| 1 | export const CHAT_LIST_ANCHOR_OFFSET = 16; |
| 2 | |
| 3 | export interface ChatListAnchoredEndSpace { |
| 4 | readonly anchorIndex: number; |
| 5 | readonly anchorOffset: number; |
| 6 | } |
| 7 | |
| 8 | export interface ChatListAnchorOptions { |
| 9 | readonly anchorOffset?: number; |
| 10 | } |
| 11 | |
| 12 | export function resolveChatListAnchoredEndSpace<Item, AnchorId>( |
| 13 | items: ReadonlyArray<Item>, |
| 14 | anchorId: AnchorId | null, |
| 15 | getAnchorId: (item: Item) => AnchorId | null, |
| 16 | options: ChatListAnchorOptions = {}, |
| 17 | ): ChatListAnchoredEndSpace | undefined { |
| 18 | if (anchorId === null) { |
| 19 | return undefined; |
| 20 | } |
| 21 | |
| 22 | for (let index = 0; index < items.length; index += 1) { |
| 23 | const item = items[index]; |
| 24 | if (item === undefined) { |
| 25 | continue; |
| 26 | } |
| 27 | |
| 28 | const itemAnchorId = getAnchorId(item); |
| 29 | if (itemAnchorId === null) { |
| 30 | continue; |
| 31 | } |
| 32 | |
| 33 | return itemAnchorId === anchorId |
| 34 | ? { |
| 35 | anchorIndex: index, |
| 36 | anchorOffset: options.anchorOffset ?? CHAT_LIST_ANCHOR_OFFSET, |
| 37 | } |
| 38 | : undefined; |
| 39 | } |
| 40 | |
| 41 | return undefined; |
| 42 | } |