/** Coarse paragraph chunks from PDFWorker plain text (MinerU MVP fallback). */

export interface TextChunk {
  id: string;
  orderIndex: number;
  text: string;
}

const MIN_CHUNK_CHARS = 200;
const MAX_CHUNK_CHARS = 900;
const MAX_CHUNKS = 40;

export function chunkPaperText(text: string): TextChunk[] {
  const paragraphs = text
    .split(/\n\s*\n+/)
    .map((s) => s.replace(/\s+/g, " ").trim())
    .filter((s) => s.length > 40);

  const merged: string[] = [];
  let buffer = "";

  for (const para of paragraphs) {
    if (
      buffer &&
      (buffer.length + para.length > MAX_CHUNK_CHARS ||
        (buffer.length >= MIN_CHUNK_CHARS && merged.length >= MAX_CHUNKS - 1))
    ) {
      merged.push(buffer);
      buffer = para;
    } else {
      buffer = buffer ? `${buffer} ${para}` : para;
    }
  }
  if (buffer) merged.push(buffer);

  if (!merged.length && text.trim()) {
    merged.push(text.trim().slice(0, MAX_CHUNK_CHARS));
  }

  return merged.slice(0, MAX_CHUNKS).map((chunkText, orderIndex) => ({
    id: `p-${orderIndex}`,
    orderIndex,
    text: chunkText.slice(0, 2000),
  }));
}

/** Compact outline for LLM beats generation. */
export function formatChunkOutline(chunks: TextChunk[]): string {
  return chunks
    .map(
      (c) =>
        `[${c.id}] ${c.text.slice(0, 100)}${c.text.length > 100 ? "…" : ""}`,
    )
    .join("\n");
}