"""One bounded, read-only metadata request to a registered loopback model service."""
import ipaddress
import json
from pathlib import Path
import re
import shlex
import urllib.error
import urllib.request
from urllib.parse import urlsplit


class NoRedirect(urllib.request.HTTPRedirectHandler):
    def redirect_request(self, *args):
        return None


def check_model(target, credential_files):
    result = {'name': '模型身份', 'ok': False, 'message': '模型目录检查未完成'}
    try:
        url = urlsplit(target['url'])
        if (url.scheme != 'http' or not ipaddress.ip_address(url.hostname).is_loopback
                or url.username or url.password or url.query or url.fragment or url.path not in ('', '/')):
            raise ValueError('仅允许登记的本机模型服务')
        key = ''
        for filename in credential_files:
            path = Path(filename)
            if path.stat().st_size > 262144:
                raise ValueError('认证引用文件过大')
            for line in path.read_text().splitlines():
                match = re.match(r'^(?:export\s+)?VLLM_API_KEY=(.*)$', line.strip())
                if not match:
                    continue
                values = shlex.split(match[1], comments=True)
                if len(values) > 1:
                    raise ValueError('认证引用格式不支持')
                key = values[0] if values else ''
        headers = {'Authorization': 'Bearer ' + key} if key else {}
        request = urllib.request.Request(target['url'].rstrip('/') + '/v1/models', headers=headers)
        opener = urllib.request.build_opener(urllib.request.ProxyHandler({}), NoRedirect())
        with opener.open(request, timeout=3) as response:
            data = response.read(262145)
        if len(data) > 262144:
            raise ValueError('模型目录超过检查上限')
        payload = json.loads(data)
        models = payload.get('data') if isinstance(payload, dict) else None
        if not isinstance(models, list) or any(not isinstance(m, dict) or not isinstance(m.get('id'), str) for m in models):
            raise ValueError('模型目录格式不支持')
        result['ok'] = any(m['id'] == target['model'] for m in models)
        result['message'] = ('已核对模型名称：' if result['ok'] else '当前服务未提供登记的模型名称：') + target['model']
    except urllib.error.HTTPError as exc:
        result['message'] = f'模型目录校验失败（HTTP {exc.code}），请核对服务与认证配置；未发送推理'
    except (OSError, ValueError, TypeError, KeyError):
        result['message'] = '模型目录或认证引用不可用，未发送推理；请核对原服务配置'
    return result