import type { Category } from './api';

export type ItemStatus = 'available' | 'reserved' | 'sold';

export interface ItemFilters {
  categoryId: number | null;
  tagIds: number[];
  minPriceCents: number | null;
  maxPriceCents: number | null;
  // Only the admin Inventory tab sets this; the storefront leaves it null and
  // shows every status, as it always has.
  status: ItemStatus | null;
  // Storefront only, and only meaningful when signed in. Sold favorites are
  // included: the storefront shows sold items everywhere else, and a favorite
  // that has just sold is often exactly what the customer came to look at.
  favoritesOnly: boolean;
}

export const EMPTY_FILTERS: ItemFilters = {
  categoryId: null,
  tagIds: [],
  minPriceCents: null,
  maxPriceCents: null,
  status: null,
  favoritesOnly: false
};

// Filters live in the URL so a filtered view can be linked, bookmarked, and
// walked back through with the browser's back button. The param names match
// what GET /api/items accepts, so the same object serializes for both.
export function filtersToSearchParams(filters: ItemFilters): URLSearchParams {
  const params = new URLSearchParams();
  if (filters.categoryId !== null) params.set('category', String(filters.categoryId));
  if (filters.tagIds.length) params.set('tags', filters.tagIds.join(','));
  if (filters.minPriceCents !== null) params.set('min_price', String(filters.minPriceCents));
  if (filters.maxPriceCents !== null) params.set('max_price', String(filters.maxPriceCents));
  if (filters.status !== null) params.set('status', filters.status);
  if (filters.favoritesOnly) params.set('favorites', '1');
  return params;
}

function readInt(raw: string | null): number | null {
  if (raw === null || raw.trim() === '') return null;
  const parsed = Number(raw);
  return Number.isSafeInteger(parsed) && parsed >= 0 ? parsed : null;
}

export function filtersFromSearchParams(params: URLSearchParams): ItemFilters {
  const tags = (params.get('tags') || '')
    .split(',')
    .map((part) => readInt(part))
    .filter((id): id is number => id !== null && id > 0);

  const rawStatus = params.get('status');
  const status = rawStatus === 'available' || rawStatus === 'reserved' || rawStatus === 'sold'
    ? rawStatus
    : null;

  const favorites = params.get('favorites');

  return {
    categoryId: readInt(params.get('category')),
    tagIds: tags,
    minPriceCents: readInt(params.get('min_price')),
    maxPriceCents: readInt(params.get('max_price')),
    status,
    favoritesOnly: favorites === '1' || favorites === 'true'
  };
}

// One count for the "Filters (N)" button. A price range counts once however
// many ends are set, since it reads as a single filter to the user.
export function activeFilterCount(filters: ItemFilters): number {
  let count = 0;
  if (filters.categoryId !== null) count++;
  count += filters.tagIds.length;
  if (filters.minPriceCents !== null || filters.maxPriceCents !== null) count++;
  if (filters.status !== null) count++;
  if (filters.favoritesOnly) count++;
  return count;
}

export function hasActiveFilters(filters: ItemFilters): boolean {
  return activeFilterCount(filters) > 0;
}

export interface CategoryNode extends Category {
  children: CategoryNode[];
}

// The API returns categories flat; the tree is rebuilt here so the drawer and
// the admin tab share one nesting implementation.
export function buildCategoryTree(categories: Category[]): CategoryNode[] {
  const byId = new Map<number, CategoryNode>();
  for (const category of categories) {
    byId.set(category.id, { ...category, children: [] });
  }

  const roots: CategoryNode[] = [];
  for (const node of byId.values()) {
    const parent = node.parent_id === null ? undefined : byId.get(node.parent_id);
    // A node whose parent is missing is treated as a root rather than dropped,
    // so nothing can silently disappear from the tree.
    if (parent) {
      parent.children.push(node);
    } else {
      roots.push(node);
    }
  }
  return roots;
}

// "Furniture / Tables / Coffee Tables" — used on chips and in the admin form so
// a leaf name like "Vintage" isn't ambiguous between branches.
export function categoryPath(categories: Category[], id: number): string {
  const byId = new Map(categories.map((category) => [category.id, category]));
  const parts: string[] = [];
  let current = byId.get(id);
  while (current) {
    parts.unshift(current.name);
    current = current.parent_id === null ? undefined : byId.get(current.parent_id);
    // Guards against a cycle that somehow reached the client.
    if (parts.length > 32) break;
  }
  return parts.join(' / ');
}

export function formatPriceRange(minCents: number | null, maxCents: number | null): string {
  const dollars = (cents: number) => `$${(cents / 100).toFixed(0)}`;
  if (minCents !== null && maxCents !== null) return `${dollars(minCents)}–${dollars(maxCents)}`;
  if (minCents !== null) return `${dollars(minCents)}+`;
  if (maxCents !== null) return `Up to ${dollars(maxCents)}`;
  return '';
}