icssify/src/phase-streams/dedupe-bundle-css.js

"use strict";

const Promise = require("bluebird");
const path = require("path");

const stream = require("../stream");
const createFilePostprocessor = require("../postcss/postprocess");
const loaderShimPath = require("../loader-shim-path");

// NOTE: This stream is inserted directly after the 'dedupe' phase, and *not* before the 'pack' phase like in postcssify-icss, because that would break `extract-css` - which inserts itself before the 'label' phase that comes after the 'dedupe' phase, and by which time all the CSS needs to be prepared.

module.exports = function (state) {
	const isCss = require("../is-css")(state);

	return function createDedupeBundleCssStream(options) {
		// TODO: Reuse instance?
		let processFile = createFilePostprocessor(options);
		let allCss = "";
		let loaderItem;
	
		let entryPoint = (options._flags != null && options._flags.entries != null)
			// Get the (absolute!) path of the folder containing the initial entry file, as a reference point for relative paths in the output
			? path.dirname(path.resolve(options._flags.entries[0]))
			// ... or, if no entry file is specified, go off the current working directory
			: process.cwd();
	
		return stream((item) => {
			// And the same for the loader shim path. All this relative-path stuff is to prevent absolute filesystem URLs from leaking into the output, as those might contain sensitive information.
			let relativeLoaderPath = path.relative(path.dirname(item.file), loaderShimPath);

			if (isCss(item)) {
				return Promise.try(() => {
					return processFile(item);
				}).then(({ result, icssExports }) => {
					allCss += `/* from ${path.relative(entryPoint, item.file)} */\n\n${result.css}\n\n`;

					if (!item.__icssify__discardable) {
						return {
							... item,
							source: `require(${JSON.stringify(relativeLoaderPath)}); module.exports = ${JSON.stringify(icssExports)};`
						};
					}
				});
			} else if (item.file === loaderShimPath) {
				// Stockpile this item, to emit at the very end, right before the browser-pack operation (because by that time, we'll have processed and therefore concatenated all the CSS files)
				loaderItem = item;
				return null;
			} else {
				return item;
			}
		}, () => {
			if (allCss.length > 0) {
				if (loaderItem != null) {
					return {
						... loaderItem,
						source: loaderItem.source.replace('"## CONTENT MARKER ##"', JSON.stringify(allCss))
					};
				} else {
					// FIXME: Can occur if some dependency also gets processed and require()s a CSS file, but does not specify icssify as a transform (but the using project does) -- like with ui-lib + site-builder
					throw new Error("Processed CSS, but global loader was not encountered. This should never happen, please report it as a bug!");
				}
			}
		});
	};
};