Add the ability to re-order sticker packs.

app/src/main/java/org/thoughtcrime/securesms/stickers/StickerManagementActivity.java

@@ -5,6 +5,7 @@ import android.content.Context;
 import android.content.Intent;
 import android.os.Bundle;
 import androidx.annotation.NonNull;
+import androidx.recyclerview.widget.ItemTouchHelper;
 import androidx.recyclerview.widget.LinearLayoutManager;
 import androidx.recyclerview.widget.RecyclerView;
 import android.view.MenuItem;
@@ -12,6 +13,7 @@ import android.view.MenuItem;
 import org.thoughtcrime.securesms.PassphraseRequiredActionBarActivity;
 import org.thoughtcrime.securesms.R;
 import org.thoughtcrime.securesms.ShareActivity;
+import org.thoughtcrime.securesms.logging.Log;
 import org.thoughtcrime.securesms.mms.GlideApp;
 import org.thoughtcrime.securesms.util.DynamicTheme;
 
@@ -22,9 +24,8 @@ public final class StickerManagementActivity extends PassphraseRequiredActionBar
 
   private final DynamicTheme dynamicTheme = new DynamicTheme();
 
-  private RecyclerView             list;
-  private StickerManagementAdapter adapter;
-
+  private RecyclerView               list;
+  private StickerManagementAdapter   adapter;
   private StickerManagementViewModel viewModel;
 
   public static Intent getIntent(@NonNull Context context) {
@@ -96,6 +97,7 @@ public final class StickerManagementActivity extends PassphraseRequiredActionBar
 
     list.setLayoutManager(new LinearLayoutManager(this));
     list.setAdapter(adapter);
+    new ItemTouchHelper(new StickerManagementItemTouchHelper(new ItemTouchCallback())).attachToRecyclerView(list);
   }
 
   private void initToolbar() {
@@ -114,4 +116,21 @@ public final class StickerManagementActivity extends PassphraseRequiredActionBar
       adapter.setPackLists(packResult.getInstalledPacks(), packResult.getAvailablePacks(), packResult.getBlessedPacks());
     });
   }
+
+  private class ItemTouchCallback implements StickerManagementItemTouchHelper.Callback {
+    @Override
+    public boolean onMove(int start, int end) {
+      return adapter.onMove(start, end);
+    }
+
+    @Override
+    public boolean isMovable(int position) {
+      return adapter.isMovable(position);
+    }
+
+    @Override
+    public void onMoveCommitted() {
+      viewModel.onOrderChanged(adapter.getInstalledPacksInOrder());
+    }
+  }
 }

app/src/main/java/org/thoughtcrime/securesms/stickers/StickerManagementAdapter.java

@@ -29,6 +29,7 @@ import org.thoughtcrime.securesms.util.adapter.SectionedRecyclerViewAdapter;
 import org.thoughtcrime.securesms.util.adapter.StableIdGenerator;
 
 import java.util.ArrayList;
+import java.util.Collections;
 import java.util.List;
 
 final class StickerManagementAdapter extends SectionedRecyclerViewAdapter<String, StickerManagementAdapter.StickerSection> {
@@ -93,6 +94,30 @@ final class StickerManagementAdapter extends SectionedRecyclerViewAdapter<String
     }
   }
 
+  boolean onMove(int start, int end) {
+    StickerSection installed = sections.get(0);
+
+    if (!installed.isContent(start)) {
+      return false;
+    }
+
+    if (!installed.isContent(end)) {
+      return false;
+    }
+
+    installed.swap(start, end);
+    notifyItemMoved(start, end);
+    return true;
+  }
+
+  boolean isMovable(int position) {
+    return sections.get(0).isContent(position);
+  }
+
+  @NonNull List<StickerPackRecord> getInstalledPacksInOrder() {
+    return sections.get(0).records;
+  }
+
   void setPackLists(@NonNull List<StickerPackRecord> installedPacks,
                     @NonNull List<StickerPackRecord> availablePacks,
                     @NonNull List<StickerPackRecord> blessedPacks)
@@ -185,6 +210,21 @@ final class StickerManagementAdapter extends SectionedRecyclerViewAdapter<String
         ((StickerViewHolder) viewHolder).bind(glideRequests, eventListener, records.get(localPosition - 1), localPosition == records.size());
       }
     }
+
+    void swap(int start, int end) {
+      int localStart = getLocalPosition(start) - 1;
+      int localEnd   = getLocalPosition(end) - 1;
+
+      if (localStart < localEnd) {
+        for (int i = localStart; i < localEnd; i++) {
+          Collections.swap(records, i, i + 1);
+        }
+      } else {
+        for (int i = localStart; i > localEnd; i--) {
+          Collections.swap(records, i, i - 1);
+        }
+      }
+    }
   }
 
   static class StickerViewHolder extends RecyclerView.ViewHolder {

app/src/main/java/org/thoughtcrime/securesms/stickers/StickerManagementItemTouchHelper.java

@@ -0,0 +1,58 @@
+package org.thoughtcrime.securesms.stickers;
+
+import androidx.annotation.NonNull;
+import androidx.recyclerview.widget.ItemTouchHelper;
+import androidx.recyclerview.widget.RecyclerView;
+
+public class StickerManagementItemTouchHelper extends ItemTouchHelper.Callback {
+
+  private final Callback callback;
+
+  public StickerManagementItemTouchHelper(Callback callback) {
+    this.callback = callback;
+  }
+
+  @Override
+  public boolean isLongPressDragEnabled() {
+    return true;
+  }
+
+  @Override
+  public boolean isItemViewSwipeEnabled() {
+    return false;
+  }
+
+  @Override
+  public int getMovementFlags(@NonNull RecyclerView recyclerView, @NonNull RecyclerView.ViewHolder viewHolder) {
+    if (callback.isMovable(viewHolder.getAdapterPosition())) {
+      int dragFlags = ItemTouchHelper.UP | ItemTouchHelper.DOWN;
+      return makeMovementFlags(dragFlags, 0);
+    } else {
+      return 0;
+    }
+  }
+
+  @Override
+  public boolean onMove(@NonNull RecyclerView recyclerView, @NonNull RecyclerView.ViewHolder viewHolder, @NonNull RecyclerView.ViewHolder target) {
+    return callback.onMove(viewHolder.getAdapterPosition(), target.getAdapterPosition());
+  }
+
+  @Override
+  public void clearView(@NonNull RecyclerView recyclerView, @NonNull RecyclerView.ViewHolder viewHolder) {
+    super.clearView(recyclerView, viewHolder);
+    callback.onMoveCommitted();
+  }
+
+  @Override
+  public void onSwiped(@NonNull RecyclerView.ViewHolder viewHolder, int direction) {
+  }
+
+  public interface Callback {
+    /**
+     * @return True if both the start and end positions are valid, and therefore the move will occur.
+     */
+    boolean onMove(int start, int end);
+    void onMoveCommitted();
+    boolean isMovable(int position);
+  }
+}

app/src/main/java/org/thoughtcrime/securesms/stickers/StickerManagementRepository.java

@@ -100,6 +100,12 @@ final class StickerManagementRepository {
     });
   }
 
+  void setPackOrder(@NonNull List<StickerPackRecord> packsInOrder) {
+    SignalExecutors.SERIAL.execute(() -> {
+      stickerDatabase.updatePackOrder(packsInOrder);
+    });
+  }
+
   static class PackResult {
 
     private final List<StickerPackRecord> installedPacks;

app/src/main/java/org/thoughtcrime/securesms/stickers/StickerManagementViewModel.java

@@ -10,8 +10,12 @@ import android.os.Handler;
 import androidx.annotation.NonNull;
 
 import org.thoughtcrime.securesms.database.DatabaseContentProviders;
+import org.thoughtcrime.securesms.database.model.StickerPackRecord;
+import org.thoughtcrime.securesms.database.model.StickerRecord;
 import org.thoughtcrime.securesms.stickers.StickerManagementRepository.PackResult;
 
+import java.util.List;
+
 final class StickerManagementViewModel extends ViewModel {
 
   private final Application                 application;
@@ -56,6 +60,10 @@ final class StickerManagementViewModel extends ViewModel {
     repository.installStickerPack(packId, packKey, false);
   }
 
+  void onOrderChanged(List<StickerPackRecord> packsInOrder) {
+    repository.setPackOrder(packsInOrder);
+  }
+
   @Override
   protected void onCleared() {
     application.getContentResolver().unregisterContentObserver(observer);