import hashlib
import logging
from django.utils import timezone
from django.db import models
from ..models import AnalysisCache

logger = logging.getLogger(__name__)


class CacheService:
    def generate_hash(self, prompt, dealer_id, language):
        """
        Generate a unique MD5 hash based on the prompt, dealer ID, and language.
        """
        key = f"{prompt}:{dealer_id or 'all'}:{language}"
        return hashlib.md5(key.encode()).hexdigest()

    def get_cached_result(self, prompt_hash, user, dealer_id):
        """
        Retrieve a cached analysis result based on hash, dealer, and optionally user.
        """
        try:
            # Check for user-specific cache if authenticated
            if user and user.is_authenticated:
                user_cache = AnalysisCache.objects.filter(
                    prompt_hash=prompt_hash,
                    user=user,
                    expires_at__gt=timezone.now()
                ).first()
                if user_cache:
                    return user_cache.result

            # Otherwise check for dealer-wide cache
            dealer_cache = AnalysisCache.objects.filter(
                prompt_hash=prompt_hash,
                dealer_id=dealer_id,
                expires_at__gt=timezone.now()
            ).first()

            return dealer_cache.result if dealer_cache else None
        except Exception as e:
            logger.warning(f"Cache retrieval failed: {str(e)}")
            return None

    def cache_result(self, prompt_hash, result, user, dealer_id, duration=3600):
        """
        Save or update a cached result with an expiration timestamp.
        """
        try:
            expires_at = timezone.now() + timezone.timedelta(seconds=duration)
            AnalysisCache.objects.update_or_create(
                prompt_hash=prompt_hash,
                user=user if user and user.is_authenticated else None,
                dealer_id=dealer_id,
                defaults={
                    'result': result,
                    'expires_at': expires_at
                }
            )
        except Exception as e:
            logger.warning(f"Cache saving failed: {str(e)}")