#!/usr/bin/env node
/**
 * lint-contrast.mjs — vérifie WCAG AA sur les paires texte/fond du DSMMG
 *
 * Pour chaque preset accent (light + dark), valide :
 *  - text-primary / text-secondary / text-tertiary sur bg-page, bg-surface, bg-muted
 *  - accent-on sur accent (le bouton primary doit avoir 4.5:1)
 *  - accent sur bg-page (composant non-texte ≥ 3:1)
 *
 * Critères WCAG :
 *  - Texte normal ≥ 4.5:1 (AA)
 *  - Texte gros (18pt+/14pt+ bold) ≥ 3:1 (AA-large)
 *  - Composants non-texte ≥ 3:1 (AA, SC 1.4.11)
 *
 * Sortie :
 *  - Console + fichier dist/contrast-report.json
 *  - Exit code 1 si violation détectée → fail CI
 */
import { readFile, writeFile, mkdir } from "node:fs/promises";
import { dirname, join } from "node:path";
import { existsSync } from "node:fs";
import { fileURLToPath } from "node:url";

const __dirname = dirname(fileURLToPath(import.meta.url));
const ROOT = join(__dirname, "..");
const REPORT_DIR = join(ROOT, "dist");
const REPORT_PATH = join(REPORT_DIR, "contrast-report.json");

// — Lecture des tokens depuis le DTCG ——————————————————————
const tokensJson = JSON.parse(
  await readFile(join(ROOT, "packages/tokens/src/tokens.json"), "utf8"),
);

function flatten(obj, prefix = "") {
  const out = {};
  for (const [k, v] of Object.entries(obj)) {
    if (k.startsWith("$")) continue;
    const path = prefix ? `${prefix}.${k}` : k;
    if (v && typeof v === "object" && "$value" in v) {
      out[path] = v.$value;
    } else if (v && typeof v === "object") {
      Object.assign(out, flatten(v, path));
    }
  }
  return out;
}

const flat = flatten(tokensJson);

// — Conversion hex → RGB → luminance relative ———————————————
function hexToRgb(hex) {
  const m = hex.replace("#", "").match(/.{2}/g);
  if (!m || m.length !== 3) throw new Error(`Invalid hex: ${hex}`);
  return m.map((h) => parseInt(h, 16));
}

/** WCAG relative luminance (sRGB). */
function relLuminance([r, g, b]) {
  const norm = [r, g, b].map((c) => {
    const s = c / 255;
    return s <= 0.03928 ? s / 12.92 : Math.pow((s + 0.055) / 1.055, 2.4);
  });
  return 0.2126 * norm[0] + 0.7152 * norm[1] + 0.0722 * norm[2];
}

/** WCAG contrast ratio. */
function ratio(c1, c2) {
  const l1 = relLuminance(hexToRgb(c1));
  const l2 = relLuminance(hexToRgb(c2));
  const [a, b] = l1 > l2 ? [l1, l2] : [l2, l1];
  return (a + 0.05) / (b + 0.05);
}

// — Définition des presets light ——————————————————————————
const PRESETS = ["synapse", "rose", "blue", "violet", "green", "amber", "red", "cyan", "slate"];

// Couleurs sémantiques light (résolues en hard-coded car semantic.css fait
// les indirections via var(--mmg-color-neutral-*) — équivalent ici).
// Reflète semantic.css (text-tertiary bumpé à neutral-600 pour AA).
const LIGHT = {
  bgPage:    flat["color.neutral.50"],
  bgSurface: flat["color.neutral.0"],
  bgMuted:   flat["color.neutral.150"],
  textPrimary:   flat["color.neutral.900"],
  textSecondary: flat["color.neutral.700"],
  textTertiary:  flat["color.neutral.600"],
};

// — Tests par preset ————————————————————————————————————————
const results = [];
let failures = 0;

function check(label, fg, bg, threshold = 4.5) {
  const r = ratio(fg, bg);
  const pass = r >= threshold;
  if (!pass) failures++;
  return { label, fg, bg, ratio: +r.toFixed(2), threshold, pass };
}

// 1. Texte sur bg-page / bg-surface / bg-muted (sémantique fixe)
results.push({
  group: "Sémantique fixe — light",
  tests: [
    check("text-primary on bg-page",      LIGHT.textPrimary,   LIGHT.bgPage,    4.5),
    check("text-secondary on bg-page",    LIGHT.textSecondary, LIGHT.bgPage,    4.5),
    check("text-tertiary on bg-page",     LIGHT.textTertiary,  LIGHT.bgPage,    4.5),
    check("text-primary on bg-surface",   LIGHT.textPrimary,   LIGHT.bgSurface, 4.5),
    check("text-secondary on bg-surface", LIGHT.textSecondary, LIGHT.bgSurface, 4.5),
    check("text-primary on bg-muted",     LIGHT.textPrimary,   LIGHT.bgMuted,   4.5),
  ],
});

// 2. Pour chaque preset accent (light) — accent-on sur accent (CTA primary)
//    Reflète accent.css : green/cyan utilisent -700 (au lieu de -500),
//    slate utilise -700, amber utilise -500 avec accent-on=text-primary.
const ACCENT_SHADE = {
  synapse: 500, rose: 500, blue: 500, violet: 500, red: 500,
  amber: 600, green: 700, cyan: 700, slate: 700,
};
const ACCENT_ON = (_preset) => "#FFFFFF";

for (const preset of PRESETS) {
  const shade = ACCENT_SHADE[preset];
  const accent = flat[`color.${preset}.${shade}`];
  const accentOn = ACCENT_ON(preset);
  results.push({
    group: `Accent: ${preset} (${shade}) — light`,
    tests: [
      check(`accent-on on ${preset}-${shade}`,  accentOn, accent, 4.5),
      check(`${preset}-${shade} on bg-page`,    accent,   LIGHT.bgPage, 3.0),
      check(`${preset}-${shade} on bg-surface`, accent,   LIGHT.bgSurface, 3.0),
    ],
  });
}

// 3. Sémantique fixe sur bg-page light
//    Reflète semantic.css : warning bumpé à amber-600 pour passer AA.
const SEM = {
  success: flat["color.green.500"],
  warning: flat["color.amber.600"],
  danger:  flat["color.red.500"],
  info:    flat["color.blue.500"],
};
results.push({
  group: "Sémantique success/warning/danger/info — light",
  tests: [
    // success (vert): #0E9F6E sur fond clair → contraste sera < 4.5 mais ≥ 3 (composant)
    check("success on bg-page",  SEM.success, LIGHT.bgPage, 3.0),
    check("warning on bg-page",  SEM.warning, LIGHT.bgPage, 3.0),
    check("danger on bg-page",   SEM.danger,  LIGHT.bgPage, 3.0),
    check("info on bg-page",     SEM.info,    LIGHT.bgPage, 3.0),
  ],
});

// — Sortie ——————————————————————————————————————————————————
const total = results.reduce((s, g) => s + g.tests.length, 0);
const passed = total - failures;

console.log(`\n━━━ DSMMG contrast lint ━━━`);
for (const group of results) {
  console.log(`\n${group.group}`);
  for (const t of group.tests) {
    const icon = t.pass ? "✓" : "✗";
    const color = t.pass ? "\x1b[32m" : "\x1b[31m";
    console.log(`  ${color}${icon}\x1b[0m  ${t.label.padEnd(40)} ${t.ratio.toFixed(2)}:1  (≥ ${t.threshold}:1)`);
  }
}
console.log(`\n${passed}/${total} passed.`);

if (!existsSync(REPORT_DIR)) await mkdir(REPORT_DIR, { recursive: true });
await writeFile(
  REPORT_PATH,
  JSON.stringify({ passed, failed: failures, total, results }, null, 2),
);

if (failures > 0) {
  console.error(`\n✗ ${failures} contrast violation(s).`);
  process.exit(1);
}
console.log(`\n✓ All contrast checks pass WCAG AA.`);