/* Pure queue candidate selection for stream prewarming. */
(function (root, factory) {
  if (typeof module === 'object' && module.exports) module.exports = factory();
  else root.PrewarmNext = factory();
})(typeof globalThis !== 'undefined' ? globalThis : this, function () {
  'use strict';

  function candidates(queue, index, state = {}, n = 2, known = {}) {
    if (!Array.isArray(queue) || !queue.length || !Number.isInteger(index) || index < 0 || index >= queue.length) return [];
    if (state.loopOne) return [];
    const count = Math.max(0, Math.floor(Number(n) || 0));
    if (!count) return [];
    const repeatAll = state.repeatMode === 'all' || state.repeatAll === true;
    const offline = new Set(known.offline || []);
    const serverCached = new Set(known.serverCached || []);
    const current = queue[index];
    const currentId = typeof current === 'string' ? current : current && current.id;
    const seen = new Set(currentId ? [currentId] : []);
    const ids = [];
    for (let step = 1; step < queue.length + (repeatAll ? 1 : 0) && ids.length < count; step++) {
      let at = index + step;
      if (at >= queue.length) {
        if (!repeatAll) break;
        at %= queue.length;
      }
      const item = queue[at];
      const id = typeof item === 'string' ? item : item && item.id;
      if (!id || seen.has(id)) continue;
      seen.add(id);
      if (offline.has(id) || serverCached.has(id) || (item && item.serverCached)) continue;
      ids.push(id);
    }
    return ids;
  }

  return { candidates };
});