#!/usr/bin/env python3
# -*- coding: utf-8 -*-
"""服务端 PNG 渲染：通过 sharp 将 SVG 转为 PNG。"""

import os
import subprocess


def _script_path():
    return os.path.join(os.path.dirname(__file__), "svg_to_png.js")


def render_png_from_svg(svg_text, width, height, *, timeout_seconds=20):
    if not svg_text or not str(svg_text).strip():
        raise ValueError("SVG 内容为空")

    script = _script_path()
    if not os.path.isfile(script):
        raise FileNotFoundError(f"未找到 SVG 转 PNG 脚本: {script}")

    safe_width = max(1, min(4096, int(round(float(width or 0) or 0))))
    safe_height = max(1, min(4096, int(round(float(height or 0) or 0))))

    cmd = [
        "node",
        script,
        "--width",
        str(safe_width),
        "--height",
        str(safe_height),
    ]

    try:
        completed = subprocess.run(
            cmd,
            input=str(svg_text).encode("utf-8"),
            stdout=subprocess.PIPE,
            stderr=subprocess.PIPE,
            timeout=timeout_seconds,
            check=False,
        )
    except FileNotFoundError as error:
        raise RuntimeError("未找到 node，请先安装 Node.js") from error

    if completed.returncode != 0:
        stderr = completed.stderr.decode("utf-8", errors="replace").strip()
        if "Cannot find module 'sharp'" in stderr:
            raise RuntimeError("缺少 sharp 依赖，请在项目根目录执行: npm install")
        raise RuntimeError(stderr or f"PNG 渲染失败，退出码: {completed.returncode}")

    png_bytes = completed.stdout
    if not png_bytes:
        raise RuntimeError("PNG 渲染失败，返回空内容")

    return png_bytes