/**
 * Network throttling presets applied via CDP's `Network.emulateNetworkConditions`.
 * Values are the same ones DevTools uses for its built-in profiles.
 */

import type { NetworkProfile } from "./types.js";

export interface NetworkConditions {
  offline: boolean;
  /** Extra round-trip latency added to every request, in ms. */
  latency: number;
  /** Download throughput in bytes / second; -1 disables throttling. */
  downloadThroughput: number;
  /** Upload throughput in bytes / second; -1 disables throttling. */
  uploadThroughput: number;
}

const BPS = 1024; // 1 kilobit in bytes (125 B/s) — keep math readable.
const KBPS = 1000 * BPS;
void BPS;
void KBPS;

export function networkConditionsFor(profile: NetworkProfile): NetworkConditions {
  switch (profile) {
    case "offline":
      return { offline: true, latency: 0, downloadThroughput: 0, uploadThroughput: 0 };
    case "slow-3g":
      // ~500 kbps down / ~500 kbps up / 2000 ms RTT — Chrome DevTools "Slow 3G".
      return {
        offline: false,
        latency: 2000,
        downloadThroughput: Math.floor((500 * 1024) / 8),
        uploadThroughput: Math.floor((500 * 1024) / 8),
      };
    case "fast-3g":
      // ~1.6 Mbps down / ~750 kbps up / 562 ms RTT — Chrome DevTools "Fast 3G".
      return {
        offline: false,
        latency: 562,
        downloadThroughput: Math.floor((1.6 * 1024 * 1024) / 8),
        uploadThroughput: Math.floor((750 * 1024) / 8),
      };
  }
}