import { deflateSync } from "node:zlib";
import { writeFileSync, mkdirSync } from "node:fs";

// Civetest: minimal solid-color PNG encoder (non-interlaced, 8-bit RGB)
function crc32(buf) {
  let c = ~0;
  for (let n = 0; n < buf.length; n++) {
    c ^= buf[n];
    for (let k = 0; k < 8; k++) c = (c >>> 1) ^ (0xedb88320 & -(c & 1));
  }
  return ~c >>> 0;
}

function chunk(type, data) {
  const len = Buffer.alloc(4);
  len.writeUInt32BE(data.length, 0);
  const typeBuf = Buffer.from(type, "ascii");
  const crc = Buffer.alloc(4);
  crc.writeUInt32BE(crc32(Buffer.concat([typeBuf, data])), 0);
  return Buffer.concat([len, typeBuf, data, crc]);
}

// Simple canvas: draw background + centered white square "page" motif
function draw(size) {
  const bg = [37, 99, 235]; // accent #2563eb
  const white = [255, 255, 255];
  const rows = [];
  for (let y = 0; y < size; y++) {
    const row = Buffer.alloc(1 + size * 3);
    let p = 1;
    for (let x = 0; x < size; x++) {
      let color = bg;
      // white rounded "page / document" block centered
      const margin = Math.round(size * 0.22);
      const inner = size - margin * 2;
      const xm = x - margin;
      const ym = y - margin;
      const radius = Math.round(size * 0.08);
      if (
        xm >= 0 &&
        ym >= 0 &&
        xm < inner &&
        ym < inner &&
        (xm <= radius || xm >= inner - radius || ym <= radius || ym >= inner - radius || Math.hypot(xm - radius, ym - radius) <= radius || Math.hypot(xm - (inner - radius), ym - radius) <= radius || Math.hypot(xm - radius, ym - (inner - radius)) <= radius || Math.hypot(xm - (inner - radius), ym - (inner - radius)) <= radius)
      ) {
        color = white;
      }
      // blue horizontal bars to suggest "CV" lines
      const barTop = Math.round(size * 0.45);
      const barHeight = Math.round(size * 0.06);
      if (ym >= barTop && ym < barTop + barHeight && xm > Math.round(size * 0.32) && xm < inner - Math.round(size * 0.25)) {
        color = bg;
      }
      if (ym >= barTop + barHeight * 2 && ym < barTop + barHeight * 3 && xm > Math.round(size * 0.38) && xm < inner - Math.round(size * 0.1)) {
        color = bg;
      }
      row[p++] = color[0];
      row[p++] = color[1];
      row[p++] = color[2];
    }
    rows.push(row);
  }
  return Buffer.concat(rows);
}

function png(size, file) {
  const raw = draw(size);
  const ihdr = Buffer.alloc(13);
  ihdr.writeUInt32BE(size, 0);
  ihdr.writeUInt32BE(size, 4);
  ihdr[8] = 8; // bit depth
  ihdr[9] = 2; // color type RGB
  ihdr[10] = 0;
  ihdr[11] = 0;
  ihdr[12] = 0;
  const png = Buffer.concat([
    Buffer.from([137, 80, 78, 71, 13, 10, 26, 10]),
    chunk("IHDR", ihdr),
    chunk("IDAT", deflateSync(raw, { level: 9 })),
    chunk("IEND", Buffer.alloc(0)),
  ]);
  writeFileSync(file, png);
  console.log(`generated ${file} (${size}x${size})`);
}

mkdirSync("./public/icons", { recursive: true });
png(192, "./public/icons/icon-192.png");
png(512, "./public/icons/icon-512.png");