refactor: Rewrite comments fragments using Paging library

app/src/main/java/com/github/libretube/ui/adapters/CommentsAdapter.kt → app/src/main/java/com/github/libretube/ui/adapters/CommentPagingAdapter.kt

@@ -1,9 +1,8 @@
 package com.github.libretube.ui.adapters
 
-import android.annotation.SuppressLint
 import android.view.LayoutInflater
+import android.view.View
 import android.view.ViewGroup
-import android.view.ViewGroup.MarginLayoutParams
 import android.widget.Toast
 import androidx.appcompat.content.res.AppCompatResources
 import androidx.core.os.bundleOf
@@ -16,13 +15,13 @@
 import androidx.fragment.app.Fragment
 import androidx.fragment.app.commit
 import androidx.fragment.app.replace
-import androidx.recyclerview.widget.RecyclerView
+import androidx.paging.PagingDataAdapter
+import androidx.recyclerview.widget.DiffUtil
 import com.github.libretube.R
 import com.github.libretube.api.obj.Comment
 import com.github.libretube.constants.IntentData
 import com.github.libretube.databinding.CommentsRowBinding
 import com.github.libretube.extensions.formatShort
-import com.github.libretube.extensions.toID
 import com.github.libretube.helpers.ClipboardHelper
 import com.github.libretube.helpers.ImageHelper
 import com.github.libretube.helpers.NavigationHelper
@@ -31,35 +30,18 @@
 import com.github.libretube.ui.viewholders.CommentsViewHolder
 import com.github.libretube.util.HtmlParser
 import com.github.libretube.util.LinkHandler
-import com.github.libretube.util.TextUtils
 
-class CommentsAdapter(
+class CommentPagingAdapter(
     private val fragment: Fragment?,
     private val videoId: String,
     private val channelAvatar: String?,
-    private val comments: MutableList<Comment>,
-    private val isRepliesAdapter: Boolean = false,
+    private val parentComment: Comment? = null,
     private val handleLink: ((url: String) -> Unit)?,
     private val dismiss: () -> Unit
-) : RecyclerView.Adapter<CommentsViewHolder>() {
+) : PagingDataAdapter<Comment, CommentsViewHolder>(CommentCallback) {
+    private val isRepliesAdapter = parentComment != null
 
-    fun clear() {
-        val size: Int = comments.size
-        comments.clear()
-        notifyItemRangeRemoved(0, size)
-    }
-
-    fun updateItems(newItems: List<Comment>) {
-        val commentsSize = comments.size
-        comments.addAll(newItems)
-        notifyItemRangeInserted(commentsSize, newItems.size)
-    }
-
-    override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): CommentsViewHolder {
-        val layoutInflater = LayoutInflater.from(parent.context)
-        val binding = CommentsRowBinding.inflate(layoutInflater, parent, false)
-        return CommentsViewHolder(binding)
-    }
+    override fun getItemCount() = (if (isRepliesAdapter) 1 else 0) + super.getItemCount()
 
     private fun navigateToReplies(comment: Comment) {
         val args = bundleOf(IntentData.videoId to videoId, IntentData.comment to comment)
@@ -69,20 +51,25 @@
         }
     }
 
-    @SuppressLint("SetTextI18n")
     override fun onBindViewHolder(holder: CommentsViewHolder, position: Int) {
-        val comment = comments[position]
+        val comment = if (parentComment != null) {
+            if (position == 0) parentComment else getItem(position - 1)!!
+        } else {
+            getItem(position)!!
+        }
         holder.binding.apply {
             commentAuthor.text = comment.author
             commentAuthor.setBackgroundResource(
                 if (comment.channelOwner) R.drawable.comment_channel_owner_bg else 0
             )
-            commentInfos.text = TextUtils.SEPARATOR + comment.commentedTime
+            commentInfos.text = root.context
+                .getString(R.string.commentedTimeWithSeparator, comment.commentedTime)
 
             commentText.movementMethod = LinkMovementMethodCompat.getInstance()
             commentText.text = comment.commentText?.replace("</a>", "</a> ")
                 ?.parseAsHtml(tagHandler = HtmlParser(LinkHandler(handleLink ?: {})))
 
+            commentorImage.setImageDrawable(null)
             ImageHelper.loadImage(comment.thumbnail, commentorImage, true)
             likesTextView.text = comment.likeCount.formatShort()
 
@@ -91,24 +78,24 @@
                 creatorReplyImageView.isVisible = true
             }
 
-            if (comment.verified) verifiedImageView.isVisible = true
-            if (comment.pinned) pinnedImageView.isVisible = true
-            if (comment.hearted) heartedImageView.isVisible = true
-            if (comment.repliesPage != null) repliesCount.isVisible = true
+            verifiedImageView.isVisible = comment.verified
+            pinnedImageView.isVisible = comment.pinned
+            heartedImageView.isVisible = comment.hearted
+            repliesCount.isVisible = comment.repliesPage != null
             if (comment.replyCount > 0L) {
                 repliesCount.text = comment.replyCount.formatShort()
             }
 
             commentorImage.setOnClickListener {
                 NavigationHelper.navigateChannel(root.context, comment.commentorUrl)
-                dismiss.invoke()
+                dismiss()
             }
 
             if (isRepliesAdapter) {
                 repliesCount.isGone = true
 
                 // highlight the comment that is being replied to
-                if (comment == comments.firstOrNull()) {
+                if (position == 0) {
                     root.setBackgroundColor(
                         ThemeHelper.getThemeColor(
                             root.context,
@@ -117,7 +104,7 @@
                     )
 
                     root.updatePadding(top = 20)
-                    root.updateLayoutParams<MarginLayoutParams> { bottomMargin = 20 }
+                    root.updateLayoutParams<ViewGroup.MarginLayoutParams> { bottomMargin = 20 }
                 } else {
                     root.background = AppCompatResources.getDrawable(
                         root.context,
@@ -127,12 +114,9 @@
             }
 
             if (!isRepliesAdapter && comment.repliesPage != null) {
-                root.setOnClickListener {
-                    navigateToReplies(comment)
-                }
-                commentText.setOnClickListener {
-                    navigateToReplies(comment)
-                }
+                val onClickListener = View.OnClickListener { navigateToReplies(comment) }
+                root.setOnClickListener(onClickListener)
+                commentText.setOnClickListener(onClickListener)
             }
             root.setOnLongClickListener {
                 ClipboardHelper.save(
@@ -145,5 +129,17 @@
         }
     }
 
-    override fun getItemCount() = comments.size
+    override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): CommentsViewHolder {
+        val layoutInflater = LayoutInflater.from(parent.context)
+        val binding = CommentsRowBinding.inflate(layoutInflater, parent, false)
+        return CommentsViewHolder(binding)
+    }
+}
+
+private object CommentCallback : DiffUtil.ItemCallback<Comment>() {
+    override fun areItemsTheSame(oldItem: Comment, newItem: Comment): Boolean {
+        return oldItem.commentId == newItem.commentId
+    }
+
+    override fun areContentsTheSame(oldItem: Comment, newItem: Comment) = true
 }

app/src/main/java/com/github/libretube/ui/fragments/CommentsMainFragment.kt

@@ -7,19 +7,22 @@ import android.view.ViewGroup
 import androidx.core.view.isVisible
 import androidx.fragment.app.Fragment
 import androidx.fragment.app.activityViewModels
+import androidx.lifecycle.Lifecycle
+import androidx.lifecycle.lifecycleScope
+import androidx.lifecycle.repeatOnLifecycle
+import androidx.paging.LoadState
 import androidx.recyclerview.widget.LinearLayoutManager
 import com.github.libretube.R
 import com.github.libretube.databinding.FragmentCommentsBinding
 import com.github.libretube.extensions.formatShort
-import com.github.libretube.ui.adapters.CommentsAdapter
+import com.github.libretube.ui.adapters.CommentPagingAdapter
 import com.github.libretube.ui.models.CommentsViewModel
 import com.github.libretube.ui.sheets.CommentsSheet
+import kotlinx.coroutines.launch
 
 class CommentsMainFragment : Fragment() {
     private var _binding: FragmentCommentsBinding? = null
-
-    private lateinit var commentsAdapter: CommentsAdapter
-
+    private val binding get() = _binding!!
     private val viewModel: CommentsViewModel by activityViewModels()
 
     override fun onCreateView(
@@ -28,13 +31,13 @@ class CommentsMainFragment : Fragment() {
         savedInstanceState: Bundle?
     ): View {
         _binding = FragmentCommentsBinding.inflate(inflater, container, false)
-        return _binding!!.root
+        return binding.root
     }
 
     override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
         super.onViewCreated(view, savedInstanceState)
 
-        val binding = _binding ?: return
+        val binding = binding
         val layoutManager = LinearLayoutManager(requireContext())
         binding.commentsRV.layoutManager = layoutManager
         binding.commentsRV.setItemViewCacheSize(20)
@@ -47,68 +50,50 @@ class CommentsMainFragment : Fragment() {
         }
 
         binding.commentsRV.viewTreeObserver.addOnScrollChangedListener {
-            val viewBinding = _binding ?: return@addOnScrollChangedListener
             // save the last scroll position to become used next time when the sheet is opened
             viewModel.currentCommentsPosition = layoutManager.findFirstVisibleItemPosition()
 
             // hide or show the scroll to top button
             commentsSheet?.binding?.btnScrollToTop?.isVisible = viewModel.currentCommentsPosition != 0
-
-            if (!viewBinding.commentsRV.canScrollVertically(1)) {
-                viewModel.fetchNextComments()
-            }
         }
         commentsSheet?.updateFragmentInfo(false, getString(R.string.comments))
 
-        commentsAdapter = CommentsAdapter(
+        val commentPagingAdapter = CommentPagingAdapter(
             this,
-            viewModel.videoId ?: return,
+            viewModel.videoIdLiveData.value ?: return,
             viewModel.channelAvatar ?: return,
-            viewModel.commentsPage.value?.comments.orEmpty().toMutableList(),
-            handleLink = viewModel.handleLink
+            handleLink = viewModel.handleLink,
         ) {
             viewModel.commentsSheetDismiss?.invoke()
         }
-        binding.commentsRV.adapter = commentsAdapter
-
-        if (viewModel.commentsPage.value?.comments.isNullOrEmpty()) {
-            viewModel.fetchComments()
-        } else {
-            binding.commentsRV.scrollToPosition(viewModel.currentCommentsPosition)
-        }
-
-        viewModel.isLoading.observe(viewLifecycleOwner) {
-            _binding?.progress?.isVisible = it == true
-        }
-
-        // listen for new comments to be loaded
-        viewModel.commentsPage.observe(viewLifecycleOwner) {
-            if (it == null) return@observe
-            val viewBinding = _binding ?: return@observe
-
-            if (it.disabled) {
-                viewBinding.errorTV.isVisible = true
-                return@observe
+        binding.commentsRV.adapter = commentPagingAdapter
+
+        viewLifecycleOwner.lifecycleScope.launch {
+            repeatOnLifecycle(Lifecycle.State.STARTED) {
+                launch {
+                    commentPagingAdapter.loadStateFlow.collect {
+                        binding.progress.isVisible = it.refresh is LoadState.Loading
+
+                        if (it.append is LoadState.NotLoading && it.append.endOfPaginationReached) {
+                            binding.errorTV.text = getString(R.string.no_comments_available)
+                            binding.errorTV.isVisible = true
+                            return@collect
+                        }
+                    }
+                }
+
+                launch {
+                    viewModel.commentsFlow.collect {
+                        commentPagingAdapter.submitData(it)
+
+                        val commentCount = commentPagingAdapter.itemCount.toLong().formatShort()
+                        commentsSheet?.updateFragmentInfo(
+                            false,
+                            getString(R.string.comments_count, commentCount)
+                        )
+                    }
+                }
             }
-
-            commentsSheet?.updateFragmentInfo(
-                false,
-                "${getString(R.string.comments)} (${it.commentCount.formatShort()})"
-            )
-            if (it.comments.isEmpty()) {
-                viewBinding.errorTV.text = getString(R.string.no_comments_available)
-                viewBinding.errorTV.isVisible = true
-                return@observe
-            }
-
-            // sometimes the received comments have the same size as the existing ones
-            // which causes comments.subList to throw InvalidArgumentException
-            if (commentsAdapter.itemCount > it.comments.size) return@observe
-
-            commentsAdapter.updateItems(
-                // only add the new comments to the recycler view
-                it.comments.subList(commentsAdapter.itemCount, it.comments.size)
-            )
         }
     }