fbarrca_obsidian-inlineAI/src/modules/messageHistory/queue.ts

/**
 * MessageQueue is a generic fixed-length queue for storing recent chat messages.
 * - When a new item is enqueued and the queue is full, the oldest item is removed.
 * - Duplicate consecutive items are not added.
 * - Provides standard queue operations: enqueue, dequeue, peek, size, isEmpty, and getItems.
 */
export class MessageQueue<T> {
    private items: T[] = [];
    private maxLength: number;

    constructor(maxLength: number) {
        this.maxLength = maxLength;
    }

    // Adds an item to the queue
    enqueue(item: T): void {
        // If the new item is exactly the same as the previous one, do not add it
        if (this.items.length > 0) {
            const lastItem = this.items[this.items.length - 1];
            if (lastItem === item) {
                return;
            }
        }
        if (this.items.length >= this.maxLength) {
            // Remove the oldest item if the queue is full
            this.items.shift();
        }
        this.items.push(item);
    }

    // Removes and returns the item at the front of the queue
    dequeue(): T | undefined {
        return this.items.shift();
    }

    // Returns the item at the front of the queue without removing it
    peek(): T | undefined {
        return this.items[0];
    }

    // Returns the current size of the queue
    size(): number {
        return this.items.length;
    }

    // Checks if the queue is empty
    isEmpty(): boolean {
        return this.items.length === 0;
    }

    // Returns the items in the queue
    getItems(): T[] {
        return [...this.items];
    }
}