112 lines
3.3 KiB
TypeScript
112 lines
3.3 KiB
TypeScript
/**
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* @license
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* Copyright 2025 Google LLC
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* SPDX-License-Identifier: Apache-2.0
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*/
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import { useState, useRef, useCallback } from 'react';
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import { HistoryItem } from '../types.js';
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// Type for the updater function passed to updateHistoryItem
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type HistoryItemUpdater = (
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prevItem: HistoryItem,
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) => Partial<Omit<HistoryItem, 'id'>>;
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export interface UseHistoryManagerReturn {
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history: HistoryItem[];
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addItem: (itemData: Omit<HistoryItem, 'id'>, baseTimestamp: number) => number; // Returns the generated ID
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updateItem: (
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id: number,
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updates: Partial<Omit<HistoryItem, 'id'>> | HistoryItemUpdater,
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) => void;
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clearItems: () => void;
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loadHistory: (newHistory: HistoryItem[]) => void;
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}
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/**
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* Custom hook to manage the chat history state.
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*
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* Encapsulates the history array, message ID generation, adding items,
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* updating items, and clearing the history.
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*/
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export function useHistory(): UseHistoryManagerReturn {
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const [history, setHistory] = useState<HistoryItem[]>([]);
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const messageIdCounterRef = useRef(0);
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// Generates a unique message ID based on a timestamp and a counter.
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const getNextMessageId = useCallback((baseTimestamp: number): number => {
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messageIdCounterRef.current += 1;
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return baseTimestamp + messageIdCounterRef.current;
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}, []);
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const loadHistory = useCallback((newHistory: HistoryItem[]) => {
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setHistory(newHistory);
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}, []);
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// Adds a new item to the history state with a unique ID.
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const addItem = useCallback(
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(itemData: Omit<HistoryItem, 'id'>, baseTimestamp: number): number => {
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const id = getNextMessageId(baseTimestamp);
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const newItem: HistoryItem = { ...itemData, id } as HistoryItem;
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setHistory((prevHistory) => {
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if (prevHistory.length > 0) {
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const lastItem = prevHistory[prevHistory.length - 1];
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// Prevent adding duplicate consecutive user messages
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if (
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lastItem.type === 'user' &&
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newItem.type === 'user' &&
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lastItem.text === newItem.text
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) {
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return prevHistory; // Don't add the duplicate
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}
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}
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return [...prevHistory, newItem];
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});
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return id; // Return the generated ID (even if not added, to keep signature)
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},
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[getNextMessageId],
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);
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/**
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* Updates an existing history item identified by its ID.
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* @deprecated Prefer not to update history item directly as we are currently
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* rendering all history items in <Static /> for performance reasons. Only use
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* if ABSOLUTELY NECESSARY
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*/
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//
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const updateItem = useCallback(
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(
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id: number,
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updates: Partial<Omit<HistoryItem, 'id'>> | HistoryItemUpdater,
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) => {
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setHistory((prevHistory) =>
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prevHistory.map((item) => {
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if (item.id === id) {
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// Apply updates based on whether it's an object or a function
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const newUpdates =
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typeof updates === 'function' ? updates(item) : updates;
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return { ...item, ...newUpdates } as HistoryItem;
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}
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return item;
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}),
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);
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},
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[],
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);
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// Clears the entire history state and resets the ID counter.
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const clearItems = useCallback(() => {
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setHistory([]);
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messageIdCounterRef.current = 0;
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}, []);
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return {
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history,
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addItem,
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updateItem,
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clearItems,
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loadHistory,
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};
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}
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