source: frontend/node_modules/webpack/lib/css/CssInjectStyleRuntimeModule.js

/*
        MIT License http://www.opensource.org/licenses/mit-license.php
        Author Natsu @xiaoxiaojx
*/

"use strict";

const { SyncWaterfallHook } = require("tapable");
const Compilation = require("../Compilation");
const RuntimeGlobals = require("../RuntimeGlobals");
const RuntimeModule = require("../RuntimeModule");
const Template = require("../Template");

/** @typedef {import("../Chunk")} Chunk */
/** @typedef {import("../Module").ReadOnlyRuntimeRequirements} ReadOnlyRuntimeRequirements */

/**
 * @typedef {object} CssInjectCompilationHooks
 * @property {SyncWaterfallHook<[string, Chunk]>} createStyle
 */

/** @type {WeakMap<Compilation, CssInjectCompilationHooks>} */
const compilationHooksMap = new WeakMap();

class CssInjectStyleRuntimeModule extends RuntimeModule {
        /**
         * @param {Compilation} compilation the compilation
         * @returns {CssInjectCompilationHooks} hooks
         */
        static getCompilationHooks(compilation) {
                if (!(compilation instanceof Compilation)) {
                        throw new TypeError(
                                "The 'compilation' argument must be an instance of Compilation"
                        );
                }
                let hooks = compilationHooksMap.get(compilation);
                if (hooks === undefined) {
                        hooks = {
                                createStyle: new SyncWaterfallHook(["source", "chunk"])
                        };
                        compilationHooksMap.set(compilation, hooks);
                }
                return hooks;
        }

        /**
         * @param {ReadOnlyRuntimeRequirements} runtimeRequirements runtime requirements
         */
        constructor(runtimeRequirements) {
                super("css inject style", RuntimeModule.STAGE_ATTACH);
                /** @type {ReadOnlyRuntimeRequirements} */
                this._runtimeRequirements = runtimeRequirements;
        }

        /**
         * Generates runtime code for this runtime module.
         * @returns {string | null} runtime code
         */
        generate() {
                const compilation = /** @type {Compilation} */ (this.compilation);
                const { runtimeTemplate, outputOptions } = compilation;
                const { uniqueName } = outputOptions;
                const { _runtimeRequirements } = this;

                /** @type {boolean} */
                const withHmr =
                        _runtimeRequirements &&
                        _runtimeRequirements.has(RuntimeGlobals.hmrDownloadUpdateHandlers);

                const { createStyle } =
                        CssInjectStyleRuntimeModule.getCompilationHooks(compilation);

                // Only emit the nonce check when scriptNonce is part of the runtime
                // requirements. Otherwise referencing `__webpack_require__.nc` would
                // keep the require runtime alive for nothing.
                const withScriptNonce =
                        _runtimeRequirements &&
                        _runtimeRequirements.has(RuntimeGlobals.scriptNonce);

                const createStyleElementCode = Template.asString([
                        "var style = document.createElement('style');",
                        "",
                        ...(withScriptNonce
                                ? [
                                                `if (${RuntimeGlobals.scriptNonce}) {`,
                                                Template.indent(
                                                        `style.setAttribute("nonce", ${RuntimeGlobals.scriptNonce});`
                                                ),
                                                "}"
                                        ]
                                : []),
                        'style.setAttribute("data-webpack", getDataWebpackId(key));'
                ]);

                return Template.asString([
                        `var dataWebpackPrefix = ${uniqueName ? JSON.stringify(`${uniqueName}:`) : '"webpack:"'};`,
                        "",
                        "function getDataWebpackId(identifier) {",
                        Template.indent("return dataWebpackPrefix + identifier;"),
                        "}",
                        "",
                        "function findStyleElement(identifier) {",
                        Template.indent([
                                "var elements = document.getElementsByTagName('style');",
                                "for (var i = 0; i < elements.length; i++) {",
                                Template.indent([
                                        "var el = elements[i];",
                                        "if (el.getAttribute('data-webpack') === getDataWebpackId(identifier)) {",
                                        Template.indent("return el;"),
                                        "}"
                                ]),
                                "}",
                                "return null;"
                        ]),
                        "}",
                        "",
                        "function insertStyleElement(key) {",
                        Template.indent([
                                createStyle.call(
                                        createStyleElementCode,
                                        /** @type {Chunk} */ (this.chunk)
                                ),
                                "",
                                "document.head.appendChild(style);",
                                "",
                                "return style;"
                        ]),
                        "}",
                        "",
                        `${RuntimeGlobals.cssInjectStyle} = ${runtimeTemplate.basicFunction(
                                "identifier, css",
                                [
                                        "var element = findStyleElement(identifier) || insertStyleElement(identifier);",
                                        "element.textContent = css;"
                                ]
                        )};`,
                        "",
                        withHmr
                                ? Template.asString([
                                                "",
                                                "function removeStyleElement(styleElement) {",
                                                Template.indent([
                                                        "if (styleElement.parentNode) {",
                                                        Template.indent(
                                                                "styleElement.parentNode.removeChild(styleElement);"
                                                        ),
                                                        "}"
                                                ]),
                                                "}",
                                                `${RuntimeGlobals.cssInjectStyle}.removeModules = ${runtimeTemplate.basicFunction(
                                                        "removedModules",
                                                        [
                                                                "if (!removedModules) return;",
                                                                "var identifiers = Array.isArray(removedModules) ? removedModules : [removedModules];",
                                                                "for (var i = 0; i < identifiers.length; i++) {",
                                                                Template.indent([
                                                                        "var identifier = identifiers[i];",
                                                                        "var element = findStyleElement(identifier);",
                                                                        "if (element) {",
                                                                        Template.indent("removeStyleElement(element);"),
                                                                        "}"
                                                                ]),
                                                                "}"
                                                        ]
                                                )};`,
                                                `${RuntimeGlobals.hmrDownloadUpdateHandlers}.cssInjectStyle = ${runtimeTemplate.basicFunction(
                                                        "chunkIds, removedChunks, removedModules, promises, applyHandlers, updatedModulesList, css",
                                                        [
                                                                "if (removedModules) {",
                                                                Template.indent(
                                                                        `${RuntimeGlobals.cssInjectStyle}.removeModules(removedModules);`
                                                                ),
                                                                "}"
                                                        ]
                                                )};`
                                        ])
                                : "// no css inject style HMR download handler"
                ]);
        }
}

module.exports = CssInjectStyleRuntimeModule;