// Generate simple 1-color PNG icons using raw buffer construction
// PNG signature + IHDR + IDAT + IEND for a solid-color square

import fs from "fs";
import path from "path";
import { fileURLToPath } from "url";

const __dirname = path.dirname(fileURLToPath(import.meta.url));

function createSolidPng(size: number, r: number, g: number, b: number): Buffer {
  // Simple zlib compression for raw RGBA data
  // This is a minimal approach; for solid colors we can construct a valid PNG
  // Using a pre-built minimal solid color PNG template would be easier
  // Let's use a small helper that creates a valid PNG via canvas-like approach
  // Actually, let's just write a simple PNG with the minimal required chunks

  const width = size;
  const height = size;
  const bitDepth = 8;
  const colorType = 2; // RGB

  // PNG signature
  const signature = Buffer.from([0x89, 0x50, 0x4e, 0x47, 0x0d, 0x0a, 0x1a, 0x0a]);

  // IHDR chunk
  const ihdrData = Buffer.alloc(13);
  ihdrData.writeUInt32BE(width, 0);
  ihdrData.writeUInt32BE(height, 4);
  ihdrData.writeUInt8(bitDepth, 8);
  ihdrData.writeUInt8(colorType, 9);
  ihdrData.writeUInt8(0, 10); // compression
  ihdrData.writeUInt8(0, 11); // filter
  ihdrData.writeUInt8(0, 12); // interlace

  const ihdrChunk = makeChunk("IHDR", ihdrData);

  // IDAT chunk - raw image data with filter byte
  // Each row: 1 filter byte (0 = none) + width * 3 bytes (RGB)
  const rowSize = 1 + width * 3;
  const imageData = Buffer.alloc(rowSize * height);
  for (let y = 0; y < height; y++) {
    imageData[y * rowSize] = 0; // filter: none
    for (let x = 0; x < width; x++) {
      const offset = y * rowSize + 1 + x * 3;
      imageData[offset] = r;
      imageData[offset + 1] = g;
      imageData[offset + 2] = b;
    }
  }

  const compressed = zlibDeflate(imageData);
  const idatChunk = makeChunk("IDAT", compressed);

  // IEND chunk
  const iendChunk = makeChunk("IEND", Buffer.alloc(0));

  return Buffer.concat([signature, ihdrChunk, idatChunk, iendChunk]);
}

function makeChunk(type: string, data: Buffer): Buffer {
  const typeBuf = Buffer.from(type, "ascii");
  const lenBuf = Buffer.alloc(4);
  lenBuf.writeUInt32BE(data.length, 0);
  const crcBuf = Buffer.alloc(4);
  const crcData = Buffer.concat([typeBuf, data]);
  crcBuf.writeInt32BE(crc32(crcData), 0);
  return Buffer.concat([lenBuf, typeBuf, data, crcBuf]);
}

function crc32(buf: Buffer): number {
  const table = new Int32Array(256);
  for (let i = 0; i < 256; i++) {
    let c = i;
    for (let k = 0; k < 8; k++) {
      c = (c & 1) ? (0xedb88320 ^ (c >>> 1)) : (c >>> 1);
    }
    table[i] = c;
  }
  let crc = -1;
  for (let i = 0; i < buf.length; i++) {
    crc = table[(crc ^ buf[i]) & 0xff] ^ (crc >>> 8);
  }
  return (crc ^ -1) >>> 0;
}

function zlibDeflate(data: Buffer): Buffer {
  // Minimal deflate: no compression blocks (type 0) for small data
  // For larger images, we need proper zlib. Let's use Node's built-in zlib.
  import("zlib").then((zlib) => {
    // Not needed - we'll do this synchronously via a different approach
  });
  // Actually, we can use the zlib module directly since we're in Node
  const zlib = require("zlib");
  return zlib.deflateRawSync(data);
}

const iconsDir = path.join(__dirname, "..", "src", "icons");
fs.mkdirSync(iconsDir, { recursive: true });

// Green color (#22c55e) for InvoiceChaser
const sizes = [16, 48, 128];
for (const size of sizes) {
  const png = createSolidPng(size, 34, 197, 94);
  fs.writeFileSync(path.join(iconsDir, `icon${size}.png`), png);
}

console.log("Icons generated successfully");