Clean up BrowseAdapter, add title grouping

Most of the cleanup is removing code related to child expansion, which
wasn't being used anyways.
Resource updates and correct handling of content forward root node will
come in followup cls.

Bug: 122455223
Bug: 112192143
Test: Manual (GPM search for grouping)
Change-Id: Ia71acc297878a509cbb498b1ef44a4954cf8b67e

2 files changed, 48 insertions, 299 deletions

diff --git a/src/com/android/car/media/browse/BrowseAdapter.java b/src/com/android/car/media/browse/BrowseAdapter.java
index bf99610..5daf031 100644
--- a/src/com/android/car/media/browse/BrowseAdapter.java
+++ b/src/com/android/car/media/browse/BrowseAdapter.java
@@ -16,8 +16,6 @@
 
 package com.android.car.media.browse;
 
-import static java.util.stream.Collectors.toList;
-
 import android.content.Context;
 import android.util.Log;
 import android.view.LayoutInflater;
@@ -32,6 +30,7 @@ import androidx.recyclerview.widget.GridLayoutManager;
 import androidx.recyclerview.widget.ListAdapter;
 import androidx.recyclerview.widget.RecyclerView;
 
+import com.android.car.media.common.MediaConstants;
 import com.android.car.media.common.MediaItemMetadata;
 
 import java.util.ArrayList;
@@ -49,9 +48,6 @@ import java.util.function.Consumer;
  * <p>This adapter assumes that the attached {@link RecyclerView} uses a {@link GridLayoutManager},
  * as it can use both grid and list elements to produce the desired representation.
  *
- * <p> The actual strategy to group and expand media items has to be supplied by providing an
- * instance of {@link ContentForwardStrategy}.
- *
  * <p>Consumers of this adapter should use {@link #registerObserver(Observer)} to receive updates.
  */
 public class BrowseAdapter extends ListAdapter<BrowseViewData, BrowseViewHolder> implements
@@ -60,8 +56,6 @@ public class BrowseAdapter extends ListAdapter<BrowseViewData, BrowseViewHolder>
     @NonNull
     private final Context mContext;
     @NonNull
-    private final ContentForwardStrategy mCFBStrategy;
-    @NonNull
     private List<Observer> mObservers = new ArrayList<>();
     @Nullable
     private CharSequence mTitle;
@@ -86,20 +80,6 @@ public class BrowseAdapter extends ListAdapter<BrowseViewData, BrowseViewHolder>
             };
 
     /**
-     * Possible states of the adapter
-     */
-    public enum State {
-        /** Loading of this item hasn't started yet */
-        IDLE,
-        /** There is pending information before this item can be displayed */
-        LOADING,
-        /** It was not possible to load metadata for this item */
-        ERROR,
-        /** Metadata for this items has been correctly loaded */
-        LOADED
-    }
-
-    /**
      * An {@link BrowseAdapter} observer.
      */
     public static abstract class Observer {
@@ -113,13 +93,7 @@ public class BrowseAdapter extends ListAdapter<BrowseViewData, BrowseViewHolder>
         /**
          * Callback invoked when a user clicks on a browsable item.
          */
-        protected void onBrowseableItemClicked(MediaItemMetadata item) {
-        }
-
-        /**
-         * Callback invoked when a user clicks on a the "more items" button on a section.
-         */
-        protected void onMoreButtonClicked(MediaItemMetadata item) {
+        protected void onBrowsableItemClicked(MediaItemMetadata item) {
         }
 
         /**
@@ -127,51 +101,14 @@ public class BrowseAdapter extends ListAdapter<BrowseViewData, BrowseViewHolder>
          */
         protected void onTitleClicked() {
         }
-
-    }
-
-    /**
-     * Represents the loading state of children of a single {@link MediaItemMetadata} in the {@link
-     * BrowseAdapter}
-     */
-    private class MediaItemState {
-        /**
-         * {@link com.android.car.media.common.MediaItemMetadata} whose children are being loaded
-         */
-        final MediaItemMetadata mItem;
-        /** Playable children of the given item */
-        List<MediaItemMetadata> mPlayableChildren = new ArrayList<>();
-        /** Browsable children of the given item */
-        List<MediaItemMetadata> mBrowsableChildren = new ArrayList<>();
-
-        MediaItemState(MediaItemMetadata item) {
-            mItem = item;
-        }
-
-        void setChildren(List<MediaItemMetadata> children) {
-            mPlayableChildren.clear();
-            mBrowsableChildren.clear();
-            for (MediaItemMetadata child : children) {
-                if (child.isBrowsable()) {
-                    // Browsable items could also be playable
-                    mBrowsableChildren.add(child);
-                } else if (child.isPlayable()) {
-                    mPlayableChildren.add(child);
-                }
-            }
-        }
     }
 
     /**
      * Creates a {@link BrowseAdapter} that displays the children of the given media tree node.
-     *
-     * @param strategy a {@link ContentForwardStrategy} that would determine which items would be
-     *                 expanded and how.
      */
-    public BrowseAdapter(@NonNull Context context, @NonNull ContentForwardStrategy strategy) {
+    public BrowseAdapter(@NonNull Context context) {
         super(DIFF_CALLBACK);
         mContext = context;
-        mCFBStrategy = strategy;
     }
 
     /**
@@ -243,12 +180,11 @@ public class BrowseAdapter extends ListAdapter<BrowseViewData, BrowseViewHolder>
     public void submitItems(@Nullable MediaItemMetadata parentItem,
             @Nullable List<MediaItemMetadata> children) {
         mParentMediaItem = parentItem;
-        List<MediaItemState> mediaItemStates =
-                children == null ? Collections.emptyList()
-                        : children.stream()
-                                .map(MediaItemState::new)
-                                .collect(toList());
-        submitList(generateViewData(mediaItemStates));
+        if (children == null) {
+            submitList(Collections.emptyList());
+            return;
+        }
+        submitList(generateViewData(children));
     }
 
     private void notify(Consumer<Observer> notification) {
@@ -277,39 +213,12 @@ public class BrowseAdapter extends ListAdapter<BrowseViewData, BrowseViewHolder>
             result.add(new BrowseViewData(item, viewType, listener));
         }
 
-        void addItems(List<MediaItemMetadata> items, BrowseItemViewType viewType, int maxRows) {
-            int spanSize = viewType.getSpanSize(mMaxSpanSize);
-            int maxChildren = maxRows * (mMaxSpanSize / spanSize);
-            result.addAll(items.stream()
-                    .limit(maxChildren)
-                    .map(item -> {
-                        Consumer<Observer> notification =
-                                item.isBrowsable()
-                                        ? observer -> observer.onBrowseableItemClicked(item)
-                                        : observer -> observer.onPlayableItemClicked(item);
-                        return new BrowseViewData(item, viewType, view ->
-                                BrowseAdapter.this.notify(notification));
-                    })
-                    .collect(toList()));
-        }
-
         void addTitle(CharSequence title, Consumer<Observer> notification) {
+            if (title == null) {
+                title = "";
+            }
             result.add(new BrowseViewData(title, BrowseItemViewType.HEADER,
                     view -> BrowseAdapter.this.notify(notification)));
-
-        }
-
-        void addBrowseBlock(MediaItemMetadata header,
-                List<MediaItemMetadata> items, BrowseItemViewType viewType, int maxChildren,
-                boolean showHeader, boolean showMoreFooter) {
-            if (showHeader) {
-                addItem(header, BrowseItemViewType.HEADER, null);
-            }
-            addItems(items, viewType, maxChildren);
-            if (showMoreFooter) {
-                addItem(header, BrowseItemViewType.MORE_FOOTER,
-                        observer -> observer.onMoreButtonClicked(header));
-            }
         }
 
         List<BrowseViewData> build() {
@@ -322,27 +231,16 @@ public class BrowseAdapter extends ListAdapter<BrowseViewData, BrowseViewHolder>
      * flickering, the flatting will stop at the first "loading" section, avoiding unnecessary
      * insertion animations during the initial data load.
      */
-    private List<BrowseViewData> generateViewData(Collection<MediaItemState> itemStates) {
+    private List<BrowseViewData> generateViewData(Collection<MediaItemMetadata> items) {
         ItemsBuilder itemsBuilder = new ItemsBuilder();
-
         if (Log.isLoggable(TAG, Log.VERBOSE)) {
             Log.v(TAG, "Generating browse view from:");
-            for (MediaItemState item : itemStates) {
+            for (MediaItemMetadata item : items) {
                 Log.v(TAG, String.format("[%s%s] '%s' (%s)",
-                        item.mItem.isBrowsable() ? "B" : " ",
-                        item.mItem.isPlayable() ? "P" : " ",
-                        item.mItem.getTitle(),
-                        item.mItem.getId()));
-                List<MediaItemMetadata> items = new ArrayList<>();
-                items.addAll(item.mBrowsableChildren);
-                items.addAll(item.mPlayableChildren);
-                for (MediaItemMetadata child : items) {
-                    Log.v(TAG, String.format("   [%s%s] '%s' (%s)",
-                            child.isBrowsable() ? "B" : " ",
-                            child.isPlayable() ? "P" : " ",
-                            child.getTitle(),
-                            child.getId()));
-                }
+                        item.isBrowsable() ? "B" : " ",
+                        item.isPlayable() ? "P" : " ",
+                        item.getTitle(),
+                        item.getId()));
             }
         }
 
@@ -350,55 +248,19 @@ public class BrowseAdapter extends ListAdapter<BrowseViewData, BrowseViewHolder>
             itemsBuilder.addTitle(mTitle, Observer::onTitleClicked);
         }
 
-        boolean containsBrowsableItems = false;
-        boolean containsPlayableItems = false;
-        for (MediaItemState itemState : itemStates) {
-            containsBrowsableItems |= itemState.mItem.isBrowsable();
-            containsPlayableItems |= itemState.mItem.isPlayable();
-        }
-
-        for (MediaItemState itemState : itemStates) {
-            MediaItemMetadata item = itemState.mItem;
-            if (containsPlayableItems && containsBrowsableItems) {
-                // If we have a mix of browsable and playable items: show them all in a list
-                itemsBuilder.addItem(item,
-                        BrowseItemViewType.PANEL_ITEM,
-                        item.isBrowsable()
-                                ? observer -> observer.onBrowseableItemClicked(item)
-                                : observer -> observer.onPlayableItemClicked(item));
-            } else if (itemState.mItem.isBrowsable()) {
-                // If we only have browsable items, check whether we should expand them or not.
-                if (!itemState.mBrowsableChildren.isEmpty()
-                        && !itemState.mPlayableChildren.isEmpty()
-                        || !mCFBStrategy.shouldBeExpanded(item)) {
-                    itemsBuilder.addItem(item,
-                            mCFBStrategy.getBrowsableViewType(mParentMediaItem), null);
-                } else if (!itemState.mPlayableChildren.isEmpty()) {
-                    itemsBuilder.addBrowseBlock(item,
-                            itemState.mPlayableChildren,
-                            mCFBStrategy.getPlayableViewType(item),
-                            mCFBStrategy.getMaxRows(item, mCFBStrategy.getPlayableViewType(item)),
-                            mCFBStrategy.includeHeader(item),
-                            mCFBStrategy.showMoreButton(item));
-                } else if (!itemState.mBrowsableChildren.isEmpty()) {
-                    itemsBuilder.addBrowseBlock(item,
-                            itemState.mBrowsableChildren,
-                            mCFBStrategy.getBrowsableViewType(item),
-                            mCFBStrategy.getMaxRows(item, mCFBStrategy.getBrowsableViewType(item)),
-                            mCFBStrategy.includeHeader(item),
-                            mCFBStrategy.showMoreButton(item));
-                } else {
-                    // We need this fallback because the local MP's children are NEVER loaded here
-                    // TODO(b/118759409) sort this out...
-                    itemsBuilder.addItem(item,
-                            mCFBStrategy.getBrowsableViewType(mParentMediaItem),
-                            observer -> observer.onBrowseableItemClicked(item));
-                }
-            } else if (item.isPlayable()) {
-                // If we only have playable items: show them as so.
-                itemsBuilder.addItem(item,
-                        mCFBStrategy.getPlayableViewType(mParentMediaItem),
+        String currentTitleGrouping = null;
+        for (MediaItemMetadata item : items) {
+            String titleGrouping = item.getTitleGrouping();
+            if (!Objects.equals(currentTitleGrouping, titleGrouping)) {
+                currentTitleGrouping = titleGrouping;
+                itemsBuilder.addTitle(titleGrouping, null);
+            }
+            if (item.isPlayable()) {
+                itemsBuilder.addItem(item, getPlayableViewType(mParentMediaItem),
                         observer -> observer.onPlayableItemClicked(item));
+            } else if (item.isBrowsable()) {
+                itemsBuilder.addItem(item, getBrowsableViewType(mParentMediaItem),
+                        observer -> observer.onBrowsableItemClicked(item));
             }
         }
 
@@ -412,4 +274,23 @@ public class BrowseAdapter extends ListAdapter<BrowseViewData, BrowseViewHolder>
                 && getItem(position).mViewType == BrowseItemViewType.PANEL_ITEM
                 && getItem(position + 1).mViewType == BrowseItemViewType.PANEL_ITEM);
     }
+
+
+    private BrowseItemViewType getBrowsableViewType(@Nullable MediaItemMetadata mediaItem) {
+        if (mediaItem == null) {
+            return BrowseItemViewType.PANEL_ITEM;
+        }
+        return (mediaItem.getBrowsableContentStyleHint()
+                == MediaConstants.CONTENT_STYLE_GRID_ITEM_HINT_VALUE)
+                ? BrowseItemViewType.PANEL_ITEM : BrowseItemViewType.LIST_ITEM;
+    }
+
+    private BrowseItemViewType getPlayableViewType(@Nullable MediaItemMetadata mediaItem) {
+        if (mediaItem == null) {
+            return BrowseItemViewType.GRID_ITEM;
+        }
+        return (mediaItem.getPlayableContentStyleHint()
+                == MediaConstants.CONTENT_STYLE_GRID_ITEM_HINT_VALUE)
+                ? BrowseItemViewType.GRID_ITEM : BrowseItemViewType.LIST_ITEM;
+    }
 }
diff --git a/src/com/android/car/media/browse/ContentForwardStrategy.java b/src/com/android/car/media/browse/ContentForwardStrategy.java
deleted file mode 100644
index 1bf44e1..0000000
--- a/src/com/android/car/media/browse/ContentForwardStrategy.java
+++ /dev/null
@@ -1,132 +0,0 @@
-/*
- * Copyright 2018 The Android Open Source Project
- *
- * 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.
- */
-
-package com.android.car.media.browse;
-
-import androidx.annotation.NonNull;
-import androidx.annotation.Nullable;
-
-import com.android.car.media.common.MediaConstants;
-import com.android.car.media.common.MediaItemMetadata;
-
-/**
- * Strategy used to group and expand media items in the {@link BrowseAdapter}
- */
-public interface ContentForwardStrategy {
-    /**
-     * @return true if a header should be included when expanding the given media item into a
-     * section. Only used if {@link #shouldBeExpanded(MediaItemMetadata)} returns true.
-     */
-    boolean includeHeader(@NonNull MediaItemMetadata mediaItem);
-
-    /**
-     * @return maximum number of rows to use when when expanding the given media item into a
-     * section. The number can be different depending on the {@link BrowseItemViewType} that will be
-     * used to represent media item children (i.e.: we might allow more rows for lists than for
-     * grids). Only used if {@link #shouldBeExpanded(MediaItemMetadata)} returns true.
-     */
-    int getMaxRows(@NonNull MediaItemMetadata mediaItem, @NonNull BrowseItemViewType viewType);
-
-    /**
-     * @return whether the given media item should be expanded or not. If not expanded, the item
-     * will be displayed according to its parent preferred view type.
-     */
-    boolean shouldBeExpanded(@NonNull MediaItemMetadata mediaItem);
-
-    /**
-     * @return view type to use to render browsable children of the given media item. Only used if
-     * {@link #shouldBeExpanded(MediaItemMetadata)} returns true.
-     */
-    BrowseItemViewType getBrowsableViewType(@Nullable MediaItemMetadata mediaItem);
-
-    /**
-     * @return view type to use to render playable children fo the given media item. Only used if
-     * {@link #shouldBeExpanded(MediaItemMetadata)} returns true.
-     */
-    BrowseItemViewType getPlayableViewType(@Nullable MediaItemMetadata mediaItem);
-
-    /**
-     * @return true if a "more" button should be displayed as a footer for a section displaying the
-     * given media item, in case that there item has more children than the ones that can be
-     * displayed according to {@link #getMaxQueueRows()}. Only used if {@link
-     * #shouldBeExpanded(MediaItemMetadata)} returns true.
-     */
-    boolean showMoreButton(@NonNull MediaItemMetadata mediaItem);
-
-    /**
-     * @return maximum number of items to show for the media queue, if one is provided.
-     */
-    int getMaxQueueRows();
-
-    /**
-     * @return view type to use to display queue items.
-     */
-    BrowseItemViewType getQueueViewType();
-
-    ContentForwardStrategy DEFAULT_STRATEGY = new ContentForwardStrategy() {
-
-        @Override
-        public boolean includeHeader(@NonNull MediaItemMetadata mediaItem) {
-            return true;
-        }
-
-        @Override
-        public int getMaxRows(@NonNull MediaItemMetadata mediaItem,
-                @NonNull BrowseItemViewType viewType) {
-            return viewType == BrowseItemViewType.GRID_ITEM ? 2 : 8;
-        }
-
-        @Override
-        public boolean shouldBeExpanded(@NonNull MediaItemMetadata mediaItem) {
-            return true;
-        }
-
-        @Override
-        public BrowseItemViewType getBrowsableViewType(@Nullable MediaItemMetadata mediaItem) {
-            if (mediaItem == null) {
-                return BrowseItemViewType.PANEL_ITEM;
-            }
-            return (mediaItem.getBrowsableContentStyleHint()
-                    == MediaConstants.CONTENT_STYLE_GRID_ITEM_HINT_VALUE)
-                    ? BrowseItemViewType.PANEL_ITEM : BrowseItemViewType.LIST_ITEM;
-        }
-
-        @Override
-        public BrowseItemViewType getPlayableViewType(@Nullable MediaItemMetadata mediaItem) {
-            if (mediaItem == null) {
-                return BrowseItemViewType.GRID_ITEM;
-            }
-            return (mediaItem.getPlayableContentStyleHint()
-                    == MediaConstants.CONTENT_STYLE_GRID_ITEM_HINT_VALUE)
-                    ? BrowseItemViewType.GRID_ITEM : BrowseItemViewType.LIST_ITEM;
-        }
-
-        @Override
-        public boolean showMoreButton(@NonNull MediaItemMetadata mediaItem) {
-            return false;
-        }
-
-        @Override
-        public int getMaxQueueRows() {
-            return 8;
-        }
-
-        @Override
-        public BrowseItemViewType getQueueViewType() {
-            return BrowseItemViewType.LIST_ITEM;
-        }
-    };
-}