import os from "node:os";

import { logDebug, logWarn } from "../logger.js";
import { getLogger } from "../logging.js";

export type GatewayBonjourAdvertiser = {
  stop: () => Promise<void>;
};

export type GatewayBonjourAdvertiseOpts = {
  instanceName?: string;
  gatewayPort: number;
  sshPort?: number;
  bridgePort?: number;
  canvasPort?: number;
  tailnetDns?: string;
  cliPath?: string;
};

function isDisabledByEnv() {
  if (process.env.CLAWDIS_DISABLE_BONJOUR === "1") return true;
  if (process.env.NODE_ENV === "test") return true;
  if (process.env.VITEST) return true;
  return false;
}

function safeServiceName(name: string) {
  const trimmed = name.trim();
  return trimmed.length > 0 ? trimmed : "Clawdis";
}

function prettifyInstanceName(name: string) {
  const normalized = name.trim().replace(/\s+/g, " ");
  return normalized.replace(/\s+\(Clawdis\)\s*$/i, "").trim() || normalized;
}

type BonjourService = {
  advertise: () => Promise<void>;
  destroy: () => Promise<void>;
  getFQDN: () => string;
  getHostname: () => string;
  getPort: () => number;
  on: (event: string, listener: (...args: unknown[]) => void) => unknown;
  serviceState: string;
};

function formatBonjourError(err: unknown): string {
  if (err instanceof Error) {
    const msg = err.message || String(err);
    return err.name && err.name !== "Error" ? `${err.name}: ${msg}` : msg;
  }
  return String(err);
}

function serviceSummary(label: string, svc: BonjourService): string {
  let fqdn = "unknown";
  let hostname = "unknown";
  let port = -1;
  try {
    fqdn = svc.getFQDN();
  } catch {
    // ignore
  }
  try {
    hostname = svc.getHostname();
  } catch {
    // ignore
  }
  try {
    port = svc.getPort();
  } catch {
    // ignore
  }
  const state =
    typeof svc.serviceState === "string" ? svc.serviceState : "unknown";
  return `${label} fqdn=${fqdn} host=${hostname} port=${port} state=${state}`;
}

export async function startGatewayBonjourAdvertiser(
  opts: GatewayBonjourAdvertiseOpts,
): Promise<GatewayBonjourAdvertiser> {
  if (isDisabledByEnv()) {
    return { stop: async () => {} };
  }

  const { getResponder, Protocol } = await import("@homebridge/ciao");
  const responder = getResponder();

  // mDNS service instance names are single DNS labels; dots in hostnames (like
  // `Mac.localdomain`) can confuse some resolvers/browsers and break discovery.
  // Keep only the first label and normalize away a trailing `.local`.
  const hostname =
    os
      .hostname()
      .replace(/\.local$/i, "")
      .split(".")[0]
      .trim() || "clawdis";
  const instanceName =
    typeof opts.instanceName === "string" && opts.instanceName.trim()
      ? opts.instanceName.trim()
      : `${hostname} (Clawdis)`;
  const displayName = prettifyInstanceName(instanceName);

  const txtBase: Record<string, string> = {
    role: "gateway",
    gatewayPort: String(opts.gatewayPort),
    lanHost: `${hostname}.local`,
    displayName,
  };
  if (typeof opts.bridgePort === "number" && opts.bridgePort > 0) {
    txtBase.bridgePort = String(opts.bridgePort);
  }
  if (typeof opts.canvasPort === "number" && opts.canvasPort > 0) {
    txtBase.canvasPort = String(opts.canvasPort);
  }
  if (typeof opts.tailnetDns === "string" && opts.tailnetDns.trim()) {
    txtBase.tailnetDns = opts.tailnetDns.trim();
  }
  if (typeof opts.cliPath === "string" && opts.cliPath.trim()) {
    txtBase.cliPath = opts.cliPath.trim();
  }

  const services: Array<{ label: string; svc: BonjourService }> = [];

  // Bridge beacon (used by macOS/iOS/Android nodes and the mac app onboarding flow).
  if (typeof opts.bridgePort === "number" && opts.bridgePort > 0) {
    const bridge = responder.createService({
      name: safeServiceName(instanceName),
      type: "clawdis-bridge",
      protocol: Protocol.TCP,
      port: opts.bridgePort,
      domain: "local",
      hostname,
      txt: {
        ...txtBase,
        sshPort: String(opts.sshPort ?? 22),
        transport: "bridge",
      },
    });
    services.push({
      label: "bridge",
      svc: bridge as unknown as BonjourService,
    });
  }

  logDebug(
    `bonjour: starting (hostname=${hostname}, instance=${JSON.stringify(
      safeServiceName(instanceName),
    )}, gatewayPort=${opts.gatewayPort}, bridgePort=${opts.bridgePort ?? 0}, sshPort=${
      opts.sshPort ?? 22
    })`,
  );

  for (const { label, svc } of services) {
    try {
      svc.on("name-change", (name: unknown) => {
        const next = typeof name === "string" ? name : String(name);
        logWarn(
          `bonjour: ${label} name conflict resolved; newName=${JSON.stringify(next)}`,
        );
      });
      svc.on("hostname-change", (nextHostname: unknown) => {
        const next =
          typeof nextHostname === "string"
            ? nextHostname
            : String(nextHostname);
        logWarn(
          `bonjour: ${label} hostname conflict resolved; newHostname=${JSON.stringify(next)}`,
        );
      });
    } catch (err) {
      logDebug(
        `bonjour: failed to attach listeners for ${label}: ${String(err)}`,
      );
    }
  }

  // Do not block gateway startup on mDNS probing/announce. Advertising can take
  // multiple seconds depending on network state; the gateway should come up even
  // if Bonjour is slow or fails.
  for (const { label, svc } of services) {
    try {
      void svc
        .advertise()
        .then(() => {
          // Keep this out of stdout/stderr (menubar + tests) but capture in the rolling log.
          getLogger().info(`bonjour: advertised ${serviceSummary(label, svc)}`);
        })
        .catch((err) => {
          logWarn(
            `bonjour: advertise failed (${serviceSummary(label, svc)}): ${formatBonjourError(err)}`,
          );
        });
    } catch (err) {
      logWarn(
        `bonjour: advertise threw (${serviceSummary(label, svc)}): ${formatBonjourError(err)}`,
      );
    }
  }

  // Watchdog: if we ever end up in an unannounced state (e.g. after sleep/wake or
  // interface churn), try to re-advertise instead of requiring a full gateway restart.
  const lastRepairAttempt = new Map<string, number>();
  const watchdog = setInterval(() => {
    for (const { label, svc } of services) {
      const stateUnknown = (svc as { serviceState?: unknown }).serviceState;
      if (typeof stateUnknown !== "string") continue;
      if (stateUnknown === "announced" || stateUnknown === "announcing")
        continue;

      let key = label;
      try {
        key = `${label}:${svc.getFQDN()}`;
      } catch {
        // ignore
      }
      const now = Date.now();
      const last = lastRepairAttempt.get(key) ?? 0;
      if (now - last < 30_000) continue;
      lastRepairAttempt.set(key, now);

      logWarn(
        `bonjour: watchdog detected non-announced service; attempting re-advertise (${serviceSummary(
          label,
          svc,
        )})`,
      );
      try {
        void svc.advertise().catch((err) => {
          logWarn(
            `bonjour: watchdog advertise failed (${serviceSummary(label, svc)}): ${formatBonjourError(err)}`,
          );
        });
      } catch (err) {
        logWarn(
          `bonjour: watchdog advertise threw (${serviceSummary(label, svc)}): ${formatBonjourError(err)}`,
        );
      }
    }
  }, 60_000);
  watchdog.unref?.();

  return {
    stop: async () => {
      clearInterval(watchdog);
      for (const { svc } of services) {
        try {
          await svc.destroy();
        } catch {
          /* ignore */
        }
      }
      try {
        await responder.shutdown();
      } catch {
        /* ignore */
      }
    },
  };
}
