import type { Context } from "../context.ts";
import { ConnectionState } from "../ConnectionState.ts";
import { AuthenticationResultByNumber, ReasonCodeByNumber } from "../deps.ts";
import type { ConnackPacket, ReasonCode } from "../deps.ts";

/**
 * Handles the CONNACK packet received from the MQTT broker
 * @param ctx - The connection context
 * @param packet - The CONNACK packet containing the connection acknowledgment
 * @returns Promise that resolves when handling is complete
 */
export async function handleConnack(ctx: Context, packet: ConnackPacket) {
  const isVersion5 = packet.protocolLevel === 5;
  const result = isVersion5 ? packet.reasonCode : packet.returnCode;
  if (result === 0) {
    ctx.connectionState = ConnectionState.connected;
    if (ctx.mqttConn) {
      ctx.mqttConn.codecOpts.protocolLevel = ctx.protocolLevel;
    }

    const serverKeepAlive = isVersion5
      ? packet.properties?.serverKeepAlive
      : undefined;

    if (serverKeepAlive === 0) {
      ctx.pingTimer?.clear(); // Server disabled keepalive
    } else if (serverKeepAlive !== undefined) {
      ctx.setPingTimer(serverKeepAlive); // Server set a new interval
    } else {
      ctx.pingTimer?.reset(); // Default fallback for V4 or V5 without override
    }
    ctx.unresolvedConnect?.resolve(result);
    // start transmitting packets that were queued before
    for await (const packet of ctx.store.pendingOutgoingPackets()) {
      await ctx.send(packet);
    }
    return;
  }

  const errMsg = packet.protocolLevel === 5
    ? ReasonCodeByNumber[result as ReasonCode]
    : AuthenticationResultByNumber[result];

  const err = new Error(
    `Connect failed: ${errMsg}`,
  );
  ctx.connectionState = ConnectionState.disconnecting;
  ctx.pingTimer?.clear();
  ctx.unresolvedConnect?.reject(err);
}