from pydantic import BaseModel 
import json
from typing import Any, List, Set

def check_serializable(obj: Any, path: str = "", errors: List[str] = [], visited: Set[int] = set()) -> List[str]:
    """
    Recursively check all fields in an object for non-JSON-serializable types, avoiding infinite recursion.
    Skips fields in Pydantic models marked with Field(..., exclude=True).
    Args:
        obj: The object to inspect (Pydantic model, dict, list, or other).
        path: The current field path (e.g., 'field1.nested_field').
        errors: List to collect error messages.
        visited: Set of object IDs to track visited objects and prevent infinite recursion.
    Returns:
        List of error messages for non-serializable fields.
    """
    # Check for circular reference by object ID
    obj_id = id(obj)
    if obj_id in visited:
        errors.append(f"Field '{path}' contains a circular reference, skipping further inspection")
        return errors

    # Add current object to visited set
    visited.add(obj_id)

    try:
        # Handle Pydantic models
        if isinstance(obj, BaseModel):
            for field_name, field_info in obj.model_fields.items():
                # Skip fields marked with exclude=True
                if field_info.exclude:
                    continue
                value = getattr(obj, field_name)
                new_path = f"{path}.{field_name}" if path else field_name
                check_serializable(value, new_path, errors, visited)

        # Handle dictionaries
        elif isinstance(obj, dict):
            for key, value in obj.items():
                new_path = f"{path}[{key}]" if path else str(key)
                check_serializable(value, new_path, errors, visited)

        # Handle lists, tuples, or other iterables
        elif isinstance(obj, (list, tuple)):
            for i, value in enumerate(obj):
                new_path = f"{path}[{i}]" if path else str(i)
                check_serializable(value, new_path, errors, visited)

        # Handle other types (check for JSON serializability)
        else:
            try:
                json.dumps(obj)
            except (TypeError, OverflowError, ValueError) as e:
                errors.append(f"Field '{path}' contains non-serializable type: {type(obj)} ({str(e)})")

    finally:
        # Remove the current object from visited to allow processing in other branches
        visited.discard(obj_id)

    return errors