src/tiers/cache.py

"""
Cache Tier - SQLite caching layer

First tier in the chain - returns cached articles if available.
"""

from __future__ import annotations

import logging
from typing import Any

from src.tiers.base import BaseTier, TierContext, TierResult


logger = logging.getLogger(__name__)


class CacheTier(BaseTier):
    """
    Cache tier for returning previously scraped articles.
    
    Priority: 0 (first in chain)
    """
    
    name = "cache"
    priority = 0
    
    def __init__(self) -> None:
        super().__init__()
        self._initialized = False
    
    async def initialize(self) -> None:
        """Initialize cache connection."""
        self._initialized = True
        self.logger.debug("Cache tier initialized")
    
    async def cleanup(self) -> None:
        """Cleanup cache resources."""
        self._initialized = False
    
    def can_handle(self, ctx: TierContext) -> bool:
        """Cache handles all URLs unless force refresh."""
        return not ctx.force_refresh
    
    async def try_scrape(self, ctx: TierContext) -> TierResult:
        """
        Try to get article from cache.
        
        Args:
            ctx: Context with URL
            
        Returns:
            Cached article or failure
        """
        try:
            from src.database import get_article
            
            article = get_article(ctx.url)
            
            if article:
                self.logger.info(f"Cache hit: {ctx.url}")
                return TierResult(
                    success=True,
                    data=article,
                    tier_name=self.name,
                    cached=True,
                )
            
            self.logger.debug(f"Cache miss: {ctx.url}")
            return TierResult(
                success=False,
                error="Not in cache",
                tier_name=self.name,
            )
            
        except Exception as e:
            self.logger.error(f"Cache error: {e}")
            return TierResult(
                success=False,
                error=str(e),
                tier_name=self.name,
            )