"""NL2SQL 查询结果的基础 Markdown 渲染。"""
from __future__ import annotations

from typing import Any


def _cell(value: Any) -> str:
    """将单元格转换为不会破坏 Markdown 表格的文本。"""
    if value is None:
        return ""
    return str(value).replace("|", "\\|").replace("\r", " ").replace("\n", " ")


def render_markdown(columns: list[str], rows: list[dict[str, Any]]) -> str:
    """将列和行渲染成 Markdown 表格，空结果返回固定提示。"""
    if not rows:
        return "暂无数据。"
    header = "| " + " | ".join(_cell(column) for column in columns) + " |"
    divider = "| " + " | ".join("---" for _ in columns) + " |"
    body = [
        "| " + " | ".join(_cell(row.get(column)) for column in columns) + " |"
        for row in rows
    ]
    return "\n".join([header, divider, *body])