open-standards/wai/live-conformance/signal_health_verify.py

#!/usr/bin/env python3
"""Independent verifier of the signal-health corpus (extensions/signal-health.md).

Written from the extension's text. It shares no code with wai-rs, which generates the corpus, and
never runs it. It takes Ed25519 verification as SPEC §7 *Signatures* states it from the routine
every Python verifier of WAI's corpora shares (`../claim-conformance/_ed25519.py`). Everything
this extension defines is written here: the record's layout and rules (§4, §6.1), its verdicts
(§6.2), the profile (§6.3), each check's values recomputed from its media (§5, §6.4), the
transport-stream indicators (§5.6) and the input switch (§7).

For every case it requires the outcome the corpus states, field for field; that every reason of
§8's table appears in the corpus; then it mutates copies of the corpus, one defect each, and
requires every copy to fail; and it drops each of its own checks in turn and requires the corpus
to catch the weakened verifier.

    python3 signal_health_verify.py <live-conformance/signal-health>

Exit status 0 only if every case verifies, every mutated copy fails and every weakened verifier is
caught. Python 3.8 or later and the standard library.
"""

import copy
import hashlib
import json
import os
import sys

HERE = os.path.dirname(os.path.abspath(__file__))
sys.path.insert(0, os.path.join(HERE, "..", "claim-conformance"))
import _ed25519 as ED  # noqa: E402

EXTENSION = os.path.join(HERE, "..", "extensions", "signal-health.md")
MAGIC = b"WSH1"
DOMAIN = b"wai:signal-health\x01"
MAX_LEN = 1024
MAX_INT = (1 << 53) - 1
NAMES = ["black", "freeze", "silence", "captions", "cues", "transport"]
NAME_BYTES = set(b"abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789._-:")
# §4.2: each code's thresholds and values, each (name, bytes).
THRESHOLDS = {
    1: [("luma_max", 1), ("ratio_ppm", 4), ("min_ms", 4)],
    2: [("mad_milli", 4), ("min_ms", 4)],
    3: [("peak_max", 2), ("min_ms", 4)],
    4: [("max_gap_ms", 4)],
    5: [("max_gap_ms", 4)],
    6: [("table_max_gap_ms", 4), ("pid_max_gap_ms", 4)],
}
RUNS = [("count", 4), ("matched", 4), ("longest_ms", 8), ("longest_at_ms", 8)]
SEEN = [("seen", 4), ("last_ms", 8), ("longest_gap_ms", 8)]
INDICATORS = [("packets", 8), ("sync_loss", 4), ("sync_byte", 4), ("pat", 4), ("cc", 4), ("pmt", 4), ("pid", 4)]
VALUES = {1: RUNS, 2: RUNS, 3: RUNS, 4: SEEN, 5: SEEN, 6: INDICATORS}

# A weakened run drops one of these checks (see `WEAKENINGS`); None checks everything.
DROPPED = None


def drops(name):
    return DROPPED == name


def reasons_table():
    """§8's codes, in order."""
    text = open(EXTENSION, encoding="utf-8").read()
    at = text.index("\n## 8. Reasons")
    end = text.find("\n## ", at + 1)
    rows = text[at:end if end >= 0 else len(text)].splitlines()
    return [r.split("`")[1] for r in rows if r.startswith("| `")]


class Refused(Exception):
    def __init__(self, reason):
        super().__init__(reason)
        self.reason = reason


# ------------------------------------------------------------------ §4, §6.1, §6.2: the record

def read(b):
    """The record as a dict, or Refused: the layout and rules of §6.1, the signature, §6.2."""
    bad = Refused("signal_health_malformed")
    if len(b) > MAX_LEN:
        raise bad
    at = 0

    def take(n):
        nonlocal at
        if at + n > len(b):
            raise bad
        s = b[at:at + n]
        at += n
        return s

    def num(n):
        return int.from_bytes(take(n), "big")

    if take(4) != MAGIC or take(1) != b"\x01":
        raise bad
    monitor = take(32)
    n = num(1)
    if not 1 <= n <= 64:
        raise bad
    name = take(n)
    if not drops("name") and any(c not in NAME_BYTES for c in name):
        raise bad
    frm, to = num(8), num(8)
    if (frm >= to and not drops("window")) or to > MAX_INT:
        raise bad
    window = to - frm
    m = num(1)
    if not 1 <= m <= 6:
        raise bad
    checks = []
    for _ in range(m):
        code = num(1)
        if not 1 <= code <= 6:
            raise bad
        if checks and checks[-1]["code"] >= code and not drops("order"):
            raise bad
        c = {"code": code, "media": take(32), "t": {}, "v": {}}
        for k, w in THRESHOLDS[code]:
            c["t"][k] = num(w)
        for k, w in VALUES[code]:
            c["v"][k] = num(w)
        c["fault"] = num(1)
        t, v = c["t"], c["v"]
        if not drops("range"):
            if code == 1 and not (1 <= t["ratio_ppm"] <= 1_000_000):
                raise bad
            if code == 3 and t["peak_max"] > 32_768:
                raise bad
            if any(t.get(k, 1) < 1 for k in ("min_ms", "table_max_gap_ms", "pid_max_gap_ms")):
                raise bad
        if not drops("values"):
            inside = lambda x: frm <= x < to  # noqa: E731
            if code <= 3:
                none = v["matched"] == 0 and v["longest_ms"] == 0 and v["longest_at_ms"] == 0
                some = v["matched"] != 0 and v["longest_ms"] != 0 and inside(v["longest_at_ms"])
                if v["matched"] > v["count"] or v["longest_ms"] > window or not (none or some):
                    raise bad
            elif code <= 5:
                none = v["seen"] == 0 and v["last_ms"] == 0 and v["longest_gap_ms"] == window
                some = v["seen"] != 0 and inside(v["last_ms"])
                if v["longest_gap_ms"] > window or not (none or some):
                    raise bad
        if c["fault"] not in (0, 1):
            raise bad
        checks.append(c)
    signed = b[:at]
    sig = take(64)
    if at != len(b):
        raise bad
    if not drops("signature") and ED.verify(monitor, DOMAIN + signed, sig) is not None:
        raise Refused("signal_health_signature_invalid")
    if not drops("verdict") and any(fails(c) != bool(c["fault"]) for c in checks):
        raise Refused("signal_health_verdict_inconsistent")
    return {"monitor": monitor, "input": name.decode("ascii"), "from": frm, "to": to, "checks": checks,
            "digest": hashlib.sha256(signed).digest()}


def fails(c):
    """§6.2: the verdict a check's values give under its thresholds."""
    t, v = c["t"], c["v"]
    if c["code"] <= 3:
        return v["longest_ms"] >= t["min_ms"]
    if c["code"] <= 5:
        return t["max_gap_ms"] != 0 and v["longest_gap_ms"] > t["max_gap_ms"]
    return any(v[k] > 0 for k in ("sync_loss", "sync_byte", "pat", "cc", "pmt", "pid"))


def faults(rec):
    return [NAMES[c["code"] - 1] for c in rec["checks"] if c["fault"]]


def conforms(rec, profile):
    """§6.3: exactly the profile's checks, each with its thresholds."""
    if drops("profile"):
        return True
    want = {NAMES.index(k) + 1: t for k, t in profile.items()}
    return len(rec["checks"]) == len(want) and all(want.get(c["code"]) == c["t"] for c in rec["checks"])


# ------------------------------------------------------------------ §5: the media

def sha(*parts):
    return hashlib.sha256(b"".join(parts)).digest()


def be(x, n):
    return x.to_bytes(n, "big")


def longest(runs):
    """The longest of runs (start, duration), the earliest of equals; (0, 0) for none."""
    best = (0, 0)
    for r in runs:
        if r[1] > best[1]:
            best = r
    return best


def runs_of(flags):
    """The runs of True in flags: (first index, last index)."""
    out, i = [], 0
    while i < len(flags):
        if flags[i]:
            j = i
            while j + 1 < len(flags) and flags[j + 1]:
                j += 1
            out.append((i, j))
            i = j + 1
        else:
            i += 1
    return out


def frames_values(frames, code, t, frm, to):
    ok = all(f["width"] >= 1 and f["height"] >= 1 and len(f["luma"]) == f["width"] * f["height"]
             and (drops("media_window") or frm <= f["at"] < to)
             and (i == 0 or frames[i - 1]["at"] < f["at"]) for i, f in enumerate(frames))
    if not ok:
        raise Refused("signal_health_media_malformed")
    digest = sha(b"wai:signal-health:video\x01",
                 *[be(f["at"], 8) + be(f["width"], 2) + be(f["height"], 2) + f["luma"] for f in frames])

    def end(i):
        return frames[i + 1]["at"] if i + 1 < len(frames) else to

    flags = []
    for i, f in enumerate(frames):
        n = len(f["luma"])
        if code == 1:
            if drops("black_ratio"):
                flags.append(all(y <= t["luma_max"] for y in f["luma"]))
            else:
                dark = sum(1 for y in f["luma"] if y <= t["luma_max"])
                flags.append(1_000_000 * dark >= t["ratio_ppm"] * n)
        else:
            if i == 0:
                flags.append(False)
                continue
            p = frames[i - 1]
            same = (p["width"], p["height"]) == (f["width"], f["height"]) or drops("freeze_size")
            sad = sum(abs(a - b) for a, b in zip(f["luma"], p["luma"]))
            flags.append(same and 1000 * sad <= t["mad_milli"] * n)
    runs = []
    for a, z in runs_of(flags):
        start = frames[a - 1]["at"] if code == 2 and not drops("freeze_hold") else frames[a]["at"]
        runs.append((start, end(z) - start))
    at, ms = longest(runs)
    return digest, {"count": len(frames), "matched": sum(flags), "longest_ms": ms, "longest_at_ms": at}


def audio_values(a, t, frm, to):
    ch, rate, s = a["channels"], a["rate"], a["samples"]
    if not (1 <= ch <= 32 and rate % 100 == 0 and 100 <= rate <= 384_000 and len(s) % (2 * ch) == 0):
        raise Refused("signal_health_media_malformed")
    vals = [int.from_bytes(s[i:i + 2], "little", signed=True) for i in range(0, len(s), 2)]
    per = rate // 100 * ch
    blocks = len(vals) // per
    if not drops("media_window") and not (a["at"] >= frm and a["at"] + 10 * blocks <= to):
        raise Refused("signal_health_media_malformed")
    digest = sha(b"wai:signal-health:audio\x01", be(a["at"], 8), be(rate, 4), be(ch, 2), s)
    flags = []
    for b in range(blocks):
        block = vals[b * per:(b + 1) * per]
        if drops("silence_channels"):
            block = block[::ch]
        flags.append(max(abs(x) for x in block) <= t["peak_max"])
    runs = [(a["at"] + 10 * x, 10 * (z - x + 1)) for x, z in runs_of(flags)]
    at, ms = longest(runs)
    return digest, {"count": blocks, "matched": sum(flags), "longest_ms": ms, "longest_at_ms": at}


def instants_values(code, inst, frm, to):
    if not all((drops("media_window") or frm <= x < to) for x in inst) or any(a > b for a, b in zip(inst, inst[1:])):
        raise Refused("signal_health_media_malformed")
    domain = b"wai:signal-health:cues\x01" if code == 5 else b"wai:signal-health:captions\x01"
    digest = sha(domain, be(len(inst), 4), *[be(x, 8) for x in inst])
    edges = list(inst) if drops("gap_edges") and inst else [frm] + list(inst) + [to]
    gaps = [b - a for a, b in zip(edges, edges[1:])]
    return digest, {"seen": len(inst), "last_ms": inst[-1] if inst else 0, "longest_gap_ms": max(gaps) if gaps else 0}


# ------------------------------------------------------------------ §5.5, §5.6: the transport stream

def transport_values(ts, t, frm, to):
    b, first, rate = ts["bytes"], ts["first_us"], ts["rate_bps"]
    n = len(b) // 188
    arrive = lambda k: first + k * 188 * 8 * 1_000_000 // rate  # noqa: E731
    if not (len(b) % 188 == 0 and n >= 1 and rate >= 1
            and (drops("media_window") or (first >= frm * 1000 and arrive(n - 1) < to * 1000))):
        raise Refused("signal_health_media_malformed")
    digest = sha(b"wai:signal-health:transport\x01", be(first, 8), be(rate, 8), b)
    tg, pg = t["table_max_gap_ms"] * 1000, t["pid_max_gap_ms"] * 1000
    v = {"packets": n, "sync_loss": 0, "sync_byte": 0, "pat": 0, "cc": 0, "pmt": 0, "pid": 0}
    st = {"cc": {}, "dups": {}, "pat": frm * 1000, "pmts": {}, "ref": {}}

    def late(anchor, a, gap):
        return a - anchor > gap

    def rerefer(a):
        union = set()
        for _, es in st["pmts"].values():
            union |= es
        for q in [q for q in st["ref"] if q not in union]:
            anchor = st["ref"].pop(q)
            if late(anchor, a, pg):
                v["pid"] += 1
        for q in union:
            st["ref"].setdefault(q, a)

    def section(p, start):
        s = start + 1 + p[start]
        return s if s < 188 else None

    def whole(p, s, least):
        if s + 3 > 188:
            return None
        ln = ((p[s + 1] & 0x0F) << 8) | p[s + 2]
        e = s + 3 + ln
        return e if ln >= least and e <= 188 else None

    def analyse(p, a):
        pid = ((p[1] & 0x1F) << 8) | p[2]
        if pid == 0x1FFF:
            return
        scr, afc, cc, pusi = p[3] >> 6, (p[3] >> 4) & 3, p[3] & 0x0F, p[1] & 0x40
        if afc == 1:
            start, disc = 4, False
        elif afc in (2, 3):
            start, disc = 5 + p[4], p[4] > 0 and p[5] & 0x80 != 0
        else:
            start, disc = 188, False
        payload = afc in (1, 3) and start < 188
        if payload:
            if pid in st["cc"]:
                last = st["cc"][pid]
                if disc and not drops("discontinuity"):
                    st["dups"][pid] = 0
                elif cc == last:
                    st["dups"][pid] = st["dups"].get(pid, 0) + 1
                    if st["dups"][pid] >= 2 or drops("duplicate"):
                        v["cc"] += 1
                else:
                    if cc != (last + 1) & 0x0F:
                        v["cc"] += 1
                    st["dups"][pid] = 0
            st["cc"][pid] = cc
        if pid in st["ref"]:
            if late(st["ref"][pid], a, pg) and not drops("pid_gap"):
                v["pid"] += 1
            st["ref"][pid] = a
        if pid == 0:
            if scr and not drops("scrambling"):
                v["pat"] += 1
            s = section(p, start) if pusi and payload else None
            if s is not None:
                if p[s] == 0x00:
                    if late(st["pat"], a, tg) and not drops("table_gap"):
                        v["pat"] += 1
                    st["pat"] = a
                    e = whole(p, s, 9)
                    if e is not None:
                        maps, i = set(), s + 8
                        while i + 4 <= e - 4:
                            if (p[i] << 8) | p[i + 1]:
                                maps.add(((p[i + 2] & 0x1F) << 8) | p[i + 3])
                            i += 4
                        for m in [m for m in st["pmts"] if m not in maps]:
                            anchor, _ = st["pmts"].pop(m)
                            if late(anchor, a, tg):
                                v["pmt"] += 1
                        for m in maps:
                            st["pmts"].setdefault(m, (a, set()))
                        rerefer(a)
                elif p[s] != 0xFF and not drops("pat_table"):
                    v["pat"] += 1
        if pid in st["pmts"]:
            if scr and not drops("scrambling"):
                v["pmt"] += 1
            s = section(p, start) if pusi and payload else None
            if s is not None and p[s] == 0x02:
                anchor, es = st["pmts"][pid]
                if late(anchor, a, tg) and not drops("table_gap"):
                    v["pmt"] += 1
                st["pmts"][pid] = (a, es)
                e = whole(p, s, 13)
                if e is not None:
                    pil = ((p[s + 10] & 0x0F) << 8) | p[s + 11]
                    new, i = set(), s + 12 + pil
                    while i + 5 <= e - 4:
                        new.add(((p[i + 1] & 0x1F) << 8) | p[i + 2])
                        i += 5 + (((p[i + 3] & 0x0F) << 8) | p[i + 4])
                    st["pmts"][pid] = (a, new if not drops("es_removed") else es | new)
                    rerefer(a)

    hunting, run, bad, locked = True, 0, 0, False
    for k in range(n):
        p = b[k * 188:(k + 1) * 188]
        good = p[0] == 0x47
        if hunting:
            if not good:
                run = 0
                continue
            run += 1
            if run == 5 or drops("hysteresis"):
                hunting, locked, bad = False, True, 0
                for j in range(k - run + 1, k + 1):
                    analyse(b[j * 188:(j + 1) * 188], arrive(j))
        elif good:
            bad = 0
            analyse(p, arrive(k))
        else:
            v["sync_byte"] += 1
            bad += 1
            if bad == 2 or drops("loss_on_two"):
                v["sync_loss"] += 1
                hunting, run = True, 0
    if n and not locked:
        v["sync_loss"] += 1
    if not drops("window_end"):
        e = to * 1000
        v["pat"] += late(st["pat"], e, tg)
        v["pmt"] += sum(1 for anchor, _ in st["pmts"].values() if late(anchor, e, tg))
        v["pid"] += sum(1 for anchor in st["ref"].values() if late(anchor, e, pg))
    return digest, v


def measure(c, media, frm, to):
    """§5: (digest, values) of the media for check c, None when not held, or Refused."""
    code, t = c["code"], c["t"]
    if code in (1, 2):
        return None if "frames" not in media else frames_values(media["frames"], code, t, frm, to)
    if code == 3:
        return None if "audio" not in media else audio_values(media["audio"], t, frm, to)
    if code in (4, 5):
        k = "captions" if code == 4 else "cues"
        return None if k not in media else instants_values(code, media[k], frm, to)
    return None if "transport" not in media else transport_values(media["transport"], t, frm, to)


def recompute(rec, media):
    """§6.4: each check's label."""
    labels = []
    for c in rec["checks"]:
        try:
            got = measure(c, media, rec["from"], rec["to"])
        except Refused as r:
            labels.append("reject reason=" + r.reason)
            continue
        if got is None:
            labels.append("not_held")
        elif got[0] != c["media"] and not drops("digest"):
            labels.append("reject reason=signal_health_media_mismatch")
        elif got[1] != c["v"]:
            labels.append("reject reason=signal_health_not_recomputed")
        else:
            labels.append("recomputed")
    return labels


# ------------------------------------------------------------------ §7: the switch

def switch(cfg, profile, records, at, current):
    states, read_ = [], {}
    for k, b in enumerate(records):
        try:
            rec = read(b)
            if not conforms(rec, profile):
                raise Refused("signal_health_profile_mismatch")
        except Refused as r:
            states.append("reject reason=" + r.reason)
            continue
        if rec["monitor"].hex() not in cfg["trusted"] and not drops("trusted"):
            states.append("untrusted")
        elif rec["to"] > at and not drops("not_yet"):
            states.append("not_yet")
        else:
            read_[k] = rec
            states.append("stands")
    top = {}
    for rec in read_.values():
        top[rec["input"]] = max(top.get(rec["input"], 0), rec["to"])
    for k, rec in read_.items():
        if rec["to"] < top[rec["input"]] and not drops("supersede"):
            states[k] = "superseded"
        elif not drops("contradiction") and any(o["input"] == rec["input"] and o["to"] == rec["to"]
                                                 and o["digest"] != rec["digest"] for o in read_.values()):
            states[k] = "contradicted"
    inputs, selected = [], None
    for name in cfg["inputs"]:
        mine = [k for k, r in read_.items() if r["input"] == name]
        standing = [k for k in mine if states[k] == "stands"]
        if any(states[k] == "contradicted" for k in mine):
            st = "contradicted"
        elif standing:
            rec = read_[standing[0]]
            if at - rec["to"] > cfg["max_age_ms"] and not drops("freshness"):
                st = "stale"
            elif faults(rec):
                st = "fault:" + "+".join(faults(rec))
            else:
                st = "healthy"
        else:
            st = "none"
        if st == "healthy" and selected is None:
            selected = name
        inputs.append(st)
    return {"records": states, "inputs": inputs, "selected": selected if selected is not None else current}


# ------------------------------------------------------------------ the corpus

def media_of(m):
    out = {}
    if "frames" in m:
        out["frames"] = [{"at": f["at_ms"], "width": f["width"], "height": f["height"],
                          "luma": bytes.fromhex(f["luma"])} for f in m["frames"]]
    if "audio" in m:
        a = m["audio"]
        out["audio"] = {"at": a["at_ms"], "rate": a["rate"], "channels": a["channels"],
                        "samples": bytes.fromhex(a["samples"])}
    for k in ("captions", "cues"):
        if k in m:
            out[k] = list(m[k])
    if "transport" in m:
        t = m["transport"]
        out["transport"] = {"first_us": t["first_us"], "rate_bps": t["rate_bps"], "bytes": bytes.fromhex(t["bytes"])}
    return out


def run(doc, kind, c):
    if kind == "records":
        try:
            rec = read(bytes.fromhex(c["bytes"]))
        except Refused as r:
            return {"outcome": "refuse", "reason": r.reason}
        return {"outcome": "read", "digest": rec["digest"].hex(), "input": rec["input"], "faults": faults(rec)}
    if kind == "checks":
        try:
            rec = read(bytes.fromhex(c["record"]))
            if c["profile"] is not None and not conforms(rec, c["profile"]):
                raise Refused("signal_health_profile_mismatch")
        except Refused as r:
            return {"record": "reject reason=" + r.reason}
        return {"record": "stands", "checks": recompute(rec, media_of(c["media"]))}
    return switch(doc["switch"], doc["profile"], [bytes.fromhex(x) for x in c["records"]], c["at_ms"], c["current"])


KINDS = ("records", "checks", "switches")


def strings(v, out):
    if isinstance(v, str):
        out.append(v)
    elif isinstance(v, list):
        for x in v:
            strings(x, out)
    elif isinstance(v, dict):
        for x in v.values():
            strings(x, out)


def check(doc, quiet=False):
    """The failures of a corpus document: each case's outcome, and every reason of §8."""
    fails = []
    for kind in KINDS:
        for c in doc[kind]:
            try:
                got = run(doc, kind, c)
            except (Refused, KeyError, TypeError, ValueError, IndexError, ZeroDivisionError) as e:
                got = {"error": repr(e)}
            if got != c["outcome"]:
                fails.append(c["name"])
                if not quiet:
                    print(f"FAIL {kind} {c['name']}\n  stated {json.dumps(c['outcome'])}\n  got    {json.dumps(got)}")
    stated = []
    for kind in KINDS:
        for c in doc[kind]:
            strings(c["outcome"], stated)
    for code in reasons_table():
        if not any(s == code or s.endswith("reason=" + code) for s in stated):
            fails.append("no case gives " + code)
    return fails


def mutations(doc):
    """Copies of the corpus, one defect each, every one of which must fail."""
    def case(d, kind, name):
        return next(c for c in d[kind] if c["name"] == name)

    def m_bit(d):
        c = case(d, "records", "healthy")
        b = bytearray.fromhex(c["bytes"])
        b[60] ^= 0x01
        c["bytes"] = b.hex()

    def m_digest(d):
        case(d, "records", "black")["outcome"]["digest"] = "00" * 32

    def m_faults(d):
        case(d, "records", "silence")["outcome"]["faults"] = []

    def m_luma(d):
        f = case(d, "checks", "black")["media"]["frames"][6]
        f["luma"] = "ff" + f["luma"][2:]

    def m_threshold(d):
        case(d, "checks", "healthy")["profile"]["black"]["min_ms"] = 800

    def m_doc_threshold(d):
        d["profile"]["transport"]["pid_max_gap_ms"] = 999

    def m_packet(d):
        t = case(d, "checks", "transport_cc")["media"]["transport"]
        b = bytearray.fromhex(t["bytes"])
        b[30 * 188 + 5] ^= 0x80
        t["bytes"] = b.hex()

    def m_rate(d):
        case(d, "checks", "transport_pid")["media"]["transport"]["rate_bps"] += 1

    def m_caption(d):
        case(d, "checks", "captions")["media"]["captions"][1] += 1

    def m_at(d):
        case(d, "switches", "primary_stale")["at_ms"] -= 2_000

    def m_inputs(d):
        d["switch"]["inputs"].reverse()

    def m_trusted(d):
        d["switch"]["trusted"].pop()

    def m_reason_gone(d):
        d["checks"].remove(case(d, "checks", "value_not_given"))

    def m_media_gone(d):
        del case(d, "checks", "healthy")["media"]["frames"]

    return [m_bit, m_digest, m_faults, m_luma, m_threshold, m_doc_threshold, m_packet, m_rate, m_caption, m_at,
            m_inputs, m_trusted, m_reason_gone, m_media_gone]


WEAKENINGS = ["name", "window", "order", "range", "values", "signature", "verdict", "profile", "digest", "media_window",
              "black_ratio", "freeze_size", "freeze_hold", "silence_channels", "gap_edges", "hysteresis", "loss_on_two",
              "duplicate", "discontinuity", "scrambling", "table_gap", "pat_table", "pid_gap", "es_removed",
              "window_end", "trusted", "not_yet", "supersede", "contradiction", "freshness"]


def main(argv):
    global DROPPED
    if len(argv) != 2:
        print(__doc__)
        return 2
    doc = json.load(open(os.path.join(argv[1], "vectors.json"), encoding="utf-8"))
    extra = sorted(set(os.listdir(argv[1])) - {"vectors.json", "README.md"})
    fails = check(doc)
    if extra:
        fails.append(f"files the corpus does not hold: {extra}")
    # §6.1's bound, which no vector carries: checked here.
    try:
        read(b"\x00" * (MAX_LEN + 1))
        fails.append("a record past 1024 bytes was read")
    except Refused as r:
        if r.reason != "signal_health_malformed":
            fails.append("a record past the bound was refused " + r.reason)
    print(f"{sum(len(doc[k]) for k in KINDS)} cases ({', '.join(f'{len(doc[k])} {k}' for k in KINDS)}): {len(fails)} failure(s)")
    caught = 0
    for m in mutations(doc):
        d = copy.deepcopy(doc)
        m(d)
        if check(d, quiet=True):
            caught += 1
        else:
            fails.append(f"mutation {m.__name__} was not caught")
    print(f"{caught} of {len(mutations(doc))} mutated copies fail")
    weak = 0
    for w in WEAKENINGS:
        DROPPED = w
        if check(doc, quiet=True):
            weak += 1
        else:
            fails.append(f"a verifier without its {w} check passes the corpus")
    DROPPED = None
    print(f"{weak} of {len(WEAKENINGS)} weakened verifiers are caught")
    for f in fails:
        print("FAIL", f)
    return 1 if fails else 0


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