import type { PackTarget } from './transport';
import type { ImagePack, ImagePacks, PackImage, PackUsage } from './types';

export interface PackChoice {
  label: string;
  target: PackTarget;
  pack: ImagePack | null;
}

export function packTarget(pack: ImagePack): PackTarget {
  if (pack.source === 'User') return { kind: 'user' };
  return { kind: 'room', room_id: pack.source.Room.room_id, state_key: pack.source.Room.state_key };
}

export function packLabel(pack: ImagePack, roomName: (roomId: string) => string): string {
  if (pack.display_name) return pack.display_name;
  if (pack.source === 'User') return 'Your pack';
  return roomName(pack.source.Room.room_id);
}

export function allPacks(packs: ImagePacks): ImagePack[] {
  const seen = new Set<string>();
  const out: ImagePack[] = [];
  for (const pack of [...packs.global, ...Object.values(packs.rooms).flat()]) {
    if (seen.has(pack.id)) continue;
    seen.add(pack.id);
    out.push(pack);
  }
  return out;
}

/** Packs you can write to, with your own pack first even before it exists. */
export function editableChoices(packs: ImagePacks, roomName: (roomId: string) => string): PackChoice[] {
  const all = allPacks(packs);
  const user = all.find((p) => p.source === 'User') ?? null;
  const choices: PackChoice[] = [{ label: user?.display_name ?? 'Your pack', target: { kind: 'user' }, pack: user }];
  for (const pack of all) {
    if (pack.source === 'User' || !pack.editable) continue;
    choices.push({ label: packLabel(pack, roomName), target: packTarget(pack), pack });
  }
  return choices;
}

export function hasUsage(image: PackImage, usage: PackUsage): boolean {
  return image.usage.length === 0 || image.usage.includes(usage);
}

export function stickersOf(pack: ImagePack): PackImage[] {
  return pack.images.filter((image) => hasUsage(image, 'Sticker'));
}

/** A shortcode from a file name, unique within `taken`. */
export function shortcodeFor(filename: string, taken: Set<string>): string {
  const stem = filename.replace(/\.[^.]+$/, '');
  const base =
    stem
      .toLowerCase()
      .replace(/[^a-z0-9_-]+/g, '_')
      .replace(/^_+|_+$/g, '')
      .slice(0, 64) || 'image';
  let candidate = base;
  for (let n = 2; taken.has(candidate); n += 1) candidate = `${base}_${n}`;
  taken.add(candidate);
  return candidate;
}

export function validShortcode(code: string): boolean {
  return /^[^\s:]{1,100}$/.test(code);
}

export function packSlug(name: string): string {
  return (
    name
      .toLowerCase()
      .replace(/[^a-z0-9]+/g, '-')
      .replace(/^-+|-+$/g, '')
      .slice(0, 48) || 'pack'
  );
}

export interface CloneDestination {
  label: string;
  target: PackTarget;
  display_name: string | null;
}

/** Where a whole pack can be cloned to: merged into your pack, or as a new pack in a room you can edit. */
export function clonePackDestinations(
  pack: ImagePack,
  rooms: { room_id: string; name: string }[],
  roomName: (roomId: string) => string
): CloneDestination[] {
  const name = packLabel(pack, roomName);
  return [
    { label: 'Merge into your pack', target: { kind: 'user' }, display_name: null },
    ...rooms.map((room) => ({
      label: `New pack in ${room.name}`,
      target: { kind: 'room', room_id: room.room_id, state_key: packSlug(name) } as PackTarget,
      display_name: name
    }))
  ];
}