"""backend/api/skills.py — P17-B2: Endpoint /api/skills/patterns.

Espone i pattern di tool-usage aggregati dal SkillTracker per sync frontend.
  GET /api/skills/patterns              → aggregato globale (tutte le sessioni)
  GET /api/skills/patterns/{session_id} → singola sessione

fix(backend): corregge IndentationError presente al commit 1e1fa65
"""
from __future__ import annotations
import logging
import math
from fastapi import APIRouter, Depends, Query
from .auth_guard import require_role, AuthRole

_logger = logging.getLogger("agente_ai.api.skills")
router  = APIRouter(prefix="/api/skills", tags=["skills"], dependencies=[Depends(require_role(AuthRole.MACHINE))])  # GAP-1-fix: router-level auth


def _wilson(success: int, total: int) -> float:
    if total == 0:
        return 0.5
    p, z = success / total, 1.96
    num  = p + z*z/(2*total) - z*math.sqrt((p*(1-p) + z*z/(4*total))/total)
    return max(0.0, min(1.0, num / (1 + z*z/total)))


@router.get("/patterns")
async def get_skill_patterns(
    limit:    int = Query(default=50, ge=1,  le=200),
    min_uses: int = Query(default=1,  ge=1,  description="Minimo utilizzi totali"),
):
    """Pattern aggregati da tutte le sessioni in memoria, ordinati per Wilson score."""
    try:
        from agents.skill_tracker import get_skill_tracker
        tracker = get_skill_tracker()
        agg: dict[str, dict] = {}
        for _sid, sess in tracker._stats.items():
            for tool, stats in sess.items():
                if tool not in agg:
                    agg[tool] = {"s": 0, "f": 0, "lat": 0.0, "sessions": 0, "last": 0.0}
                agg[tool]["s"]        += stats.success_count
                agg[tool]["f"]        += stats.fail_count
                agg[tool]["lat"]      += stats.total_latency_ms
                agg[tool]["sessions"] += 1
                agg[tool]["last"]      = max(agg[tool]["last"], stats.last_used)

        out = []
        for tool, a in agg.items():
            total = a["s"] + a["f"]
            if total < min_uses:
                continue
            out.append({
                "tool":           tool,
                "total":          total,
                "success":        a["s"],
                "fail":           a["f"],
                "success_rate":   round(a["s"] / total if total else 1.0, 4),
                "wilson_score":   round(_wilson(a["s"], total), 4),
                "avg_latency_ms": round(a["lat"] / total if total else 0.0, 1),
                "sessions":       a["sessions"],
                "last_used":      a["last"],
            })
        out.sort(key=lambda x: x["wilson_score"], reverse=True)
        return {"patterns": out[:limit], "total": len(out)}
    except Exception as exc:
        _logger.error("[skills/patterns] %s", exc)
        return {"patterns": [], "total": 0, "error": str(exc)[:200]}


@router.get("/patterns/{session_id}")
async def get_session_patterns(session_id: str):
    """Pattern per una singola sessione."""
    try:
        from agents.skill_tracker import get_skill_tracker
        tracker = get_skill_tracker()
        sess    = tracker._stats.get(session_id, {})
        out = []
        for tool, stats in sess.items():
            total = stats.total_count
            out.append({
                "tool":           tool,
                "total":          total,
                "success":        stats.success_count,
                "fail":           stats.fail_count,
                "success_rate":   round(stats.success_rate, 4),
                "wilson_score":   round(stats.wilson_score(), 4),
                "avg_latency_ms": round(stats.avg_latency_ms, 1),
                "last_used":      stats.last_used,
            })
        out.sort(key=lambda x: x["wilson_score"], reverse=True)
        return {"session_id": session_id, "patterns": out, "total": len(out)}
    except Exception as exc:
        _logger.error("[skills/patterns/%s] %s", session_id, exc)
        return {"session_id": session_id, "patterns": [], "total": 0, "error": str(exc)[:200]}