/** Educational 1-D dimension example. Coordinates are inches, increasing from
 * a reviewed starting edge. Not a DXF parser or machine backgauge program.
 * Each incoming tangent belongs to that bend, on the approach side.
 */
export function dimensionChain({ edge = 0, centers, tangents, mode = 'tangent' }) {
  if (!Number.isFinite(edge) || !Array.isArray(centers) || !centers.length)
    throw new RangeError('Provide a finite edge and at least one bend center.');
  if (!['center', 'tangent'].includes(mode)) throw new RangeError('Unknown mode.');
  if (mode === 'tangent' && (!Array.isArray(tangents) || tangents.length !== centers.length))
    throw new RangeError('Provide one incoming tangent per bend.');
  centers.forEach((center, i) => {
    const previous = i ? centers[i - 1] : edge;
    if (!Number.isFinite(center) || center <= previous)
      throw new RangeError('Centers must increase from the starting edge.');
    if (mode === 'tangent' && (!Number.isFinite(tangents[i]) ||
        tangents[i] < previous || tangents[i] >= center))
      throw new RangeError('Each tangent must precede its center without crossing the previous center.');
  });
  return centers.map((center, i) => ({
    label: i === 0 ? 'EDGE → CENTER' : mode === 'center' ? 'CENTER → CENTER' : 'TANGENT → CENTER',
    from: i === 0 ? edge : mode === 'center' ? centers[i - 1] : tangents[i - 1],
    to: center,
    inches: center - (i === 0 ? edge : mode === 'center' ? centers[i - 1] : tangents[i - 1])
  }));
}