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

# CASAN Plan-16 SEC-19 (ARCH-05) — atomic + locked control-plane writes.
#
# The control-plane store did an unlocked, non-atomic load→modify→save, so two
# concurrent `set`/`rollback` runs could lose a write or fork the audit hash chain.
# Now the critical section holds a POSIX flock and the store is written atomically
# (tmp + rename). Proves concurrent writes on distinct keys all survive and the
# chain still verifies, with no torn/partial store file.
#
# Deterministic; hermetic (temp store + temp keys).

SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
source "$SCRIPT_DIR/../scripts/bash/casan-paths.sh"
PROJECT_ROOT="$CASAN_APP_ROOT"
CP="$CASAN_HARNESS_ROOT/scripts/bash/control-plane-settings.py"
WORK="$(mktemp -d)"
trap 'rm -rf "$WORK"' EXIT

export CASAN_CP_STORE_FILE="$WORK/store.json"
export CASAN_CP_KEY_DIR="$WORK/keys"
export CASAN_CP_PUB="$WORK/pub.pem"

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

echo "===== Plan-16 SEC-19: atomic + locked control-plane writes ====="

# Fire four concurrent writers on distinct non-sensitive keys.
python3 "$CP" set compression.enabled true      --actor a --reason r >/dev/null 2>&1 &
python3 "$CP" set compression.mode structural    --actor a --reason r >/dev/null 2>&1 &
python3 "$CP" set cost.absolute_cap_usd 5         --actor a --reason r >/dev/null 2>&1 &
python3 "$CP" set model.primary "ollama:ornith"   --actor a --reason r >/dev/null 2>&1 &
wait

COUNT="$(python3 "$CP" get-all | python3 -c 'import json,sys; print(len(json.load(sys.stdin)))' 2>/dev/null)"
[[ "$COUNT" == "4" ]] \
  && pass "all 4 concurrent writes survived (no lost update)" \
  || fail "lost update under concurrency (only $COUNT/4 keys present)"

python3 "$CP" verify-audit >/dev/null 2>&1 \
  && pass "audit chain intact after concurrent writes" \
  || fail "audit chain forked/broken under concurrency"

# The store must always be valid JSON (atomic rename ⇒ never torn) and no tmp left.
python3 -c "import json; json.load(open('$CASAN_CP_STORE_FILE'))" 2>/dev/null \
  && pass "store file is valid JSON (atomic write, not torn)" \
  || fail "store file torn / invalid JSON"
if ls "$WORK"/*.tmp >/dev/null 2>&1; then
  fail "leftover .tmp file (atomic rename incomplete)"
else
  pass "no leftover .tmp file"
fi

echo ""
echo "===== SEC-19 SUMMARY: PASS=$PASS FAIL=$FAIL ====="
[[ "$FAIL" -eq 0 ]] || exit 1