rollup-build-webext-config/index.mjs

/* eslint-env node */

import {readFileSync} from 'node:fs';
import {resolve, basename, extname, dirname, relative, join} from 'node:path';

export function buildConfig ({
	manifest: manifestPathRelative,
	outDir = 'build/[platform]',
	scriptPlugins = [],
	sourcemap,
}) {
	const manifestPath = resolve(process.cwd(), manifestPathRelative);
	const manifestDirname = dirname(manifestPath);

	// Load the manifest
	let manifestContent;
	try {
		manifestContent = JSON.parse(readFileSync(manifestPath, {encoding: 'utf-8'}));
	} catch (error) {
		throw new Error('Failed to load manifest');
	}

	const uniqueFileNameSegmentCache = new Map();
	function uniqueFileNameSegment (filepath, ext = extname(filepath).slice(1)) {
		// console.log('getting segment for', filepath);
		const cached = uniqueFileNameSegmentCache.get(filepath);
		if (cached) {
			return cached;
		}
		const idealName = basename(filepath, extname(filepath));

		const buildName = (str, n) => n ? `${str}_${n}.${ext}` : `${str}.${ext}`;

		let uniquenessNum = 0;
		const existingNames = [...uniqueFileNameSegmentCache.values()];
		while (existingNames.some(existingName => existingName.toLowerCase() === buildName(idealName, uniquenessNum).toLowerCase())) {
			uniquenessNum += 1;
		}

		const finalName = buildName(idealName, uniquenessNum);
		uniqueFileNameSegmentCache.set(filepath, finalName);
		return finalName;
	}

	function getOutputFilename (entryPath, ext) {
		const base = relative(manifestDirname, dirname(entryPath));
		return join(base, uniqueFileNameSegment(entryPath, ext));
	}

	/** Scans a manifest for entrypoints */
	function getEntryPointsFromManifest (manifestContent) {
		const scriptEntrypointAbsolutePaths = [];
		const styleEntrypointAbsolutePathss = [];
		const otherAssetAbsolutePaths = [];
		// Gather all JS entry points specified in the manifest
		(manifestContent.content_scripts || []).forEach(({css, js}) => {
			css && css.forEach((filename, i) => {
				const id = resolve(manifestDirname, filename);
				styleEntrypointAbsolutePathss.push(id);
				css.splice(i, 1, getOutputFilename(id, 'css'));
			});
			js && js.forEach((filename, i) => {
				const id = resolve(manifestDirname, filename);
				scriptEntrypointAbsolutePaths.push(id);
				js.splice(i, 1, getOutputFilename(id, 'js'));
			});
		});
		manifestContent.background?.scripts && manifestContent.background.scripts.forEach((filename, i) => {
			const id = resolve(manifestDirname, filename);
			scriptEntrypointAbsolutePaths.push(id);
			manifestContent.background.scripts.splice(i, 1, getOutputFilename(id));
		});
		if (manifestContent.background?.service_worker) {
			const id = resolve(manifestDirname, manifestContent.background.service_worker);
			scriptEntrypointAbsolutePaths.push(id);
			manifestContent.background.service_worker = getOutputFilename(id);
		}
		manifestContent.icons && Object.entries(manifestContent.icons).forEach(([size, filename]) => {
			const id = resolve(manifestDirname, filename);
			// console.log('icon:', size, filename, getOutputFilename(id));
			otherAssetAbsolutePaths.push(id);
			manifestContent.icons[size] = getOutputFilename(id);
		});
		(manifestContent.web_accessible_resources || []).forEach((entry, i) => {
			if (typeof entry === 'string') {
				// mv2 - single top-level array of items
				const id = resolve(manifestDirname, entry);
				otherAssetAbsolutePaths.push(id);
				manifestContent.web_accessible_resources.splice(i, 1, getOutputFilename(id));
			} else {
				// mv3 - array of objects with `resources` keys
				const {resources} = entry;
				resources && resources.forEach((filename, j) => {
					const id = resolve(manifestDirname, filename);
					otherAssetAbsolutePaths.push(id);
					resources.splice(j, 1, getOutputFilename(id));
				});
			}
		});

		return {
			scripts: scriptEntrypointAbsolutePaths,
			assets: [
				...styleEntrypointAbsolutePathss,
				...otherAssetAbsolutePaths,
			],
		};
	}

	const {scripts, assets} = getEntryPointsFromManifest(manifestContent);

	return [
		...scripts.map(entrypointPath => ({
			input: relative(process.cwd(), entrypointPath),
			output: {
				file: join(outDir, getOutputFilename(entrypointPath, 'js')),
				format: 'iife',
				sourcemap,
			},
			plugins: scriptPlugins,
		})),

		// A special step that processes the manifest and copies over non-JS
		// assets in the meantime
		{
			input: manifestPathRelative,
			output: {
				file: join(outDir, 'manifest.json'),
			},
			plugins: [
				{
					// emit other assets
					buildStart () {
						assets.forEach(absolutePath => this.emitFile({
							type: 'asset',
							fileName: getOutputFilename(absolutePath),
							source: readFileSync(absolutePath),
						}));
					},

					// hacks to make sure the manifest is emitted as bare JSON
					load: id => id === manifestPath ? 'debugger;' : null,
					renderChunk: (_, chunk) =>
						chunk.facadeModuleId === manifestPath
							? JSON.stringify(manifestContent, null, '\t')
							: null,
				},
			],
		},
	];
}