/*
 * Helpdesk Dialer patch — always-on reverse-command foreground service.
 * Part of the com.android.dialer.helpdesk overlay (see components/dialer-patch).
 */
package com.android.dialer.helpdesk;

import android.app.Notification;
import android.app.NotificationChannel;
import android.app.NotificationManager;
import android.app.Service;
import android.content.Context;
import android.content.Intent;
import android.os.Build;
import android.os.IBinder;

/**
 * Keeps the reverse-command channel ({@link CommandChannelClient}) alive 24/7 as a foreground service,
 * so the console can drive the phone <em>between</em> calls — most importantly click-to-dial, whose
 * {@code dial} command is by definition issued while the phone is idle.
 *
 * <p>Why a persistent service: {@code CommandChannelClient} used to be created in
 * {@code InCallServiceImpl}, which Telecom binds ONLY during an active call, so an idle {@code dial}
 * command was never drained. This service owns the single, process-wide poller instead (using the shared
 * {@link CallIdRegistry#get()} so it can still resolve in-call verbs answer/mute/hold during a call —
 * {@code CallList}/{@code TelecomAdapter} are process singletons). The in-call poller has been removed to
 * avoid two pollers racing on the same destructive command queue.
 *
 * <p>Lifecycle: started at BOOT_COMPLETED (via {@link HelpdeskHeartbeat.Receiver}, an allowed FGS-start
 * exemption) and on first InCallService init; {@code START_STICKY} so the platform recreates it if killed.
 * targetSdk 30 permits a typeless foreground service, so no foregroundServiceType is needed. Battery is a
 * non-issue on the always-charging office handset.
 */
public final class HelpdeskCommandService extends Service {

  private static final String TAG = "HelpdeskCmdSvc";
  private static final String CH_ID = "helpdesk_command_channel";
  private static final int NOTIF_ID = 0xC0DE;

  private CommandChannelClient client;

  /** Idempotent start — safe to call repeatedly (boot, app init). */
  public static void ensureRunning(Context ctx) {
    try {
      ctx.getApplicationContext().startForegroundService(
          new Intent(ctx.getApplicationContext(), HelpdeskCommandService.class));
    } catch (Throwable t) {
      android.util.Log.w(TAG, "startForegroundService failed", t);
    }
  }

  @Override
  public void onCreate() {
    super.onCreate();
    goForeground();
    if (client == null) {
      client = new CommandChannelClient(this, CallIdRegistry.get());
      android.util.Log.i(TAG, "reverse-command poller started (always-on)");
    }
  }

  @Override
  public int onStartCommand(Intent intent, int flags, int startId) {
    goForeground(); // re-assert FGS on a sticky restart (intent may be null)
    if (client == null) {
      client = new CommandChannelClient(this, CallIdRegistry.get());
    }
    return START_STICKY;
  }

  @Override
  public IBinder onBind(Intent intent) {
    return null; // started service, not bound
  }

  @Override
  public void onDestroy() {
    if (client != null) {
      client.stop();
      client = null;
    }
    super.onDestroy();
  }

  private void goForeground() {
    if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
      NotificationManager nm = getSystemService(NotificationManager.class);
      if (nm != null && nm.getNotificationChannel(CH_ID) == null) {
        NotificationChannel ch = new NotificationChannel(
            CH_ID, "Helpdesk connection", NotificationManager.IMPORTANCE_MIN);
        ch.setShowBadge(false);
        nm.createNotificationChannel(ch);
      }
    }
    startForeground(NOTIF_ID, buildNotification()); // typeless FGS — allowed on targetSdk 30
  }

  @SuppressWarnings("deprecation") // Notification.Builder(Context) below API 26 (minSdk 24)
  private Notification buildNotification() {
    Notification.Builder b = (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O)
        ? new Notification.Builder(this, CH_ID)
        : new Notification.Builder(this);
    return b.setSmallIcon(android.R.drawable.sym_action_call)
        .setContentTitle("Helpdesk connected")
        .setContentText("Ready for calls from the console")
        .setOngoing(true)
        .build();
  }
}