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/**
* @license
* Copyright 2025 Google LLC
* SPDX-License-Identifier: Apache-2.0
*/
import { useState, useRef, useCallback } from 'react';
import { HistoryItem } from '../types.js';
export interface UseHistoryManagerReturn {
history: HistoryItem[];
addItemToHistory: (
itemData: Omit<HistoryItem, 'id'>,
baseTimestamp: number,
) => number; // Return the ID of the added item
updateHistoryItem: (
id: number,
updates: Partial<Omit<HistoryItem, 'id'>>,
) => void;
clearHistory: () => void;
}
/**
* Custom hook to manage the chat history state.
*
* Encapsulates the history array, message ID generation, adding items,
* updating items, and clearing the history.
*/
export function useHistoryManager(): UseHistoryManagerReturn {
const [history, setHistory] = useState<HistoryItem[]>([]);
const messageIdCounterRef = useRef(0);
// Generates a unique message ID based on a timestamp and a counter.
const getNextMessageId = useCallback((baseTimestamp: number): number => {
// Increment *before* adding to ensure uniqueness against the base timestamp
messageIdCounterRef.current += 1;
return baseTimestamp + messageIdCounterRef.current;
}, []);
// Adds a new item to the history state with a unique ID and returns the ID.
const addItemToHistory = useCallback(
(itemData: Omit<HistoryItem, 'id'>, baseTimestamp: number): number => {
const id = getNextMessageId(baseTimestamp);
const newItem: HistoryItem = { ...itemData, id } as HistoryItem;
setHistory((prevHistory) => [...prevHistory, newItem]);
return id; // Return the generated ID
},
[getNextMessageId],
);
// Updates an existing history item identified by its ID.
const updateHistoryItem = useCallback(
(id: number, updates: Partial<Omit<HistoryItem, 'id'>>) => {
setHistory((prevHistory) =>
prevHistory.map((item) =>
item.id === id ? ({ ...item, ...updates } as HistoryItem) : item,
),
);
},
[],
);
// Clears the entire history state.
const clearHistory = useCallback(() => {
setHistory([]);
messageIdCounterRef.current = 0; // Reset counter when history is cleared
}, []);
return { history, addItemToHistory, updateHistoryItem, clearHistory };
}
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