Request permissions at runtime if needed

app/src/main/java/me/impy/aegis/MainActivity.java

@@ -1,5 +1,6 @@
 package me.impy.aegis;
 
+import android.Manifest;
 import android.content.ClipData;
 import android.content.ClipboardManager;
 import android.content.Context;
@@ -37,11 +38,13 @@ import java.util.List;
 import me.impy.aegis.crypto.MasterKey;
 import me.impy.aegis.db.DatabaseEntry;
 import me.impy.aegis.db.DatabaseManager;
+import me.impy.aegis.helpers.PermissionHelper;
 import me.impy.aegis.importers.DatabaseImporter;
 import me.impy.aegis.helpers.SimpleItemTouchHelperCallback;
 import me.impy.aegis.util.ByteInputStream;
 
 public class MainActivity extends AppCompatActivity implements KeyProfileAdapter.Listener {
+    // activity request codes
     private static final int CODE_GET_KEYINFO = 0;
     private static final int CODE_ADD_KEYINFO = 1;
     private static final int CODE_DO_INTRO = 2;
@@ -49,6 +52,11 @@ public class MainActivity extends AppCompatActivity implements KeyProfileAdapter
     private static final int CODE_IMPORT = 4;
     private static final int CODE_PREFERENCES = 5;
 
+    // permission request codes
+    private static final int CODE_PERM_EXPORT = 0;
+    private static final int CODE_PERM_IMPORT = 1;
+    private static final int CODE_PERM_CAMERA = 2;
+
     private KeyProfileAdapter _keyProfileAdapter;
     private DatabaseManager _db;
 
@@ -103,8 +111,7 @@ public class MainActivity extends AppCompatActivity implements KeyProfileAdapter
         FloatingActionButton fab = findViewById(R.id.fab);
         fab.setEnabled(true);
         fab.setOnClickListener(view -> {
-            Intent scannerActivity = new Intent(getApplicationContext(), ScannerActivity.class);
+            onGetKeyInfo();
-            startActivityForResult(scannerActivity, CODE_GET_KEYINFO);
         });
 
         RecyclerView rvKeyProfiles = findViewById(R.id.rvKeyProfiles);
@@ -146,6 +153,26 @@ public class MainActivity extends AppCompatActivity implements KeyProfileAdapter
         }
     }
 
+    @Override
+    public void onRequestPermissionsResult(int requestCode, String[] permissions, int[] grantResults) {
+        if (!PermissionHelper.checkResults(grantResults)) {
+            Toast.makeText(this, "Permission denied", Toast.LENGTH_SHORT).show();
+            return;
+        }
+
+        switch (requestCode) {
+            case CODE_PERM_EXPORT:
+                onExport();
+                break;
+            case CODE_PERM_IMPORT:
+                onImport();
+                break;
+            case CODE_PERM_CAMERA:
+                onGetKeyInfo();
+                break;
+        }
+    }
+
     private void onPreferencesResult(int resultCode, Intent data) {
         // refresh the entire key profile list if needed
         if (data.getBooleanExtra("needsRefresh", false)) {
@@ -156,6 +183,16 @@ public class MainActivity extends AppCompatActivity implements KeyProfileAdapter
         int action = data.getIntExtra("action", -1);
         switch (action) {
             case PreferencesActivity.ACTION_EXPORT:
+                onExport();
+                break;
+        }
+    }
+
+    private void onExport() {
+        if (!PermissionHelper.request(this, CODE_PERM_EXPORT, Manifest.permission.WRITE_EXTERNAL_STORAGE)) {
+            return;
+        }
+
         // TODO: create a custom layout to show a message AND a checkbox
         final boolean[] checked = {true};
         AlertDialog.Builder builder = new AlertDialog.Builder(MainActivity.this)
@@ -189,8 +226,12 @@ public class MainActivity extends AppCompatActivity implements KeyProfileAdapter
             builder.setMessage("This action will export the database out of Android's private storage.");
         }
         builder.show();
-                break;
     }
+
+    private void onImport() {
+        Intent intent = new Intent(Intent.ACTION_GET_CONTENT);
+        intent.setType("*/*");
+        startActivityForResult(intent, CODE_IMPORT);
     }
 
     private void onImportResult(int resultCode, Intent data) {
@@ -251,6 +292,15 @@ public class MainActivity extends AppCompatActivity implements KeyProfileAdapter
         saveDatabase();
     }
 
+    private void onGetKeyInfo() {
+        if (!PermissionHelper.request(this, CODE_PERM_CAMERA, Manifest.permission.CAMERA)) {
+            return;
+        }
+
+        Intent scannerActivity = new Intent(getApplicationContext(), ScannerActivity.class);
+        startActivityForResult(scannerActivity, CODE_GET_KEYINFO);
+    }
+
     private void onGetKeyInfoResult(int resultCode, Intent data) {
         if (resultCode == RESULT_OK) {
             KeyProfile keyProfile = (KeyProfile)data.getSerializableExtra("KeyProfile");
@@ -420,9 +470,9 @@ public class MainActivity extends AppCompatActivity implements KeyProfileAdapter
                 startActivityForResult(preferencesActivity, CODE_PREFERENCES);
                 return true;
             case R.id.action_import:
-                Intent intent = new Intent(Intent.ACTION_GET_CONTENT);
+                if (PermissionHelper.request(this, CODE_PERM_IMPORT, Manifest.permission.CAMERA)) {
-                intent.setType("*/*");
+                    onImport();
-                startActivityForResult(intent, CODE_IMPORT);
+                }
                 return true;
             case R.id.action_lock:
                 // TODO: properly close the database

app/src/main/java/me/impy/aegis/helpers/PermissionHelper.java

@@ -0,0 +1,39 @@
+package me.impy.aegis.helpers;
+
+import android.app.Activity;
+import android.content.pm.PackageManager;
+import android.support.v4.app.ActivityCompat;
+
+import java.util.ArrayList;
+import java.util.List;
+
+public class PermissionHelper {
+    private PermissionHelper() {
+
+    }
+
+    public static boolean request(Activity activity, int requestCode, String... perms) {
+        List<String> deniedPerms = new ArrayList<>();
+        for (String permission : perms) {
+            if (ActivityCompat.checkSelfPermission(activity, permission) == PackageManager.PERMISSION_DENIED) {
+                deniedPerms.add(permission);
+            }
+        }
+
+        int size = deniedPerms.size();
+        if (size > 0) {
+            String[] array = new String[size];
+            ActivityCompat.requestPermissions(activity, deniedPerms.toArray(array), requestCode);
+        }
+        return size == 0;
+    }
+
+    public static boolean checkResults(int[] grantResults) {
+        for (int result : grantResults) {
+            if (result != PackageManager.PERMISSION_GRANTED) {
+                return false;
+            }
+        }
+        return true;
+    }
+}