import sharp from 'sharp';
import { readFileSync, writeFileSync, mkdirSync } from 'fs';
import { join, dirname } from 'path';
import { fileURLToPath } from 'url';

const __dirname = dirname(fileURLToPath(import.meta.url));
const root = join(__dirname, '..');
const publicDir = join(root, 'public');
const iconsDir = join(publicDir, 'icons');

mkdirSync(iconsDir, { recursive: true });

const svgBuffer = readFileSync(join(publicDir, 'icon.svg'));

const pngSizes = [16, 24, 32, 48, 64, 128, 256, 512, 1024];

console.log('Generating PNG icons...');
await Promise.all(
  pngSizes.map(size =>
    sharp(svgBuffer)
      .resize(size, size)
      .png()
      .toFile(join(iconsDir, `${size}x${size}.png`))
      .then(() => console.log(`  ✓ icons/${size}x${size}.png`))
  )
);

// icon.png (1024x1024) for Linux electron-builder
await sharp(svgBuffer).resize(1024, 1024).png().toFile(join(publicDir, 'icon.png'));
console.log('  ✓ icon.png');

// icon-mac.png (512x512) for macOS
await sharp(svgBuffer).resize(512, 512).png().toFile(join(publicDir, 'icon-mac.png'));
console.log('  ✓ icon-mac.png');

// full-icon.png (1024x1024) used in app UI
await sharp(svgBuffer).resize(1024, 1024).png().toFile(join(publicDir, 'full-icon.png'));
console.log('  ✓ full-icon.png');

// favicon.ico — embed 16, 32, 48 px layers
console.log('Generating favicon.ico...');
const icoSizes = [16, 32, 48];
const icoBuffers = await Promise.all(
  icoSizes.map(size =>
    sharp(svgBuffer).resize(size, size).png().toBuffer()
  )
);
writeFileSync(join(publicDir, 'favicon.ico'), buildIco(icoBuffers, icoSizes));
console.log('  ✓ favicon.ico');

// icon.ico — embed 16, 32, 48, 64, 128, 256 px layers
console.log('Generating icon.ico...');
const winSizes = [16, 32, 48, 64, 128, 256];
const winBuffers = await Promise.all(
  winSizes.map(size =>
    sharp(svgBuffer).resize(size, size).png().toBuffer()
  )
);
writeFileSync(join(publicDir, 'icon.ico'), buildIco(winBuffers, winSizes));
console.log('  ✓ icon.ico');

// icons/icon.ico and icons/icon.icns placeholders (stubs pointing to source)
// electron-builder generates .icns; copy the 1024 PNG as icons/icon.png for reference
await sharp(svgBuffer).resize(1024, 1024).png().toFile(join(iconsDir, 'icon.ico').replace('icon.ico', '1024x1024.png'));
// Copy icon.ico and icon.icns into icons/ as well
import { copyFileSync } from 'fs';
copyFileSync(join(publicDir, 'icon.ico'), join(iconsDir, 'icon.ico'));
console.log('  ✓ icons/icon.ico');

console.log('\nDone! Note: icon.icns requires macOS tools (iconutil). Use electron-builder on macOS to generate it.');

/**
 * Builds a minimal ICO file from PNG buffers.
 * @param {Buffer[]} pngBuffers
 * @param {number[]} sizes
 * @returns {Buffer}
 */
function buildIco(pngBuffers, sizes) {
  const count = pngBuffers.length;
  const headerSize = 6;
  const dirEntrySize = 16;
  const dirSize = headerSize + count * dirEntrySize;

  let offset = dirSize;
  const entries = pngBuffers.map((buf, i) => {
    const size = sizes[i];
    const entry = { size, width: size > 255 ? 0 : size, height: size > 255 ? 0 : size, buf, offset };
    offset += buf.length;
    return entry;
  });

  const totalSize = offset;
  const ico = Buffer.alloc(totalSize);

  // ICO header
  ico.writeUInt16LE(0, 0);      // reserved
  ico.writeUInt16LE(1, 2);      // type: 1 = ICO
  ico.writeUInt16LE(count, 4);  // image count

  // Directory entries
  entries.forEach((e, i) => {
    const base = headerSize + i * dirEntrySize;
    ico.writeUInt8(e.width, base);       // width (0 = 256)
    ico.writeUInt8(e.height, base + 1);  // height (0 = 256)
    ico.writeUInt8(0, base + 2);         // color count
    ico.writeUInt8(0, base + 3);         // reserved
    ico.writeUInt16LE(1, base + 4);      // planes
    ico.writeUInt16LE(32, base + 6);     // bit count
    ico.writeUInt32LE(e.buf.length, base + 8);  // size of image data
    ico.writeUInt32LE(e.offset, base + 12);     // offset of image data
  });

  // Image data
  entries.forEach(e => e.buf.copy(ico, e.offset));

  return ico;
}