import { Env } from '../worker.js';
interface RateLimitEntry {
count: number;
window_start: number;
reset_at: number;
}
export class RateLimiter {
private readonly windowMs = 60000; // 1 minute window
private readonly maxRequests: number;
constructor(private env: Env) {
this.maxRequests = parseInt(env.MAX_REQUESTS_PER_MINUTE || '100');
}
/**
* Checks if a user has exceeded their rate limit
*/
async checkLimit(userId: string, action: string = 'default'): Promise<boolean> {
const key = `rate:${userId}:${action}`;
const now = Date.now();
// Get current rate limit entry
const data = await this.env.RATE_LIMITS.get(key);
let entry: RateLimitEntry;
if (data) {
entry = JSON.parse(data);
// Check if window has expired
if (now >= entry.reset_at) {
// Reset the window
entry = {
count: 1,
window_start: now,
reset_at: now + this.windowMs
};
} else {
// Within current window
if (entry.count >= this.maxRequests) {
return false; // Rate limit exceeded
}
entry.count++;
}
} else {
// First request in this window
entry = {
count: 1,
window_start: now,
reset_at: now + this.windowMs
};
}
// Store updated entry with TTL
await this.env.RATE_LIMITS.put(
key,
JSON.stringify(entry),
{
expirationTtl: Math.ceil(this.windowMs / 1000) + 60 // Extra 60 seconds buffer
}
);
return true;
}
/**
* Gets remaining requests for a user
*/
async getRemainingRequests(userId: string, action: string = 'default'): Promise<{
remaining: number;
reset_at: number;
}> {
const key = `rate:${userId}:${action}`;
const now = Date.now();
const data = await this.env.RATE_LIMITS.get(key);
if (!data) {
return {
remaining: this.maxRequests,
reset_at: now + this.windowMs
};
}
const entry: RateLimitEntry = JSON.parse(data);
if (now >= entry.reset_at) {
return {
remaining: this.maxRequests,
reset_at: now + this.windowMs
};
}
return {
remaining: Math.max(0, this.maxRequests - entry.count),
reset_at: entry.reset_at
};
}
/**
* Resets rate limit for a user
*/
async resetLimit(userId: string, action: string = 'default'): Promise<void> {
const key = `rate:${userId}:${action}`;
await this.env.RATE_LIMITS.delete(key);
}
/**
* Gets custom rate limits for premium users
*/
async getPremiumLimits(userId: string): Promise<number> {
// Premium users get 5x the rate limit
return this.maxRequests * 5;
}
/**
* Checks rate limit with tier-based limits
*/
async checkLimitWithTier(
userId: string,
action: string,
isPremium: boolean
): Promise<boolean> {
const limit = isPremium
? await this.getPremiumLimits(userId)
: this.maxRequests;
const key = `rate:${userId}:${action}`;
const now = Date.now();
const data = await this.env.RATE_LIMITS.get(key);
let entry: RateLimitEntry;
if (data) {
entry = JSON.parse(data);
if (now >= entry.reset_at) {
entry = {
count: 1,
window_start: now,
reset_at: now + this.windowMs
};
} else {
if (entry.count >= limit) {
return false;
}
entry.count++;
}
} else {
entry = {
count: 1,
window_start: now,
reset_at: now + this.windowMs
};
}
await this.env.RATE_LIMITS.put(
key,
JSON.stringify(entry),
{
expirationTtl: Math.ceil(this.windowMs / 1000) + 60
}
);
return true;
}
}
