karate_halloween/lib/rate-limit.ts

interface DeviceUsage {
  count: number;
  firstUsedAt: number;
}

// In-memory usage map (or keyed by hashed client token)
const usageStore = new Map<string, DeviceUsage>();

export interface RateLimitResult {
  allowed: boolean;
  remaining: number;
  resetMinutes: number;
}

export function checkRateLimit(
  clientId: string,
  maxAllowed: number,
  cooldownMinutes: number
): RateLimitResult {
  if (!maxAllowed || maxAllowed <= 0) {
    return { allowed: true, remaining: 999999, resetMinutes: 0 };
  }

  const now = Date.now();
  const cooldownMs = cooldownMinutes * 60 * 1000;
  const usage = usageStore.get(clientId);

  if (!usage) {
    return { allowed: true, remaining: maxAllowed, resetMinutes: 0 };
  }

  // Check if cooldown period has elapsed since first use
  if (now - usage.firstUsedAt > cooldownMs) {
    usageStore.delete(clientId);
    return { allowed: true, remaining: maxAllowed, resetMinutes: 0 };
  }

  const remaining = Math.max(0, maxAllowed - usage.count);
  const remainingCooldownMs = cooldownMs - (now - usage.firstUsedAt);
  const resetMinutes = Math.ceil(remainingCooldownMs / (60 * 1000));

  return {
    allowed: usage.count < maxAllowed,
    remaining,
    resetMinutes,
  };
}

export function incrementRateLimit(clientId: string): void {
  const now = Date.now();
  const usage = usageStore.get(clientId);

  if (!usage) {
    usageStore.set(clientId, { count: 1, firstUsedAt: now });
  } else {
    usage.count += 1;
  }
}