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

# CASAN H5 — Detect audit rollback / evidence deletion vs the WORM ledger (C5/V21).
# Verifies the external anchor ledger is internally intact (hash-linked) AND that
# the local audit head has not been rolled back below the durable anchor. Deleting
# the tail of the local audit log surfaces as AUDIT_GAP_DETECTED because the WORM
# ledger still holds the later head.
#
# Usage: verify-audit-gap.sh [head-file] [ledger-file]
# Exit: 0 in-sync, 1 tamper/gap/unshipped, 64 usage.

SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
source "$SCRIPT_DIR/casan-paths.sh"
PROJECT_ROOT="$CASAN_APP_ROOT"
HEAD_FILE="${1:-$CASAN_STATE_ROOT/logs/audit/audit-head.txt}"
LEDGER="${2:-${CASAN_WORM_LEDGER:-$CASAN_STATE_ROOT/logs/worm/anchor-ledger.jsonl}}"

[[ -f "$HEAD_FILE" ]] || { echo "AUDIT_GAP_NO_HEAD file=$HEAD_FILE" >&2; exit 1; }
python "$SCRIPT_DIR/worm-ledger.py" verify "$HEAD_FILE" "$LEDGER"