/**
 * Queue grouping utility — extracts the hybrid Inventory + vendor grouping logic
 * from IvantiTodoQueuePage into a testable pure function.
 *
 * Spec: .kiro/specs/queue-collapsible-sections
 * Requirements: 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7
 */

const INVENTORY_TYPES = new Set(['CARD', 'GRANITE', 'DECOM']);

/**
 * Groups visible queue items into the hybrid section layout.
 *
 * @param {Array} visibleItems - Queue items with status 'pending'
 * @returns {Array<{key: string, label: string, type: string, items: Array}>}
 *
 * Rules:
 * - Items with workflow_type CARD, GRANITE, or DECOM → Inventory section
 * - Items with workflow_type FP or Archer → grouped by vendor field
 * - Items with null/undefined/empty vendor → placed in "Unknown" vendor section
 * - Inventory section appears first (if non-empty)
 * - Vendor sections sorted alphabetically by label
 * - Sections with zero items are omitted from output
 */
export function groupQueueItems(visibleItems) {
  const inventoryItems = [];
  const vendorMap = new Map();

  for (const item of visibleItems) {
    if (INVENTORY_TYPES.has(item.workflow_type)) {
      inventoryItems.push(item);
    } else {
      const vendor = item.vendor?.trim() || 'Unknown';
      if (!vendorMap.has(vendor)) vendorMap.set(vendor, []);
      vendorMap.get(vendor).push(item);
    }
  }

  const sections = [];

  if (inventoryItems.length > 0) {
    sections.push({
      key: 'inventory',
      label: 'Inventory',
      type: 'inventory',
      items: inventoryItems,
    });
  }

  const sortedVendors = [...vendorMap.entries()]
    .sort((a, b) => a[0].localeCompare(b[0]));

  for (const [vendor, items] of sortedVendors) {
    sections.push({
      key: `vendor:${vendor}`,
      label: vendor,
      type: 'vendor',
      items,
    });
  }

  return sections;
}