Aniworld/src/server/error_handler.py

"""
Error handling and recovery strategies for core providers.

This module provides custom exceptions and decorators for handling
errors in provider operations with automatic retry mechanisms.
"""

import functools
import logging
from typing import Any, Callable, Optional, TypeVar

logger = logging.getLogger(__name__)

# Type variable for decorator
F = TypeVar("F", bound=Callable[..., Any])


class RetryableError(Exception):
    """Exception that indicates an operation can be safely retried."""

    pass


class NonRetryableError(Exception):
    """Exception that indicates an operation should not be retried."""

    pass


class NetworkError(Exception):
    """Exception for network-related errors."""

    pass


class DownloadError(Exception):
    """Exception for download-related errors."""

    pass


class RecoveryStrategies:
    """Strategies for handling errors and recovering from failures."""

    def __init__(
        self,
        max_retries: int = 3,
        base_delay: float = 1.0,
        max_delay: float = 60.0,
        exponential_base: float = 2.0,
    ) -> None:
        """Initialize recovery strategies.

        Args:
            max_retries: Maximum number of retry attempts.
            base_delay: Initial delay between retries in seconds.
            max_delay: Maximum delay between retries in seconds.
            exponential_base: Base for exponential backoff multiplier.
        """
        self.max_retries = max_retries
        self.base_delay = base_delay
        self.max_delay = max_delay
        self.exponential_base = exponential_base

    def _calculate_delay(self, attempt: int) -> float:
        """Calculate delay for given retry attempt using exponential backoff.

        Args:
            attempt: Zero-based retry attempt number.

        Returns:
            Delay in seconds before next retry.
        """
        delay = self.base_delay * (self.exponential_base ** attempt)
        return min(delay, self.max_delay)

    @staticmethod
    def handle_network_failure(
        func: Callable, *args: Any, **kwargs: Any
    ) -> Any:
        """Handle network failures with exponential backoff retry logic."""
        last_error: Optional[Exception] = None
        max_retries = 3
        base_delay = 1.0
        max_delay = 60.0
        exponential_base = 2.0
        
        for attempt in range(max_retries):
            try:
                return func(*args, **kwargs)
            except (NetworkError, ConnectionError, TimeoutError) as exc:
                last_error = exc
                if attempt < max_retries - 1:
                    delay = base_delay * (exponential_base ** attempt)
                    delay = min(delay, max_delay)
                    logger.warning(
                        "Network error on attempt %d/%d, retrying in %.1fs: %s",
                        attempt + 1, max_retries, delay, exc
                    )
                    import time
                    time.sleep(delay)
                    continue
        if last_error:
            raise last_error
        raise NetworkError("Network failure after retries")

    @staticmethod
    def handle_download_failure(
        func: Callable, *args: Any, **kwargs: Any
    ) -> Any:
        """Handle download failures with exponential backoff retry logic."""
        last_error: Optional[Exception] = None
        max_retries = 2
        base_delay = 1.0
        max_delay = 60.0
        exponential_base = 2.0
        
        for attempt in range(max_retries):
            try:
                return func(*args, **kwargs)
            except DownloadError as exc:
                last_error = exc
                if attempt < max_retries - 1:
                    delay = base_delay * (exponential_base ** attempt)
                    delay = min(delay, max_delay)
                    logger.warning(
                        "Download error on attempt %d/%d, retrying in %.1fs: %s",
                        attempt + 1, max_retries, delay, exc
                    )
                    import time
                    time.sleep(delay)
                    continue
        if last_error:
            raise last_error
        raise DownloadError("Download failed after retries")


class FileCorruptionDetector:
    """Detector for corrupted files."""

    @staticmethod
    def is_valid_video_file(filepath: str) -> bool:
        """Check if a video file is valid and not corrupted."""
        try:
            import os
            if not os.path.exists(filepath):
                return False
            
            file_size = os.path.getsize(filepath)
            # Video files should be at least 1MB
            return file_size > 1024 * 1024
        except Exception as e:
            logger.error("Error checking file validity: %s", e)
            return False


def with_error_recovery(
    max_retries: int = 3, context: str = ""
) -> Callable[[F], F]:
    """
    Decorator for adding error recovery to functions.
    
    Args:
        max_retries: Maximum number of retry attempts
        context: Context string for logging
        
    Returns:
        Decorated function with retry logic
    """

    def decorator(func: F) -> F:
        @functools.wraps(func)
        def wrapper(*args: Any, **kwargs: Any) -> Any:
            last_error = None
            for attempt in range(max_retries):
                try:
                    return func(*args, **kwargs)
                except NonRetryableError:
                    raise
                except Exception as e:
                    last_error = e
                    if attempt < max_retries - 1:
                        logger.warning(
                            "Error in %s (attempt %d/%d): %s, retrying...",
                            context,
                            attempt + 1,
                            max_retries,
                            e,
                        )
                    else:
                        logger.error(
                            "Error in %s failed after %d attempts: %s",
                            context,
                            max_retries,
                            e,
                        )

            if last_error:
                raise last_error
            
            raise RuntimeError(
                f"Unexpected error in {context} after {max_retries} attempts"
            )

        return wrapper  # type: ignore

    return decorator


# Create module-level instances for use in provider code
recovery_strategies = RecoveryStrategies()
file_corruption_detector = FileCorruptionDetector()