"""
Shared backend utilities
"""
import os
import logging
from contextlib import contextmanager
from pathlib import Path
import shutil
import tempfile


logger = logging.getLogger(__name__)


@contextmanager
def without_hf_auth():
    """
    Context manager to temporarily disable HuggingFace authentication.

    Usage:
        with without_hf_auth():
            # Code that should run without cached tokens
            model_info(model_name, token=None)
    """
    # Save environment variables
    saved_env = {}
    env_vars = ['HF_TOKEN', 'HUGGINGFACE_HUB_TOKEN', 'HF_HOME']
    for var in env_vars:
        if var in os.environ:
            saved_env[var] = os.environ[var]
            del os.environ[var]

    # Save disable flag
    saved_disable = os.environ.get('HF_HUB_DISABLE_IMPLICIT_TOKEN')
    os.environ['HF_HUB_DISABLE_IMPLICIT_TOKEN'] = '1'

    # Move token files temporarily
    token_files = []
    token_locations = [
        Path.home() / '.cache' / 'huggingface' / 'token',
        Path.home() / '.huggingface' / 'token'
    ]

    for token_loc in token_locations:
        if token_loc.exists():
            temp = tempfile.NamedTemporaryFile(delete=False)
            temp.close()
            shutil.move(str(token_loc), temp.name)
            token_files.append((token_loc, temp.name))

    try:
        yield
    finally:
        # Restore tokens
        for original, temp in token_files:
            try:
                original.parent.mkdir(parents=True, exist_ok=True)
                shutil.move(temp, str(original))
            except Exception as e:
                logger.error(f"Failed to restore token {original}: {e}")

        # Restore environment
        for var, value in saved_env.items():
            os.environ[var] = value

        if saved_disable is not None:
            os.environ['HF_HUB_DISABLE_IMPLICIT_TOKEN'] = saved_disable
        else:
            os.environ.pop('HF_HUB_DISABLE_IMPLICIT_TOKEN', None)
pass

def format_error_message(error: Exception, model_name: str) -> str:
    """
    Format user-friendly error messages for common issues.

    Args:
        error: The exception that occurred
        model_name: Name of the model being loaded

    Returns:
        User-friendly error string
    """
    error_str = str(error).lower()
    model_short = model_name.split('/')[-1] if '/' in model_name else model_name

    if "repository not found" in error_str or "404" in error_str:
        return f"Model '{model_short}' not found. Check the model name."

    if "401" in error_str or "unauthorized" in error_str:
        return f"Authentication failed for '{model_short}'. Please provide a valid HF token."

    if "gated" in error_str or "access to model" in error_str:
        return f"Model '{model_short}' requires authentication. Please provide a valid HF token."

    if "invalid user token" in error_str:
        return "Invalid HF token. Please check your token and try again."

    if "memory" in error_str or "cuda" in error_str or "mlx" in error_str or "out of memory" in error_str:
        from utils.hardware import get_device
        device = get_device()
        device_label = {"cuda": "GPU", "mlx": "Apple Silicon GPU", "cpu": "system"}.get(device.value, "GPU")
        return f"Not enough {device_label} memory to load '{model_short}'. Try a smaller model or free memory."

    # Generic fallback
    return str(error)
pass