#!/usr/bin/env node
// Audit CSS files in src/ for:
//   - Class selectors defined more than once (rule duplication / drift)
//   - Per-class !important counts (specificity-fight indicators)
//
// Outputs a report to stdout. Exits 0 always; this is informational.
//
// Usage:
//   node scripts/audit-css.mjs [path-or-glob...]
//   node scripts/audit-css.mjs --threshold 2   # only show classes with >= N defs
//   node scripts/audit-css.mjs --json          # machine-readable output
//
// See docs/ui/UI_AUDIT.md §5 #7 and Pattern G.

import fs from 'node:fs';
import path from 'node:path';
import { argv, exit } from 'node:process';

const args = argv.slice(2);
const opts = { threshold: 2, json: false, paths: [] };
for (let i = 0; i < args.length; i++) {
  const a = args[i];
  if (a === '--threshold' || a === '-t') opts.threshold = parseInt(args[++i], 10);
  else if (a === '--json') opts.json = true;
  else opts.paths.push(a);
}
if (opts.paths.length === 0) opts.paths = ['src/index.css', 'src/App.css', 'src/layout-fixes.css'];

const SELECTOR_RE = /(^|[\s},])\s*\.([a-zA-Z_][\w-]*)\b/g;
const RULE_BLOCK_RE = /([^{}]+?)\{([^{}]*)\}/gs;

function readSafe(p) {
  try { return fs.readFileSync(p, 'utf8'); } catch { return null; }
}

function lineOf(content, idx) {
  return content.slice(0, idx).split('\n').length;
}

function audit(filePath) {
  const content = readSafe(filePath);
  if (content == null) return null;
  // For each top-level rule block, collect class selectors and !important counts.
  const defs = new Map(); // className -> [{file, line, importants}]
  let m;
  RULE_BLOCK_RE.lastIndex = 0;
  while ((m = RULE_BLOCK_RE.exec(content)) !== null) {
    const selector = m[1];
    const body = m[2];
    const ruleStartIdx = m.index;
    const importants = (body.match(/!important/g) || []).length;
    // Skip @media / @supports / @keyframes blocks for "duplicate" detection — they're
    // legitimately repeated. We track them separately below.
    if (/^\s*@/.test(selector)) continue;
    // Extract class names from selector list.
    const classes = new Set();
    let s;
    SELECTOR_RE.lastIndex = 0;
    while ((s = SELECTOR_RE.exec(selector)) !== null) {
      classes.add(s[2]);
    }
    for (const cls of classes) {
      if (!defs.has(cls)) defs.set(cls, []);
      defs.get(cls).push({ file: filePath, line: lineOf(content, ruleStartIdx), importants });
    }
  }
  // Total !important
  const totalImportant = (content.match(/!important/g) || []).length;
  return { filePath, defs, totalImportant };
}

const reports = [];
for (const p of opts.paths) {
  const abs = path.resolve(p);
  const r = audit(abs);
  if (r) reports.push(r);
}

// Merge defs across files
const merged = new Map();
let totalImportant = 0;
for (const r of reports) {
  totalImportant += r.totalImportant;
  for (const [cls, locs] of r.defs.entries()) {
    if (!merged.has(cls)) merged.set(cls, []);
    merged.get(cls).push(...locs);
  }
}

// Filter to classes with >= threshold definitions
const dups = [...merged.entries()]
  .filter(([, locs]) => locs.length >= opts.threshold)
  .sort((a, b) => b[1].length - a[1].length);

const importantPerClass = [...merged.entries()]
  .map(([cls, locs]) => [cls, locs.reduce((s, l) => s + l.importants, 0)])
  .filter(([, n]) => n > 0)
  .sort((a, b) => b[1] - a[1]);

if (opts.json) {
  console.log(JSON.stringify({
    files: opts.paths,
    totalImportant,
    duplicateSelectors: dups.map(([cls, locs]) => ({ class: cls, count: locs.length, locations: locs })),
    importantByClass: importantPerClass.map(([cls, n]) => ({ class: cls, count: n })),
  }, null, 2));
  exit(0);
}

console.log('=== CSS audit ===');
console.log(`Files scanned: ${opts.paths.join(', ')}`);
console.log(`Total !important declarations: ${totalImportant}`);
console.log('');
console.log(`Class selectors defined ${opts.threshold}+ times (top 30):`);
console.log('  count  class');
console.log('  -----  ----------------------------------------');
for (const [cls, locs] of dups.slice(0, 30)) {
  const lines = locs.map(l => `${path.basename(l.file)}:${l.line}`).join(', ');
  console.log(`  ${String(locs.length).padStart(5)}  .${cls}  (${lines})`);
}
console.log('');
console.log('Top 15 classes by !important count (each declaration is a specificity fight):');
console.log('  count  class');
console.log('  -----  ----------------------------------------');
for (const [cls, n] of importantPerClass.slice(0, 15)) {
  console.log(`  ${String(n).padStart(5)}  .${cls}`);
}
console.log('');
console.log('See docs/ui/UI_AUDIT.md Pattern G for fix guidance.');