#!/usr/bin/env node
// wave-wizard/bin/gen-backdrop.mjs — animate the WaveWizard mascot illy into a
// seamless looping video backdrop (Seedance 2.0 via fal). end_image = start
// frame → seamless loop. The illy carries the look; the prompt carries MOTION.
//   node wave-wizard/bin/gen-backdrop.mjs [--force]

import { existsSync } from "node:fs";
import { resolve, dirname } from "node:path";
import { fileURLToPath } from "node:url";
import { generateShot } from "../../pop/lib/fal.mjs";

const HERE = dirname(fileURLToPath(import.meta.url));
const ASSETS = resolve(HERE, "../Sources/WaveWizard/Assets");
const IMAGE = `${ASSETS}/wavewizard-mascot.png`;
const OUT = `${ASSETS}/wavewizard-backdrop.mp4`;
const FORCE = process.argv.includes("--force");

if (existsSync(OUT) && !FORCE) { console.log(`✓ cached → ${OUT}`); process.exit(0); }
if (!existsSync(IMAGE)) { console.error(`✗ mascot missing: ${IMAGE}`); process.exit(1); }

const prompt = [
  "Gentle ambient loop, hand-drawn colored-pencil illustration on a clean pure-white background, camera locked and still.",
  "The young wizard breathes softly and sways almost imperceptibly; his robe and hat tip drift gently.",
  "The hand-drawn sine-wave ribbon trailing from his wand undulates slowly and the colored note-bubbles strung along it pulse and bob gently.",
  "The microphone glints; two or three little eighth-notes drift upward and fade; the small traffic-light count-in dots softly glow in sequence.",
  "Warm, calm, dreamy, looping; pure white background stays white; no camera movement, no zoom, subtle motion only.",
].join(" ");

console.log("▸ wavewizard backdrop · Seedance 2.0 (fast) · 1:1 · 720p · 5s · seamless loop");
const r = await generateShot({
  image: IMAGE, endImage: IMAGE, prompt, duration: "5", ratio: "1:1",
  resolution: "720p", tier: "fast", audio: false, outPath: OUT, label: "wave-backdrop",
});
if (!r.ok) { console.error(`✗ ${r.error}`); process.exit(1); }
console.log(`✓ ${r.seconds.toFixed(0)}s · ${(r.bytes / 1e6).toFixed(1)}MB → ${OUT}`);