Carlos Florêncio
40 lines
1.5 KiB
TypeScript
40 lines
1.5 KiB
TypeScript
import { useMemo } from "react";
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import { useAppStore } from "@/components/state-provider";
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const EMPTY_KEY = "";
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/**
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* Prev/next navigation between user messages in a session, sourced directly from
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* the store rather than a drilled `allMessages` array.
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*
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* The selector returns a value-stable key (the comma-joined ids of the session's
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* user messages). During agent token streaming the user-message set is unchanged,
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* so the key is referentially equal and the subscribing message does not
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* re-render — which keeps `ChatMessage` memoized instead of re-running its
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* markdown render on every streamed token.
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*/
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export function useUserMessageNavigation(sessionId: string | null, currentMessageId: string) {
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const userIdsKey = useAppStore((state) => {
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const messages = sessionId ? state.messages.bySession[sessionId] : undefined;
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if (!messages) return EMPTY_KEY;
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let key = EMPTY_KEY;
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for (const message of messages) {
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if (message.author_type === "user") key += `${message.id},`;
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}
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return key;
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});
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return useMemo(() => {
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const ids = userIdsKey ? userIdsKey.slice(0, -1).split(",") : [];
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const index = ids.indexOf(currentMessageId);
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const previousId = index > 0 ? ids[index - 1] : null;
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const nextId = index >= 0 && index < ids.length - 1 ? ids[index + 1] : null;
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return {
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hasPrevious: previousId !== null,
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hasNext: nextId !== null,
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previousId,
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nextId,
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};
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}, [userIdsKey, currentMessageId]);
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}
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