export class RequestQueue<T> {
    private pendingPromise = false;
    private items: Array<{
        action: (prevPayload?: T | null) => Promise<T>;
        resolve: (value: T) => void;
        reject: (reason?: any) => void;
    }> = [];

    enqueue(action: (prevPayload?: T | null) => Promise<T>) {
        return new Promise((resolve, reject) => {
            if (this.items.length === 2) {
                this.items[1] = { action, resolve, reject };
            } else {
                this.items.push({ action, resolve, reject });
            }
            this.dequeue();
        });
    }

    async dequeue(prevPayload?: T | null) {
        if (this.pendingPromise) return;

        const item = this.items.shift();
        if (!item) return;

        let payload: T | null = null;

        try {
            this.pendingPromise = true;
            payload = await item.action(prevPayload);
            this.pendingPromise = false;

            item.resolve(payload);
        } catch (e) {
            this.pendingPromise = false;
            item.reject(e);
        } finally {
            this.dequeue(payload);
        }
    }
}