from datetime import datetime, timedelta
from typing import Any, Dict, Optional

from flask import Flask


class CacheManager:
    """Manages general purpose caching for the application."""

    def __init__(self):
        """Initialize the cache manager."""
        self.cache = {}

    def init_app(self, app: Flask) -> None:
        pass

    def get(self, key: str) -> Optional[Any]:
        """Get a value from cache if it exists and is not expired."""
        if key not in self.cache:
            return None

        entry = self.cache[key]
        if datetime.utcnow() > entry['expires_at']:
            self.delete(key)
            return None

        return entry['value']

    def set(self, key: str, value: Any, ttl: int = 3600) -> None:
        """Set a value in cache with a TTL in seconds."""
        expires_at = datetime.utcnow() + timedelta(seconds=ttl)
        self.cache[key] = {
            'value': value,
            'expires_at': expires_at
        }

    def delete(self, key: str) -> None:
        """Delete a value from cache."""
        if key in self.cache:
            del self.cache[key]

    def clear(self) -> None:
        """Clear all cached values."""
        self.cache = {}

    def cleanup(self) -> None:
        """Remove all expired cache entries."""
        now = datetime.utcnow()
        expired_keys = [
            key for key, entry in self.cache.items()
            if now > entry['expires_at']
        ]
        for key in expired_keys:
            del self.cache[key]