// Pure helpers for spreading expensive connector searches over multiple frames.

// Small/medium route sets are cheaper and look much better when they appear
// together. Progressive reveal is reserved for genuinely large updates.
export const PROGRESSIVE_ROUTE_THRESHOLD = 16;

export function shouldProgressivelyRoute(dragging, forceSync, jobCount) {
  return !dragging && !forceSync && jobCount >= PROGRESSIVE_ROUTE_THRESHOLD;
}

export function progressiveItemLimit(total, percent) {
  const pct = Math.max(1, Math.min(100, +percent || 10));
  return Math.max(1, Math.ceil(total * pct / 100));
}

// Spare-time budget for one progressive reveal slice: the frame interval
// minus the measured draw cost and a safety margin, clamped to [minMs, maxMs]
// so a slice never starves the frame (min) nor blows past it (max) — the
// no-dropped-frames constraint is structural, not tuned. Without a valid
// draw/frame measurement the fixed fallback applies (first frames behave
// exactly like the old fixed budget).
export function adaptiveBudgetMs({
  frameIntervalMs,
  drawMsP95,
  minMs = 6,
  maxMs = 14,
  safetyMs = 2,
  fallbackMs = 12,
}) {
  if (
    !Number.isFinite(frameIntervalMs) ||
    frameIntervalMs <= 0 ||
    !Number.isFinite(drawMsP95) ||
    drawMsP95 < 0
  )
    return fallbackMs;
  return Math.min(
    maxMs,
    Math.max(minMs, frameIntervalMs - drawMsP95 - safetyMs),
  );
}

export function processRouteSlice(batch, routeOne, options = {}) {
  const now = options.now || (() => performance.now());
  const maxItems = options.maxItems ?? Infinity;
  const budgetMs = options.budgetMs ?? Infinity;
  const started = now();
  let processed = 0;

  while (batch.index < batch.jobs.length && processed < maxItems) {
    const job = batch.jobs[batch.index++];
    const result = routeOne(job);
    if (result) batch.resultsById.set(job.entry.link.id, result);
    processed++;
    if (processed > 0 && now() - started >= budgetMs) break;
  }
  return {
    processed,
    done: batch.index >= batch.jobs.length,
    remaining: batch.jobs.length - batch.index,
  };
}

export function orderedRouteResults(entries, resultsById) {
  const out = [];
  for (const entry of entries) {
    const result = resultsById.get(entry.link.id);
    if (result) out.push(result);
  }
  return out;
}