utils/error_handler.py

import logging
from functools import wraps
from typing import Callable, Any
import time

logger = logging.getLogger(__name__)

class RateLimiter:
    """Simple rate limiter for API calls."""
    
    def __init__(self, max_calls: int = 10, time_window: int = 60):
        self.max_calls = max_calls
        self.time_window = time_window
        self.calls = []
    
    def is_allowed(self, key: str) -> bool:
        """Check if call is allowed within rate limit."""
        
        current_time = time.time()
        
        self.calls = [
            (k, t) for k, t in self.calls 
            if current_time - t < self.time_window
        ]
        
        key_calls = [t for k, t in self.calls if k == key]
        
        if len(key_calls) >= self.max_calls:
            return False
        
        self.calls.append((key, current_time))
        return True
    
    def get_wait_time(self, key: str) -> float:
        """Get wait time in seconds before next allowed call."""
        
        current_time = time.time()
        key_calls = [
            t for k, t in self.calls 
            if k == key and current_time - t < self.time_window
        ]
        
        if len(key_calls) < self.max_calls:
            return 0.0
        
        oldest_call = min(key_calls)
        wait_time = self.time_window - (current_time - oldest_call)
        return max(0.0, wait_time)

rate_limiter = RateLimiter(max_calls=20, time_window=60)

def with_retry(max_retries: int = 3, delay: float = 1.0):
    """Decorator to retry function on failure."""
    
    def decorator(func: Callable) -> Callable:
        @wraps(func)
        def wrapper(*args, **kwargs) -> Any:
            last_exception = None
            
            for attempt in range(max_retries):
                try:
                    return func(*args, **kwargs)
                except Exception as e:
                    last_exception = e
                    logger.warning(
                        f"Attempt {attempt + 1}/{max_retries} failed for {func.__name__}: {e}"
                    )
                    
                    if attempt < max_retries - 1:
                        time.sleep(delay * (attempt + 1))
            
            logger.error(f"All {max_retries} attempts failed for {func.__name__}")
            raise last_exception
        
        return wrapper
    return decorator

def with_fallback(fallback_value: Any = None):
    """Decorator to return fallback value on error."""
    
    def decorator(func: Callable) -> Callable:
        @wraps(func)
        def wrapper(*args, **kwargs) -> Any:
            try:
                return func(*args, **kwargs)
            except Exception as e:
                logger.error(f"Error in {func.__name__}: {e}. Returning fallback.")
                return fallback_value
        
        return wrapper
    return decorator

def log_execution_time(func: Callable) -> Callable:
    """Decorator to log function execution time."""
    
    @wraps(func)
    def wrapper(*args, **kwargs) -> Any:
        start_time = time.time()
        result = func(*args, **kwargs)
        end_time = time.time()
        
        execution_time = end_time - start_time
        logger.info(f"{func.__name__} executed in {execution_time:.2f}s")
        
        return result
    
    return wrapper

class APIError(Exception):
    """Custom API error."""
    pass

class RateLimitError(Exception):
    """Rate limit exceeded error."""
    pass

class CacheError(Exception):
    """Cache operation error."""
    pass