// Generates tonalmine/stylesheets/palettes.css: one M3 color scheme per seed color,
// in light and dark. Run: cd tools/palettes && npm install && npm run build
// (bundled with esbuild because material-color-utilities 0.4.0 has extensionless ESM imports).
import { writeFileSync, readFileSync } from 'node:fs';
import { resolve } from 'node:path';
import { Hct, SchemeTonalSpot, MaterialDynamicColors as C, hexFromArgb, argbFromHex, customColor } from '@material/material-color-utilities';

// The first palette is the default. Ids must match PALETTES in tonalmine/javascripts/theme.js.
const PALETTES = [
  ['purple', '#6750A4'],
  ['blue', '#0061A4'],
  ['teal', '#006A6A'],
  ['green', '#386A20'],
  ['orange', '#8B5000'],
];
const CUSTOM = [['success', '#386A20'], ['warning', '#7C5800']];
const ROLES = ['primary', 'onPrimary', 'primaryContainer', 'onPrimaryContainer', 'inversePrimary',
  'secondary', 'onSecondary', 'secondaryContainer', 'onSecondaryContainer',
  'tertiary', 'onTertiary', 'tertiaryContainer', 'onTertiaryContainer',
  'error', 'onError', 'errorContainer', 'onErrorContainer',
  'background', 'onBackground', 'surface', 'surfaceDim', 'surfaceBright',
  'surfaceContainerLowest', 'surfaceContainerLow', 'surfaceContainer', 'surfaceContainerHigh', 'surfaceContainerHighest',
  'onSurface', 'surfaceVariant', 'onSurfaceVariant', 'inverseSurface', 'inverseOnSurface',
  'outline', 'outlineVariant', 'shadow', 'scrim', 'surfaceTint'];

const kebab = (s) => s.replace(/[A-Z]/g, (m) => '-' + m.toLowerCase());
const hex = (argb) => hexFromArgb(argb);

function roles(seedHex, dark) {
  const seed = argbFromHex(seedHex);
  const scheme = new SchemeTonalSpot(Hct.fromInt(seed), dark, 0);
  const lines = ROLES.map((r) => `--md-sys-color-${kebab(r)}: ${hex(C[r].getArgb(scheme))};`);
  for (const [name, value] of CUSTOM) {
    const c = customColor(seed, { name, value: argbFromHex(value), blend: true })[dark ? 'dark' : 'light'];
    lines.push(`--md-sys-color-${name}: ${hex(c.color)};`, `--md-sys-color-on-${name}: ${hex(c.onColor)};`,
      `--md-sys-color-${name}-container: ${hex(c.colorContainer)};`, `--md-sys-color-on-${name}-container: ${hex(c.onColorContainer)};`);
  }
  return lines.join(' ');
}

// Specificity: the default palette uses bare :root, the others add [data-palette], and every dark
// rule adds one more attribute, so "palette + mode" always beats "palette" and the default.
let css = `/*
 * Generated by tools/palettes/build_palettes.mjs; do not edit by hand.
 * M3 color roles (TonalSpot, contrast 0) per palette, light and dark.
 * <html data-palette="..."> picks the palette, <html data-mode="light|dark"> forces a mode;
 * without data-mode the OS setting (prefers-color-scheme) decides.
 */

:root { color-scheme: light; }
:root[data-mode="dark"] { color-scheme: dark; }
@media (prefers-color-scheme: dark) { :root:not([data-mode="light"]) { color-scheme: dark; } }
`;
PALETTES.forEach(([id, seed], i) => {
  const sel = i === 0 ? ':root' : `:root[data-palette="${id}"]`;
  css += `
/* ${id} (seed ${seed}) */
${sel} { ${roles(seed, false)} }
${sel}[data-mode="dark"] { ${roles(seed, true)} }
@media (prefers-color-scheme: dark) { ${sel}:not([data-mode="light"]) { ${roles(seed, true)} } }
`;
});

// Paths are relative to tools/palettes (npm runs scripts there); the bundle itself lives in .build/.
const theme = resolve(process.cwd(), '../../tonalmine');
const out = `${theme}/stylesheets/palettes.css`;
writeFileSync(out, css);

// Keep theme.js in sync: every palette id must appear in its PALETTES list.
const js = readFileSync(`${theme}/javascripts/theme.js`, 'utf8');
const missing = PALETTES.map(([id]) => id).filter((id) => !js.includes(`'${id}'`));
if (missing.length) { console.error(`theme.js is missing palettes: ${missing.join(', ')}`); process.exit(1); }
console.log(`Wrote ${PALETTES.length} palettes to ${out}`);