Use ViewModel for EditActivity

This is capable of solving #270 (NullPointerException when saving new card after rotating the device)

5 files changed, 242 insertions, 230 deletions

diff --git a/app/src/main/java/it/niedermann/nextcloud/deck/ui/card/CardTabAdapter.java b/app/src/main/java/it/niedermann/nextcloud/deck/ui/card/CardTabAdapter.java
index 408e1123c..0c384837f 100644
--- a/app/src/main/java/it/niedermann/nextcloud/deck/ui/card/CardTabAdapter.java
+++ b/app/src/main/java/it/niedermann/nextcloud/deck/ui/card/CardTabAdapter.java
@@ -40,7 +40,7 @@ public class CardTabAdapter extends FragmentStateAdapter {
     public Fragment createFragment(int position) {
         switch (position) {
             case 0:
-                return CardDetailsFragment.newInstance(accountId, localId, boardId, canEdit);
+                return CardDetailsFragment.newInstance();
             case 1:
                 return CardAttachmentsFragment.newInstance(accountId, localId, boardId, canEdit);
             case 2:
diff --git a/app/src/main/java/it/niedermann/nextcloud/deck/ui/card/EditActivity.java b/app/src/main/java/it/niedermann/nextcloud/deck/ui/card/EditActivity.java
index 1b4348c35..cbfd5047b 100644
--- a/app/src/main/java/it/niedermann/nextcloud/deck/ui/card/EditActivity.java
+++ b/app/src/main/java/it/niedermann/nextcloud/deck/ui/card/EditActivity.java
@@ -9,19 +9,14 @@ import android.view.MenuInflater;
 import android.view.MenuItem;
 import android.view.WindowManager;
 
+import androidx.lifecycle.ViewModelProvider;
+
 import com.google.android.material.tabs.TabLayout;
 import com.google.android.material.tabs.TabLayoutMediator;
 
-import java.util.ArrayList;
-import java.util.Date;
-
 import it.niedermann.nextcloud.deck.R;
 import it.niedermann.nextcloud.deck.databinding.ActivityEditBinding;
 import it.niedermann.nextcloud.deck.model.Attachment;
-import it.niedermann.nextcloud.deck.model.Card;
-import it.niedermann.nextcloud.deck.model.Label;
-import it.niedermann.nextcloud.deck.model.User;
-import it.niedermann.nextcloud.deck.model.full.FullCard;
 import it.niedermann.nextcloud.deck.model.ocs.Version;
 import it.niedermann.nextcloud.deck.model.ocs.comment.DeckComment;
 import it.niedermann.nextcloud.deck.persistence.sync.SyncManager;
@@ -30,7 +25,6 @@ import it.niedermann.nextcloud.deck.ui.branding.BrandedAlertDialogBuilder;
 import it.niedermann.nextcloud.deck.ui.card.attachments.NewCardAttachmentHandler;
 import it.niedermann.nextcloud.deck.ui.card.comments.CommentAddedListener;
 import it.niedermann.nextcloud.deck.ui.card.comments.CommentDeletedListener;
-import it.niedermann.nextcloud.deck.ui.card.details.CardDetailsListener;
 import it.niedermann.nextcloud.deck.ui.exception.ExceptionHandler;
 import it.niedermann.nextcloud.deck.util.CardUtil;
 
@@ -41,11 +35,12 @@ import static it.niedermann.nextcloud.deck.ui.card.CardAdapter.BUNDLE_KEY_LOCAL_
 import static it.niedermann.nextcloud.deck.ui.card.CardAdapter.BUNDLE_KEY_STACK_ID;
 import static it.niedermann.nextcloud.deck.ui.card.CardAdapter.NO_LOCAL_ID;
 
-public class EditActivity extends BrandedActivity implements CardDetailsListener, CommentAddedListener, CommentDeletedListener, NewCardAttachmentHandler {
+public class EditActivity extends BrandedActivity implements CommentAddedListener, CommentDeletedListener, NewCardAttachmentHandler {
 
     private ActivityEditBinding binding;
     private SyncManager syncManager;
-    boolean hasCommentsAbility = false;
+
+    private EditCardViewModel viewModel;
 
     private static final int[] tabTitles = new int[]{
             R.string.card_edit_details,
@@ -73,18 +68,11 @@ public class EditActivity extends BrandedActivity implements CardDetailsListener
             R.drawable.ic_activity_light_grey
     };
 
-    private FullCard originalCard;
-    private FullCard fullCard;
-
     private long accountId;
     private long boardId;
     private long stackId;
     private long localId;
 
-    private boolean pendingCreation = false;
-    private boolean canEdit;
-    private boolean createMode;
-
     @Override
     public void onCreate(Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
@@ -96,7 +84,7 @@ public class EditActivity extends BrandedActivity implements CardDetailsListener
 
         setSupportActionBar(binding.toolbar);
 
-        Bundle args = getIntent().getExtras();
+        final Bundle args = getIntent().getExtras();
 
         if (args == null || !args.containsKey(BUNDLE_KEY_ACCOUNT_ID) || !args.containsKey(BUNDLE_KEY_BOARD_ID)) {
             throw new IllegalArgumentException("Provide at least " + BUNDLE_KEY_ACCOUNT_ID + " and " + BUNDLE_KEY_BOARD_ID + " so we know where to create this new card.");
@@ -106,8 +94,11 @@ public class EditActivity extends BrandedActivity implements CardDetailsListener
         boardId = args.getLong(BUNDLE_KEY_BOARD_ID);
         localId = args.getLong(BUNDLE_KEY_LOCAL_ID, NO_LOCAL_ID);
 
+        viewModel = new ViewModelProvider(this).get(EditCardViewModel.class);
+        syncManager = new SyncManager(this);
+
         if (localId == NO_LOCAL_ID) {
-            createMode = true;
+            viewModel.setCreateMode(true);
             if (args.containsKey(BUNDLE_KEY_STACK_ID)) {
                 stackId = args.getLong(BUNDLE_KEY_STACK_ID);
             } else {
@@ -115,28 +106,19 @@ public class EditActivity extends BrandedActivity implements CardDetailsListener
             }
         }
 
-        syncManager = new SyncManager(this);
-
         observeOnce(syncManager.getFullBoardById(accountId, boardId), EditActivity.this, (fullBoard -> {
-            canEdit = fullBoard.getBoard().isPermissionEdit();
+            viewModel.setCanEdit(fullBoard.getBoard().isPermissionEdit());
             invalidateOptionsMenu();
-            if (createMode) {
-                fullCard = new FullCard();
-                originalCard = new FullCard();
-                fullCard.setLabels(new ArrayList<>());
-                fullCard.setAssignedUsers(new ArrayList<>());
-                fullCard.setAttachments(new ArrayList<>());
-                Card card = new Card();
-                card.setStackId(stackId);
-                fullCard.setCard(card);
+            if (viewModel.isCreateMode()) {
+                viewModel.initializeNewCard(accountId, boardId, stackId);
+
                 setupViewPager();
-                setupTitle(createMode);
+                setupTitle(viewModel.isCreateMode());
             } else {
                 observeOnce(syncManager.getCardByLocalId(accountId, localId), EditActivity.this, (next) -> {
-                    fullCard = next;
-                    originalCard = new FullCard(fullCard);
+                    viewModel.initializeExistingCard(accountId, boardId, next);
                     setupViewPager();
-                    setupTitle(createMode);
+                    setupTitle(viewModel.isCreateMode());
                 });
             }
         }));
@@ -144,7 +126,7 @@ public class EditActivity extends BrandedActivity implements CardDetailsListener
 
     @Override
     public boolean onCreateOptionsMenu(Menu menu) {
-        if (canEdit) {
+        if (viewModel.canEdit()) {
             MenuInflater inflater = getMenuInflater();
             inflater.inflate(R.menu.card_edit_menu, menu);
         } else {
@@ -162,23 +144,24 @@ public class EditActivity extends BrandedActivity implements CardDetailsListener
     }
 
     private void saveAndFinish() {
-        if (!pendingCreation) {
-            pendingCreation = true;
-            if (fullCard.getCard().getTitle() == null || fullCard.getCard().getTitle().isEmpty()) {
-                fullCard.getCard().setTitle(CardUtil.generateTitleFromDescription(fullCard.getCard().getDescription()));
+        if (!viewModel.isPendingCreation()) {
+            viewModel.setPendingCreation(true);
+            final String title = viewModel.getFullCard().getCard().getTitle();
+            if (title == null || title.isEmpty()) {
+                viewModel.getFullCard().getCard().setTitle(CardUtil.generateTitleFromDescription(viewModel.getFullCard().getCard().getDescription()));
             }
-            if (fullCard.getCard().getTitle().isEmpty()) {
+            if (viewModel.getFullCard().getCard().getTitle().isEmpty()) {
                 new BrandedAlertDialogBuilder(this)
                         .setTitle(R.string.title_is_mandatory)
                         .setMessage(R.string.provide_at_least_a_title_or_description)
                         .setPositiveButton(android.R.string.ok, null)
-                        .setOnDismissListener(dialog -> pendingCreation = false)
+                        .setOnDismissListener(dialog -> viewModel.setPendingCreation(false))
                         .show();
             } else {
-                if (createMode) {
-                    observeOnce(syncManager.createFullCard(accountId, boardId, stackId, fullCard), EditActivity.this, (card) -> super.finish());
+                if (viewModel.isCreateMode()) {
+                    observeOnce(syncManager.createFullCard(accountId, boardId, stackId, viewModel.getFullCard()), EditActivity.this, (card) -> super.finish());
                 } else {
-                    observeOnce(syncManager.updateCard(fullCard), EditActivity.this, (card) -> super.finish());
+                    observeOnce(syncManager.updateCard(viewModel.getFullCard()), EditActivity.this, (card) -> super.finish());
                 }
             }
         }
@@ -188,23 +171,21 @@ public class EditActivity extends BrandedActivity implements CardDetailsListener
         binding.tabLayout.removeAllTabs();
         binding.tabLayout.setTabGravity(TabLayout.GRAVITY_FILL);
 
-        CardTabAdapter adapter = new CardTabAdapter(
+        final CardTabAdapter adapter = new CardTabAdapter(
                 getSupportFragmentManager(),
                 getLifecycle(),
                 accountId,
                 localId,
                 boardId,
-                canEdit);
-        TabLayoutMediator mediator = new TabLayoutMediator(binding.tabLayout, binding.pager, (tab, position) -> {
-            tab.setIcon(
-                    hasCommentsAbility
-                            ? tabIconsWithComments[position]
-                            : tabIcons[position]
+                viewModel.canEdit());
+        final TabLayoutMediator mediator = new TabLayoutMediator(binding.tabLayout, binding.pager, (tab, position) -> {
+            tab.setIcon(viewModel.isHasCommentsAbility()
+                    ? tabIconsWithComments[position]
+                    : tabIcons[position]
             );
-            tab.setContentDescription(
-                    hasCommentsAbility
-                            ? tabTitlesWithComments[position]
-                            : tabTitles[position]
+            tab.setContentDescription(viewModel.isHasCommentsAbility()
+                    ? tabTitlesWithComments[position]
+                    : tabTitles[position]
             );
         });
         runOnUiThread(() -> {
@@ -214,10 +195,10 @@ public class EditActivity extends BrandedActivity implements CardDetailsListener
         });
 
         // Comments API only available starting with version 1.0.0-alpha1
-        if (!createMode) {
+        if (!viewModel.isCreateMode()) {
             syncManager.readAccount(accountId).observe(this, (account) -> {
-                hasCommentsAbility = ((account.getServerDeckVersionAsObject().compareTo(new Version("1.0.0", 1, 0, 0)) >= 0));
-                if (hasCommentsAbility) {
+                viewModel.setHasCommentsAbility(account.getServerDeckVersionAsObject().isGreaterOrEqualTo(new Version("1.0.0", 1, 0, 0)));
+                if (viewModel.isHasCommentsAbility()) {
                     runOnUiThread(() -> {
                         mediator.detach();
                         adapter.enableComments();
@@ -230,20 +211,20 @@ public class EditActivity extends BrandedActivity implements CardDetailsListener
     }
 
     private void setupTitle(boolean createMode) {
-        binding.title.setText(fullCard.getCard().getTitle());
-        if (canEdit) {
+        binding.title.setText(viewModel.getFullCard().getCard().getTitle());
+        if (viewModel.canEdit()) {
             if (createMode) {
                 binding.title.requestFocus();
                 getWindow().setSoftInputMode(WindowManager.LayoutParams.SOFT_INPUT_STATE_ALWAYS_VISIBLE);
-                if (fullCard.getCard().getTitle() != null) {
-                    binding.title.setSelection(fullCard.getCard().getTitle().length());
+                if (viewModel.getFullCard().getCard().getTitle() != null) {
+                    binding.title.setSelection(viewModel.getFullCard().getCard().getTitle().length());
                 }
             }
             binding.title.setHint(getString(createMode ? R.string.simple_add : R.string.edit));
             binding.title.addTextChangedListener(new TextWatcher() {
                 @Override
                 public void onTextChanged(CharSequence s, int start, int before, int count) {
-                    fullCard.getCard().setTitle(binding.title.getText().toString());
+                    viewModel.getFullCard().getCard().setTitle(binding.title.getText().toString());
                 }
 
                 @Override
@@ -261,36 +242,6 @@ public class EditActivity extends BrandedActivity implements CardDetailsListener
     }
 
     @Override
-    public void onDescriptionChanged(String description) {
-        this.fullCard.getCard().setDescription(description);
-    }
-
-    @Override
-    public void onUserAdded(User user) {
-        this.fullCard.getAssignedUsers().add(user);
-    }
-
-    @Override
-    public void onUserRemoved(User user) {
-        this.fullCard.getAssignedUsers().remove(user);
-    }
-
-    @Override
-    public void onLabelAdded(Label label) {
-        this.fullCard.getLabels().add(label);
-    }
-
-    @Override
-    public void onLabelRemoved(Label label) {
-        this.fullCard.getLabels().remove(label);
-    }
-
-    @Override
-    public void onDueDateChanged(Date dueDate) {
-        this.fullCard.getCard().setDueDate(dueDate);
-    }
-
-    @Override
     public boolean onSupportNavigateUp() {
         finish(); // close this activity as oppose to navigating up
         return true;
@@ -303,7 +254,7 @@ public class EditActivity extends BrandedActivity implements CardDetailsListener
 
     @Override
     public void finish() {
-        if (!fullCard.equals(originalCard) && canEdit) {
+        if (!viewModel.hasChanges() && viewModel.canEdit()) {
             new BrandedAlertDialogBuilder(this)
                     .setTitle(R.string.simple_save)
                     .setMessage(R.string.do_you_want_to_save_your_changes)
@@ -321,12 +272,12 @@ public class EditActivity extends BrandedActivity implements CardDetailsListener
 
     @Override
     public void attachmentAdded(Attachment attachment) {
-        fullCard.getAttachments().add(attachment);
+        viewModel.getFullCard().getAttachments().add(attachment);
     }
 
     @Override
     public void attachmentRemoved(Attachment attachment) {
-        fullCard.getAttachments().remove(attachment);
+        viewModel.getFullCard().getAttachments().remove(attachment);
     }
 
     @Override
diff --git a/app/src/main/java/it/niedermann/nextcloud/deck/ui/card/EditCardViewModel.java b/app/src/main/java/it/niedermann/nextcloud/deck/ui/card/EditCardViewModel.java
new file mode 100644
index 000000000..f89a95a66
--- /dev/null
+++ b/app/src/main/java/it/niedermann/nextcloud/deck/ui/card/EditCardViewModel.java
@@ -0,0 +1,102 @@
+package it.niedermann.nextcloud.deck.ui.card;
+
+import androidx.annotation.NonNull;
+import androidx.lifecycle.ViewModel;
+
+import java.util.ArrayList;
+
+import it.niedermann.nextcloud.deck.model.Card;
+import it.niedermann.nextcloud.deck.model.full.FullCard;
+
+@SuppressWarnings("WeakerAccess")
+public class EditCardViewModel extends ViewModel {
+
+    private long accountId;
+    private long boardId;
+    private FullCard originalCard;
+    private FullCard fullCard;
+    private boolean hasCommentsAbility = false;
+    private boolean pendingCreation = false;
+    private boolean canEdit = false;
+    private boolean createMode = false;
+
+    /**
+     * Stores a deep copy of the given fullCard to be able to compare the state at every time in #{@link EditCardViewModel#hasChanges()}
+     *
+     * @param accountId Expecting a positive long value
+     * @param boardId   Local ID, expecting a positive long value
+     * @param fullCard  The card that is currently edited
+     */
+    public void initializeExistingCard(long accountId, long boardId, @NonNull FullCard fullCard) {
+        this.accountId = accountId;
+        this.boardId = boardId;
+        this.fullCard = fullCard;
+        this.originalCard = new FullCard(this.fullCard);
+    }
+
+    /**
+     * Stores a deep copy of the given fullCard to be able to compare the state at every time in #{@link EditCardViewModel#hasChanges()}
+     *
+     * @param accountId Expecting a positive long value
+     * @param boardId   Local ID, expecting a positive long value
+     * @param stackId   Local ID, expecting a positive long value where the card should be created
+     */
+    public void initializeNewCard(long accountId, long boardId, long stackId) {
+        final FullCard fullCard = new FullCard();
+        fullCard.setLabels(new ArrayList<>());
+        fullCard.setAssignedUsers(new ArrayList<>());
+        fullCard.setAttachments(new ArrayList<>());
+        final Card card = new Card();
+        card.setStackId(stackId);
+        fullCard.setCard(card);
+        initializeExistingCard(accountId, boardId, fullCard);
+    }
+
+    public boolean hasChanges() {
+        return fullCard.equals(originalCard);
+    }
+
+    public boolean isHasCommentsAbility() {
+        return hasCommentsAbility;
+    }
+
+    public void setHasCommentsAbility(boolean hasCommentsAbility) {
+        this.hasCommentsAbility = hasCommentsAbility;
+    }
+
+    public long getAccountId() {
+        return accountId;
+    }
+
+    public FullCard getFullCard() {
+        return fullCard;
+    }
+
+    public boolean isPendingCreation() {
+        return pendingCreation;
+    }
+
+    public void setPendingCreation(boolean pendingCreation) {
+        this.pendingCreation = pendingCreation;
+    }
+
+    public boolean canEdit() {
+        return canEdit;
+    }
+
+    public void setCanEdit(boolean canEdit) {
+        this.canEdit = canEdit;
+    }
+
+    public boolean isCreateMode() {
+        return createMode;
+    }
+
+    public void setCreateMode(boolean createMode) {
+        this.createMode = createMode;
+    }
+
+    public long getBoardId() {
+        return boardId;
+    }
+}
diff --git a/app/src/main/java/it/niedermann/nextcloud/deck/ui/card/details/CardDetailsFragment.java b/app/src/main/java/it/niedermann/nextcloud/deck/ui/card/details/CardDetailsFragment.java
index 81efacba8..adb8e15e3 100644
--- a/app/src/main/java/it/niedermann/nextcloud/deck/ui/card/details/CardDetailsFragment.java
+++ b/app/src/main/java/it/niedermann/nextcloud/deck/ui/card/details/CardDetailsFragment.java
@@ -15,9 +15,12 @@ import android.widget.LinearLayout;
 
 import androidx.annotation.NonNull;
 import androidx.annotation.Nullable;
+import androidx.annotation.Px;
 import androidx.appcompat.app.AppCompatActivity;
 import androidx.core.graphics.ColorUtils;
 import androidx.core.graphics.drawable.DrawableCompat;
+import androidx.fragment.app.Fragment;
+import androidx.lifecycle.ViewModelProvider;
 
 import com.google.android.material.chip.Chip;
 import com.google.android.material.snackbar.Snackbar;
@@ -39,55 +42,40 @@ import java.util.Locale;
 import it.niedermann.nextcloud.deck.DeckLog;
 import it.niedermann.nextcloud.deck.R;
 import it.niedermann.nextcloud.deck.databinding.FragmentCardEditTabDetailsBinding;
-import it.niedermann.nextcloud.deck.model.Card;
 import it.niedermann.nextcloud.deck.model.Label;
 import it.niedermann.nextcloud.deck.model.User;
-import it.niedermann.nextcloud.deck.model.full.FullCard;
 import it.niedermann.nextcloud.deck.persistence.sync.SyncManager;
 import it.niedermann.nextcloud.deck.ui.branding.BrandedDatePickerDialog;
 import it.niedermann.nextcloud.deck.ui.branding.BrandedFragment;
 import it.niedermann.nextcloud.deck.ui.branding.BrandedTimePickerDialog;
+import it.niedermann.nextcloud.deck.ui.card.EditCardViewModel;
 import it.niedermann.nextcloud.deck.ui.card.LabelAutoCompleteAdapter;
 import it.niedermann.nextcloud.deck.ui.card.UserAutoCompleteAdapter;
 import it.niedermann.nextcloud.deck.util.ColorUtil;
-import it.niedermann.nextcloud.deck.util.DimensionUtil;
 import it.niedermann.nextcloud.deck.util.MarkDownUtil;
 import it.niedermann.nextcloud.deck.util.ViewUtil;
 
+import static android.text.format.DateFormat.getDateFormat;
 import static it.niedermann.nextcloud.deck.persistence.sync.adapters.db.util.LiveDataHelper.observeOnce;
 import static it.niedermann.nextcloud.deck.ui.branding.BrandedActivity.applyBrandToEditText;
-import static it.niedermann.nextcloud.deck.ui.card.CardAdapter.BUNDLE_KEY_ACCOUNT_ID;
-import static it.niedermann.nextcloud.deck.ui.card.CardAdapter.BUNDLE_KEY_BOARD_ID;
-import static it.niedermann.nextcloud.deck.ui.card.CardAdapter.BUNDLE_KEY_CAN_EDIT;
-import static it.niedermann.nextcloud.deck.ui.card.CardAdapter.BUNDLE_KEY_LOCAL_ID;
-import static it.niedermann.nextcloud.deck.ui.card.CardAdapter.NO_LOCAL_ID;
+import static it.niedermann.nextcloud.deck.util.DimensionUtil.dpToPx;
 
 public class CardDetailsFragment extends BrandedFragment implements OnDateSetListener, OnTimeSetListener {
 
     private FragmentCardEditTabDetailsBinding binding;
-
-    private boolean canEdit = false;
-    private FullCard fullCard;
+    private EditCardViewModel viewModel;
     private SyncManager syncManager;
     private DateFormat dateFormat;
     private DateFormat dueTime = new SimpleDateFormat("HH:mm", Locale.ROOT);
     private String baseUrl;
+    @Px
     private int avatarSize;
     private LinearLayout.LayoutParams avatarLayoutParams;
-    private CardDetailsListener cardDetailsListener;
     private AppCompatActivity activity;
 
-    public CardDetailsFragment() {
-    }
-
     @Override
     public void onAttach(@NonNull Context context) {
         super.onAttach(context);
-        if (context instanceof CardDetailsListener) {
-            this.cardDetailsListener = (CardDetailsListener) context;
-        } else {
-            throw new ClassCastException("Caller must implement " + CardDetailsListener.class.getCanonicalName());
-        }
         if (context instanceof AppCompatActivity) {
             this.activity = (AppCompatActivity) context;
         } else {
@@ -95,17 +83,8 @@ public class CardDetailsFragment extends BrandedFragment implements OnDateSetLis
         }
     }
 
-    public static CardDetailsFragment newInstance(long accountId, long localId, long boardId, boolean canEdit) {
-        Bundle bundle = new Bundle();
-        bundle.putLong(BUNDLE_KEY_ACCOUNT_ID, accountId);
-        bundle.putLong(BUNDLE_KEY_BOARD_ID, boardId);
-        bundle.putLong(BUNDLE_KEY_LOCAL_ID, localId);
-        bundle.putBoolean(BUNDLE_KEY_CAN_EDIT, canEdit);
-
-        CardDetailsFragment fragment = new CardDetailsFragment();
-        fragment.setArguments(bundle);
-
-        return fragment;
+    public static Fragment newInstance() {
+        return new CardDetailsFragment();
     }
 
     @Override
@@ -113,53 +92,58 @@ public class CardDetailsFragment extends BrandedFragment implements OnDateSetLis
                              ViewGroup container,
                              Bundle savedInstanceState) {
         binding = FragmentCardEditTabDetailsBinding.inflate(inflater, container, false);
-        dateFormat = android.text.format.DateFormat.getDateFormat(activity);
-
-        Bundle args = getArguments();
-        if (args != null) {
-            long accountId = args.getLong(BUNDLE_KEY_ACCOUNT_ID);
-            long localId = args.getLong(BUNDLE_KEY_LOCAL_ID);
-            long boardId = args.getLong(BUNDLE_KEY_BOARD_ID);
-            if (args.containsKey(BUNDLE_KEY_CAN_EDIT)) {
-                this.canEdit = args.getBoolean(BUNDLE_KEY_CAN_EDIT);
-            }
+        dateFormat = getDateFormat(activity);
 
-            syncManager = new SyncManager(activity);
-
-            if (NO_LOCAL_ID.equals(localId)) {
-                fullCard = new FullCard();
-                fullCard.setCard(new Card());
-                setupView(accountId, boardId, canEdit);
-            } else {
-                observeOnce(syncManager.getCardByLocalId(accountId, localId), CardDetailsFragment.this, (next) -> {
-                    fullCard = next;
-                    binding.description.setText(fullCard.getCard().getDescription());
-                    setupView(accountId, boardId, canEdit);
-                });
-            }
-        }
+        viewModel = new ViewModelProvider(activity).get(EditCardViewModel.class);
+        syncManager = new SyncManager(activity);
 
-        avatarSize = DimensionUtil.dpToPx(requireContext(), R.dimen.avatar_size);
+        avatarSize = dpToPx(requireContext(), R.dimen.avatar_size);
         avatarLayoutParams = new LinearLayout.LayoutParams(avatarSize, avatarSize);
-        avatarLayoutParams.setMargins(0, 0, requireContext().getResources().getDimensionPixelSize(R.dimen.spacer_1x), 0);
+        avatarLayoutParams.setMargins(0, 0, dpToPx(requireContext(), R.dimen.spacer_1x), 0);
 
         try {
             baseUrl = syncManager.getServerUrl();
         } catch (NextcloudFilesAppAccountNotFoundException | NoCurrentAccountSelectedException e) {
             DeckLog.logError(e);
         }
-        return binding.getRoot();
-    }
 
-    private void setupView(long accountId, long boardId, boolean canEdit) {
-        setupPeople(accountId, boardId);
-        setupLabels(accountId, boardId, canEdit);
+        setupPeople();
+        setupLabels();
         setupDueDate();
         setupDescription();
+        binding.description.setText(viewModel.getFullCard().getCard().getDescription());
+
+        return binding.getRoot();
+    }
+
+
+    @Override
+    public void onResume() {
+        super.onResume();
+
+        // https://github.com/wdullaer/MaterialDateTimePicker#why-are-my-callbacks-lost-when-the-device-changes-orientation
+        final DatePickerDialog dpd = (DatePickerDialog) getChildFragmentManager().findFragmentByTag(BrandedDatePickerDialog.class.getCanonicalName());
+        final TimePickerDialog tpd = (TimePickerDialog) getChildFragmentManager().findFragmentByTag(BrandedTimePickerDialog.class.getCanonicalName());
+        if (tpd != null) tpd.setOnTimeSetListener(this);
+        if (dpd != null) dpd.setOnDateSetListener(this);
+    }
+
+    @Override
+    public void onPause() {
+        super.onPause();
+    }
+
+    @Override
+    public void applyBrand(int mainColor, int textColor) {
+        applyBrandToEditText(mainColor, textColor, binding.labels);
+        applyBrandToEditText(mainColor, textColor, binding.dueDateDate);
+        applyBrandToEditText(mainColor, textColor, binding.dueDateTime);
+        applyBrandToEditText(mainColor, textColor, binding.people);
+        applyBrandToEditText(mainColor, textColor, binding.description);
     }
 
     private void setupDescription() {
-        if (canEdit) {
+        if (viewModel.canEdit()) {
             MarkdownProcessor markdownProcessor = new MarkdownProcessor(requireContext());
             markdownProcessor.config(MarkDownUtil.getMarkDownConfiguration(binding.description.getContext()).build());
             markdownProcessor.factory(EditFactory.create());
@@ -167,9 +151,8 @@ public class CardDetailsFragment extends BrandedFragment implements OnDateSetLis
             binding.description.addTextChangedListener(new TextWatcher() {
                 @Override
                 public void onTextChanged(CharSequence s, int start, int before, int count) {
-                    if (fullCard != null) {
-                        cardDetailsListener.onDescriptionChanged(binding.description.getText().toString());
-                        fullCard.getCard().setDescription(binding.description.getText().toString());
+                    if (viewModel.getFullCard() != null) {
+                        viewModel.getFullCard().getCard().setDescription(binding.description.getText().toString());
                     }
                 }
 
@@ -225,9 +208,9 @@ public class CardDetailsFragment extends BrandedFragment implements OnDateSetLis
     }
 
     private void setupDueDate() {
-        if (this.fullCard.getCard().getDueDate() != null) {
-            binding.dueDateDate.setText(dateFormat.format(this.fullCard.getCard().getDueDate()));
-            binding.dueDateTime.setText(dueTime.format(this.fullCard.getCard().getDueDate()));
+        if (this.viewModel.getFullCard().getCard().getDueDate() != null) {
+            binding.dueDateDate.setText(dateFormat.format(this.viewModel.getFullCard().getCard().getDueDate()));
+            binding.dueDateTime.setText(dueTime.format(this.viewModel.getFullCard().getCard().getDueDate()));
             binding.clearDueDate.setVisibility(View.VISIBLE);
         } else {
             binding.clearDueDate.setVisibility(View.GONE);
@@ -235,29 +218,28 @@ public class CardDetailsFragment extends BrandedFragment implements OnDateSetLis
             binding.dueDateTime.setText(null);
         }
 
-        if (canEdit) {
+        if (viewModel.canEdit()) {
 
             binding.dueDateDate.setOnClickListener(v -> {
-                if (fullCard != null && fullCard.getCard() != null) {
-                    createDatePickerDialogFromDate(this, fullCard.getCard().getDueDate()).show(getChildFragmentManager(), BrandedDatePickerDialog.class.getCanonicalName());
+                if (viewModel.getFullCard() != null && viewModel.getFullCard().getCard() != null) {
+                    createDatePickerDialogFromDate(this, viewModel.getFullCard().getCard().getDueDate()).show(getChildFragmentManager(), BrandedDatePickerDialog.class.getCanonicalName());
                 } else {
                     createDatePickerDialogFromDate(this, null).show(getChildFragmentManager(), BrandedDatePickerDialog.class.getCanonicalName());
                 }
             });
 
             binding.dueDateTime.setOnClickListener(v -> {
-                if (fullCard != null && fullCard.getCard() != null) {
-                    createTimePickerDialogFromDate(this, fullCard.getCard().getDueDate()).show(getChildFragmentManager(), BrandedTimePickerDialog.class.getCanonicalName());
+                if (viewModel.getFullCard() != null && viewModel.getFullCard().getCard() != null) {
+                    createTimePickerDialogFromDate(this, viewModel.getFullCard().getCard().getDueDate()).show(getChildFragmentManager(), BrandedTimePickerDialog.class.getCanonicalName());
                 } else {
                     createTimePickerDialogFromDate(this, null).show(getChildFragmentManager(), BrandedTimePickerDialog.class.getCanonicalName());
                 }
             });
 
             binding.clearDueDate.setOnClickListener(v -> {
-                cardDetailsListener.onDueDateChanged(null);
                 binding.dueDateDate.setText(null);
                 binding.dueDateTime.setText(null);
-                fullCard.getCard().setDueDate(null);
+                viewModel.getFullCard().getCard().setDueDate(null);
                 binding.clearDueDate.setVisibility(View.GONE);
             });
         } else {
@@ -267,10 +249,12 @@ public class CardDetailsFragment extends BrandedFragment implements OnDateSetLis
         }
     }
 
-    private void setupLabels(long accountId, long boardId, boolean canEdit) {
+    private void setupLabels() {
+        long accountId = viewModel.getAccountId();
+        long boardId = viewModel.getBoardId();
         binding.labelsGroup.removeAllViews();
-        if (canEdit) {
-            Long localCardId = fullCard.getCard().getLocalId();
+        if (viewModel.canEdit()) {
+            Long localCardId = viewModel.getFullCard().getCard().getLocalId();
             localCardId = localCardId == null ? -1 : localCardId;
             binding.labels.setAdapter(new LabelAutoCompleteAdapter(activity, accountId, boardId, localCardId));
             binding.labels.setOnItemClickListener((adapterView, view, position, id) -> {
@@ -283,13 +267,13 @@ public class CardDetailsFragment extends BrandedFragment implements OnDateSetLis
                     observeOnce(syncManager.createLabel(accountId, newLabel, boardId), CardDetailsFragment.this, createdLabel -> {
                         newLabel.setLocalId(createdLabel.getLocalId());
                         ((LabelAutoCompleteAdapter) binding.labels.getAdapter()).exclude(createdLabel);
-                        cardDetailsListener.onLabelAdded(createdLabel);
+                        viewModel.getFullCard().getLabels().add(createdLabel);
                         binding.labelsGroup.addView(createChipFromLabel(newLabel));
                         binding.labelsGroup.setVisibility(View.VISIBLE);
                     });
                 } else {
                     ((LabelAutoCompleteAdapter) binding.labels.getAdapter()).exclude(label);
-                    cardDetailsListener.onLabelAdded(label);
+                    viewModel.getFullCard().getLabels().add(label);
                     binding.labelsGroup.addView(createChipFromLabel(label));
                     binding.labelsGroup.setVisibility(View.VISIBLE);
                 }
@@ -299,8 +283,8 @@ public class CardDetailsFragment extends BrandedFragment implements OnDateSetLis
         } else {
             binding.labels.setEnabled(false);
         }
-        if (fullCard.getLabels() != null && fullCard.getLabels().size() > 0) {
-            for (Label label : fullCard.getLabels()) {
+        if (viewModel.getFullCard().getLabels() != null && viewModel.getFullCard().getLabels().size() > 0) {
+            for (Label label : viewModel.getFullCard().getLabels()) {
                 binding.labelsGroup.addView(createChipFromLabel(label));
             }
             binding.labelsGroup.setVisibility(View.VISIBLE);
@@ -313,12 +297,12 @@ public class CardDetailsFragment extends BrandedFragment implements OnDateSetLis
     private Chip createChipFromLabel(Label label) {
         final Chip chip = new Chip(activity);
         chip.setText(label.getTitle());
-        if (canEdit) {
+        if (viewModel.canEdit()) {
             chip.setCloseIcon(getResources().getDrawable(R.drawable.ic_close_circle_grey600));
             chip.setCloseIconVisible(true);
             chip.setOnCloseIconClickListener(v -> {
                 binding.labelsGroup.removeView(chip);
-                cardDetailsListener.onLabelRemoved(label);
+                viewModel.getFullCard().getLabels().remove(label);
                 ((LabelAutoCompleteAdapter) binding.labels.getAdapter()).exclude(label);
             });
         }
@@ -338,14 +322,14 @@ public class CardDetailsFragment extends BrandedFragment implements OnDateSetLis
         return chip;
     }
 
-    private void setupPeople(long accountId, long boardId) {
-        if (canEdit) {
-            Long localCardId = fullCard.getCard().getLocalId();
+    private void setupPeople() {
+        if (viewModel.canEdit()) {
+            Long localCardId = viewModel.getFullCard().getCard().getLocalId();
             localCardId = localCardId == null ? -1 : localCardId;
-            binding.people.setAdapter(new UserAutoCompleteAdapter(activity, accountId, boardId, localCardId));
+            binding.people.setAdapter(new UserAutoCompleteAdapter(activity, viewModel.getAccountId(), viewModel.getBoardId(), localCardId));
             binding.people.setOnItemClickListener((adapterView, view, position, id) -> {
                 User user = (User) adapterView.getItemAtPosition(position);
-                cardDetailsListener.onUserAdded(user);
+                viewModel.getFullCard().getAssignedUsers().add(user);
                 ((UserAutoCompleteAdapter) binding.people.getAdapter()).exclude(user);
                 if (baseUrl != null) {
                     addAvatar(baseUrl, user);
@@ -353,10 +337,10 @@ public class CardDetailsFragment extends BrandedFragment implements OnDateSetLis
                 binding.people.setText("");
             });
 
-            if (this.fullCard.getAssignedUsers() != null) {
+            if (this.viewModel.getFullCard().getAssignedUsers() != null) {
                 binding.peopleList.removeAllViews();
                 if (baseUrl != null) {
-                    for (User user : this.fullCard.getAssignedUsers()) {
+                    for (User user : this.viewModel.getFullCard().getAssignedUsers()) {
                         addAvatar(baseUrl, user);
                     }
                 }
@@ -369,16 +353,16 @@ public class CardDetailsFragment extends BrandedFragment implements OnDateSetLis
     private void addAvatar(String baseUrl, User user) {
         ImageView avatar = new ImageView(activity);
         avatar.setLayoutParams(avatarLayoutParams);
-        if (canEdit) {
+        if (viewModel.canEdit()) {
             avatar.setOnClickListener(v -> {
-                cardDetailsListener.onUserRemoved(user);
+                viewModel.getFullCard().getAssignedUsers().remove(user);
                 binding.peopleList.removeView(avatar);
                 ((UserAutoCompleteAdapter) binding.people.getAdapter()).include(user);
                 Snackbar.make(
                         requireView(), getString(R.string.unassigned_user, user.getDisplayname()),
                         Snackbar.LENGTH_LONG)
                         .setAction(R.string.simple_undo, v1 -> {
-                            cardDetailsListener.onUserAdded(user);
+                            viewModel.getFullCard().getAssignedUsers().add(user);
                             ((UserAutoCompleteAdapter) binding.people.getAdapter()).exclude(user);
                             addAvatar(baseUrl, user);
                         }).show();
@@ -390,50 +374,24 @@ public class CardDetailsFragment extends BrandedFragment implements OnDateSetLis
     }
 
     @Override
-    public void onResume() {
-        super.onResume();
-
-        // https://github.com/wdullaer/MaterialDateTimePicker#why-are-my-callbacks-lost-when-the-device-changes-orientation
-        final DatePickerDialog dpd = (DatePickerDialog) getChildFragmentManager().findFragmentByTag(BrandedDatePickerDialog.class.getCanonicalName());
-        final TimePickerDialog tpd = (TimePickerDialog) getChildFragmentManager().findFragmentByTag(BrandedTimePickerDialog.class.getCanonicalName());
-        if (tpd != null) tpd.setOnTimeSetListener(this);
-        if (dpd != null) dpd.setOnDateSetListener(this);
-    }
-
-    @Override
-    public void onPause() {
-        super.onPause();
-    }
-
-    @Override
-    public void applyBrand(int mainColor, int textColor) {
-        applyBrandToEditText(mainColor, textColor, binding.labels);
-        applyBrandToEditText(mainColor, textColor, binding.dueDateDate);
-        applyBrandToEditText(mainColor, textColor, binding.dueDateTime);
-        applyBrandToEditText(mainColor, textColor, binding.people);
-        applyBrandToEditText(mainColor, textColor, binding.description);
-    }
-
-    @Override
     public void onDateSet(com.wdullaer.materialdatetimepicker.date.DatePickerDialog view, int year, int monthOfYear, int dayOfMonth) {
         Calendar c = Calendar.getInstance();
         int hourOfDay;
         int minute;
 
         if (binding.dueDateTime.getText() != null && binding.dueDateTime.length() > 0) {
-            hourOfDay = this.fullCard.getCard().getDueDate().getHours();
-            minute = this.fullCard.getCard().getDueDate().getMinutes();
+            hourOfDay = this.viewModel.getFullCard().getCard().getDueDate().getHours();
+            minute = this.viewModel.getFullCard().getCard().getDueDate().getMinutes();
         } else {
             hourOfDay = 0;
             minute = 0;
         }
 
         c.set(year, monthOfYear, dayOfMonth, hourOfDay, minute);
-        this.fullCard.getCard().setDueDate(c.getTime());
+        this.viewModel.getFullCard().getCard().setDueDate(c.getTime());
         binding.dueDateDate.setText(dateFormat.format(c.getTime()));
-        cardDetailsListener.onDueDateChanged(fullCard.card.getDueDate());
 
-        if (this.fullCard.getCard().getDueDate() == null || this.fullCard.getCard().getDueDate().getTime() == 0) {
+        if (this.viewModel.getFullCard().getCard().getDueDate() == null || this.viewModel.getFullCard().getCard().getDueDate().getTime() == 0) {
             binding.clearDueDate.setVisibility(View.GONE);
         } else {
             binding.clearDueDate.setVisibility(View.VISIBLE);
@@ -442,14 +400,13 @@ public class CardDetailsFragment extends BrandedFragment implements OnDateSetLis
 
     @Override
     public void onTimeSet(com.wdullaer.materialdatetimepicker.time.TimePickerDialog view, int hourOfDay, int minute, int second) {
-        if (this.fullCard.getCard().getDueDate() == null) {
-            this.fullCard.getCard().setDueDate(new Date());
+        if (this.viewModel.getFullCard().getCard().getDueDate() == null) {
+            this.viewModel.getFullCard().getCard().setDueDate(new Date());
         }
-        this.fullCard.getCard().getDueDate().setHours(hourOfDay);
-        this.fullCard.getCard().getDueDate().setMinutes(minute);
-        binding.dueDateTime.setText(dueTime.format(this.fullCard.getCard().getDueDate().getTime()));
-        cardDetailsListener.onDueDateChanged(fullCard.card.getDueDate());
-        if (this.fullCard.getCard().getDueDate() == null || this.fullCard.getCard().getDueDate().getTime() == 0) {
+        this.viewModel.getFullCard().getCard().getDueDate().setHours(hourOfDay);
+        this.viewModel.getFullCard().getCard().getDueDate().setMinutes(minute);
+        binding.dueDateTime.setText(dueTime.format(this.viewModel.getFullCard().getCard().getDueDate().getTime()));
+        if (this.viewModel.getFullCard().getCard().getDueDate() == null || this.viewModel.getFullCard().getCard().getDueDate().getTime() == 0) {
             binding.clearDueDate.setVisibility(View.GONE);
         } else {
             binding.clearDueDate.setVisibility(View.VISIBLE);
diff --git a/app/src/main/java/it/niedermann/nextcloud/deck/util/DimensionUtil.java b/app/src/main/java/it/niedermann/nextcloud/deck/util/DimensionUtil.java
index 19c01a06f..6ff22eace 100644
--- a/app/src/main/java/it/niedermann/nextcloud/deck/util/DimensionUtil.java
+++ b/app/src/main/java/it/niedermann/nextcloud/deck/util/DimensionUtil.java
@@ -4,11 +4,13 @@ import android.content.Context;
 
 import androidx.annotation.DimenRes;
 import androidx.annotation.NonNull;
+import androidx.annotation.Px;
 
 public final class DimensionUtil {
     private DimensionUtil() {
     }
 
+    @Px
     public static int dpToPx(@NonNull Context context, @DimenRes int resource) {
         return context.getResources().getDimensionPixelSize(resource);
     }