/**
 * iOS-VoIP-Push via PushKit + APNs HTTP/2.
 *
 * Unterschied zu services/push.ts (Expo Server SDK):
 *   - Reguläre Pushes laufen über Expo's Proxy (token = ExponentPushToken[xxx])
 *   - VoIP-Pushes MÜSSEN direkt an APNs gehen (Apple verbietet Proxy für PushKit)
 *   - Nutzt das VoIP-Services-Cert (.p12) das wir bei Apple beantragt haben
 *   - Wake-from-killed-State: einziger Weg ein iOS-App aufzuwecken um CallKit
 *     UI anzuzeigen
 *
 * Env-Vars (aus Infisical):
 *   APNS_VOIP_P12_PATH       Pfad zur .p12-Datei (z.B. /root/.secrets/rebreak-voip.p12)
 *   APNS_VOIP_P12_PASSWORD   Cert-Password
 *   APNS_VOIP_TOPIC          Bundle-ID + ".voip" (org.rebreak.app.voip)
 *   APNS_VOIP_PRODUCTION     "true" für Production-APNs-Endpoint
 *
 * Wenn ENV-Vars fehlen: Service no-op (kein Error, nur Log-Warnung beim ersten Send).
 * → Macht reguläre Pushes nicht kaputt wenn das VoIP-Setup noch unfertig ist.
 */
import apn from "@parse/node-apn";
import fs from "node:fs";

let provider: apn.Provider | null = null;
let initialized = false;
let topic: string | null = null;

function getProvider(): apn.Provider | null {
  if (initialized) return provider;
  initialized = true;

  const p12Path = process.env.APNS_VOIP_P12_PATH;
  const p12Pass = process.env.APNS_VOIP_P12_PASSWORD;
  const tpc = process.env.APNS_VOIP_TOPIC;
  const production = process.env.APNS_VOIP_PRODUCTION === "true";

  if (!p12Path || !p12Pass || !tpc) {
    console.warn(
      "[voip-push] disabled — missing env (APNS_VOIP_P12_PATH/PASSWORD/TOPIC)",
    );
    return null;
  }
  if (!fs.existsSync(p12Path)) {
    console.warn(`[voip-push] disabled — p12 file not found at ${p12Path}`);
    return null;
  }

  try {
    topic = tpc;
    provider = new apn.Provider({
      pfx: p12Path,
      passphrase: p12Pass,
      production,
    });
    console.log(`[voip-push] initialized (topic=${tpc}, production=${production})`);
    return provider;
  } catch (err) {
    console.error("[voip-push] init failed:", err);
    return null;
  }
}

export interface VoIPCallPayload {
  /** VoIP-PushKit-Token des Empfänger-Devices (64-char hex, NICHT der Expo-Token) */
  voipToken: string;
  /** Eindeutige Call-ID (matcht callIdToUuid() im Client) */
  callId: string;
  /** Display-Name für CallKit-UI */
  callerName: string;
  /** User-ID des Anrufers — Client braucht das um peer-Profile zu fetchen */
  callerId: string;
  callerNickname: string;
  callerAvatar: string | null;
}

/**
 * Sendet einen VoIP-Push an genau ein iOS-Device.
 *
 * Apple-Vorgaben (verifiziert via developer.apple.com/documentation/pushkit):
 *   - apns-push-type: voip
 *   - apns-topic: bundle-id + ".voip" (NICHT der reguläre bundle-id)
 *   - apns-priority: 10
 *   - apns-expiration: 0 (kein Storage — wenn Device offline, verworfen)
 *
 * @returns true bei Erfolg (oder no-op wenn Service disabled), false bei Fehler.
 */
export async function sendVoIPPush(payload: VoIPCallPayload): Promise<boolean> {
  const p = getProvider();
  if (!p || !topic) return true; // no-op, regulärer Push übernimmt

  const note = new apn.Notification();
  note.topic = topic;
  note.expiry = 0; // sofort verwerfen wenn Device unreachable
  note.priority = 10;
  note.pushType = "voip";
  note.payload = {
    type: "call",
    callId: payload.callId,
    callerName: payload.callerName,
    from: {
      id: payload.callerId,
      nickname: payload.callerNickname,
      avatar: payload.callerAvatar,
    },
  };

  try {
    const result = await p.send(note, payload.voipToken);
    if (result.failed.length > 0) {
      const f = result.failed[0];
      console.warn(
        `[voip-push] failed token=${payload.voipToken.slice(0, 8)}… reason=`,
        f.response ?? f.error,
      );
      return false;
    }
    return true;
  } catch (err) {
    console.error("[voip-push] send threw:", err);
    return false;
  }
}

/** Cleanup bei Server-Shutdown — wichtig wegen HTTP/2-Verbindung an Apple. */
export function shutdownVoIPProvider(): void {
  if (provider) {
    provider.shutdown();
    provider = null;
    initialized = false;
  }
}