"""GET /api/operator/failure-patterns — failure patterns + safety signals (TASK-08-03, TASK-10-02, D-053).

Auth-gated. Returns failure pattern metrics: failure_mode frequency (cells
with metric prefix `failure_mode:`) + branch outcome distribution (cells
with metric prefix `branch:`) + the assist guardrail block rate safety signal
(TASK-10-02 — `assist_guardrail_block_rate`). Weak-spot rubric criteria
(mean < 3.0) are highlighted by the frontend. All k-anonymized.

The `assist_guardrail_block_rate` is a safety signal for operators: a sudden
spike signals either a prompt regression or learners pushing boundaries. High
block rate = flag for operator review.
"""

from __future__ import annotations

import datetime as _dt

from fastapi import APIRouter, Depends, Request

from server.auth.dependencies import current_operator
from server.auth.models import Operator
from server.operator._common import (
    ViewResponse,
    all_recent_aggregates,
    group_by_path,
    require_pg_store,
)

router = APIRouter(prefix="/api/operator", tags=["operator-failure-patterns"])

# The assist guardrail block-rate safety signal (TASK-10-02, D-060 layer 3).
ASSIST_GUARDRAIL_BLOCK_RATE = "assist_guardrail_block_rate"


def _is_failure_metric(metric: str) -> bool:
    # Failure patterns (v0.4) + the assist guardrail block-rate safety signal (v0.5).
    return (
        metric.startswith("failure_mode:")
        or metric.startswith("branch:")
        or metric == ASSIST_GUARDRAIL_BLOCK_RATE
    )


@router.get("/failure-patterns", response_model=ViewResponse)
async def failure_patterns_view(
    request: Request,
    op: Operator = Depends(current_operator),
) -> ViewResponse:
    pg_store = await require_pg_store(request)
    since = _dt.date.today() - _dt.timedelta(days=30)
    rows = await all_recent_aggregates(pg_store, since)
    failure_rows = [r for r in rows if _is_failure_metric(r.get("metric", ""))]
    views, last_updated = group_by_path(failure_rows)
    return ViewResponse(views=views, last_updated=last_updated)


__all__ = ["router"]