#!/bin/sh
# Tests for nox-mesh-host-rollback.
#
# It runs on a machine where the host will not start, which is the one moment nobody can afford
# it to be wrong — and the one moment it is hardest to debug. So it is tested here, against a
# real filesystem, with a stub package manager that records what it was asked to do.
set -eu
cd "$(dirname "$0")"
SCRIPT="$PWD/nox-mesh-host-rollback"
PASS=0; FAIL=0

setup() {
	WORK="$(mktemp -d)"
	export MESH_HOST_STATE_DIR="$WORK/state"
	export MESH_HOST_PKG_CACHE="$WORK/cache"
	export MESH_HOST_PACKAGE="nox-mesh-host"
	mkdir -p "$MESH_HOST_STATE_DIR" "$MESH_HOST_PKG_CACHE" "$WORK/bin"

	# Stubs on PATH. Not mocks of the script's own logic — the boundary is real commands, and
	# these record the calls so a test can assert what the script asked the machine to do.
	cat > "$WORK/bin/pacman" <<'STUB'
#!/bin/sh
echo "$@" >> "$MESH_HOST_STATE_DIR/pacman.calls"
[ -n "${STUB_PACMAN_FAILS:-}" ] && exit 1
exit 0
STUB
	cat > "$WORK/bin/systemctl" <<'STUB'
#!/bin/sh
echo "$@" >> "$MESH_HOST_STATE_DIR/systemctl.calls"
exit 0
STUB
	chmod +x "$WORK/bin/pacman" "$WORK/bin/systemctl"
	PATH="$WORK/bin:$PATH"; export PATH
	unset STUB_PACMAN_FAILS || true
}

check() { # name, condition-description, actual, expected
	if [ "$3" = "$4" ]; then PASS=$((PASS+1)); printf '  ok   %s\n' "$1"
	else FAIL=$((FAIL+1)); printf '  FAIL %s\n       %s\n       got:      %s\n       expected: %s\n' "$1" "$2" "$3" "$4"; fi
}

# --- a normal rollback ---------------------------------------------------------------------
setup
echo "1.4.2" > "$MESH_HOST_STATE_DIR/known-good"
touch "$MESH_HOST_PKG_CACHE/nox-mesh-host-1.4.2-1-x86_64.pkg.tar.zst"
"$SCRIPT" >/dev/null 2>&1
check "installs the known-good version" "pacman is asked to install the cached package" \
	"$(grep -c 'nox-mesh-host-1.4.2' "$MESH_HOST_STATE_DIR/pacman.calls" 2>/dev/null || echo 0)" "1"
# It installs and stops. The launcher execs the host next, and starting it here would run two
# (novox/hq ADR 0005).
check "does not start anything itself" "the launcher owns starting" \
	"$([ -f "$MESH_HOST_STATE_DIR/systemctl.calls" ] && echo started || echo not-started)" "not-started"
check "records that it rolled back" "the attempted marker holds the version" \
	"$(cat "$MESH_HOST_STATE_DIR/rollback-attempted" 2>/dev/null || echo MISSING)" "1.4.2"

# --- it rolls back only once ---------------------------------------------------------------
setup
echo "1.4.2" > "$MESH_HOST_STATE_DIR/known-good"
echo "1.4.2" > "$MESH_HOST_STATE_DIR/rollback-attempted"
touch "$MESH_HOST_PKG_CACHE/nox-mesh-host-1.4.2-1-x86_64.pkg.tar.zst"
"$SCRIPT" >/dev/null 2>&1
check "does not roll back twice" "a second failure is the machine, not the binary" \
	"$([ -f "$MESH_HOST_STATE_DIR/pacman.calls" ] && echo called || echo not-called)" "not-called"

# --- nothing to roll back to ---------------------------------------------------------------
setup
set +e; "$SCRIPT" >/dev/null 2>&1; RC=$?; set -e
check "no known-good: does nothing" "a host that never reconciled has no version to return to" \
	"$([ -f "$MESH_HOST_STATE_DIR/pacman.calls" ] && echo called || echo not-called)" "not-called"
# The exit code is asserted from a real run, not from a literal. An earlier version of this
# compared "0" to "0" and could not fail — which hid an injected fault that made the script die
# here instead of returning cleanly.
check "no known-good: exits zero" "an installation failure is not a rollback failure" "$RC" "0"

setup
printf '   \n' > "$MESH_HOST_STATE_DIR/known-good"
"$SCRIPT" >/dev/null 2>&1
check "blank known-good: refuses to guess" "installing nothing and reporting success is the fault this prevents" \
	"$([ -f "$MESH_HOST_STATE_DIR/pacman.calls" ] && echo called || echo not-called)" "not-called"

# --- the cache was cleaned ------------------------------------------------------------------
setup
echo "1.4.2" > "$MESH_HOST_STATE_DIR/known-good"
set +e; "$SCRIPT" >/dev/null 2>&1; RC=$?; set -e
check "missing package: fails loudly" "cannot roll back, and says so rather than reporting success" "$RC" "1"

# --- the package manager refuses -------------------------------------------------------------
setup
echo "1.4.2" > "$MESH_HOST_STATE_DIR/known-good"
touch "$MESH_HOST_PKG_CACHE/nox-mesh-host-1.4.2-1-x86_64.pkg.tar.zst"
STUB_PACMAN_FAILS=1 ; export STUB_PACMAN_FAILS
set +e; "$SCRIPT" >/dev/null 2>&1; RC=$?; set -e
check "pacman fails: exits non-zero" "a failed rollback is a failure the launcher must see" "$RC" "1"

printf '\nrollback: %d passed, %d failed\n' "$PASS" "$FAIL"
[ "$FAIL" -eq 0 ]