import type { CodecOpts, PacketId } from "./types.ts";
import type { ProtocolLevelNoV5 } from "./protocolLevels.ts";
import type { UnsubackProperties } from "./Properties.ts";
import type { ReasonCode } from "./ReasonCode.ts";
import { PacketType } from "./PacketType.ts";
import { Decoder, hasEmptyFlags } from "./decoder.ts";
import { Encoder } from "./encoder.ts";

export type UnsubackPacketV4 = {
  type: PacketType;
  protocolLevel: ProtocolLevelNoV5;
  id: PacketId;
};

export type UnsubackPacketV5 = {
  type: PacketType;
  protocolLevel: 5;
  id: PacketId;
  properties: UnsubackProperties;
  reasonCodes: Array<ReasonCode>;
};

/**
 * UnsubackPacket is sent by the server to the client to confirm receipt
 * of an UnsubscribePacket.
 */
export type UnsubackPacket = UnsubackPacketV4 | UnsubackPacketV5;

export function encode(
  packet: UnsubackPacket,
  codecOpts: CodecOpts,
): Uint8Array {
  const flags = 0;
  const encoder = new Encoder(packet.type);
  encoder.setInt16(packet.id);
  if (packet.protocolLevel === 5) {
    encoder.setProperties(
      packet.properties || {},
      PacketType.unsuback,
      codecOpts.maxOutgoingPacketSize,
    );
    for (const reasonCode of packet.reasonCodes) {
      encoder.setByte(reasonCode);
    }
  }
  return encoder.done(flags);
}

export function decode(
  buffer: Uint8Array,
  flags: number,
  codecOpts: CodecOpts,
  packetType: PacketType,
): UnsubackPacket {
  hasEmptyFlags(flags);
  const decoder = new Decoder(packetType, buffer);
  const id = decoder.getInt16();
  if (codecOpts.protocolLevel === 5) {
    const properties = decoder.getProperties(PacketType.unsuback);
    const reasonCodes = [];
    while (!decoder.atEnd()) {
      const reasonCode = decoder.geReasonCode();
      reasonCodes.push(reasonCode);
    }
    return {
      type: PacketType.unsuback,
      protocolLevel: 5,
      id,
      properties,
      reasonCodes: reasonCodes as Array<ReasonCode>,
    };
  }
  decoder.done();
  return {
    type: PacketType.unsuback,
    protocolLevel: codecOpts.protocolLevel,
    id,
  };
}