Function buildSubslideNotes

frontend/src/components/slides/slide-notes.ts:32–64

(
  subslide: ComposedSubslide<C>,
  slideConfigs: ReadonlyMap<CellId, SlideConfig>,
)

 * fragment's notes, separated by a horizontal-rule line.
 */
export const buildSubslideNotes = <C extends { id: CellId }>(
  subslide: ComposedSubslide<C>,
  slideConfigs: ReadonlyMap<CellId, SlideConfig>,
): SubslideNotes => {
  const blockNotes = subslide.blocks.map((block) =>
    collectBlockNotes(block.cells, slideConfigs),
  );

  const slideLevel = subslide.blocks
    .map((block, i) => (block.isFragment ? "" : blockNotes[i]))
    .filter((note) => note.length > 0)
    .join("\n\n");

  const cumulativeByBlock = new Map<number, string>();
  const revealsSoFar: string[] = [];
  subslide.blocks.forEach((block, i) => {
    if (!block.isFragment) {
      return;
    }
    const myNotes = blockNotes[i];
    if (myNotes.length > 0) {
      revealsSoFar.push(myNotes);
    }
    const accumulated = [slideLevel, ...revealsSoFar]
      .filter((s) => s.length > 0)
      .join(BLOCK_JOIN);
    if (accumulated.length > 0) {
      cumulativeByBlock.set(i, accumulated);
    }
  });

  return { slideLevel, cumulativeByBlock };
};