import json
import re

from app.core.exceptions import LLMParseError


def extract_json(text: str) -> any:
    """Parse JSON from LLM response, stripping Markdown code fences if present."""
    text = text.strip()

    # Strip ```json ... ``` or ``` ... ``` fences
    fence_match = re.search(r"```(?:json)?\s*([\s\S]+?)\s*```", text)
    if fence_match:
        text = fence_match.group(1).strip()

    try:
        return json.loads(text)
    except json.JSONDecodeError as e:
        raise LLMParseError(f"大模型返回非合法 JSON: {e}") from e