"""find_blender / run_blender_script：model_decimate 与 model_bake 共享的
headless Blender 运行器（与 model_translator.py 同模式，脚本名与参数泛化）。"""
import json
import os
import shutil
import subprocess
import sys

DEFAULT_BLENDER = r"D:\tools\blender-5.0.0-windows-x64\blender.exe"
HERE = os.path.dirname(os.path.abspath(__file__))


def find_blender(cli_arg):
    for cand in (cli_arg, os.environ.get("BLENDER_EXE"), DEFAULT_BLENDER,
                 shutil.which("blender")):
        if cand and os.path.isfile(cand):
            return cand
    sys.exit("找不到 blender.exe，请用 --blender 指定或设置环境变量 BLENDER_EXE")


def run_blender_script(blender, script, script_args):
    """跑 HERE 下的 bl_*.py，返回 MT_SUMMARY JSON；失败或 summary 带 error 则退出。"""
    cmd = [blender, "-b", "--factory-startup",
           "--python", os.path.join(HERE, script), "--"] + list(script_args)
    proc = subprocess.run(cmd, capture_output=True, text=True, encoding="utf-8",
                          errors="replace")
    summary = None
    for line in (proc.stdout or "").splitlines():
        if line.startswith("MT_SUMMARY "):
            summary = json.loads(line[len("MT_SUMMARY "):])
    if proc.returncode != 0 or summary is None or "error" in summary:
        sys.stderr.write((proc.stdout or "")[-2000:] + "\n" +
                         (proc.stderr or "")[-2000:] + "\n")
        err = summary["error"] if summary and "error" in summary else script
        sys.exit("Blender 执行失败：%s" % err)
    return summary