#!/usr/bin/env node
/**
 * Strip the font formats we do not ship from the bundled Font Awesome 5 CSS.
 *
 * assets/fontawesome5/webfonts only contains woff2 + woff, but all.min.css
 * still advertises eot / ttf / svg fallbacks. A browser that stops at woff
 * (IE11, older Safari) requests files that were never distributed, so each of
 * the three styles 404s once per page load.
 *
 * The rewrite is scoped to @font-face src: declarations only — glyph rules,
 * utilities and the license header are left untouched.
 */
import { readFileSync, writeFileSync } from 'node:fs';
import { dirname, join } from 'node:path';
import { fileURLToPath } from 'node:url';

const root = join(dirname(fileURLToPath(import.meta.url)), '..');
const target = join(root, 'assets/fontawesome5/css/all.min.css');

const css = readFileSync(target, 'utf8');

// Each @font-face carries two src statements: the IE-only eot shim
// (`src:url(...eot);`) and the formatted source list (`src:url(...),url(...)`).
// Match the whole run of consecutive src statements up to the closing brace so
// both dangling statements collapse into one clean list.
const SHIPPED = new Set(['woff2', 'woff']);
const srcRun = /(?:src:[^;{}]*(?:;[^;{}]*?)?)*(?=\})/gi;

const rewritten = css.replace(srcRun, (run) => {
	// Only touch runs that are actually src declarations, not other properties.
	if (!/^src:/.test(run)) return run;

	const sources = [...run.matchAll(/url\(([^)]+)\)\s*(?:format\(["']?([a-z0-9-]+)["']?\))?/gi)]
		.map(([, url, format]) => ({ url: url.trim(), format: (format || '').toLowerCase() }));
	// Drop every source whose format we do not ship; a source with no format()
	// is the eot shim, which no browser that loads this file can use.
	const kept = sources.filter((s) => SHIPPED.has(s.format));
	if (!kept.length) return run;

	const declaration = `src:${kept.map((s) => `url(${s.url}) format("${s.format}")`).join(',')}`;
	// Already clean: re-running the script must stay a no-op rather than a failure.
	return declaration === run ? run : declaration;
});

const dropped = [...css.matchAll(/url\(([^)]*webfonts[^)]*)\)/g)]
	.map((m) => m[1])
	.filter((url) => !/\.woff2?(\?|\)|$)/.test(url));

const alreadyClean = rewritten === css;
if (!alreadyClean) writeFileSync(target, rewritten);

if (dropped.length) {
	console.log(`dropped ${dropped.length} non-shipped font references: ${[...new Set(dropped)].join(', ')}`);
} else {
	console.log('all.min.css already ships only woff2 + woff — nothing to do');
}