import { PacketType } from "./PacketType.ts";
import { Encoder, EncoderError } from "./encoder.ts";
import { Decoder, DecoderError, hasEmptyFlags } from "./decoder.ts";
import type { ReasonCode } from "./ReasonCode.ts";
import type { AuthProperties } from "./Properties.ts";
import type { CodecOpts } from "./types.ts";
import { MQTTLevel } from "./protocolLevels.ts";

// AuthPacket does not exist on protocol levels < 5
export type AuthPacketV5 = {
  type: PacketType;
  protocolLevel: 5;
  reasonCode: ReasonCode;
  properties?: AuthProperties;
};

/**
 * An AUTH packet is sent from Client to Server or Server to Client as part of an extended
 * authentication exchange, such as challenge / response authentication.
 * It is a Protocol Error for the Client or Server to send an AUTH packet
 * if the CONNECT packet did not contain the same Authentication Method.
 */
export type AuthPacket = AuthPacketV5;

export function encode(packet: AuthPacket, codecOpts: CodecOpts): Uint8Array {
  // deno-coverage-ignore-start
  if (packet.protocolLevel !== 5) {
    throw new EncoderError("Invalid protocol level");
  }
  // deno-coverage-ignore-stop
  const encoder = new Encoder(packet.type);
  encoder
    .seReasonCode(packet.reasonCode || 0)
    .setProperties(
      packet.properties || {},
      packet.type,
      codecOpts.maxOutgoingPacketSize,
    );
  return encoder.done(0);
}

export function decode(
  buffer: Uint8Array,
  flags: number,
  codecOpts: CodecOpts,
  packetType: PacketType,
): AuthPacket {
  // Bits 3,2,1 and 0 of the Fixed Header of the AUTH packet are reserved and MUST all be set to 0.
  // The Client or Server MUST treat any other value as malformed and close the Network Connection [MQTT-3.15.1-1].
  hasEmptyFlags(flags);
  if (codecOpts.protocolLevel !== 5) {
    throw new DecoderError("Invalid protocol level");
  }
  const decoder = new Decoder(packetType, buffer);
  const reasonCode = decoder.geReasonCode();
  const properties = decoder.getProperties(PacketType.auth);
  decoder.done();
  return {
    type: PacketType.auth,
    protocolLevel: MQTTLevel.v5,
    reasonCode,
    properties,
  };
}