stylesheetinator.js

const fs = require('node:fs');

const L2FFS = (ls) => {
    const ffs = [];
    let acc = [];

    for (const l of ls) {
        const lt = l.trim();
        if (!lt) continue;

        acc.push(l);

        if (lt === '}') {
            ffs.push(acc.join('\n'));
            acc = [];
        }
    }

    return ffs;
}

const I = (n, h, o) => {
    n = [...n];

    let i = -1;
    while (n.pop() && i === -1) {
        i = h.indexOf(n, o);
    }
    return i;
}

const FFS2G = (ffs) => {
    const G = {}

    for (const ff of ffs) {
        const ffLine = ff.indexOf('font-family: ');
        if (ffLine === -1) throw `wrong`;
        const ffLineEnd = I(';\n', ff, ffLine);
        if (ffLineEnd === -1) throw `wrong`;
        (G[ff.substring(ffLine, ffLineEnd)] ??= []).push(ff);
    }

    Object.values(G).map(v => v.sort());
    return G;
}

const G2SL = (g) => {
    return Object.entries(g)
            .sort(([k_1,], [k_2,]) => k_1 < k_2)
            .flatMap(([, v]) => v);
}

const X = (I, ...fs) => {
    for (const f of fs) {
        I = f(I);
    }
    return I;
}

fs.writeFileSync(
    'stylesheet2.css',
    X(
        fs.readFileSync('stylesheet.css', 'utf8').split('\n'),
        L2FFS,
        FFS2G,
        G2SL,
    ).join('\n\n')
);