"""
app/audit.py
Helper centralizado para registrar eventos de auditoría.
Se llama desde los routers después de cada operación exitosa.
"""
import json
from datetime import datetime
from typing import Any, Optional
 
from sqlalchemy.orm import Session
 
import models
 
 
def _serialize(obj: Any) -> Optional[str]:
    """Serializa un objeto a JSON string. Devuelve None si obj es None."""
    if obj is None:
        return None
    if hasattr(obj, '__dict__'):
        # SQLAlchemy model — serializar atributos no privados
        data = {
            k: v for k, v in obj.__dict__.items()
            if not k.startswith('_')
        }
        # Convertir datetime a string para que sea serializable
        for key, value in data.items():
            if isinstance(value, datetime):
                data[key] = value.isoformat()
        return json.dumps(data, default=str)
    if isinstance(obj, dict):
        return json.dumps(obj, default=str)
    return str(obj)
 
 
def log_action(
    db:          Session,
    entity_type: str,
    entity_id:   Any,
    action:      str,
    user_id:     Optional[Any] = None, 
    before:      Any = None,
    after:       Any = None,
    ip_address:  Optional[str] = None,
) -> None:
    # Convertir "system" (feeder) a -1, y cualquier valor no numérico también
    if user_id == "system" or user_id is None:
        resolved_user_id = -1
    else:
        try:
            resolved_user_id = int(user_id)
        except (ValueError, TypeError):
            resolved_user_id = -1

    entry = models.AuditLog(
        entity_type=entity_type,
        entity_id=str(entity_id),
        action=action,
        user_id=resolved_user_id,
        before_value=_serialize(before),
        after_value=_serialize(after),
        timestamp=datetime.utcnow(),
        ip_address=ip_address,
    )
    db.add(entry)