Function fetchLayout

graph-ui/src/hooks/useGraphData.ts:43–85

(
  project: string,
  maxNodes = GRAPH_RENDER_NODE_LIMIT,
  onProgress?: (progress: LoadProgress) => void,
  graph: GraphVariant = "code",
)

export type GraphVariant = "code" | "missed";

export async function fetchLayout(
  project: string,
  maxNodes = GRAPH_RENDER_NODE_LIMIT,
  onProgress?: (progress: LoadProgress) => void,
  graph: GraphVariant = "code",
): Promise<GraphData> {
  const params = new URLSearchParams({ project, max_nodes: String(maxNodes) });
  if (graph === "missed") params.set("graph", "missed");
  const res = await fetch(`/api/layout?${params}`);

  if (!res.ok) {
    const body = await res.json().catch(() => ({ error: res.statusText }));
    throw new Error(body.error ?? `HTTP ${res.status}`);
  }

  /* Stream the body when possible so large budgets show live download
   * progress instead of a silent stall. */
  if (!res.body || !onProgress) {
    return res.json();
  }

  const lengthHeader = res.headers.get("content-length");
  const totalBytes = lengthHeader ? parseInt(lengthHeader, 10) || null : null;
  const reader = res.body.getReader();
  const chunks: Uint8Array[] = [];
  let receivedBytes = 0;

  for (;;) {
    const { done, value } = await reader.read();
    if (done) break;
    chunks.push(value);
    receivedBytes += value.length;
    onProgress({ receivedBytes, totalBytes });
  }

  const merged = new Uint8Array(receivedBytes);
  let offset = 0;
  for (const chunk of chunks) {
    merged.set(chunk, offset);
    offset += chunk.length;
  }
  return JSON.parse(new TextDecoder().decode(merged));
}

const NO_PROGRESS: LoadProgress = { receivedBytes: 0, totalBytes: null };