import { PacketType } from "./PacketType.ts";
import { hasEmptyFlags, isEmptyBuf } from "./decoder.ts";
import type { CodecOpts } from "./types.ts";
import type { ProtocolLevel } from "./protocolLevels.ts";

/**
 * PingresPacket is  an empty packet that is sent by the server in response to a PingreqPacket.
 * It is used to indicate that the client is still connected to the server.
 */
export type PingresPacket = {
  type: PacketType;
  protocolLevel: ProtocolLevel;
};

const PINGRES_PACKET = new Uint8Array([PacketType.pingres << 4, 0]);

export function encode(
  _packet: PingresPacket,
  _codecOpts: CodecOpts,
): Uint8Array {
  return PINGRES_PACKET;
}

export function decode(
  buffer: Uint8Array,
  flags: number,
  codecOpts: CodecOpts,
  _packetType: PacketType,
): PingresPacket {
  hasEmptyFlags(flags);
  isEmptyBuf(buffer);
  return {
    type: PacketType.pingres,
    protocolLevel: codecOpts.protocolLevel,
  };
}