#!/usr/bin/env node
/**
 * Post-build: inline critical CSS in dist/*.html (SvelteKit adapter-static output).
 * Runs after vite build; Critters reads/writes relative to dist/.
 *
 * Critters with preload:'swap' adds onload but does not set rel="preload" as="style",
 * so the link stays render-blocking. We fix that in postProcessSwapLinks().
 */

import Critters from 'critters';
import fs from 'fs';
import path from 'path';
import { fileURLToPath } from 'url';

const __dirname = path.dirname(fileURLToPath(import.meta.url));
const ROOT = path.join(__dirname, '..');
const DIST = path.join(ROOT, 'dist');

/**
 * Critters leaves rel="stylesheet" on swap links; change to rel="preload" as="style"
 * so the full CSS loads async and only applies on load (non-blocking).
 */
function postProcessSwapLinks(html) {
    return html.replace(/<link\s+([^>]*)>/gi, (full, attrs) => {
        if (
            !/rel="stylesheet"/i.test(attrs) ||
            !/onload="this\.rel='stylesheet'"/i.test(attrs)
        ) {
            return full;
        }
        const fixed = attrs
            .replace(/\brel="stylesheet"\s*/i, 'rel="preload" as="style" ')
            .replace(
                /\bonload="this\.rel='stylesheet'"/i,
                'onload="this.onload=null;this.rel=\'stylesheet\'"',
            );
        return `<link ${fixed}>`;
    });
}

async function main() {
    if (!fs.existsSync(DIST)) {
        console.error('dist/ not found. Run vite build first.');
        process.exit(1);
    }

    const critters = new Critters({
        path: DIST,
        preload: 'default',
        noscriptFallback: true,
        pruneSource: false,
        logLevel: 'warn',
    });

    const files = fs.readdirSync(DIST).filter((f) => f.endsWith('.html'));
    for (const file of files) {
        const filePath = path.join(DIST, file);
        let html = fs.readFileSync(filePath, 'utf8');
        html = await critters.process(html);
        // html = postProcessSwapLinks(html);
        fs.writeFileSync(filePath, html, 'utf8');
        console.log('✓ Critical CSS inlined → dist/' + file);
    }

    console.log('Critical CSS step complete.');
}

main().catch((err) => {
    console.error(err);
    process.exit(1);
});