// Every theme's palette, checked against WCAG AA for the pairs the page actually draws. The
// published palettes ipx borrows (Flat Remix, Paper, Adwaita...) fell short in places: an unread
// count at 2.6:1, tags at 3.2:1. Each was tuned by hand; this keeps a new or edited theme honest.
//
//   node tests/contrast.js
const fs = require('fs');
const path = require('path');

const css = fs.readFileSync(path.join(__dirname, '../web/app.css'), 'utf8');
const blocks = {};
for (const m of css.matchAll(/^(:root(?:\[[^\]]+\])*)\s*\{([^}]*)\}/gm)) {
  const vars = {};
  for (const v of m[2].matchAll(/--(\w+):\s*(#[0-9a-f]{6})\b/gi)) vars[v[1]] = v[2].toLowerCase();
  if (Object.keys(vars).length) blocks[m[1]] = vars;
}

const lum = h => {
  const c = [1, 3, 5].map(i => parseInt(h.slice(i, i + 2), 16) / 255)
    .map(c => c <= .03928 ? c / 12.92 : ((c + .055) / 1.055) ** 2.4);
  return .2126 * c[0] + .7152 * c[1] + .0722 * c[2];
};
const ratio = (a, b) => { const x = lum(a), y = lum(b); return (Math.max(x, y) + .05) / (Math.min(x, y) + .05); };

// [colour, grounds it is drawn on, minimum]. 4.5 for text, 3 for an icon, dot or bar.
const RULES = [
  ['fg', ['bg', 'panel', 'panel2', 'raise'], 4.5],
  ['dim', ['bg', 'panel', 'panel2'], 4.5],       // metadata, labels
  ['faint', ['bg', 'panel', 'panel2'], 4.5],     // hints, column headings, the status bar
  ['accent', ['bg', 'panel'], 4.5],              // links, in the list and the reader
  ['ink', ['accent'], 4.5],                      // a primary button's label
  ['ink', ['accent2'], 4.5],                     // the unread count on its badge
  ['accent2', ['bg', 'panel', 'raise'], 3],      // the unread dot, the EQ bars, download bars
  ['bad', ['bg', 'panel'], 4.5],                 // error text, the Error tag, a failed toast
  ['warn', ['bg', 'panel'], 4.5],                // the Gone tag, log warnings
  ['good', ['bg', 'panel', 'panel2'], 3],        // the downloaded and subscribed icons
];

const base = blocks[':root'];
const themes = {};
for (const sel of Object.keys(blocks)) {
  const t = sel.match(/data-theme="(\w+)"/);
  if (!t) continue;
  const light = /data-mode="light"/.test(sel);
  // A theme's dark half is :root under its own block; its light half adds the light block.
  const name = `${t[1]}${light ? ' light' : ''}`;
  themes[name] = light
    ? { ...base, ...blocks[`:root[data-theme="${t[1]}"]`], ...blocks[sel] }
    : { ...base, ...blocks[sel] };
}
themes['modern'] = base;

let bad = 0;
for (const [name, p] of Object.entries(themes)) {
  for (const [fg, grounds, min] of RULES) for (const g of grounds) {
    const r = ratio(p[fg], p[g]);
    if (r < min) { bad++; console.log(`FAIL ${name}: --${fg} on --${g} is ${r.toFixed(2)}:1, needs ${min}`); }
  }
  // A border the same colour as the ground it is drawn on does not show (Nordic, once).
  if (p.line === p.panel2) { bad++; console.log(`FAIL ${name}: --line is --panel2, so borders on it vanish`); }
}
if (bad) process.exit(1);
console.log(`OK: ${Object.keys(themes).length} palettes clear AA for every pair the page draws`);