add date separators

app/src/main/java/im/conversations/android/database/model/MessageAdapterItem.java

@@ -0,0 +1,15 @@
+package im.conversations.android.database.model;
+
+import java.time.Instant;
+
+public sealed interface MessageAdapterItem
+        permits MessageAdapterItem.MessageDateSeparator, MessageWithContentReactions {
+
+    final class MessageDateSeparator implements MessageAdapterItem {
+        public final Instant date;
+
+        public MessageDateSeparator(Instant date) {
+            this.date = date;
+        }
+    }
+}

app/src/main/java/im/conversations/android/database/model/MessageWithContentReactions.java

@@ -25,7 +25,8 @@ import org.jxmpp.jid.impl.JidCreate;
 import org.jxmpp.jid.parts.Resourcepart;
 import org.whispersystems.libsignal.IdentityKey;
 
-public class MessageWithContentReactions implements IndividualName, KnownSender {
+public final class MessageWithContentReactions
+        implements IndividualName, KnownSender, MessageAdapterItem {
 
     public long accountId;
 

app/src/main/java/im/conversations/android/ui/BindingAdapters.java

@@ -105,6 +105,29 @@ public class BindingAdapters {
         }
     }
 
+    @BindingAdapter("date")
+    public static void setDate(final TextView textView, final Instant instant) {
+        if (instant == null || instant.toEpochMilli() <= 0) {
+            textView.setVisibility(View.INVISIBLE);
+        } else {
+            final Context context = textView.getContext();
+            final Instant now = Instant.now();
+            if (sameYear(instant, now) || now.minus(THREE_MONTH).isBefore(instant)) {
+                textView.setVisibility(View.VISIBLE);
+                textView.setText(
+                        DateUtils.formatDateTime(
+                                context,
+                                instant.toEpochMilli(),
+                                DateUtils.FORMAT_SHOW_DATE | DateUtils.FORMAT_NO_YEAR));
+            } else {
+                textView.setVisibility(View.VISIBLE);
+                textView.setText(
+                        DateUtils.formatDateTime(
+                                context, instant.toEpochMilli(), DateUtils.FORMAT_SHOW_DATE));
+            }
+        }
+    }
+
     @BindingAdapter("android:text")
     public static void setSender(final TextView textView, final ChatOverviewItem.Sender sender) {
         if (sender == null) {

app/src/main/java/im/conversations/android/ui/adapter/MessageAdapter.java

@@ -9,32 +9,35 @@ import androidx.paging.PagingDataAdapter;
 import androidx.recyclerview.widget.DiffUtil;
 import androidx.recyclerview.widget.RecyclerView;
 import im.conversations.android.R;
+import im.conversations.android.database.model.MessageAdapterItem;
 import im.conversations.android.database.model.MessageWithContentReactions;
 import im.conversations.android.databinding.ItemMessageReceivedBinding;
 import im.conversations.android.databinding.ItemMessageSentBinding;
+import im.conversations.android.databinding.ItemMessageSeparatorBinding;
 import im.conversations.android.ui.AvatarFetcher;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
 public class MessageAdapter
-        extends PagingDataAdapter<
+        extends PagingDataAdapter<MessageAdapterItem, MessageAdapter.AbstractMessageViewHolder> {
-                MessageWithContentReactions, MessageAdapter.AbstractMessageViewHolder> {
 
     private static final int VIEW_TYPE_RECEIVED = 0;
     private static final int VIEW_TYPE_SENT = 1;
+    private static final int VIEW_TYPE_SEPARATOR = 2;
 
     private static final Logger LOGGER = LoggerFactory.getLogger(MessageAdapter.class);
 
-    public MessageAdapter(
+    public MessageAdapter(@NonNull DiffUtil.ItemCallback<MessageAdapterItem> diffCallback) {
-            @NonNull DiffUtil.ItemCallback<MessageWithContentReactions> diffCallback) {
         super(diffCallback);
     }
 
     @Override
     public int getItemViewType(final int position) {
-        final var message = getItem(position);
+        final var item = peek(position);
-        if (message != null && message.outgoing) {
+        if (item instanceof MessageAdapterItem.MessageDateSeparator) {
-            return VIEW_TYPE_SENT;
+            return VIEW_TYPE_SEPARATOR;
+        } else if (item instanceof MessageWithContentReactions m) {
+            return m.outgoing ? VIEW_TYPE_SENT : VIEW_TYPE_RECEIVED;
         } else {
             return VIEW_TYPE_RECEIVED;
         }
@@ -53,26 +56,47 @@ public class MessageAdapter
             return new MessageSentViewHolder(
                     DataBindingUtil.inflate(
                             layoutInflater, R.layout.item_message_sent, parent, false));
+        } else if (viewType == VIEW_TYPE_SEPARATOR) {
+            return new MessageDateSeparator(
+                    DataBindingUtil.inflate(
+                            layoutInflater, R.layout.item_message_separator, parent, false));
         }
         throw new IllegalArgumentException(String.format("viewType %d not implemented", viewType));
     }
 
     @Override
     public void onBindViewHolder(@NonNull AbstractMessageViewHolder holder, int position) {
-        final var message = getItem(position);
+        final var item = getItem(position);
-        if (message == null) {
+        if (item == null) {
-            holder.setMessage(null);
+            holder.setItem(null);
+        } else if (item instanceof MessageWithContentReactions message) {
+            this.onBindViewHolder(holder, message);
+        } else if (item instanceof MessageAdapterItem.MessageDateSeparator dateSeparator) {
+            this.onBindViewHolder(holder, dateSeparator);
+        } else {
+            throw new IllegalArgumentException(
+                    String.format(
+                            "%s is not a known implementation", item.getClass().getSimpleName()));
         }
-        LOGGER.info("onBindViewHolder({})", message == null ? null : message.id);
+    }
-        holder.setMessage(message);
+
+    private void onBindViewHolder(
+            @NonNull final AbstractMessageViewHolder holder,
+            @NonNull final MessageAdapterItem.MessageDateSeparator dateSeparator) {
+        holder.setItem(dateSeparator);
+    }
+
+    private void onBindViewHolder(
+            @NonNull AbstractMessageViewHolder holder,
+            @NonNull final MessageWithContentReactions message) {
+        holder.setItem(message);
         if (holder instanceof MessageReceivedViewHolder messageReceivedViewHolder) {
-            final var addressWithName = message == null ? null : message.getAddressWithName();
+            final var addressWithName = message.getAddressWithName();
-            final var avatar = message == null ? null : message.getAvatar();
+            final var avatar = message.getAvatar();
+            messageReceivedViewHolder.binding.avatar.setVisibility(View.VISIBLE);
             if (avatar != null) {
-                messageReceivedViewHolder.binding.avatar.setVisibility(View.VISIBLE);
                 AvatarFetcher.fetchInto(messageReceivedViewHolder.binding.avatar, avatar);
-            } else if (addressWithName != null) {
+            } else {
-                messageReceivedViewHolder.binding.avatar.setVisibility(View.VISIBLE);
                 AvatarFetcher.setDefault(messageReceivedViewHolder.binding.avatar, addressWithName);
             }
         }
@@ -84,7 +108,7 @@ public class MessageAdapter
             super(itemView);
         }
 
-        protected abstract void setMessage(final MessageWithContentReactions message);
+        protected abstract void setItem(final MessageAdapterItem item);
     }
 
     public static class MessageReceivedViewHolder extends AbstractMessageViewHolder {
@@ -97,8 +121,12 @@ public class MessageAdapter
         }
 
         @Override
-        protected void setMessage(final MessageWithContentReactions message) {
+        protected void setItem(final MessageAdapterItem item) {
+            if (item instanceof MessageWithContentReactions message) {
                 this.binding.setMessage(message);
+            } else {
+                this.binding.setMessage(null);
+            }
         }
     }
 
@@ -112,8 +140,31 @@ public class MessageAdapter
         }
 
         @Override
-        protected void setMessage(MessageWithContentReactions message) {
+        protected void setItem(MessageAdapterItem item) {
+            if (item instanceof MessageWithContentReactions message) {
                 this.binding.setMessage(message);
+            } else {
+                this.binding.setMessage(null);
+            }
+        }
+    }
+
+    public static class MessageDateSeparator extends AbstractMessageViewHolder {
+
+        private final ItemMessageSeparatorBinding binding;
+
+        private MessageDateSeparator(@NonNull ItemMessageSeparatorBinding binding) {
+            super(binding.getRoot());
+            this.binding = binding;
+        }
+
+        @Override
+        protected void setItem(MessageAdapterItem item) {
+            if (item instanceof MessageAdapterItem.MessageDateSeparator dateSeparator) {
+                this.binding.setTimestamp(dateSeparator.date);
+            } else {
+                this.binding.setTimestamp(null);
+            }
         }
     }
 }

app/src/main/java/im/conversations/android/ui/adapter/MessageComparator.java

@@ -2,29 +2,44 @@ package im.conversations.android.ui.adapter;
 
 import androidx.annotation.NonNull;
 import androidx.recyclerview.widget.DiffUtil;
+import im.conversations.android.database.model.MessageAdapterItem;
 import im.conversations.android.database.model.MessageWithContentReactions;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
-public class MessageComparator extends DiffUtil.ItemCallback<MessageWithContentReactions> {
+public class MessageComparator extends DiffUtil.ItemCallback<MessageAdapterItem> {
 
     private static final Logger LOGGER = LoggerFactory.getLogger(MessageComparator.class);
 
     @Override
     public boolean areItemsTheSame(
-            @NonNull MessageWithContentReactions oldItem,
+            @NonNull MessageAdapterItem oldItem, @NonNull MessageAdapterItem newItem) {
-            @NonNull MessageWithContentReactions newItem) {
+        if (oldItem instanceof MessageWithContentReactions oldMessage
-        return oldItem.id == newItem.id;
+                && newItem instanceof MessageWithContentReactions newMessage) {
+            return oldMessage.id == newMessage.id;
+        } else if (oldItem instanceof MessageAdapterItem.MessageDateSeparator oldSeparator
+                && newItem instanceof MessageAdapterItem.MessageDateSeparator newSeparator) {
+            return oldSeparator.date.equals(newSeparator.date);
+        } else {
+            return false;
+        }
     }
 
     @Override
     public boolean areContentsTheSame(
-            @NonNull MessageWithContentReactions oldItem,
+            @NonNull MessageAdapterItem oldItem, @NonNull MessageAdapterItem newItem) {
-            @NonNull MessageWithContentReactions newItem) {
+        if (oldItem instanceof MessageWithContentReactions oldMessage
-        final var areContentsTheSame = oldItem.equals(newItem);
+                && newItem instanceof MessageWithContentReactions newMessage) {
+            final var areContentsTheSame = oldMessage.equals(newMessage);
             if (!areContentsTheSame) {
-            LOGGER.info("Message {} got modified", oldItem.id);
+                LOGGER.info("Message {} got modified", oldMessage.id);
             }
             return areContentsTheSame;
+        } else if (oldItem instanceof MessageAdapterItem.MessageDateSeparator oldSeparator
+                && newItem instanceof MessageAdapterItem.MessageDateSeparator newSeparator) {
+            return oldSeparator.date.equals(newSeparator.date);
+        } else {
+            return false;
+        }
     }
 }

app/src/main/java/im/conversations/android/ui/fragment/main/ChatFragment.java

@@ -8,8 +8,12 @@ import androidx.annotation.NonNull;
 import androidx.databinding.DataBindingUtil;
 import androidx.fragment.app.Fragment;
 import androidx.lifecycle.ViewModelProvider;
+import androidx.paging.PagingData;
+import androidx.paging.PagingDataTransforms;
 import androidx.recyclerview.widget.LinearLayoutManager;
+import com.google.common.util.concurrent.MoreExecutors;
 import im.conversations.android.R;
+import im.conversations.android.database.model.MessageAdapterItem;
 import im.conversations.android.databinding.FragmentChatBinding;
 import im.conversations.android.ui.Activities;
 import im.conversations.android.ui.NavControllers;
@@ -17,6 +21,7 @@ import im.conversations.android.ui.RecyclerViewScroller;
 import im.conversations.android.ui.adapter.MessageAdapter;
 import im.conversations.android.ui.adapter.MessageComparator;
 import im.conversations.android.ui.model.ChatViewModel;
+import java.time.temporal.ChronoUnit;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
@@ -53,7 +58,35 @@ public class ChatFragment extends Fragment {
                 .getMessages()
                 .observe(
                         getViewLifecycleOwner(),
-                        pagingData -> messageAdapter.submitData(getLifecycle(), pagingData));
+                        pagingData -> {
+                            final PagingData<MessageAdapterItem> foo =
+                                    PagingDataTransforms.insertSeparators(
+                                            pagingData,
+                                            MoreExecutors.directExecutor(),
+                                            (before, after) -> {
+                                                final var dayBefore =
+                                                        before == null
+                                                                ? null
+                                                                : before.sentAt.truncatedTo(
+                                                                        ChronoUnit.DAYS);
+                                                final var dayAfter =
+                                                        after == null
+                                                                ? null
+                                                                : after.sentAt.truncatedTo(
+                                                                        ChronoUnit.DAYS);
+                                                if (dayAfter == null && dayBefore != null) {
+                                                    return new MessageAdapterItem
+                                                            .MessageDateSeparator(dayBefore);
+                                                } else if (dayBefore == null
+                                                        || dayBefore.equals(dayAfter)) {
+                                                    return null;
+                                                } else {
+                                                    return new MessageAdapterItem
+                                                            .MessageDateSeparator(dayBefore);
+                                                }
+                                            });
+                            messageAdapter.submitData(getLifecycle(), foo);
+                        });
         this.binding.materialToolbar.setNavigationOnClickListener(
                 view -> {
                     NavControllers.findNavController(requireActivity(), R.id.nav_host_fragment)

app/src/main/res/drawable/background_message_separator.xml

@@ -0,0 +1,5 @@
+<?xml version="1.0" encoding="utf-8"?>
+<shape xmlns:android="http://schemas.android.com/apk/res/android">
+    <solid android:color="?colorPrimaryContainer"/>
+    <corners android:radius="8dp"/>
+</shape>

app/src/main/res/layout/item_message_separator.xml

@@ -0,0 +1,48 @@
+<?xml version="1.0" encoding="utf-8"?>
+<layout xmlns:android="http://schemas.android.com/apk/res/android"
+    xmlns:app="http://schemas.android.com/apk/res-auto"
+    xmlns:tools="http://schemas.android.com/tools">
+
+    <androidx.constraintlayout.widget.ConstraintLayout
+        android:layout_width="match_parent"
+        android:layout_height="wrap_content"
+        android:paddingVertical="6dp">
+
+        <androidx.constraintlayout.widget.ConstraintLayout
+            android:id="@+id/content"
+            android:layout_width="wrap_content"
+            android:layout_height="wrap_content"
+            android:layout_marginHorizontal="8dp"
+            android:background="@drawable/background_message_separator"
+            android:paddingVertical="2sp"
+            android:paddingHorizontal="16dp"
+            app:layout_constrainedWidth="true"
+            app:layout_constraintEnd_toEndOf="parent"
+            app:layout_constraintHorizontal_bias="0.5"
+            app:layout_constraintStart_toStartOf="parent"
+            app:layout_constraintTop_toTopOf="parent">
+
+
+            <TextView
+                android:id="@+id/date"
+                android:layout_width="wrap_content"
+                android:layout_height="wrap_content"
+                app:date="@{timestamp}"
+                android:textAppearance="?textAppearanceBodyMedium"
+                android:textColor="?colorOnPrimaryContainer"
+                app:layout_constraintBottom_toBottomOf="parent"
+                app:layout_constraintStart_toStartOf="parent"
+                app:layout_constraintTop_toTopOf="parent"
+                tools:text="June 12th 2022" />
+        </androidx.constraintlayout.widget.ConstraintLayout>
+    </androidx.constraintlayout.widget.ConstraintLayout>
+
+    <data>
+
+        <import type="android.view.View" />
+
+        <variable
+            name="timestamp"
+            type="java.time.Instant" />
+    </data>
+</layout>