#!/usr/bin/env bash
set -uo pipefail

# CASAN Plan-16 SEC-01 (H-01) — "unsigned = FAIL" in enforced mode.
#
# Proves that verify-audit-chain / verify-tool-audit / telemetry-integrity /
# evidence-pack all treat a missing (or unverifiable) signature as a FAILURE when
# strict enforcement is on, while keeping the permissive dev default unchanged.
# Enforcement is triggered by either CASAN_VERIFY_STRICT=1 or CASAN_PROFILE=prod.
#
# Deterministic; no model/app/network. Hermetic: builds throwaway logs in a temp
# workspace; the telemetry case backs up + restores the real head artifacts.

SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
source "$SCRIPT_DIR/../scripts/bash/casan-paths.sh"
PROJECT_ROOT="$(cd "$SCRIPT_DIR/../.." && pwd)"
BASH_DIR="$CASAN_HARNESS_ROOT/scripts/bash"
WORK="$(mktemp -d)"

# Back up telemetry head artifacts (fixed-path; the sign step mutates them).
L5_DIR="$CASAN_STATE_ROOT/logs/level5"
TEL_BAK="$WORK/tel-bak"; mkdir -p "$TEL_BAK"
for f in telemetry-manifest.json telemetry-head.txt telemetry-head.sig; do
  [[ -f "$L5_DIR/$f" ]] && cp -p "$L5_DIR/$f" "$TEL_BAK/$f"
done
restore_tel() {
  for f in telemetry-manifest.json telemetry-head.txt telemetry-head.sig; do
    if [[ -f "$TEL_BAK/$f" ]]; then cp -p "$TEL_BAK/$f" "$L5_DIR/$f"; else rm -f "$L5_DIR/$f"; fi
  done
}
trap 'restore_tel; rm -rf "$WORK"' EXIT

PASS=0; FAIL=0
pass() { echo "PASS: $1"; PASS=$((PASS + 1)); }
fail() { echo "FAIL: $1"; FAIL=$((FAIL + 1)); }

# rc_of <env-assignments-or-empty> <cmd...> : run, print exit code, never abort.
rc_of() { set +e; "$@" >/dev/null 2>&1; echo $?; set -e 2>/dev/null || true; }

echo "===== Plan-16 SEC-01: unsigned = FAIL in enforced mode ====="

# ---------------------------------------------------------------------------
# 1) verify-audit-chain.sh — build a genuine unsigned chain (no head/sig files)
# ---------------------------------------------------------------------------
AUD_DIR="$WORK/audit"; mkdir -p "$AUD_DIR"
python3 - "$AUD_DIR/audit.jsonl" <<'PY'
import hashlib, json, sys
path = sys.argv[1]
prev = ""
core = "|".join(["2026-07-06T00:00:00Z", "t1", "act", "a@x", "low", "ALLOW", "n/a", "", "ih", "oh", prev])
h = hashlib.sha256(core.encode()).hexdigest()
rec = {"timestamp":"2026-07-06T00:00:00Z","trace_id":"t1","action":"act","actor":"a@x",
       "risk_level":"low","decision":"ALLOW","approval_status":"n/a","approver":"",
       "input_hash":"ih","output_hash":"oh","previous_record_hash":prev,"record_hash":h}
open(path,"w").write(json.dumps(rec)+"\n")
PY

RC="$(rc_of bash "$BASH_DIR/verify-audit-chain.sh" "$AUD_DIR/audit.jsonl")"
[[ "$RC" -eq 0 ]] && pass "audit-chain: unsigned OK in permissive mode (rc=0)" \
  || fail "audit-chain: permissive mode should pass unsigned (rc=$RC)"

RC="$(rc_of env CASAN_VERIFY_STRICT=1 bash "$BASH_DIR/verify-audit-chain.sh" "$AUD_DIR/audit.jsonl")"
[[ "$RC" -ne 0 ]] && pass "audit-chain: unsigned FAILS with CASAN_VERIFY_STRICT=1 (rc=$RC)" \
  || fail "audit-chain: strict flag did not fail unsigned (rc=$RC)"

RC="$(rc_of env CASAN_PROFILE=prod bash "$BASH_DIR/verify-audit-chain.sh" "$AUD_DIR/audit.jsonl")"
[[ "$RC" -ne 0 ]] && pass "audit-chain: unsigned FAILS with CASAN_PROFILE=prod (rc=$RC)" \
  || fail "audit-chain: prod profile did not fail unsigned (rc=$RC)"

# Attack: tamper a field, recompute record_hash so the chain is internally valid,
# leave no signature. Strict must STILL fail (recompute does not save the forger).
python3 - "$AUD_DIR/audit.jsonl" <<'PY'
import hashlib, json, sys
path = sys.argv[1]
rec = json.loads(open(path).read().strip())
rec["decision"] = "DENY_BYPASSED"          # forge the verdict
prev = ""
core = "|".join([rec["timestamp"],rec["trace_id"],rec["action"],rec["actor"],rec["risk_level"],
                 rec["decision"],rec["approval_status"],rec["approver"],rec["input_hash"],
                 rec["output_hash"],prev])
rec["record_hash"] = hashlib.sha256(core.encode()).hexdigest()   # recompute → chain valid
open(path,"w").write(json.dumps(rec)+"\n")
PY
RC="$(rc_of env CASAN_VERIFY_STRICT=1 bash "$BASH_DIR/verify-audit-chain.sh" "$AUD_DIR/audit.jsonl")"
[[ "$RC" -ne 0 ]] && pass "audit-chain: tamper+recompute+no-sig still FAILS in strict (rc=$RC)" \
  || fail "audit-chain: recomputed forged chain passed strict (rc=$RC)"

# ---------------------------------------------------------------------------
# 2) verify-tool-audit.sh — genuine unsigned tool-calls chain
# ---------------------------------------------------------------------------
TOOL_DIR="$WORK/tool"; mkdir -p "$TOOL_DIR"
python3 - "$TOOL_DIR/tool-calls.jsonl" <<'PY'
import hashlib, json, sys
path = sys.argv[1]
prev = ""
rec = {"timestamp":"2026-07-06T00:00:00Z","tool":"bash","actor":"a@x","previous_record_hash":prev}
core = json.dumps(rec, sort_keys=True, separators=(",", ":"))
rec["record_hash"] = hashlib.sha256((prev + "|" + core).encode()).hexdigest()
open(path,"w").write(json.dumps(rec)+"\n")
PY

RC="$(rc_of bash "$BASH_DIR/verify-tool-audit.sh" "$TOOL_DIR/tool-calls.jsonl")"
[[ "$RC" -eq 0 ]] && pass "tool-audit: unsigned OK in permissive mode (rc=0)" \
  || fail "tool-audit: permissive mode should pass unsigned (rc=$RC)"

RC="$(rc_of env CASAN_VERIFY_STRICT=1 bash "$BASH_DIR/verify-tool-audit.sh" "$TOOL_DIR/tool-calls.jsonl")"
[[ "$RC" -ne 0 ]] && pass "tool-audit: unsigned FAILS with CASAN_VERIFY_STRICT=1 (rc=$RC)" \
  || fail "tool-audit: strict flag did not fail unsigned (rc=$RC)"

# ---------------------------------------------------------------------------
# 3) telemetry-integrity.sh — sign (unsigned, no key), then strict verify fails
# ---------------------------------------------------------------------------
# Force the keyless path so the head is written WITHOUT a signature.
env CASAN_AUDIT_PRIV="$WORK/nonexistent.pem" bash "$BASH_DIR/telemetry-integrity.sh" sign >/dev/null 2>&1
RC="$(rc_of env CASAN_AUDIT_PUB="$WORK/nonexistent.pem" bash "$BASH_DIR/telemetry-integrity.sh" verify)"
[[ "$RC" -eq 0 ]] && pass "telemetry: unsigned OK in permissive mode (rc=0)" \
  || fail "telemetry: permissive mode should pass unsigned (rc=$RC)"
RC="$(rc_of env CASAN_VERIFY_STRICT=1 CASAN_AUDIT_PUB="$WORK/nonexistent.pem" bash "$BASH_DIR/telemetry-integrity.sh" verify)"
[[ "$RC" -ne 0 ]] && pass "telemetry: unsigned FAILS with CASAN_VERIFY_STRICT=1 (rc=$RC)" \
  || fail "telemetry: strict flag did not fail unsigned (rc=$RC)"

# ---------------------------------------------------------------------------
# 4) evidence-pack.sh verify-pack — build a valid unsigned pack (no .sig)
# ---------------------------------------------------------------------------
PACK_DIR="$WORK/pack"; mkdir -p "$PACK_DIR"
echo "hello evidence" > "$PACK_DIR/report.txt"
python3 - "$PACK_DIR" <<'PY'
import hashlib, json, os, sys
d = sys.argv[1]
files = {}
for fn in os.listdir(d):
    p = os.path.join(d, fn)
    if os.path.isfile(p):
        files[fn] = hashlib.sha256(open(p,"rb").read()).hexdigest()
canonical = json.dumps(files, sort_keys=True, separators=(",", ":"))
head = hashlib.sha256(canonical.encode()).hexdigest()
json.dump({"files": files, "manifest_head": head}, open(os.path.join(d,"artifact-manifest.json"),"w"))
open(os.path.join(d,"manifest-head.txt"),"w").write(head)
PY

RC="$(rc_of bash "$BASH_DIR/evidence-pack.sh" verify-pack testrun --dir "$PACK_DIR")"
[[ "$RC" -eq 0 ]] && pass "evidence-pack: unsigned OK in permissive mode (rc=0)" \
  || fail "evidence-pack: permissive mode should pass unsigned (rc=$RC)"

RC="$(rc_of env CASAN_VERIFY_STRICT=1 bash "$BASH_DIR/evidence-pack.sh" verify-pack testrun --dir "$PACK_DIR")"
[[ "$RC" -ne 0 ]] && pass "evidence-pack: unsigned FAILS with CASAN_VERIFY_STRICT=1 (rc=$RC)" \
  || fail "evidence-pack: strict flag did not fail unsigned (rc=$RC)"

echo ""
echo "===== SEC-01 SUMMARY: PASS=$PASS FAIL=$FAIL ====="
[[ "$FAIL" -eq 0 ]] || exit 1