1 files changed, 159 insertions, 0 deletions
diff --git a/ui/src/main/java/com/wireguard/android/databinding/ObservableKeyedRecyclerViewAdapter.java b/ui/src/main/java/com/wireguard/android/databinding/ObservableKeyedRecyclerViewAdapter.java
new file mode 100644
index 00000000..8b40dd91
--- /dev/null
+++ b/ui/src/main/java/com/wireguard/android/databinding/ObservableKeyedRecyclerViewAdapter.java
@@ -0,0 +1,159 @@
+/*
+ * Copyright © 2017-2019 WireGuard LLC. All Rights Reserved.
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+package com.wireguard.android.databinding;
+
+import android.content.Context;
+import androidx.databinding.DataBindingUtil;
+import androidx.databinding.ObservableList;
+import androidx.databinding.ViewDataBinding;
+import androidx.annotation.Nullable;
+import androidx.recyclerview.widget.RecyclerView;
+import androidx.recyclerview.widget.RecyclerView.Adapter;
+import android.view.LayoutInflater;
+import android.view.ViewGroup;
+
+import com.wireguard.android.BR;
+import com.wireguard.android.util.ObservableKeyedList;
+import com.wireguard.util.Keyed;
+
+import java.lang.ref.WeakReference;
+
+/**
+ * A generic {@code RecyclerView.Adapter} backed by a {@code ObservableKeyedList}.
+ */
+
+public class ObservableKeyedRecyclerViewAdapter<K, E extends Keyed<? extends K>> extends Adapter<ObservableKeyedRecyclerViewAdapter.ViewHolder> {
+
+    private final OnListChangedCallback<E> callback = new OnListChangedCallback<>(this);
+    private final int layoutId;
+    private final LayoutInflater layoutInflater;
+    @Nullable private ObservableKeyedList<K, E> list;
+    @Nullable private RowConfigurationHandler rowConfigurationHandler;
+
+    ObservableKeyedRecyclerViewAdapter(final Context context, final int layoutId,
+                                       final ObservableKeyedList<K, E> list) {
+        this.layoutId = layoutId;
+        layoutInflater = LayoutInflater.from(context);
+        setList(list);
+    }
+
+    @Nullable
+    private E getItem(final int position) {
+        if (list == null || position < 0 || position >= list.size())
+            return null;
+        return list.get(position);
+    }
+
+    @Override
+    public int getItemCount() {
+        return list != null ? list.size() : 0;
+    }
+
+    @Override
+    public long getItemId(final int position) {
+        final K key = getKey(position);
+        return key != null ? key.hashCode() : -1;
+    }
+
+    @Nullable
+    private K getKey(final int position) {
+        final E item = getItem(position);
+        return item != null ? item.getKey() : null;
+    }
+
+    @SuppressWarnings("unchecked")
+    @Override
+    public void onBindViewHolder(final ViewHolder holder, final int position) {
+        holder.binding.setVariable(BR.collection, list);
+        holder.binding.setVariable(BR.key, getKey(position));
+        holder.binding.setVariable(BR.item, getItem(position));
+        holder.binding.executePendingBindings();
+
+        if (rowConfigurationHandler != null) {
+            final E item = getItem(position);
+            if (item != null) {
+                rowConfigurationHandler.onConfigureRow(holder.binding, item, position);
+            }
+        }
+    }
+
+    @Override
+    public ViewHolder onCreateViewHolder(final ViewGroup parent, final int viewType) {
+        return new ViewHolder(DataBindingUtil.inflate(layoutInflater, layoutId, parent, false));
+    }
+
+    void setList(@Nullable final ObservableKeyedList<K, E> newList) {
+        if (list != null)
+            list.removeOnListChangedCallback(callback);
+        list = newList;
+        if (list != null) {
+            list.addOnListChangedCallback(callback);
+        }
+        notifyDataSetChanged();
+    }
+
+    void setRowConfigurationHandler(final RowConfigurationHandler rowConfigurationHandler) {
+        this.rowConfigurationHandler = rowConfigurationHandler;
+    }
+
+    public interface RowConfigurationHandler<B extends ViewDataBinding, T> {
+        void onConfigureRow(B binding, T item, int position);
+    }
+
+    private static final class OnListChangedCallback<E extends Keyed<?>>
+            extends ObservableList.OnListChangedCallback<ObservableList<E>> {
+
+        private final WeakReference<ObservableKeyedRecyclerViewAdapter<?, E>> weakAdapter;
+
+        private OnListChangedCallback(final ObservableKeyedRecyclerViewAdapter<?, E> adapter) {
+            weakAdapter = new WeakReference<>(adapter);
+        }
+
+        @Override
+        public void onChanged(final ObservableList<E> sender) {
+            final ObservableKeyedRecyclerViewAdapter adapter = weakAdapter.get();
+            if (adapter != null)
+                adapter.notifyDataSetChanged();
+            else
+                sender.removeOnListChangedCallback(this);
+        }
+
+        @Override
+        public void onItemRangeChanged(final ObservableList<E> sender, final int positionStart,
+                                       final int itemCount) {
+            onChanged(sender);
+        }
+
+        @Override
+        public void onItemRangeInserted(final ObservableList<E> sender, final int positionStart,
+                                        final int itemCount) {
+            onChanged(sender);
+        }
+
+        @Override
+        public void onItemRangeMoved(final ObservableList<E> sender, final int fromPosition,
+                                     final int toPosition, final int itemCount) {
+            onChanged(sender);
+        }
+
+        @Override
+        public void onItemRangeRemoved(final ObservableList<E> sender, final int positionStart,
+                                       final int itemCount) {
+            onChanged(sender);
+        }
+    }
+
+    public static class ViewHolder extends RecyclerView.ViewHolder {
+        final ViewDataBinding binding;
+
+        public ViewHolder(final ViewDataBinding binding) {
+            super(binding.getRoot());
+
+            this.binding = binding;
+        }
+    }
+
+}