refactor: lazily query saved and read state in UI

Having this always be read from the UI avoids values going stale inside data models

Fixes #641

CHANGELOG.md

@@ -11,6 +11,10 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 - Opening posts you have previously seen will show the number of new comments since last visit
 
+### Fixed
+
+- Saving posts no longer triggers a page refresh that invalidates scroll position
+
 ### Changed
 
 - Change submitter text to 'authored' when applicable

android/src/main/kotlin/dev/msfjarvis/claw/android/paging/LobstersPagingSource.kt

@@ -14,16 +14,12 @@ import dagger.assisted.Assisted
 import dagger.assisted.AssistedFactory
 import dagger.assisted.AssistedInject
 import dev.msfjarvis.claw.android.ui.toError
-import dev.msfjarvis.claw.android.viewmodel.ReadPostsRepository
-import dev.msfjarvis.claw.android.viewmodel.SavedPostsRepository
 import dev.msfjarvis.claw.core.injection.IODispatcher
-import dev.msfjarvis.claw.database.local.SavedPost
 import dev.msfjarvis.claw.model.LobstersPost
 import dev.msfjarvis.claw.model.UIPost
 import dev.msfjarvis.claw.model.toUIPost
 import java.io.IOException
 import kotlinx.coroutines.CoroutineDispatcher
-import kotlinx.coroutines.flow.first
 import kotlinx.coroutines.withContext
 
 class LobstersPagingSource
@@ -31,33 +27,14 @@ class LobstersPagingSource
 constructor(
   @Assisted private val remoteFetcher: RemoteFetcher<LobstersPost>,
   @IODispatcher private val ioDispatcher: CoroutineDispatcher,
-  private val savedPostsRepository: SavedPostsRepository,
-  private val readPostsRepository: ReadPostsRepository,
 ) : PagingSource<Int, UIPost>() {
-  private lateinit var savedPosts: List<String>
-  private lateinit var readPosts: List<String>
-
   override suspend fun load(params: LoadParams<Int>): LoadResult<Int, UIPost> {
-    if (!::savedPosts.isInitialized) {
-      savedPosts = savedPostsRepository.savedPosts.first().map(SavedPost::shortId)
-    }
-    if (!::readPosts.isInitialized) {
-      readPosts = readPostsRepository.readPosts.first()
-    }
     val page = params.key ?: STARTING_PAGE_INDEX
     return when (val result = withContext(ioDispatcher) { remoteFetcher.getItemsAtPage(page) }) {
       is Success ->
         LoadResult.Page(
           itemsBefore = (page - 1) * PAGE_SIZE,
-          data =
+          data = result.value.map(LobstersPost::toUIPost),
-            result.value.map {
-              it
-                .toUIPost()
-                .copy(
-                  isSaved = savedPosts.contains(it.shortId),
-                  isRead = readPosts.contains(it.shortId),
-                )
-            },
           prevKey = if (page == STARTING_PAGE_INDEX) null else page - 1,
           nextKey = page + 1,
         )

android/src/main/kotlin/dev/msfjarvis/claw/android/paging/SearchPagingSource.kt

@@ -15,16 +15,13 @@ import dagger.assisted.AssistedInject
 import dev.msfjarvis.claw.android.paging.LobstersPagingSource.Companion.PAGE_SIZE
 import dev.msfjarvis.claw.android.paging.LobstersPagingSource.Companion.STARTING_PAGE_INDEX
 import dev.msfjarvis.claw.android.ui.toError
-import dev.msfjarvis.claw.android.viewmodel.ReadPostsRepository
-import dev.msfjarvis.claw.android.viewmodel.SavedPostsRepository
 import dev.msfjarvis.claw.api.LobstersSearchApi
 import dev.msfjarvis.claw.core.injection.IODispatcher
-import dev.msfjarvis.claw.database.local.SavedPost
+import dev.msfjarvis.claw.model.LobstersPost
 import dev.msfjarvis.claw.model.UIPost
 import dev.msfjarvis.claw.model.toUIPost
 import java.io.IOException
 import kotlinx.coroutines.CoroutineDispatcher
-import kotlinx.coroutines.flow.first
 import kotlinx.coroutines.withContext
 
 /**
@@ -39,19 +36,8 @@ constructor(
   private val searchApi: LobstersSearchApi,
   @Assisted private val queryProvider: () -> String,
   @IODispatcher private val ioDispatcher: CoroutineDispatcher,
-  private val savedPostsRepository: SavedPostsRepository,
-  private val readPostsRepository: ReadPostsRepository,
 ) : PagingSource<Int, UIPost>() {
-  private lateinit var savedPosts: List<String>
-  private lateinit var readPosts: List<String>
-
   override suspend fun load(params: LoadParams<Int>): LoadResult<Int, UIPost> {
-    if (!::savedPosts.isInitialized) {
-      savedPosts = savedPostsRepository.savedPosts.first().map(SavedPost::shortId)
-    }
-    if (!::readPosts.isInitialized) {
-      readPosts = readPostsRepository.readPosts.first()
-    }
     val searchQuery = queryProvider()
     // If there is no query, we don't need to call the API at all.
     if (searchQuery.isEmpty()) {
@@ -66,15 +52,7 @@ constructor(
         val nextKey = if (result.value.isEmpty()) null else page + 1
         LoadResult.Page(
           itemsBefore = (page - 1) * PAGE_SIZE,
-          data =
+          data = result.value.map(LobstersPost::toUIPost),
-            result.value.map {
-              it
-                .toUIPost()
-                .copy(
-                  isSaved = savedPosts.contains(it.shortId),
-                  isRead = readPosts.contains(it.shortId),
-                )
-            },
           prevKey = if (page == STARTING_PAGE_INDEX) null else page - 1,
           nextKey = nextKey,
         )

android/src/main/kotlin/dev/msfjarvis/claw/android/ui/ext.kt

@@ -70,6 +70,10 @@ fun rememberPostActions(
         context.startActivity(shareIntent)
       }
 
+      override fun isPostRead(post: UIPost): Boolean = viewModel.isPostRead(post)
+
+      override fun isPostSaved(post: UIPost): Boolean = viewModel.isPostSaved(post)
+
       override suspend fun getComments(postId: String): UIPost {
         return viewModel.getPostComments(postId)
       }

android/src/main/kotlin/dev/msfjarvis/claw/android/ui/lists/DatabasePosts.kt

@@ -54,7 +54,7 @@ fun DatabasePosts(
         items.forEach { (month, posts) ->
           stickyHeader(contentType = "month-header") { MonthHeader(label = month) }
           items(items = posts, key = { it.shortId }, contentType = { "LobstersItem" }) { item ->
-            LobstersListItem(item = item, refresh = {}, postActions = postActions)
+            LobstersListItem(item = item, postActions = postActions)
             HorizontalDivider()
           }
         }

android/src/main/kotlin/dev/msfjarvis/claw/android/ui/lists/LobstersListItem.kt

@@ -20,12 +20,7 @@ import me.saket.swipe.SwipeAction
 import me.saket.swipe.SwipeableActionsBox
 
 @Composable
-fun LobstersListItem(
+fun LobstersListItem(item: UIPost, postActions: PostActions, modifier: Modifier = Modifier) {
-  item: UIPost,
-  postActions: PostActions,
-  refresh: () -> Unit,
-  modifier: Modifier = Modifier,
-) {
   val commentsAction =
     SwipeAction(
       icon = rememberVectorPainter(Icons.AutoMirrored.Filled.Reply),
@@ -39,6 +34,6 @@ fun LobstersListItem(
       onSwipe = { postActions.share(item) },
     )
   SwipeableActionsBox(startActions = listOf(shareAction), endActions = listOf(commentsAction)) {
-    LobstersCard(post = item, postActions = postActions, refresh = refresh, modifier = modifier)
+    LobstersCard(post = item, postActions = postActions, modifier = modifier)
   }
 }

android/src/main/kotlin/dev/msfjarvis/claw/android/ui/lists/NetworkPosts.kt

@@ -73,11 +73,7 @@ fun NetworkPosts(
         ) { index ->
           val item = lazyPagingItems[index]
           if (item != null) {
-            LobstersListItem(
+            LobstersListItem(item = item, postActions = postActions)
-              item = item,
-              postActions = postActions,
-              refresh = { lazyPagingItems.refresh() },
-            )
             HorizontalDivider()
           }
         }

android/src/main/kotlin/dev/msfjarvis/claw/android/viewmodel/ClawViewModel.kt

@@ -133,6 +133,14 @@ constructor(
     }
   }
 
+  fun isPostRead(post: UIPost): Boolean {
+    return _readPosts.contains(post.shortId)
+  }
+
+  fun isPostSaved(post: UIPost): Boolean {
+    return _savedPosts.contains(post.shortId)
+  }
+
   suspend fun getPostComments(postId: String) =
     withContext(ioDispatcher) {
       when (val result = api.getPostDetails(postId)) {

android/src/main/kotlin/dev/msfjarvis/claw/android/viewmodel/SavedPostsRepository.kt

@@ -16,6 +16,7 @@ import dev.msfjarvis.claw.model.toSavedPost
 import io.github.aakira.napier.Napier
 import javax.inject.Inject
 import kotlinx.coroutines.CoroutineDispatcher
+import kotlinx.coroutines.flow.firstOrNull
 import kotlinx.coroutines.withContext
 
 class SavedPostsRepository
@@ -27,7 +28,7 @@ constructor(
   val savedPosts = savedPostQueries.selectAllPosts().asFlow().mapToList(dbDispatcher)
 
   suspend fun toggleSave(post: UIPost) {
-    if (post.isSaved) {
+    if (savedPosts.firstOrNull().orEmpty().any { it.shortId == post.shortId }) {
       Napier.d(tag = TAG) { "Removing post: ${post.shortId}" }
       withContext(dbDispatcher) { savedPostQueries.deletePost(post.shortId) }
     } else {

common/src/main/kotlin/dev/msfjarvis/claw/common/posts/LobstersCard.kt

@@ -38,6 +38,7 @@ import androidx.compose.material3.MaterialTheme
 import androidx.compose.material3.Text
 import androidx.compose.material3.minimumInteractiveComponentSize
 import androidx.compose.runtime.Composable
+import androidx.compose.runtime.derivedStateOf
 import androidx.compose.runtime.getValue
 import androidx.compose.runtime.mutableStateOf
 import androidx.compose.runtime.remember
@@ -60,23 +61,14 @@ import kotlinx.collections.immutable.ImmutableList
 import kotlinx.collections.immutable.toImmutableList
 
 @Composable
-fun LobstersCard(
+fun LobstersCard(post: UIPost, postActions: PostActions, modifier: Modifier = Modifier) {
-  post: UIPost,
+  val readState by remember(post.shortId) { derivedStateOf { postActions.isPostRead(post) } }
-  postActions: PostActions,
+  val savedState by remember(post.shortId) { derivedStateOf { postActions.isPostSaved(post) } }
-  refresh: () -> Unit,
-  modifier: Modifier = Modifier,
-) {
-  var localReadState by remember(post) { mutableStateOf(post.isRead) }
-  var localSavedState by remember(post) { mutableStateOf(post.isSaved) }
   Box(
     modifier =
       modifier
         .fillMaxWidth()
-        .clickable {
+        .clickable { postActions.viewPost(post.shortId, post.url, post.commentsUrl) }
-          postActions.viewPost(post.shortId, post.url, post.commentsUrl)
-          localReadState = true
-          refresh()
-        }
         .background(MaterialTheme.colorScheme.background)
         .padding(start = 8.dp, top = 2.dp, bottom = 2.dp)
   ) {
@@ -86,7 +78,7 @@ fun LobstersCard(
     ) {
       PostDetails(
         post = post,
-        isRead = localReadState,
+        isRead = { readState },
         singleLineTitle = true,
         modifier = Modifier.weight(1f),
       )
@@ -94,25 +86,14 @@ fun LobstersCard(
         modifier = Modifier.wrapContentHeight(),
         horizontalAlignment = Alignment.CenterHorizontally,
       ) {
-        SaveButton(
+        SaveButton(isSaved = { savedState }, onClick = { postActions.toggleSave(post) })
-          isSaved = localSavedState,
-          modifier =
-            Modifier.clickable(role = Role.Button) {
-              localSavedState = !localSavedState
-              postActions.toggleSave(post)
-            },
-        )
         HorizontalDivider(modifier = Modifier.width(48.dp))
         CommentsButton(
           commentCount = post.commentCount,
           modifier =
             Modifier.clickable(
               role = Role.Button,
-              onClick = {
+              onClick = { postActions.viewComments(post.shortId) },
-                postActions.viewComments(post.shortId)
-                localReadState = true
-                refresh()
-              },
             ),
         )
       }
@@ -123,12 +104,12 @@ fun LobstersCard(
 @Composable
 fun PostDetails(
   post: UIPost,
-  isRead: Boolean,
+  isRead: () -> Boolean,
   singleLineTitle: Boolean,
   modifier: Modifier = Modifier,
 ) {
   Column(modifier = modifier, verticalArrangement = Arrangement.spacedBy(8.dp)) {
-    PostTitle(title = post.title, isRead = isRead, singleLineTitle = singleLineTitle)
+    PostTitle(title = post.title, isRead = isRead(), singleLineTitle = singleLineTitle)
     TagRow(tags = post.tags.toImmutableList())
     Spacer(Modifier.height(4.dp))
     Submitter(
@@ -189,14 +170,19 @@ internal fun Submitter(
 }
 
 @Composable
-private fun SaveButton(isSaved: Boolean, modifier: Modifier = Modifier) {
+private fun SaveButton(isSaved: () -> Boolean, onClick: () -> Unit, modifier: Modifier = Modifier) {
-  Crossfade(targetState = isSaved, label = "save-button") { saved ->
+  var localSavedState by remember { mutableStateOf(isSaved()) }
+  Crossfade(targetState = localSavedState, label = "save-button") { saved ->
     Box(modifier = modifier.minimumInteractiveComponentSize()) {
       Icon(
         imageVector = if (saved) Icons.Filled.Favorite else Icons.Filled.FavoriteBorder,
         tint = MaterialTheme.colorScheme.secondary,
         contentDescription = if (saved) "Remove from saved posts" else "Add to saved posts",
-        modifier = Modifier.align(Alignment.Center).testTag("save_button"),
+        modifier =
+          Modifier.align(Alignment.Center).testTag("save_button").clickable(role = Role.Button) {
+            onClick()
+            localSavedState = !localSavedState
+          },
       )
     }
   }
@@ -266,6 +252,14 @@ val TEST_POST_ACTIONS =
 
     override fun share(post: UIPost) {}
 
+    override fun isPostRead(post: UIPost): Boolean {
+      return true
+    }
+
+    override fun isPostSaved(post: UIPost): Boolean {
+      return true
+    }
+
     override suspend fun getComments(postId: String): UIPost {
       return UIPost(
         shortId = "ooga",
@@ -298,12 +292,10 @@ val TEST_POST =
     submitter = "Haki",
     tags = listOf("databases", "apis"),
     description = "",
-    isSaved = true,
-    isRead = true,
   )
 
 @ThemePreviews
 @Composable
 private fun LobstersCardPreview() {
-  LobstersTheme { LobstersCard(post = TEST_POST, postActions = TEST_POST_ACTIONS, refresh = {}) }
+  LobstersTheme { LobstersCard(post = TEST_POST, postActions = TEST_POST_ACTIONS) }
 }

common/src/main/kotlin/dev/msfjarvis/claw/common/posts/PostActions.kt

@@ -22,6 +22,10 @@ interface PostActions {
 
   fun share(post: UIPost)
 
+  fun isPostRead(post: UIPost): Boolean
+
+  fun isPostSaved(post: UIPost): Boolean
+
   suspend fun getComments(postId: String): UIPost
 
   suspend fun getLinkMetadata(url: String): LinkMetadata

model/src/main/kotlin/dev/msfjarvis/claw/model/UIPost.kt

@@ -27,8 +27,6 @@ data class UIPost(
   @SerialName("submitter_user") val submitter: String,
   val tags: List<String>,
   val comments: List<Comment> = emptyList(),
-  val isSaved: Boolean = false,
-  val isRead: Boolean = false,
   val userIsAuthor: Boolean = false,
 ) {
   @KonvertFrom(
@@ -37,7 +35,6 @@ data class UIPost(
       [
         Mapping(target = "submitter", expression = "it.submitterName"),
         Mapping(target = "commentCount", expression = "it.commentCount ?: 0"),
-        Mapping(target = "isSaved", expression = "true"),
       ],
   )
   companion object