NFC card emulation (#100)

* - NFC card emulation mode for sharing DCC on View cert page. Host apdu service with NFC Forum type 4 implementation for NDEF message exchange;
- NFC reader mode on main certificates page;

* - add base binding fragment;
- clean up logic;

* - claim certificate when received via NFC;

* - detect and handle DCC sent event in service;
- display toast when dcc sent;

* - code refactor;

* - remove NFC reader initialization from cert fragment;
- remove UI component;
- parse message in activity and navigate to claim cert fragment;
- send qr code text only via nfc;

* - navigate to claim cert view on app start;

* - merge main branch;
- remove unused images;

* - revert changes to claim viewModel;

* - update button style;

app/src/main/AndroidManifest.xml

@@ -5,6 +5,7 @@
 
     <uses-permission android:name="android.permission.INTERNET" />
     <uses-permission android:name="android.permission.CAMERA" />
+    <uses-permission android:name="android.permission.NFC" />
 
     <application
         android:name=".DgcaWalletApplication"
@@ -15,12 +16,21 @@
         android:supportsRtl="true"
         android:theme="@style/Theme.DgcaWalletAppAndroid">
 
-        <activity android:name=".MainActivity">
+        <activity
+            android:name=".MainActivity"
+            android:exported="true"
+            android:launchMode="singleInstance">
             <intent-filter>
                 <action android:name="android.intent.action.MAIN" />
 
                 <category android:name="android.intent.category.LAUNCHER" />
             </intent-filter>
+
+            <intent-filter>
+                <action android:name="android.nfc.action.NDEF_DISCOVERED" />
+                <category android:name="android.intent.category.DEFAULT" />
+                <data android:mimeType="text/plain" />
+            </intent-filter>
         </activity>
 
         <activity
@@ -33,6 +43,19 @@
             android:exported="false"
             tools:node="remove" />
 
+        <service
+            android:name=".nfc.DCCApduService"
+            android:exported="true"
+            android:permission="android.permission.BIND_NFC_SERVICE">
+            <intent-filter>
+                <action android:name="android.nfc.cardemulation.action.HOST_APDU_SERVICE" />
+                <category android:name="android.intent.category.DEFAULT" />
+            </intent-filter>
+            <meta-data
+                android:name="android.nfc.cardemulation.host_apdu_service"
+                android:resource="@xml/nfc_application_ids" />
+        </service>
+
         <provider
             android:name="androidx.core.content.FileProvider"
             android:authorities="${applicationId}.provider"

app/src/main/java/dgca/wallet/app/android/MainActivity.kt

@@ -22,38 +22,61 @@
 
 package dgca.wallet.app.android
 
+import android.content.Intent
+import android.nfc.NdefMessage
+import android.nfc.NfcAdapter
 import android.os.Bundle
 import android.view.Menu
 import android.view.MenuItem
 import android.view.WindowManager
 import androidx.appcompat.app.AppCompatActivity
 import androidx.core.content.ContextCompat
+import androidx.navigation.NavController
 import androidx.navigation.fragment.NavHostFragment
 import androidx.navigation.ui.AppBarConfiguration
 import androidx.navigation.ui.setupWithNavController
 import dagger.hilt.android.AndroidEntryPoint
+import dgca.wallet.app.android.certificate.CertificatesFragmentDirections
 import dgca.wallet.app.android.databinding.ActivityMainBinding
+import dgca.wallet.app.android.nfc.NdefParser
+import timber.log.Timber
 
 @AndroidEntryPoint
 class MainActivity : AppCompatActivity() {
+
     private lateinit var binding: ActivityMainBinding
+    private lateinit var navController: NavController
 
     override fun onCreate(savedInstanceState: Bundle?) {
         super.onCreate(savedInstanceState)
+
         window.setFlags(WindowManager.LayoutParams.FLAG_SECURE, WindowManager.LayoutParams.FLAG_SECURE)
 
         binding = ActivityMainBinding.inflate(layoutInflater)
         setContentView(binding.root)
 
         val navHostFragment = supportFragmentManager.findFragmentById(R.id.nav_host_fragment) as NavHostFragment
-        val navController = navHostFragment.navController
+        navController = navHostFragment.navController
+
         val appBarConfiguration = AppBarConfiguration(
             topLevelDestinationIds = setOf(),
             fallbackOnNavigateUpListener = ::onSupportNavigateUp
         )
         binding.toolbar.setupWithNavController(navController, appBarConfiguration)
 
         setSupportActionBar(binding.toolbar)
+
+        navController.addOnDestinationChangedListener { _, destination, _ ->
+            if (destination.id == R.id.certificatesFragment) {
+                checkNdefMessage(intent)
+            }
+        }
+    }
+
+    override fun onNewIntent(intent: Intent) {
+        super.onNewIntent(intent)
+
+        checkNdefMessage(intent)
     }
 
     override fun onCreateOptionsMenu(menu: Menu?): Boolean {
@@ -62,8 +85,6 @@ class MainActivity : AppCompatActivity() {
     }
 
     override fun onOptionsItemSelected(item: MenuItem): Boolean {
-        val navHostFragment = supportFragmentManager.findFragmentById(R.id.nav_host_fragment) as NavHostFragment
-        val navController = navHostFragment.navController
         return when (item.itemId) {
             R.id.settings -> {
                 navController.navigate(R.id.settingsFragment)
@@ -74,11 +95,49 @@ class MainActivity : AppCompatActivity() {
         }
     }
 
+    override fun onSupportNavigateUp(): Boolean {
+        return navController.navigateUp() || super.onSupportNavigateUp()
+    }
+
     fun clearBackground() {
         window.setBackgroundDrawable(ContextCompat.getDrawable(this, R.color.white))
     }
 
     fun disableBackButton() {
         binding.toolbar.navigationIcon = null
     }
+
+    private fun checkNdefMessage(intent: Intent) {
+        if (NfcAdapter.ACTION_NDEF_DISCOVERED == intent.action) {
+            intent.getParcelableArrayExtra(NfcAdapter.EXTRA_NDEF_MESSAGES)?.also { rawMessages ->
+                val messages: List<NdefMessage> = rawMessages.map { it as NdefMessage }
+                parseNdefMessages(messages)
+                intent.removeExtra(NfcAdapter.EXTRA_NDEF_MESSAGES)
+            }
+        }
+    }
+
+    private fun parseNdefMessages(messages: List<NdefMessage>) {
+        if (messages.isEmpty()) {
+            return
+        }
+
+        val builder = StringBuilder()
+        val records = NdefParser.parse(messages[0])
+        val size = records.size
+
+        for (i in 0 until size) {
+            val record = records[i]
+            val str = record.str()
+            builder.append(str)
+        }
+
+        val qrCodeText = builder.toString()
+        if (qrCodeText.isNotEmpty()) {
+            val action = CertificatesFragmentDirections.actionCertificatesFragmentToClaimCertificateFragment(qrCodeText)
+            navController.navigate(action)
+        } else {
+            Timber.d("Received empty NDEFMessage")
+        }
+    }
 }

app/src/main/java/dgca/wallet/app/android/base/BindingFragment.kt

@@ -0,0 +1,58 @@
+/*
+ *  ---license-start
+ *  eu-digital-green-certificates / dgca-verifier-app-android
+ *  ---
+ *  Copyright (C) 2021 T-Systems International GmbH and all other contributors
+ *  ---
+ *  Licensed under the Apache License, Version 2.0 (the "License");
+ *  you may not use this file except in compliance with the License.
+ *  You may obtain a copy of the License at
+ *
+ *       http://www.apache.org/licenses/LICENSE-2.0
+ *
+ *  Unless required by applicable law or agreed to in writing, software
+ *  distributed under the License is distributed on an "AS IS" BASIS,
+ *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *  See the License for the specific language governing permissions and
+ *  limitations under the License.
+ *  ---license-end
+ *
+ *  Created by mykhailo.nester on 18/08/2021, 17:21
+ */
+
+package dgca.wallet.app.android.base
+
+import android.os.Bundle
+import android.view.LayoutInflater
+import android.view.View
+import android.view.ViewGroup
+import androidx.fragment.app.Fragment
+import androidx.viewbinding.ViewBinding
+
+abstract class BindingFragment<T : ViewBinding> : Fragment() {
+
+    private var _binding: T? = null
+    val binding get() = _binding!!
+
+    abstract fun onCreateBinding(inflater: LayoutInflater, container: ViewGroup?): T
+
+    open fun onDestroyBinding(binding: T) {
+    }
+
+    override fun onCreateView(inflater: LayoutInflater, container: ViewGroup?, savedInstanceState: Bundle?): View {
+        val innerBinding = onCreateBinding(inflater, container)
+        _binding = innerBinding
+        return innerBinding.root
+    }
+
+    override fun onDestroyView() {
+        val innerBinding = _binding
+        if (innerBinding != null) {
+            onDestroyBinding(innerBinding)
+        }
+
+        _binding = null
+
+        super.onDestroyView()
+    }
+}

app/src/main/java/dgca/wallet/app/android/certificate/CertificatesFragment.kt

@@ -28,46 +28,41 @@ import android.view.View
 import android.view.ViewGroup
 import androidx.activity.addCallback
 import androidx.core.view.isVisible
-import androidx.fragment.app.Fragment
 import androidx.fragment.app.setFragmentResultListener
 import androidx.fragment.app.viewModels
 import androidx.navigation.fragment.findNavController
 import androidx.recyclerview.widget.LinearLayoutManager
 import dagger.hilt.android.AndroidEntryPoint
 import dgca.wallet.app.android.MainActivity
+import dgca.wallet.app.android.base.BindingFragment
 import dgca.wallet.app.android.databinding.FragmentCertificatesBinding
 import java.io.File
 
 @AndroidEntryPoint
-class CertificatesFragment : Fragment(), CertificateCardsAdapter.CertificateCardClickListener,
+class CertificatesFragment : BindingFragment<FragmentCertificatesBinding>(),
+    CertificateCardsAdapter.CertificateCardClickListener,
     CertificateCardsAdapter.FileCardClickListener {
 
     private val viewModel by viewModels<CertificatesViewModel>()
-    private var _binding: FragmentCertificatesBinding? = null
-    private val binding get() = _binding!!
 
     override fun onCreate(savedInstanceState: Bundle?) {
         super.onCreate(savedInstanceState)
         (activity as MainActivity).clearBackground()
     }
 
-    override fun onCreateView(inflater: LayoutInflater, container: ViewGroup?, savedInstanceState: Bundle?): View {
-        (activity as MainActivity).disableBackButton()
-        _binding = FragmentCertificatesBinding.inflate(inflater, container, false)
-        return binding.root
-    }
+    override fun onCreateBinding(inflater: LayoutInflater, container: ViewGroup?): FragmentCertificatesBinding =
+        FragmentCertificatesBinding.inflate(inflater, container, false)
 
     override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
         super.onViewCreated(view, savedInstanceState)
+
+        (activity as MainActivity).disableBackButton()
         requireActivity().onBackPressedDispatcher.addCallback(viewLifecycleOwner) { requireActivity().finish() }
         binding.scanCode.setOnClickListener { showAddNewDialog() }
 
-        viewModel.certificates.observe(viewLifecycleOwner, {
-            setCertificateCards(it)
-        })
-        viewModel.inProgress.observe(viewLifecycleOwner, {
-            binding.progressView.isVisible = it
-        })
+        viewModel.certificates.observe(viewLifecycleOwner, { setCertificateCards(it) })
+        viewModel.inProgress.observe(viewLifecycleOwner, { binding.progressView.isVisible = it })
+
         viewModel.fetchCertificates()
 
         setFragmentResultListener(AddNewBottomDialogFragment.REQUEST_KEY) { key, bundle ->
@@ -104,11 +99,6 @@ class CertificatesFragment : Fragment(), CertificateCardsAdapter.CertificateCard
         }
     }
 
-    override fun onDestroyView() {
-        super.onDestroyView()
-        _binding = null
-    }
-
     private fun showCodeReader() {
         val action = CertificatesFragmentDirections.actionCertificatesFragmentToCodeReaderFragment()
         findNavController().navigate(action)