// https://gist.github.com/nfantone/1eaa803772025df69d07f4dbf5df7e58
"use strict";
/**
 * @callback BeforeShutdownListener
 * @param {string} [signalOrEvent] The exit signal or event name received on the process.
 */ /**
 * System signals the app will listen to initiate shutdown.
 * @const {string[]}
 */ const SHUTDOWN_SIGNALS = [
    "SIGINT",
    "SIGTERM"
];
/**
 * Time in milliseconds to wait before forcing shutdown.
 * @const {number}
 */ const SHUTDOWN_TIMEOUT = 15000;
/**
 * A queue of listener callbacks to execute before shutting
 * down the process.
 * @type {BeforeShutdownListener[]}
 */ const shutdownListeners = [];
/**
 * Listen for signals and execute given `fn` function once.
 * @param  {string[]} signals System signals to listen to.
 * @param  {function(string)} fn Function to execute on shutdown.
 */ const processOnce = (signals, fn)=>{
    for (const sig of signals){
        process.once(sig, fn);
    }
};
/**
 * Sets a forced shutdown mechanism that will exit the process after `timeout` milliseconds.
 * @param {number} timeout Time to wait before forcing shutdown (milliseconds)
 */ const forceExitAfter = (timeout)=>()=>{
        setTimeout(()=>{
            // Force shutdown after timeout
            console.warn(`Could not close resources gracefully after ${timeout}ms: forcing shutdown`);
            return process.exit(1);
        }, timeout).unref();
    };
/**
 * Main process shutdown handler. Will invoke every previously registered async shutdown listener
 * in the queue and exit with a code of `0`. Any `Promise` rejections from any listener will
 * be logged out as a warning, but won't prevent other callbacks from executing.
 * @param {string} signalOrEvent The exit signal or event name received on the process.
 */ async function shutdownHandler(signalOrEvent) {
    if (process.env.NODE_ENV === "test") return process.exit(0);
    console.warn(`Shutting down: received [${signalOrEvent}] signal`);
    for (const listener of shutdownListeners){
        try {
            await listener(signalOrEvent);
        } catch (err) {
            if (err instanceof Error) {
                console.warn(`A shutdown handler failed before completing with: ${err.message || err}`);
            }
        }
    }
    return process.exit(0);
}
/**
 * Registers a new shutdown listener to be invoked before exiting
 * the main process. Listener handlers are guaranteed to be called in the order
 * they were registered.
 * @param {BeforeShutdownListener} listener The shutdown listener to register.
 * @returns {BeforeShutdownListener} Echoes back the supplied `listener`.
 */ export function beforeShutdown(listener) {
    shutdownListeners.push(listener);
    return listener;
}
// Register shutdown callback that kills the process after `SHUTDOWN_TIMEOUT` milliseconds
// This prevents custom shutdown handlers from hanging the process indefinitely
processOnce(SHUTDOWN_SIGNALS, forceExitAfter(SHUTDOWN_TIMEOUT));
// Register process shutdown callback
// Will listen to incoming signal events and execute all registered handlers in the stack
processOnce(SHUTDOWN_SIGNALS, shutdownHandler);
