"""Formal validators: JSON schema, policy constraints, lint/type check on outputs."""

import json
from typing import Any

from fusionagi._logger import logger


class FormalValidators:
    """
    Validates outputs against JSON schema, policy constraints.
    Extend with lint/type check for code outputs.
    """

    def __init__(self) -> None:
        self._schemas: dict[str, dict[str, Any]] = {}  # name -> JSON schema

    def register_schema(self, name: str, schema: dict[str, Any]) -> None:
        """Register a JSON schema for output validation."""
        self._schemas[name] = schema

    def validate_json(self, data: str | dict[str, Any], schema_name: str | None = None) -> tuple[bool, str]:
        """
        Validate JSON structure. If schema_name given, validate against that schema
        (requires jsonschema lib for full validation; else structure-only).
        Returns (valid, error_message).
        """
        if isinstance(data, dict):
            obj = data
        else:
            try:
                obj = json.loads(data)
            except json.JSONDecodeError as e:
                return False, str(e)
        if schema_name and schema_name in self._schemas:
            try:
                import jsonschema
                jsonschema.validate(instance=obj, schema=self._schemas[schema_name])
            except ImportError:
                logger.warning("jsonschema not installed; skipping schema validation")
            except Exception as e:
                return False, str(e)
        return True, ""

    def validate_policy(self, action: str, context: dict[str, Any]) -> tuple[bool, str]:
        """
        Check action against policy (context has tool_name, domain, etc.).
        Returns (allowed, reason).
        """
        # Placeholder: no policy rules by default
        return True, ""