packages/local_auth/android/src/main/java/io/flutter/plugins/localauth/LocalAuthPlugin.java

// Copyright 2017 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

package io.flutter.plugins.localauth;

import android.app.Activity;
import android.content.pm.PackageManager;
import android.os.Build;
import androidx.fragment.app.FragmentActivity;
import androidx.lifecycle.Lifecycle;
import io.flutter.embedding.engine.plugins.FlutterPlugin;
import io.flutter.embedding.engine.plugins.activity.ActivityAware;
import io.flutter.embedding.engine.plugins.activity.ActivityPluginBinding;
import io.flutter.embedding.engine.plugins.lifecycle.FlutterLifecycleAdapter;
import io.flutter.plugin.common.MethodCall;
import io.flutter.plugin.common.MethodChannel;
import io.flutter.plugin.common.MethodChannel.MethodCallHandler;
import io.flutter.plugin.common.MethodChannel.Result;
import io.flutter.plugin.common.PluginRegistry.Registrar;
import io.flutter.plugins.localauth.AuthenticationHelper.AuthCompletionHandler;
import java.util.ArrayList;
import java.util.concurrent.atomic.AtomicBoolean;

/**
 * Flutter plugin providing access to local authentication.
 *
 * <p>Instantiate this in an add to app scenario to gracefully handle activity and context changes.
 */
@SuppressWarnings("deprecation")
public class LocalAuthPlugin implements MethodCallHandler, FlutterPlugin, ActivityAware {
  private static final String CHANNEL_NAME = "plugins.flutter.io/local_auth";

  private Activity activity;
  private final AtomicBoolean authInProgress = new AtomicBoolean(false);
  private AuthenticationHelper authenticationHelper;

  // These are null when not using v2 embedding.
  private MethodChannel channel;
  private Lifecycle lifecycle;

  /**
   * Registers a plugin with the v1 embedding api {@code io.flutter.plugin.common}.
   *
   * <p>Calling this will register the plugin with the passed registrar. However, plugins
   * initialized this way won't react to changes in activity or context.
   *
   * @param registrar attaches this plugin's {@link
   *     io.flutter.plugin.common.MethodChannel.MethodCallHandler} to the registrar's {@link
   *     io.flutter.plugin.common.BinaryMessenger}.
   */
  public static void registerWith(Registrar registrar) {
    final MethodChannel channel = new MethodChannel(registrar.messenger(), CHANNEL_NAME);
    channel.setMethodCallHandler(new LocalAuthPlugin(registrar.activity()));
  }

  private LocalAuthPlugin(Activity activity) {
    this.activity = activity;
  }

  /**
   * Default constructor for LocalAuthPlugin.
   *
   * <p>Use this constructor when adding this plugin to an app with v2 embedding.
   */
  public LocalAuthPlugin() {}

  @Override
  public void onMethodCall(MethodCall call, final Result result) {
    if (call.method.equals("authenticateWithBiometrics")) {
      if (authInProgress.get()) {
        // Apps should not invoke another authentication request while one is in progress,
        // so we classify this as an error condition. If we ever find a legitimate use case for
        // this, we can try to cancel the ongoing auth and start a new one but for now, not worth
        // the complexity.
        result.error("auth_in_progress", "Authentication in progress", null);
        return;
      }

      if (activity == null || activity.isFinishing()) {
        result.error("no_activity", "local_auth plugin requires a foreground activity", null);
        return;
      }

      if (!(activity instanceof FragmentActivity)) {
        result.error(
            "no_fragment_activity",
            "local_auth plugin requires activity to be a FragmentActivity.",
            null);
        return;
      }
      authInProgress.set(true);
      authenticationHelper =
          new AuthenticationHelper(
              lifecycle,
              (FragmentActivity) activity,
              call,
              new AuthCompletionHandler() {
                @Override
                public void onSuccess() {
                  if (authInProgress.compareAndSet(true, false)) {
                    result.success(true);
                  }
                }

                @Override
                public void onFailure() {
                  if (authInProgress.compareAndSet(true, false)) {
                    result.success(false);
                  }
                }

                @Override
                public void onError(String code, String error) {
                  if (authInProgress.compareAndSet(true, false)) {
                    result.error(code, error, null);
                  }
                }
              });
      authenticationHelper.authenticate();
    } else if (call.method.equals("getAvailableBiometrics")) {
      try {
        if (activity == null || activity.isFinishing()) {
          result.error("no_activity", "local_auth plugin requires a foreground activity", null);
          return;
        }
        ArrayList<String> biometrics = new ArrayList<String>();
        PackageManager packageManager = activity.getPackageManager();
        if (Build.VERSION.SDK_INT >= 23) {
          if (packageManager.hasSystemFeature(PackageManager.FEATURE_FINGERPRINT)) {
            biometrics.add("fingerprint");
          }
        }
        if (Build.VERSION.SDK_INT >= 29) {
          if (packageManager.hasSystemFeature(PackageManager.FEATURE_FACE)) {
            biometrics.add("face");
          }
          if (packageManager.hasSystemFeature(PackageManager.FEATURE_IRIS)) {
            biometrics.add("iris");
          }
        }
        result.success(biometrics);
      } catch (Exception e) {
        result.error("no_biometrics_available", e.getMessage(), null);
      }
    } else if (call.method.equals(("stopAuthentication"))) {
      stopAuthentication(result);
    } else {
      result.notImplemented();
    }
  }

  /*
   Stops the authentication if in progress.
  */
  private void stopAuthentication(Result result) {
    try {
      if (authenticationHelper != null && authInProgress.get()) {
        authenticationHelper.stopAuthentication();
        authenticationHelper = null;
        result.success(true);
        return;
      }
      result.success(false);
    } catch (Exception e) {
      result.success(false);
    }
  }

  @Override
  public void onAttachedToEngine(FlutterPluginBinding binding) {
    channel = new MethodChannel(binding.getBinaryMessenger(), CHANNEL_NAME);
  }

  @Override
  public void onDetachedFromEngine(FlutterPluginBinding binding) {}

  @Override
  public void onAttachedToActivity(ActivityPluginBinding binding) {
    activity = binding.getActivity();
    lifecycle = FlutterLifecycleAdapter.getActivityLifecycle(binding);
    channel.setMethodCallHandler(this);
  }

  @Override
  public void onDetachedFromActivityForConfigChanges() {
    lifecycle = null;
    activity = null;
  }

  @Override
  public void onReattachedToActivityForConfigChanges(ActivityPluginBinding binding) {
    activity = binding.getActivity();
    lifecycle = FlutterLifecycleAdapter.getActivityLifecycle(binding);
  }

  @Override
  public void onDetachedFromActivity() {
    activity = null;
    lifecycle = null;
    channel.setMethodCallHandler(null);
  }
}