"""变异检查：把"motor/start 许可判定"逐条退回旧形状，门槛必须变红。

存在理由：`node scripts/test_ecat_autostart.mjs` 全绿只说明"当前实现满足了断言"，
不说明断言有灵敏度 —— 本项目反复栽在"测试绿着但判据永不触发"（tx 冻结守卫、
t8_soak 反极性都是同族）。这份脚本把实现改坏，看测试是否变红；只要有一条仍全绿，
那条断言就是自证的空话，禁止当成验收凭据。

它会**原地改写**两个 JS 文件再逐字节还原，所以要求这两个文件在工作树里是干净的
（有自己的未提交改动时先 commit 或 stash，别在这儿叠）。

用法：python scripts/check_fe_guard_mutation.py [--keep-report]
退出码：0=每条变异都被测出（且还原后基线仍绿） 1=有空断言或还原失败 2=前置不满足
"""
import os
import re
import subprocess
import sys

ROOT = os.path.abspath(os.path.join(os.path.dirname(__file__), os.pardir))
BUS = os.path.join(ROOT, "js", "common", "ecat-bus.js")
TR = os.path.join(ROOT, "js", "motor", "transport-ecat.js")
TEST = os.path.join("scripts", "test_ecat_autostart.mjs")
FAIL_MARK = chr(10007)          # ✗
SUMMARY = "通过 (\\d+) 项，失败 (\\d+) 项"

# (说明, 文件, 原文, 改成的旧形状)
MUTS = [
    ("healthCheck 不再走 repairEcatDc（退回什么都不自愈）", TR,
     "        await repairEcatDc(api, h.raw);", "        /* MUTATED */"),
    ("proveEcatDc 把缺字段当成配错（7ea80f0 内联副本的形状）", BUS,
     '  if (h.dc == null && h.period_ms == null && h.dc_cycle_us == null) return "unknown";',
     "  /* MUTATED */"),
    ("去掉自动重启的最小间隔", BUS,
     "export const AUTO_START_MIN_INTERVAL_MS = 20000;",
     "export const AUTO_START_MIN_INTERVAL_MS = 0;"),
    ("去掉「native 正在全量重连时不动总线」", BUS,
     "  if (h.recovering) return null;" + chr(10) + "  return ecatPost",
     "  /* MUTATED */" + chr(10) + "  return ecatPost"),
    ("proveEcatLoop 把「读不到」当成 down（抹掉 unknown 三态）", BUS,
     '  if (!h || h.ok !== true) {' + chr(10)
     + '    return (opts && opts.treatOfflineAsDown) ? "down" : "unknown";' + chr(10) + '  }',
     '  if (!h || h.ok !== true) return "down";'),
    ("去掉连续封顶（AUTO_START_MAX_STREAK 无限大）", BUS,
     "export const AUTO_START_MAX_STREAK = 3;",
     "export const AUTO_START_MAX_STREAK = 9999;"),
]


def run_suite():
    p = subprocess.run(["node", TEST], cwd=ROOT, capture_output=True, text=True,
                       encoding="utf-8", errors="replace", timeout=300)
    out = p.stdout or ""
    m = re.search(SUMMARY, out)
    reds = [l.split(FAIL_MARK)[1].strip()[:44] for l in out.splitlines() if FAIL_MARK in l]
    if not m:
        why = (out.strip().splitlines() or [""])[-1] or (p.stderr or "").strip()[:80]
        return (-1, 1), ["（无汇总行，进程提前退出）" + why]
    return (int(m.group(1)), int(m.group(2))), reds


def dirty(paths):
    try:
        r = subprocess.run(["git", "status", "--porcelain", "--"] + paths,
                           cwd=ROOT, capture_output=True, text=True, timeout=20)
        return bool((r.stdout or "").strip())
    except Exception:
        return True


def main():
    if dirty([os.path.relpath(BUS, ROOT), os.path.relpath(TR, ROOT)]):
        print("BLOCKED 目标文件有未提交改动，变异脚本不做叠写；先 commit 或 stash")
        print("VERDICT BLOCKED")
        return 2
    bak = {f: open(f, "rb").read() for f in (BUS, TR)}

    def restore():
        for f, b in bak.items():
            open(f, "wb").write(b)
        for f, b in bak.items():
            assert open(f, "rb").read() == b, "还原失败: " + f

    base, _ = run_suite()
    print("基线：通过 %d 失败 %d" % base)
    if base[1] != 0 or base[0] < 0:
        print("VERDICT FAIL 基线就没绿，变异检查无从谈起")
        return 1
    vacuous = []
    for name, path, old, new in MUTS:
        s = open(path, "rb").read().decode("utf-8")
        if s.count(old) != 1:
            vacuous.append(name + "（锚点命中 %d 次：实现已漂移，先更新本脚本）" % s.count(old))
            print("%-56s 锚点失效" % name)
            continue
        open(path, "wb").write(s.replace(old, new, 1).encode("utf-8"))
        try:
            (np, nf), reds = run_suite()
        finally:
            restore()
        hit = nf > 0
        print("%-56s 通过 %2d 失败 %2d  %s" % (name, np, nf, "变红 OK" if hit else "仍全绿 = 空断言"))
        for r in reds[:3]:
            print("      红:", r)
        if not hit:
            vacuous.append(name)
    again, _ = run_suite()
    print("还原后复核：通过 %d 失败 %d" % again)
    if vacuous or again[1] != 0:
        print("VERDICT FAIL vacuous=%d" % len(vacuous))
        for v in vacuous:
            print("  -", v)
        return 1
    print("VERDICT PASS mutations=%d" % len(MUTS))
    return 0


if __name__ == "__main__":
    sys.exit(main())