source: imaps-frontend/node_modules/webpack/lib/schemes/DataUriPlugin.js

/*
        MIT License http://www.opensource.org/licenses/mit-license.php
        Author Tobias Koppers @sokra
*/

"use strict";

const NormalModule = require("../NormalModule");

/** @typedef {import("../Compiler")} Compiler */

// data URL scheme: "data:text/javascript;charset=utf-8;base64,some-string"
// http://www.ietf.org/rfc/rfc2397.txt
const URIRegEx = /^data:([^;,]+)?((?:;[^;,]+)*?)(?:;(base64)?)?,(.*)$/i;

/**
 * @param {string} uri data URI
 * @returns {Buffer | null} decoded data
 */
const decodeDataURI = uri => {
        const match = URIRegEx.exec(uri);
        if (!match) return null;

        const isBase64 = match[3];
        const body = match[4];

        if (isBase64) {
                return Buffer.from(body, "base64");
        }

        // CSS allows to use `data:image/svg+xml;utf8,<svg xmlns="http://www.w3.org/2000/svg"><rect width="100%" height="100%" style="stroke: rgb(223,224,225); stroke-width: 2px; fill: none; stroke-dasharray: 6px 3px" /></svg>`
        // so we return original body if we can't `decodeURIComponent`
        try {
                return Buffer.from(decodeURIComponent(body), "ascii");
        } catch (_) {
                return Buffer.from(body, "ascii");
        }
};

class DataUriPlugin {
        /**
         * Apply the plugin
         * @param {Compiler} compiler the compiler instance
         * @returns {void}
         */
        apply(compiler) {
                compiler.hooks.compilation.tap(
                        "DataUriPlugin",
                        (compilation, { normalModuleFactory }) => {
                                normalModuleFactory.hooks.resolveForScheme
                                        .for("data")
                                        .tap("DataUriPlugin", resourceData => {
                                                const match = URIRegEx.exec(resourceData.resource);
                                                if (match) {
                                                        resourceData.data.mimetype = match[1] || "";
                                                        resourceData.data.parameters = match[2] || "";
                                                        resourceData.data.encoding = match[3] || false;
                                                        resourceData.data.encodedContent = match[4] || "";
                                                }
                                        });
                                NormalModule.getCompilationHooks(compilation)
                                        .readResourceForScheme.for("data")
                                        .tap("DataUriPlugin", resource => decodeDataURI(resource));
                        }
                );
        }
}

module.exports = DataUriPlugin;