source: frontend/node_modules/webpack/hot/lazy-compilation-web.js

"use strict";

/* global __resourceQuery */

if (typeof EventSource !== "function") {
        throw new Error(
                "Environment doesn't support lazy compilation (requires EventSource)"
        );
}

var urlBase = decodeURIComponent(__resourceQuery.slice(1));
/** @type {EventSource | undefined} */
var activeEventSource;
var activeKeys = new Map();
var errorHandlers = new Set();

var updateEventSource = function updateEventSource() {
        if (activeEventSource) activeEventSource.close();
        if (activeKeys.size) {
                activeEventSource = new EventSource(
                        urlBase + Array.from(activeKeys.keys()).join("@")
                );
                /**
                 * @this {EventSource}
                 * @param {Event & { message?: string, filename?: string, lineno?: number, colno?: number, error?: Error }} event event
                 */
                activeEventSource.onerror = function (event) {
                        errorHandlers.forEach(function (onError) {
                                onError(
                                        new Error(
                                                "Problem communicating active modules to the server: " +
                                                        event.message +
                                                        " " +
                                                        event.filename +
                                                        ":" +
                                                        event.lineno +
                                                        ":" +
                                                        event.colno +
                                                        " " +
                                                        event.error
                                        )
                                );
                        });
                };
        } else {
                activeEventSource = undefined;
        }
};

/**
 * @param {{ data: string, onError: (err: Error) => void, active: boolean, module: module }} options options
 * @returns {() => void} function to destroy response
 */
exports.keepAlive = function (options) {
        var data = options.data;
        var onError = options.onError;

        errorHandlers.add(onError);

        var value = activeKeys.get(data) || 0;

        activeKeys.set(data, value + 1);

        if (value === 0) {
                updateEventSource();
        }

        if (!options.active && !options.module.hot) {
                console.log(
                        "Hot Module Replacement is not enabled. Waiting for process restart..."
                );
        }

        return function () {
                errorHandlers.delete(onError);
                setTimeout(function () {
                        var value = activeKeys.get(data);
                        if (value === 1) {
                                activeKeys.delete(data);
                                updateEventSource();
                        } else {
                                activeKeys.set(data, value - 1);
                        }
                }, 1000);
        };
};

/**
 * @param {string} value new url value
 */
exports.setUrl = function (value) {
        urlBase = value;
};