#!/usr/bin/env python3
"""AM-1 / M-D1-COV: every numbered GR-rule needs >=1 scenario.

Compares the rule IDs declared in specs/GroundRules.md against the
`covers:` lists in scenarios/ground/*.yaml. Exits non-zero when a
scenario claims a rule the spec does not define, so coverage can never
be inflated by a typo'd or invented rule ID.

Stated limit (InnerLoop implementation rule 4): this gate counts tags. It
proves no rule is unclaimed and no claimed rule is invented. It does NOT
prove a scenario exercises the rule it names.

Positive control (InnerLoop v1.1 §Step 5): the run asserts it actually
found rules and scenarios. Before this was added, a broken spec regex
yielded rules=[] and missing=[] and the tool exited 0 reporting "0/0" —
the harness-does-nothing class, in the tool that reports our headline
coverage number.

Usage:
  python3 tools/rule-coverage.py
  python3 tools/rule-coverage.py --self-test
"""
import glob
import re
import sys

RULE_RE = r"\*\*(GR-[A-Z]+\d+)"
COVERS_RE = r"covers: \[(.*?)\]"
AGGREGATE = "games/ground/src/lib.rs"
# CB-WP-0003 T08: a provisional default with no expiry can shape the kernel
# indefinitely while looking handled. CI warns; it does not break the build,
# because the ruling is a ground-game decision we cannot make for them.
PROVISIONAL_WARN_DAYS = 30
ID_RE = r"GR-[A-Z]+\d+"


def parse_rules(spec_text):
    return sorted(set(re.findall(RULE_RE, spec_text)))


def parse_code_ids(text):
    """Rule IDs named anywhere in the aggregate source (T09)."""
    return set(re.findall(ID_RE, text))


def provisional_items(paths):
    """(path, owner, raised) for every scenario encoding a U-item default."""
    out = []
    for path in paths:
        text = open(path).read()
        if not re.search(r"^provisional:\s*true", text, re.M):
            continue
        owner = re.search(r"^provisional_owner:\s*(\S+)", text, re.M)
        raised = re.search(r"^provisional_raised:\s*(\S+)", text, re.M)
        out.append((path,
                    owner.group(1) if owner else None,
                    raised.group(1) if raised else None))
    return out


def parse_covers(text):
    match = re.search(COVERS_RE, text, re.S)
    if not match:
        return set()
    return {c.strip() for c in match.group(1).split(",") if c.strip()}


def self_test():
    """Each assertion pins a failure this tool must detect."""
    results = []

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

    # The defect that motivated this control: a spec that parses to zero
    # rules must not be reportable as coverage.
    check("zero rules detected as a failure", parse_rules("no rules here") == [],
          "empty spec yields no rules; main() now aborts on this")
    # The matcher must actually match the real format.
    check("rule matcher works on real spec format",
          parse_rules("**GR-R06** something\n**GR-A12** other")
          == ["GR-A12", "GR-R06"])
    # covers: parsing, including the empty case.
    check("covers matcher works", parse_covers("covers: [GR-R06, GR-A12]")
          == {"GR-R06", "GR-A12"})
    check("missing covers yields empty set", parse_covers("no covers key") == set())
    # T09: the spec -> code link must be detectable.
    check("code-id matcher finds ids in source",
          parse_code_ids("// GR-R06: lead first\nfn f(){} // GR-A12")
          == {"GR-R06", "GR-A12"})
    check("code-id matcher finds none in unmarked source",
          parse_code_ids("fn f() { let x = 1; }") == set())
    # T08: every provisional scenario must carry an owner and a date.
    import glob as _g
    prov = provisional_items(sorted(_g.glob("scenarios/ground/*.yaml")))
    check("every provisional item has an owner and a raised date",
          bool(prov) and all(o and r for _, o, r in prov),
          f"{len(prov)} provisional item(s)")

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


def main():
    if "--self-test" in sys.argv:
        return self_test()

    rules = parse_rules(open("specs/GroundRules.md").read())
    paths = sorted(glob.glob("scenarios/ground/*.yaml"))

    # Positive control: refuse to report a percentage over nothing.
    if not rules:
        print("ERROR — no GR-rules parsed from specs/GroundRules.md; "
              "refusing to report coverage", file=sys.stderr)
        return 1
    if not paths:
        print("ERROR — no scenarios found in scenarios/ground/; "
              "refusing to report coverage", file=sys.stderr)
        return 1

    covered = set()
    for path in paths:
        covered |= parse_covers(open(path).read())

    known = set(rules)
    hit = sorted(known & covered)
    missing = [r for r in rules if r not in covered]
    invented = sorted(covered - known)

    # T09: the spec -> code -> scenario chain, made mechanical. A rule a
    # scenario claims should also be named in the aggregate, or the claim
    # rests on nothing but a tag.
    code_ids = parse_code_ids(open(AGGREGATE).read())
    unlinked = sorted((known & covered) - code_ids)
    phantom = sorted(code_ids - known)

    pct = 100 * len(hit) // len(rules)
    linked = len((known & covered) & code_ids)
    print(f"AM-1 rule coverage: {len(hit)}/{len(rules)} ({pct}%) "
          f"over {len(paths)} scenarios")
    print(f"AM-1b spec->code link: {linked}/{len(hit)} claimed rules also "
          f"named in {AGGREGATE}")
    print("  NOTE: counts tags; does not prove a scenario exercises what it names")
    if unlinked:
        print("  unlinked (claimed by a scenario, absent from the aggregate):")
        print("   ", " ".join(unlinked))
    if phantom:
        print("  ERROR — rule id in code that the spec does not define:",
              " ".join(phantom), file=sys.stderr)
        return 1
    # T08: provisional items are reported with an owner and an age.
    prov = provisional_items(paths)
    if prov:
        import datetime
        today = datetime.date.today()
        print(f"\nprovisional U-item defaults: {len(prov)}")
        unowned, stale = [], []
        for path, owner, raised in prov:
            age = "?"
            if raised:
                try:
                    age = (today - datetime.date.fromisoformat(raised)).days
                except ValueError:
                    age = "?"
            name = path.split("/")[-1]
            print(f"  {name:<34} owner={owner or 'NONE':<12} age={age}d")
            if not owner:
                unowned.append(name)
            if isinstance(age, int) and age > PROVISIONAL_WARN_DAYS:
                stale.append(f"{name} ({age}d)")
        if unowned:
            print("  WARN — provisional with no owner:", " ".join(unowned))
        if stale:
            print(f"  WARN — provisional for over {PROVISIONAL_WARN_DAYS} days:",
                  " ".join(stale))
        print("  NOTE: evidence files must list these; a ruling flips the "
              "scenario, not the kernel")

    if missing:
        print("  uncovered:", " ".join(missing))
    if invented:
        print("  ERROR — claimed but not defined in the spec:", " ".join(invented),
              file=sys.stderr)
        return 1
    return 0 if not missing else 2


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