposal"] = None
        return retry_trace

    failure_type = fc["failure_type"]
    nr = route_retry_failure(failure_type)

    retry_trace["failure_classification"] = {
        "failure_type": failure_type,
        "failure_type_description": FAILURE_TYPE_DESCRIPTIONS.get(failure_type, ""),
        "classification_rule": fc["classification_rule"],
    }
    retry_trace["next_action_proposal"] = nr
    return retry_trace