"""Check cached-prefix retrieval at several document positions, including changed suffixes."""
import json
import re
import urllib.request
from pathlib import Path

base = 'http://127.0.0.1:8000'
key = Path('/run/secrets/qwen_api_key').read_text().strip()
headers = {'Authorization': 'Bearer ' + key, 'Content-Type': 'application/json'}
def request(path, payload=None):
    req = urllib.request.Request(base+path, headers=headers,
        data=json.dumps(payload).encode() if payload is not None else None)
    with urllib.request.urlopen(req, timeout=600) as response:
        return response.read().decode()
def hits():
    return sum(float(line.split()[-1]) for line in request('/metrics').splitlines()
               if line.startswith('vllm:prefix_cache_hits_total'))

rows = [f'归档记录{i}：此行仅供背景阅读，无有效预算。' for i in range(700)]
for position, name, amount in [(20,'青松','17391'),(350,'白鹭','28647'),(670,'海棠','39583')]:
    rows[position] = f'已核定：{name}项目预算为{amount}元。'
document = '\n'.join(rows)
before = hits()
for name, expected in [('青松','17391'),('白鹭','28647'),('海棠','39583'),('青松','17391')]:
    # Only the question suffix changes. The document prefix is identical.
    payload = {'model':'qwen3.8-flash-next', 'temperature':0, 'seed':42,
        'reasoning_effort':'low','max_tokens':512,
        'messages':[{'role':'user','content':'请根据以下档案回答，忽略无效归档行。\n<档案>\n'+document+'\n</档案>\n'+name+'项目的已核定预算是多少元？只输出数字。'}]}
    result = json.loads(request('/v1/chat/completions',payload))
    choice = result['choices'][0]
    content = choice['message'].get('content') or ''
    correct = content.strip() == expected and choice['finish_reason']=='stop'
    print(json.dumps({'project':name,'expected':expected,'content':content,
        'correct':correct,'usage':result.get('usage')},ensure_ascii=False),flush=True)
    assert correct, 'Cached prefix answer mismatch'
delta = hits()-before
print(json.dumps({'prefix_cache_hits_delta':delta}),flush=True)
assert delta>0, 'No actual cache hits measured'
print('PREFIX_CHECK_PASS',flush=True)