#!/usr/bin/env python3
"""Is the vendored edition still what ground-game published? (ADR-0011 D2)

`editions/ground-darvo-r0/` is a copy of content owned by another repo.
A stale copy is worse than no copy, so the digest is committed and this
compares it.

**An absent upstream is reported absent, never as a pass.** That is the
shape ADR-0009 used for `node`: a check that cannot run says so, because
a silent skip is the class this project has found seven times.
"""
import hashlib
import os
import re
import sys

from repo import ROOT, enter_root

VENDORED = "editions/ground-darvo-r0/Problems.csv"
PROVENANCE = "editions/ground-darvo-r0/PROVENANCE.md"
UPSTREAM = os.path.join(os.path.dirname(ROOT), "ground-game", VENDORED)


def digest(path):
    return hashlib.sha256(open(path, "rb").read()).hexdigest()


def recorded():
    text = open(os.path.join(ROOT, PROVENANCE)).read()
    m = re.search(r"sha256\s+([0-9a-f]{64})", text)
    if not m:
        raise ValueError(f"{PROVENANCE} records no sha256 digest")
    return m.group(1)


def check():
    have = digest(os.path.join(ROOT, VENDORED))
    want = recorded()
    print("edition-check — vendored data against its provenance")
    if have != want:
        print(f"  [FAIL] {VENDORED} does not match its recorded digest")
        print(f"         recorded {want}\n         actual   {have}")
        return 1
    print(f"  [ok  ] vendored copy matches its recorded digest")

    if not os.path.exists(UPSTREAM):
        # NOT a pass and NOT a failure: the question could not be asked.
        print("  [----] upstream not checked out — freshness UNVERIFIED")
        print(f"         expected {UPSTREAM}")
        return 0
    up = digest(UPSTREAM)
    if up != have:
        print("  [FAIL] upstream has changed since this copy was vendored")
        print(f"         upstream {up}\n         vendored {have}")
        print("         ground-game froze point_value and required_solution")
        print("         within r0 — a change here is a new revision, or a")
        print("         contract violation worth raising.")
        return 1
    print("  [ok  ] vendored copy is current with ../ground-game")
    return 0


def self_test():
    """A checker that cannot detect a mismatch is decoration."""
    results = []

    def chk(name, ok, detail=""):
        results.append((name, ok, detail))

    chk("the vendored file exists", os.path.exists(os.path.join(ROOT, VENDORED)))
    chk("provenance records a digest", len(recorded()) == 64)
    chk("digest of the real file matches provenance",
        digest(os.path.join(ROOT, VENDORED)) == recorded())
    # The control that matters: a changed byte must be detected.
    import tempfile
    with tempfile.NamedTemporaryFile("wb", delete=False) as fh:
        fh.write(open(os.path.join(ROOT, VENDORED), "rb").read() + b"\n#tamper\n")
        tampered = fh.name
    chk("a tampered copy has a different digest",
        digest(tampered) != recorded(), "otherwise the check is decoration")
    os.unlink(tampered)

    print("edition-check self-test (positive control)")
    ok = True
    for name, passed, det in results:
        print(f"  [{'ok ' if passed else 'FAIL'}] {name}" + (f"  — {det}" if det else ""))
        ok &= passed
    return 0 if ok else 1


if __name__ == "__main__":
    enter_root()
    raise SystemExit(self_test() if "--self-test" in sys.argv else check())