#!/usr/bin/env bash
# =============================================================================
# L0 static check (offline, no cluster) — admission-policies-actually-applied
# Serves: R-SEC-01, R-SEC-02 (admission enforcement is only real if it is APPLIED)
#
# WHY THIS EXISTS — a policy that ships green and never reaches the cluster.
#
# platform/kyverno/ holds THREE lists, and only one of them applies anything:
#   1. platform/kyverno/admission/kustomization.yaml  — reference only. Its own sibling says
#      "kept as reference; THIS file is the buildable render root".
#   2. platform/kyverno/kustomization.yaml            — that render root: namespace +
#      HelmRelease ONLY. It explicitly notes the ClusterPolicies are applied elsewhere.
#   3. platform-config/kustomization.yaml             — THE ONE. Kyverno CRs go here because
#      they need the CRDs from the HelmRelease in (2), so they reconcile a tier later.
#
# On 2026-09-29 a ClusterPolicy (conformance-trigger-job-shape, the R-SEC-02 boundary bounding
# what the conformance CI trigger may create) was added to (1). Everything went green: the file
# parsed, `kyverno test` exercised it BY PATH and passed, the gate passed, Flux reported
# `platform` Ready at the new revision — and the policy was never in any applied set. The
# cluster ended up running the conformance-trigger ServiceAccount with NOTHING bounding it,
# which is precisely the state that identity's own RBAC header says must never exist.
#
# Nothing could have caught it. `kyverno test` proves a policy is CORRECT, not that it is
# DEPLOYED. This check asserts the second thing.
#
# GIVEN the repository as git tracks it,
# WHEN  every file under platform/kyverno/ that declares a ClusterPolicy is enumerated,
# THEN  each one is either referenced by platform-config/kustomization.yaml (so Flux applies
#       it), or named in CI_ONLY below with a reason — and CI_ONLY itself may not name a
#       policy that IS applied, so the exemption list cannot rot into a lie either way.
# =============================================================================
set -euo pipefail
DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
ROOT="$(cd "${DIR}/../../../.." && pwd)"        # repo root
exec python3 - "$ROOT" <<'PY'
import sys, subprocess
from pathlib import Path

ROOT = Path(sys.argv[1])
FAILURES, CHECKS = [], 0

def check(cond, desc):
    global CHECKS
    CHECKS += 1
    if not cond:
        FAILURES.append(desc)

# Policies authored for the CI L0 gate that are deliberately NOT applied in-cluster. Each needs
# a reason, and each is asserted BELOW to really be absent from the applied set — an exemption
# that silently starts being applied is as much a lie as one that silently stops.
CI_ONLY = {
    "disallow-plaintext-secrets":
        "CI-only by design: it requires a top-level `sops` block, which is IMPOSSIBLE at "
        "admission because Flux decrypts before the Secret reaches the API server. Its "
        "in-cluster counterpart is admission/secret-provenance.yaml.",
}

tracked = subprocess.run(["git", "ls-files", "-z", "--", "platform/kyverno/**/*.yaml",
                          "platform/kyverno/*.yaml"],
                         cwd=ROOT, capture_output=True, text=True, check=True)
files = [ROOT / p for p in tracked.stdout.split("\0") if p]

# A ClusterPolicy file, identified without a YAML parse of every doc: cheap and sufficient.
policies = {}
for f in files:
    try:
        txt = f.read_text()
    except Exception:
        continue
    if "kind: ClusterPolicy" not in txt:
        continue
    for line in txt.splitlines():
        st = line.strip()
        if st.startswith("name:") and "  name:" in line:
            policies[f.relative_to(ROOT).as_posix()] = st.split("name:", 1)[1].strip()
            break

check(len(policies) >= 6,
      f"(0) the scan found {len(policies)} ClusterPolicy file(s) under platform/kyverno/ — "
      f"too few means the scan broke, and every assertion below would be vacuous")

applied_txt = (ROOT / "platform-config" / "kustomization.yaml").read_text()

unapplied, wrongly_exempt = [], []
for rel, name in sorted(policies.items()):
    # platform-config references these as ../platform/kyverno/...
    referenced = rel in applied_txt or rel.replace("platform/", "../platform/", 1) in applied_txt
    if name in CI_ONLY:
        if referenced:
            wrongly_exempt.append(f"{name} ({rel}) is listed CI_ONLY but IS applied by platform-config")
    elif not referenced:
        unapplied.append(f"{name} ({rel})")

check(not unapplied,
      f"(1) every in-cluster ClusterPolicy is referenced by platform-config/kustomization.yaml "
      f"— an unreferenced policy is authored, tested, green, and NEVER APPLIED {unapplied if unapplied else ''}")

check(not wrongly_exempt,
      f"(2) no CI_ONLY exemption names a policy that IS applied — a stale exemption hides a "
      f"real deployment {wrongly_exempt if wrongly_exempt else ''}")

for name, reason in CI_ONLY.items():
    check(bool(reason.strip()),
          f"(3) CI_ONLY['{name}'] carries a reason — an unexplained exemption is how this "
          f"list stops being reviewable")

check(CHECKS >= 4,
      f"only {CHECKS} assertions ran — the check degenerated to a near-no-op")

if FAILURES:
    print(f"CHECK FAIL (admission-policies-actually-applied): {len(FAILURES)} of {CHECKS} assertions failed",
          file=sys.stderr)
    for f in FAILURES:
        print(f"  - {f}", file=sys.stderr)
    raise SystemExit(1)
print(f"check OK: admission-policies-actually-applied — {CHECKS} assertions; "
      f"{len(policies)} ClusterPolicy file(s), {len(policies) - len(CI_ONLY)} applied by "
      f"platform-config, {len(CI_ONLY)} CI-only with reasons. Proves policies are DEPLOYED, "
      f"not that they are correct — `kyverno test` is what proves correctness.")
PY