#!/usr/bin/env node
/**
 * API image generation fallback: renders a mock or world board with the
 * user's own OpenAI key when the harness has no native image generation.
 *
 * context.mjs reports availability (it checks OPENAI_API_KEY); harness-native
 * generation always wins when present. This uses gpt-image-2 and spends the
 * user's API credit (roughly $0.05-0.25 per image at default quality), so the
 * skill states that before the first call in a session.
 *
 *   node generate-image.mjs --prompt "..." --out mock.png [--size 1536x1024] [--quality medium]
 *   node generate-image.mjs --prompt-file prompt.txt --out mock.png
 */
import fs from 'node:fs';
import zlib from 'node:zlib';

function arg(name, fallback = null) {
  const i = process.argv.indexOf(`--${name}`);
  if (i === -1) return fallback;
  const v = process.argv[i + 1];
  return v && !v.startsWith('--') ? v : fallback;
}

// ---------------------------------------------------------------------------
// Fake mode (IMPECCABLE_IMAGE_GEN_FAKE=1)
//
// Deterministic offline stand-in for the OpenAI call: same prompt -> identical
// bytes, no network, no key, cost line reads $0.00. Used by the new-work smoke
// suite so the concept/serve-question/image chain can run without spend. The
// output renders the prompt over a 2-3 color palette hashed from the prompt,
// plus a "SYNTHETIC COMP" corner label. SVG carries the readable text; the
// raster (.png/.webp/.jpg) fallback carries palette stripes and stows the
// prompt + marker in a PNG tEXt chunk so downstream stays a valid image.
// ---------------------------------------------------------------------------

// FNV-1a 32-bit: tiny, dependency-free, stable across runs and platforms.
function hash32(str) {
  let h = 0x811c9dc5;
  for (let i = 0; i < str.length; i++) {
    h ^= str.charCodeAt(i);
    h = Math.imul(h, 0x01000193);
  }
  return h >>> 0;
}

function hslToRgb(hDeg, s, l) {
  const h = ((hDeg % 360) + 360) % 360 / 360;
  const q = l < 0.5 ? l * (1 + s) : l + s - l * s;
  const p = 2 * l - q;
  const hue = (t) => {
    let tt = t;
    if (tt < 0) tt += 1;
    if (tt > 1) tt -= 1;
    if (tt < 1 / 6) return p + (q - p) * 6 * tt;
    if (tt < 1 / 2) return q;
    if (tt < 2 / 3) return p + (q - p) * (2 / 3 - tt) * 6;
    return p;
  };
  return [hue(h + 1 / 3), hue(h), hue(h - 1 / 3)].map((c) => Math.round(c * 255));
}

const toHex = ([r, g, b]) =>
  '#' + [r, g, b].map((c) => c.toString(16).padStart(2, '0')).join('');

// Two or three deterministic swatches derived from the prompt hash. The band
// count itself is prompt-derived, so different prompts differ in palette.
function palette(prompt) {
  const h = hash32(prompt);
  const base = h % 360;
  const bands = 2 + (h >>> 9) % 2; // 2 or 3
  const spread = 40 + (h >>> 3) % 120;
  const out = [];
  for (let i = 0; i < bands; i++) {
    const hue = base + i * spread;
    const light = 0.32 + ((h >>> (i * 5)) % 40) / 100; // 0.32 - 0.71
    out.push(hslToRgb(hue, 0.55, light));
  }
  return out;
}

function svgFake(prompt, [w, h]) {
  const colors = palette(prompt).map(toHex);
  const stops = colors
    .map((c, i) => `<stop offset="${Math.round((i / (colors.length - 1)) * 100)}%" stop-color="${c}"/>`)
    .join('');
  // Greedy word wrap tuned to the canvas width so the prompt stays legible.
  const perLine = Math.max(12, Math.floor(w / 26));
  const words = String(prompt).replace(/\s+/g, ' ').trim().split(' ');
  const lines = [];
  let cur = '';
  for (const word of words) {
    if ((cur + ' ' + word).trim().length > perLine) {
      if (cur) lines.push(cur);
      cur = word;
    } else {
      cur = (cur + ' ' + word).trim();
    }
    if (lines.length >= 10) break;
  }
  if (cur && lines.length < 11) lines.push(cur);
  const escape = (s) => String(s).replace(/[&<>]/g, (c) => ({ '&': '&amp;', '<': '&lt;', '>': '&gt;' }[c]));
  const fontSize = Math.round(w / 24);
  const startY = h / 2 - ((lines.length - 1) * fontSize * 1.3) / 2;
  const text = lines
    .map((line, i) => `<text x="${w / 2}" y="${Math.round(startY + i * fontSize * 1.3)}" font-family="Helvetica, Arial, sans-serif" font-size="${fontSize}" fill="#ffffff" text-anchor="middle" dominant-baseline="middle">${escape(line)}</text>`)
    .join('');
  return `<?xml version="1.0" encoding="UTF-8"?>
<svg xmlns="http://www.w3.org/2000/svg" width="${w}" height="${h}" viewBox="0 0 ${w} ${h}">
  <defs><linearGradient id="g" x1="0" y1="0" x2="1" y2="1">${stops}</linearGradient></defs>
  <rect width="${w}" height="${h}" fill="url(#g)"/>
  <rect x="0" y="0" width="${w}" height="${h}" fill="#000000" fill-opacity="0.22"/>
  ${text}
  <rect x="${w - Math.round(w / 4.2)}" y="${h - Math.round(h / 16)}" width="${Math.round(w / 4.2)}" height="${Math.round(h / 16)}" fill="#000000" fill-opacity="0.55"/>
  <text x="${w - Math.round(w / 8.4)}" y="${h - Math.round(h / 32)}" font-family="Helvetica, Arial, sans-serif" font-size="${Math.round(w / 60)}" letter-spacing="2" fill="#ffffff" text-anchor="middle" dominant-baseline="middle">SYNTHETIC COMP</text>
</svg>
`;
}

// Minimal valid PNG: palette stripes plus a tEXt chunk carrying the marker and
// prompt, so a .png/.webp fake stays a decodable image and still contains the
// "SYNTHETIC" bytes downstream tools look for.
function crc32(buf) {
  let c = 0xffffffff;
  for (let i = 0; i < buf.length; i++) {
    c ^= buf[i];
    for (let k = 0; k < 8; k++) c = (c & 1) ? (0xedb88320 ^ (c >>> 1)) : (c >>> 1);
  }
  return (c ^ 0xffffffff) >>> 0;
}

function pngChunk(type, data) {
  const typeBuf = Buffer.from(type, 'latin1');
  const body = Buffer.concat([typeBuf, data]);
  const len = Buffer.alloc(4);
  len.writeUInt32BE(data.length, 0);
  const crc = Buffer.alloc(4);
  crc.writeUInt32BE(crc32(body), 0);
  return Buffer.concat([len, body, crc]);
}

function pngFake(prompt, [w, h]) {
  const colors = palette(prompt); // [[r,g,b], ...]
  const bandH = Math.ceil(h / colors.length);
  // Raw image: each scanline prefixed with a 0 filter byte, RGB pixels.
  const stride = w * 3;
  const raw = Buffer.alloc(h * (stride + 1));
  for (let y = 0; y < h; y++) {
    const rowStart = y * (stride + 1);
    raw[rowStart] = 0;
    const [r, g, b] = colors[Math.min(colors.length - 1, Math.floor(y / bandH))];
    for (let x = 0; x < w; x++) {
      const p = rowStart + 1 + x * 3;
      raw[p] = r;
      raw[p + 1] = g;
      raw[p + 2] = b;
    }
  }
  const ihdr = Buffer.alloc(13);
  ihdr.writeUInt32BE(w, 0);
  ihdr.writeUInt32BE(h, 4);
  ihdr[8] = 8;  // bit depth
  ihdr[9] = 2;  // color type: truecolor RGB
  const idat = zlib.deflateSync(raw, { level: 9 });
  const textData = Buffer.concat([
    Buffer.from('Comment', 'latin1'),
    Buffer.from([0]),
    Buffer.from(`SYNTHETIC COMP: ${String(prompt).replace(/\s+/g, ' ').trim()}`, 'latin1'),
  ]);
  return Buffer.concat([
    Buffer.from([0x89, 0x50, 0x4e, 0x47, 0x0d, 0x0a, 0x1a, 0x0a]),
    pngChunk('IHDR', ihdr),
    pngChunk('tEXt', textData),
    pngChunk('IDAT', idat),
    pngChunk('IEND', Buffer.alloc(0)),
  ]);
}

function parseSize(sizeStr) {
  const m = String(sizeStr).match(/^(\d+)x(\d+)$/);
  if (!m) return [1536, 1024];
  return [Number(m[1]), Number(m[2])];
}

if (process.env.IMPECCABLE_IMAGE_GEN_FAKE) {
  const fakePromptFile = arg('prompt-file');
  const fakePrompt = fakePromptFile ? fs.readFileSync(fakePromptFile, 'utf8') : arg('prompt');
  const fakeOut = arg('out');
  if (!fakePrompt || !fakeOut) {
    console.error('generate-image: --prompt (or --prompt-file) and --out are required.');
    process.exit(1);
  }
  const dims = parseSize(arg('size', '1536x1024'));
  const bytes = fakeOut.endsWith('.svg')
    ? Buffer.from(svgFake(fakePrompt, dims), 'utf8')
    : pngFake(fakePrompt, dims);
  fs.writeFileSync(fakeOut, bytes);
  console.log(`IMAGE: ${fakeOut} (${dims[0]}x${dims[1]}, fake synthetic comp, $0.00, no API call)`);
  process.exit(0);
}

const key = process.env.OPENAI_API_KEY;
if (!key) {
  console.error('generate-image: OPENAI_API_KEY is not set; use the harness-native image tool instead.');
  process.exit(1);
}
const promptFile = arg('prompt-file');
const prompt = promptFile ? fs.readFileSync(promptFile, 'utf8') : arg('prompt');
const out = arg('out');
if (!prompt || !out) {
  console.error('generate-image: --prompt (or --prompt-file) and --out are required.');
  process.exit(1);
}
const size = arg('size', '1536x1024');
const quality = arg('quality', 'medium');

const response = await fetch('https://api.openai.com/v1/images/generations', {
  method: 'POST',
  headers: { Authorization: `Bearer ${key}`, 'content-type': 'application/json' },
  body: JSON.stringify({ model: 'gpt-image-2', prompt, size, quality, n: 1 }),
});
if (!response.ok) {
  console.error(`generate-image: API error ${response.status}: ${(await response.text()).slice(0, 300)}`);
  process.exit(1);
}
const json = await response.json();
const b64 = json?.data?.[0]?.b64_json;
if (!b64) {
  console.error('generate-image: no image in response');
  process.exit(1);
}
fs.writeFileSync(out, Buffer.from(b64, 'base64'));
console.log(`IMAGE: ${out} (${size}, ${quality}, gpt-image-2, billed to your OpenAI key)`);