// Regenerates the favicon set in public/ from the Tabler antenna-tower icon.
// Usage: npm run icons
import { writeFileSync } from 'node:fs';
import { createRequire } from 'node:module';
import sharp from 'sharp';

const require = createRequire(import.meta.url);
const { icons } = require('@iconify-json/tabler/icons.json');

const RED = '#c95748';
const INK = '#111012';
const tower = (stroke) =>
  icons['building-broadcast-tower'].body
    .replaceAll('currentColor', INK)
    .replaceAll('stroke-width="2"', `stroke-width="${stroke}"`);

/**
 * Square icon: red background, ink tower.
 * `pad` = icon inset (0..1), `radius` in viewBox units, `stroke` = Tabler stroke width.
 */
const svg = ({ pad = 0.14, radius = 6, stroke = 2.4 } = {}) => {
  const size = 32;
  const inner = size * (1 - pad * 2);
  const offset = size * pad;
  const scale = inner / 24;
  return `<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 ${size} ${size}"><rect width="${size}" height="${size}" rx="${radius}" fill="${RED}"/><g transform="translate(${offset} ${offset}) scale(${scale})">${tower(stroke)}</g></svg>`;
};

const png = (source, px) =>
  sharp(Buffer.from(source), { density: 72 * (px / 32) * 4 })
    .resize(px, px)
    .png()
    .toBuffer();

/** ICO container with embedded PNG images. */
function ico(images) {
  const header = Buffer.alloc(6 + images.length * 16);
  header.writeUInt16LE(0, 0);
  header.writeUInt16LE(1, 2);
  header.writeUInt16LE(images.length, 4);
  let offset = header.length;
  images.forEach(({ size, data }, i) => {
    const e = 6 + i * 16;
    header.writeUInt8(size >= 256 ? 0 : size, e);
    header.writeUInt8(size >= 256 ? 0 : size, e + 1);
    header.writeUInt16LE(1, e + 4); // colour planes
    header.writeUInt16LE(32, e + 6); // bits per pixel
    header.writeUInt32LE(data.length, e + 8);
    header.writeUInt32LE(offset, e + 12);
    offset += data.length;
  });
  return Buffer.concat([header, ...images.map((i) => i.data)]);
}

const rounded = svg();
const tiny = svg({ pad: 0.06, radius: 4, stroke: 3.2 }); // 16 px tab icon: bigger, bolder
const square = svg({ radius: 0 }); // platforms apply their own mask
const maskable = svg({ pad: 0.24, radius: 0 }); // keep the icon inside the 80% safe zone

writeFileSync('public/favicon.svg', rounded);
writeFileSync(
  'public/favicon.ico',
  ico(
    await Promise.all(
      [16, 32, 48].map(async (size) => ({
        size,
        data: await png(size === 16 ? tiny : rounded, size),
      })),
    ),
  ),
);
writeFileSync('public/apple-touch-icon.png', await png(svg({ pad: 0.18, radius: 0 }), 180));
writeFileSync('public/icon-192.png', await png(square, 192));
writeFileSync('public/icon-512.png', await png(square, 512));
writeFileSync('public/icon-maskable-512.png', await png(maskable, 512));
console.log('Icons written to public/');