"""
cache_endpoints.py — Endpoint API per Gestione Cache

Endpoint:
  GET  /api/cache/stats           — Statistiche cache
  POST /api/cache/invalidate      — Invalida un entry
  GET  /api/cache/health          — Health check cache
  POST /api/cache/reset-stats     — Resetta statistiche
"""

from fastapi import APIRouter, HTTPException
from pydantic import BaseModel
from typing import Optional
import logging

# Import cache manager
try:
    from backend.api.cache_manager import (
        get_cache_stats,
        reset_cache_stats,
        invalidate_cache,
        CacheStrategy,
        CACHE_ENABLED,
    )
except ImportError:
    from cache_manager import (
        get_cache_stats,
        reset_cache_stats,
        invalidate_cache,
        CacheStrategy,
        CACHE_ENABLED,
    )

_logger = logging.getLogger("cache_endpoints")

router = APIRouter(prefix="/api/cache", tags=["cache"])


# ── Modelli Pydantic ──────────────────────────────────────────────────────
class InvalidateCacheRequest(BaseModel):
    strategy: str  # "query", "memory", "embedding", "conversation", "analytics"
    identifier: str


class CacheStatsResponse(BaseModel):
    enabled: bool
    hits: int
    misses: int
    sets: int
    deletes: int
    evictions: int
    hit_rate_percent: float
    total_requests: int


class CacheHealthResponse(BaseModel):
    ok: bool
    cache_enabled: bool
    message: str


# ── Endpoint: Statistiche Cache ────────────────────────────────────────────
@router.get("/stats", response_model=CacheStatsResponse)
async def cache_stats():
    """Ritorna le statistiche del cache layer."""
    try:
        stats = get_cache_stats()
        return CacheStatsResponse(**stats)
    except Exception as exc:
        _logger.error(f"Error fetching cache stats: {exc}")
        raise HTTPException(500, "Error fetching cache stats")


# ── Endpoint: Invalida Cache ──────────────────────────────────────────────
@router.post("/invalidate")
async def invalidate_cache_entry(req: InvalidateCacheRequest):
    """Invalida un entry specifico dalla cache."""
    try:
        # Valida strategy
        try:
            strategy = CacheStrategy(req.strategy)
        except ValueError:
            raise HTTPException(
                400,
                f"Invalid strategy. Must be one of: {', '.join([s.value for s in CacheStrategy])}",
            )
        
        # Invalida
        success = await invalidate_cache(strategy, req.identifier)
        
        return {
            "ok": success,
            "strategy": req.strategy,
            "identifier": req.identifier,
            "message": "Cache entry invalidated" if success else "Failed to invalidate cache entry",
        }
    except HTTPException:
        raise
    except Exception as exc:
        _logger.error(f"Error invalidating cache: {exc}")
        raise HTTPException(500, "Error invalidating cache")


# ── Endpoint: Health Check ────────────────────────────────────────────────
@router.get("/health", response_model=CacheHealthResponse)
async def cache_health():
    """Health check per il cache layer."""
    try:
        stats = get_cache_stats()
        
        return CacheHealthResponse(
            ok=True,
            cache_enabled=CACHE_ENABLED,
            message=f"Cache layer operational. Hit rate: {stats.get('hit_rate_percent', 0):.1f}%",
        )
    except Exception as exc:
        _logger.error(f"Cache health check failed: {exc}")
        return CacheHealthResponse(
            ok=False,
            cache_enabled=CACHE_ENABLED,
            message=f"Cache health check failed: {str(exc)}",
        )


# ── Endpoint: Reset Statistiche ───────────────────────────────────────────
@router.post("/reset-stats")
async def reset_stats():
    """Resetta le statistiche del cache."""
    try:
        reset_cache_stats()
        return {
            "ok": True,
            "message": "Cache statistics reset",
        }
    except Exception as exc:
        _logger.error(f"Error resetting cache stats: {exc}")
        raise HTTPException(500, "Error resetting cache stats")


# ── Endpoint: Info Cache ──────────────────────────────────────────────────
@router.get("/info")
async def cache_info():
    """Ritorna informazioni sulla configurazione del cache."""
    try:
        from cache_manager import (
            CACHE_ENABLED,
            CACHE_TTL_DEFAULT,
            CACHE_MAX_SIZE,
            CACHE_TTL_BY_STRATEGY,
            SUPABASE_A_URL,
            SUPABASE_B_URL,
        )
        
        return {
            "enabled": CACHE_ENABLED,
            "ttl_default_seconds": CACHE_TTL_DEFAULT,
            "max_size": CACHE_MAX_SIZE,
            "ttl_by_strategy": {k.value: v for k, v in CACHE_TTL_BY_STRATEGY.items()},
            "supabase_a_configured": bool(SUPABASE_A_URL),
            "supabase_b_configured": bool(SUPABASE_B_URL),
        }
    except Exception as exc:
        _logger.error(f"Error fetching cache info: {exc}")
        raise HTTPException(500, "Error fetching cache info")