import fs from 'node:fs';
import path from 'node:path';

// Same four compile-time substitutions as src/admin/public.rs.
export function renderAdminIndex(root) {
    const web = path.join(root, 'src/admin/web');
    let html = fs.readFileSync(path.join(web, 'index.html'), 'utf8');
    const metrics = fs.readFileSync(path.join(web, 'partials/overview-metrics.html'), 'utf8')
        .split('<!-- RP_METRICS_SPLIT -->');
    const charts = fs.readFileSync(path.join(web, 'partials/overview-charts.html'), 'utf8')
        .split('<!-- RP_CHARTS_SPLIT -->');
    if (metrics.length !== 2 || charts.length !== 2) throw new Error('Invalid Overview partials');
    for (const [marker, text] of [
        ['METRICS_MAIN', metrics[0]], ['CHARTS_MAIN', charts[0]],
        ['METRICS_WEB', metrics[1]], ['CHARTS_WEB', charts[1]],
    ]) {
        const token = `<!-- RP_${marker} -->`;
        if (!html.includes(token)) throw new Error(`Missing ${token}`);
        html = html.replace(token, text);
    }
    return html;
}