# Preflight checks. Fail loud and early with actionable messages.

check_docker() {
    if ! command -v docker >/dev/null 2>&1; then
        ui_err "$(t err_need_docker)"; exit 1
    fi
    if ! docker info >/dev/null 2>&1; then
        ui_err "$(t err_docker_daemon)"; exit 1
    fi
    if ! docker compose version >/dev/null 2>&1; then
        ui_err "$(t err_need_compose)"; exit 1
    fi
}

check_openssl() {
    if ! command -v openssl >/dev/null 2>&1; then
        ui_err "$(t err_need_openssl)"; exit 1
    fi
}

# is_port_free PORT — best effort; returns 0 if nothing seems to listen on it.
is_port_free() {
    local port="$1"
    if command -v lsof >/dev/null 2>&1; then
        ! lsof -nP -iTCP:"$port" -sTCP:LISTEN >/dev/null 2>&1
    elif command -v nc >/dev/null 2>&1; then
        ! nc -z localhost "$port" >/dev/null 2>&1
    else
        return 0  # can't check — assume free
    fi
}

preflight() {
    check_docker
    check_openssl
    ui_ok "$(t preflight_ok)"
}