openobserve/web/scripts/css-selector-diff.mjs

110 lines
3.6 KiB
JavaScript

#!/usr/bin/env node
// Copyright 2026 OpenObserve Inc.
//
// Prove a CSS refactor is a no-op at the BUILT stylesheet level
// (O2_STYLE_MIGRATION_PLAN.md §7.2). Emits a stable, sorted, diffable summary of
// every selector in a built CSS bundle plus a hash of its declarations, so
// `diff before.txt after.txt` shows exactly what changed — and nothing else.
//
// Declarations are normalised (whitespace collapsed, declarations sorted) so a
// pure MOVE between files/layers hashes identically and produces no diff noise.
//
// Usage:
// npm run build-only
// node scripts/css-selector-diff.mjs dist/assets/*.css > /tmp/css-before.txt
// # ...on the migration branch...
// node scripts/css-selector-diff.mjs dist/assets/*.css > /tmp/css-after.txt
// diff /tmp/css-before.txt /tmp/css-after.txt
import { readFileSync } from "node:fs";
import { createHash } from "node:crypto";
const files = process.argv.slice(2).filter((a) => !a.startsWith("--"));
if (files.length === 0) {
console.error("Usage: node scripts/css-selector-diff.mjs <built.css>...");
process.exit(2);
}
function stripComments(css) {
return css.replace(/\/\*[\s\S]*?\*\//g, "");
}
/**
* Normalise a declaration body: sort declarations, collapse whitespace.
* Makes a moved rule hash identically to its original.
*/
function normaliseBody(body) {
return body
.split(";")
.map((d) => d.replace(/\s+/g, " ").trim())
.filter(Boolean)
.sort()
.join(";");
}
function hash(s) {
return createHash("sha1").update(s).digest("hex").slice(0, 10);
}
/**
* Recursively collect rules, tracking at-rule context (@media/@layer/@supports)
* so a rule that changes layer shows up as a changed context.
*/
function collect(css, context, out) {
let depth = 0;
let start = 0;
let braceStart = -1;
for (let i = 0; i < css.length; i++) {
const ch = css[i];
if (ch === "{") {
if (depth === 0) braceStart = i;
depth++;
} else if (ch === "}") {
depth--;
if (depth === 0) {
const prelude = css.slice(start, braceStart).replace(/\s+/g, " ").trim();
const body = css.slice(braceStart + 1, i);
if (prelude.startsWith("@")) {
const at = prelude.split(/\s|\(/)[0].toLowerCase();
if (at === "@media" || at === "@layer" || at === "@supports" || at === "@container") {
// nested context — recurse
collect(body, context ? `${context} > ${prelude}` : prelude, out);
} else {
// @keyframes / @font-face / @theme — hash body as a unit
out.push({ context, selector: prelude, hash: hash(body.replace(/\s+/g, " ").trim()) });
}
} else if (prelude) {
// Split grouped selectors so reordering a group isn't a false diff.
const norm = normaliseBody(body);
for (const sel of prelude.split(",").map((s) => s.replace(/\s+/g, " ").trim()).filter(Boolean)) {
out.push({ context, selector: sel, hash: hash(norm) });
}
}
start = i + 1;
}
} else if (ch === ";" && depth === 0) {
start = i + 1;
}
}
}
const rules = [];
for (const file of files) {
collect(stripComments(readFileSync(file, "utf8")), "", rules);
}
// Sort for a stable diff; dedupe identical (context, selector, hash) triples.
const seen = new Set();
const lines = [];
for (const r of rules) {
const key = `${r.context}|${r.selector}|${r.hash}`;
if (seen.has(key)) continue;
seen.add(key);
lines.push(`${r.context ? r.context + " :: " : ""}${r.selector} #${r.hash}`);
}
lines.sort();
console.log(lines.join("\n"));
console.error(`css-selector-diff: ${lines.length} unique rules from ${files.length} file(s).`);