/**
* Purdue Brightspace MCP Server
* Copyright (c) 2025 Rohan Muppa. All rights reserved.
* Licensed under AGPL-3.0 — see LICENSE file for details.
*/
// Token bucket rate limiter - allows bursts up to capacity
// Conservative defaults: capacity 10, refill 3/sec
export class TokenBucket {
private tokens: number;
private lastRefill: number;
private readonly capacity: number;
private readonly refillRate: number; // tokens per second
constructor(capacity: number, refillRate: number) {
this.capacity = capacity;
this.refillRate = refillRate;
this.tokens = capacity; // Start with full bucket
this.lastRefill = Date.now();
}
private refill(): void {
const now = Date.now();
const elapsedMs = now - this.lastRefill;
const elapsedSeconds = elapsedMs / 1000;
// Add tokens based on elapsed time
const tokensToAdd = elapsedSeconds * this.refillRate;
this.tokens = Math.min(this.capacity, this.tokens + tokensToAdd);
this.lastRefill = now;
}
async consume(count: number = 1): Promise<void> {
this.refill();
if (this.tokens >= count) {
// Enough tokens available - consume immediately
this.tokens -= count;
return;
}
// Not enough tokens - calculate wait time
const tokensNeeded = count - this.tokens;
const waitTimeMs = (tokensNeeded / this.refillRate) * 1000;
// Wait for tokens to refill
await new Promise((resolve) => setTimeout(resolve, waitTimeMs));
// Refill and consume
this.refill();
this.tokens -= count;
}
tryConsume(count: number = 1): boolean {
this.refill();
if (this.tokens >= count) {
this.tokens -= count;
return true;
}
return false;
}
get availableTokens(): number {
this.refill();
return this.tokens;
}
}
