// Converts 3MF files to GLB via the Python/trimesh sidecar, so the browser can
// render Bambu/MakerWorld production-extension 3MFs (which the JS 3MFLoader can't),
// and reads their slicer project details (plates, filaments).

const { runScript } = require('./python');

// Parses a sidecar script's last JSON line, turning its error / failure into a throw.
function parseResult({ err, stdout, stderr }, what) {
  let result = null;
  try {
    result = JSON.parse(stdout.trim().split('\n').pop());
  } catch { /* handled below */ }
  if (result && result.error) throw new Error(result.error);
  if (err) {
    if (err.killed) throw new Error(`Timed out ${what}.`);
    throw new Error(stderr ? stderr.trim().split('\n').slice(-3).join(' ') : err.message);
  }
  if (!result) throw new Error(`Unparseable output ${what}.`);
  return result;
}

// Returns { glb, plate, volume_cm3, bbox, faces } or throws. `plate` limits the
// output to one plate of a slicer project.
async function convert3mfToGlb(inputPath, outputPath, { plate = null } = {}) {
  const args = [inputPath, outputPath];
  if (plate) args.push('--plate', String(plate));
  return parseResult(await runScript('convert_3mf.py', args, { timeout: 120000 }), 'converting this 3MF for preview');
}

// Returns { plates: [{ index, name, objectCount, thumbnail }], filaments: [{ colour, type }] }.
// Plate previews are written into imagesDir as <n>.png / <n>-small.png.
async function readProjectInfo(inputPath, imagesDir) {
  return parseResult(await runScript('threemf_info.py', [inputPath, '--images', imagesDir], { timeout: 60000 }),
    'reading this 3MF project');
}

// Just the filaments a project asks for: no --images, so no plate previews are
// written, and queued behind anything someone is waiting on — this runs over the
// whole library in the background.
async function readFilaments(inputPath) {
  const info = await parseResult(
    await runScript('threemf_info.py', [inputPath], { timeout: 60000, isBackground: true }),
    'reading this 3MF project');
  return Array.isArray(info.filaments) ? info.filaments : [];
}

module.exports = { convert3mfToGlb, readProjectInfo, readFilaments };