Add custom Activity to show libraries licenses without proprietary de…

…pendency (#55)

app/build.gradle

@@ -100,8 +100,6 @@ dependencies {
 
     implementation Deps.timber
 
-    implementation Deps.google_licenses
-
     testImplementation Deps.test_junit
 
     androidTestImplementation Deps.test_ext

app/src/main/AndroidManifest.xml

@@ -24,10 +24,7 @@
         </activity>
 
         <activity
-            android:name="com.google.android.gms.oss.licenses.OssLicensesMenuActivity"
-            android:theme="@style/Theme.DgcaVerifierAppAndroid.Licensing" />
-        <activity
-            android:name="com.google.android.gms.oss.licenses.OssLicensesActivity"
+            android:name=".LicensesActivity"
             android:theme="@style/Theme.DgcaVerifierAppAndroid.Licensing" />
 
         <provider

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

@@ -0,0 +1,112 @@
+/*
+ *  ---license-start
+ *  eu-digital-green-certificates / dgca-verifier-app-android
+ *  ---
+ *  Copyright (C) 2021 T-Systems International GmbH and all other contributors
+ *  ---
+ *  This Source Code Form is subject to the terms of the Mozilla Public
+ *  License, v. 2.0. If a copy of the MPL was not distributed with this
+ *  file, You can obtain one at http://mozilla.org/MPL/2.0/.
+ *
+ *  ---license-end
+ *
+ *  Created by Matthieu De Beule on 11/06/2021, 08:39
+ */
+
+package dgca.wallet.app.android;
+
+import android.graphics.Typeface
+import android.os.Bundle
+import android.text.util.Linkify
+import android.widget.ArrayAdapter
+import android.widget.ListView
+import android.widget.TextView
+import androidx.appcompat.app.AlertDialog
+import androidx.appcompat.app.AppCompatActivity
+import dgca.wallet.app.android.databinding.ActivityLicensesBinding
+import dgca.wallet.app.android.databinding.FragmentSettingsBinding
+import java.nio.charset.Charset
+import java.util.*
+
+//Largely inspired by https://github.com/mozilla-mobile/fenix/pull/13767/
+class LicensesActivity : AppCompatActivity() {
+    private lateinit var binding: ActivityLicensesBinding
+
+    override fun onCreate(savedInstanceState: Bundle?) {
+        super.onCreate(savedInstanceState)
+        binding = ActivityLicensesBinding.inflate(layoutInflater)
+
+        setTitle(R.string.licenses)
+        setContentView(binding.root)
+
+        supportActionBar?.setDisplayHomeAsUpEnabled(true)
+
+        setupLibrariesListView()
+    }
+
+    override fun onSupportNavigateUp(): Boolean {
+        onBackPressed()
+        return true
+    }
+
+    private fun setupLibrariesListView() {
+        val libraries = parseLibraries()
+        val listView = binding.licensesListview
+        listView.adapter = ArrayAdapter(this, android.R.layout.simple_list_item_1, libraries)
+        listView.setOnItemClickListener { _, _, position, _ ->
+            showLicenseDialog(libraries[position])
+        }
+    }
+
+    private fun parseLibraries(): List<LibraryItem> {
+        /*
+            The gradle plugin "oss-licenses-plugin" creates two "raw" resources:
+               - third_party_licenses which is the binary concatenation of all the licenses text for
+                 all the libraries. License texts can either be an URL to a license file or just the
+                 raw text of the license.
+               - third_party_licenses_metadata which contains one dependency per line formatted in
+                 the following way: "[start_offset]:[length] [name]"
+                 [start_offset]     : first byte in third_party_licenses that contains the license
+                                      text for this library.
+                 [length]           : length of the license text for this library in
+                                      third_party_licenses.
+                 [name]             : either the name of the library, or its artifact name.
+            See https://github.com/google/play-services-plugins/tree/master/oss-licenses-plugin
+        */
+        val licensesData = resources
+            .openRawResource(R.raw.third_party_licenses)
+            .readBytes()
+        val licensesMetadataReader = resources
+            .openRawResource(R.raw.third_party_license_metadata)
+            .bufferedReader()
+
+        return licensesMetadataReader.use { reader -> reader.readLines() }.map { line ->
+            val (section, name) = line.split(" ", limit = 2)
+            val (startOffset, length) = section.split(":", limit = 2).map(String::toInt)
+            val licenseData = licensesData.sliceArray(startOffset until startOffset + length)
+            val licenseText = licenseData.toString(Charset.forName("UTF-8"))
+            LibraryItem(name, licenseText)
+        }.sortedBy { item -> item.name.toLowerCase(Locale.ROOT) }
+    }
+
+    private fun showLicenseDialog(libraryItem: LibraryItem) {
+        val dialog: AlertDialog = AlertDialog.Builder(this).let {
+            it.setTitle(libraryItem.name)
+            it.setMessage(libraryItem.license)
+            it.show()
+        }
+
+        dialog.findViewById<TextView>(android.R.id.message)!!.let {
+            Linkify.addLinks(it, Linkify.ALL)
+            it.linksClickable = true
+            it.textSize = 10F
+            it.typeface = Typeface.MONOSPACE
+        }
+    }
+}
+
+private class LibraryItem(val name: String, val license: String) {
+    override fun toString(): String {
+        return name
+    }
+}

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

@@ -30,7 +30,6 @@ import android.view.Menu
 import android.view.View
 import android.view.ViewGroup
 import androidx.fragment.app.Fragment
-import com.google.android.gms.oss.licenses.OssLicensesMenuActivity
 import dagger.hilt.android.AndroidEntryPoint
 import dgca.wallet.app.android.databinding.FragmentSettingsBinding
 
@@ -72,9 +71,9 @@ class SettingsFragment : Fragment() {
     }
 
     private fun openLicenses() {
-        OssLicensesMenuActivity.setActivityTitle(getString(R.string.licenses))
+        val intent = Intent(requireContext(), LicensesActivity::class.java)
         requireContext().apply {
-            startActivity(Intent(this, OssLicensesMenuActivity::class.java))
+            startActivity(intent)
         }
     }
 }

app/src/main/res/layout/activity_licenses.xml

@@ -0,0 +1,32 @@
+<?xml version="1.0" encoding="utf-8"?><!--
+  ~  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 Matthieu De Beule on 11/06/2021, 08:43
+  -->
+
+<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
+    android:layout_width="match_parent"
+    android:layout_height="match_parent">
+
+    <ListView
+        android:layout_width="match_parent"
+        android:layout_height="match_parent"
+        android:id="@+id/licenses_listview" />
+
+</androidx.constraintlayout.widget.ConstraintLayout>

buildSrc/src/main/java/Dependencies.kt

@@ -67,8 +67,6 @@ object Deps {
 
     const val timber = "com.jakewharton.timber:timber:${Versions.timber}"
 
-    const val google_licenses = "com.google.android.gms:play-services-oss-licenses:${Versions.google_licenses}"
-
     const val test_junit = "junit:junit:${Versions.junit}"
     const val test_junit_jupiter_api = "org.junit.jupiter:junit-jupiter-api:${Versions.junit_jupiter}"
     const val test_junit_jupiter_params = "org.junit.jupiter:junit-jupiter-params:${Versions.junit_jupiter}"