import { jspack } from "jspack";
import { randomBytes, createHash } from "crypto";
import { Transport } from "./vendor/dtls";
import { Connection } from "./vendor/ice";

export function generateUUID(): string {
  return new Array(4)
    .fill(0)
    .map(() => Math.floor(Math.random() * Number.MAX_SAFE_INTEGER).toString(16))
    .join("-");
}

export function random32() {
  return jspack.Unpack("!L", randomBytes(4))[0];
}

export function uint16Add(a: number, b: number) {
  return (a + b) & 0xfff;
}

export function uint16Gt(a: number, b: number) {
  const halfMod = 0x8000;
  return (a < b && b - a > halfMod) || (a > b && a - b < halfMod);
}

export function uint16Gte(a: number, b: number) {
  return a === b || uint16Gt(a, b);
}

export function uint32Gt(a: number, b: number) {
  const halfMod = 0x80000000;
  return (a < b && b - a > halfMod) || (a > b && a - b < halfMod);
}

export function uint32Gte(a: number, b: number) {
  return a === b || uint32Gt(a, b);
}

const upper = (s: string) => s.toUpperCase();
const colon = (s: any) => s.match(/(.{2})/g).join(":");

export function fingerprint(file: Buffer, hashname: string) {
  const hash = createHash(hashname).update(file).digest("hex");

  return colon(upper(hash));
}

export class IceTransport implements Transport {
  constructor(private ice: Connection) {
    ice.onData.subscribe((buf) => {
      if (this.onData) this.onData(buf);
    });
  }
  onData?: (buf: Buffer) => void;

  send(buf: Buffer) {
    this.ice.send(buf);
  }

  close() {
    this.ice.close();
  }
}

export const createIceTransport = (ice: Connection) => new IceTransport(ice);