refactor(android): move UIPost rewrite into PagingSource

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

@@ -1,5 +1,5 @@
 /*
- * Copyright © 2021-2023 Harsh Shandilya.
+ * Copyright © 2021-2024 Harsh Shandilya.
  * Use of this source code is governed by an MIT-style
  * license that can be found in the LICENSE file or at
  * https://opensource.org/licenses/MIT.
@@ -13,8 +13,12 @@ import com.slack.eithernet.ApiResult.Success
 import dagger.assisted.Assisted
 import dagger.assisted.AssistedFactory
 import dagger.assisted.AssistedInject
+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.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.withContext
@@ -24,15 +28,25 @@ class LobstersPagingSource
 constructor(
   @Assisted private val remoteFetcher: RemoteFetcher<LobstersPost>,
   @IODispatcher private val ioDispatcher: CoroutineDispatcher,
-) : PagingSource<Int, LobstersPost>() {
+  private val savedPostsRepository: SavedPostsRepository,
+  private val readPostsRepository: ReadPostsRepository,
+) : PagingSource<Int, UIPost>() {
 
-  override suspend fun load(params: LoadParams<Int>): LoadResult<Int, LobstersPost> {
+  override suspend fun load(params: LoadParams<Int>): LoadResult<Int, UIPost> {
     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 = result.value,
+          data =
+            result.value.map {
+              it
+                .toUIPost()
+                .copy(
+                  isSaved = savedPostsRepository.isPostSaved(it.shortId),
+                  isRead = readPostsRepository.isPostRead(it.shortId),
+                )
+            },
           prevKey = if (page == STARTING_PAGE_INDEX) null else page - 1,
           nextKey = page + 1,
         )
@@ -43,7 +57,7 @@ constructor(
     }
   }
 
-  override fun getRefreshKey(state: PagingState<Int, LobstersPost>): Int? {
+  override fun getRefreshKey(state: PagingState<Int, UIPost>): Int? {
     return state.anchorPosition?.let { anchorPosition ->
       (anchorPosition / PAGE_SIZE).coerceAtLeast(STARTING_PAGE_INDEX)
     }

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

@@ -1,5 +1,5 @@
 /*
- * Copyright © 2021-2023 Harsh Shandilya.
+ * Copyright © 2021-2024 Harsh Shandilya.
  * Use of this source code is governed by an MIT-style
  * license that can be found in the LICENSE file or at
  * https://opensource.org/licenses/MIT.
@@ -14,9 +14,12 @@ import dagger.assisted.AssistedFactory
 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.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.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.withContext
@@ -33,14 +36,16 @@ constructor(
   private val searchApi: LobstersSearchApi,
   @Assisted private val queryProvider: () -> String,
   @IODispatcher private val ioDispatcher: CoroutineDispatcher,
-) : PagingSource<Int, LobstersPost>() {
+  private val savedPostsRepository: SavedPostsRepository,
-  override fun getRefreshKey(state: PagingState<Int, LobstersPost>): Int? {
+  private val readPostsRepository: ReadPostsRepository,
+) : PagingSource<Int, UIPost>() {
+  override fun getRefreshKey(state: PagingState<Int, UIPost>): Int? {
     return state.anchorPosition?.let { anchorPosition ->
       (anchorPosition / PAGE_SIZE).coerceAtLeast(STARTING_PAGE_INDEX)
     }
   }
 
-  override suspend fun load(params: LoadParams<Int>): LoadResult<Int, LobstersPost> {
+  override suspend fun load(params: LoadParams<Int>): LoadResult<Int, UIPost> {
     val searchQuery = queryProvider()
     // If there is no query, we don't need to call the API at all.
     if (searchQuery.isEmpty()) {
@@ -55,7 +60,15 @@ constructor(
         val nextKey = if (result.value.isEmpty()) null else page + 1
         LoadResult.Page(
           itemsBefore = (page - 1) * PAGE_SIZE,
-          data = result.value,
+          data =
+            result.value.map {
+              it
+                .toUIPost()
+                .copy(
+                  isSaved = savedPostsRepository.isPostSaved(it.shortId),
+                  isRead = readPostsRepository.isPostRead(it.shortId),
+                )
+            },
           prevKey = if (page == STARTING_PAGE_INDEX) null else page - 1,
           nextKey = nextKey,
         )

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

@@ -18,9 +18,7 @@ import androidx.lifecycle.AndroidViewModel
 import androidx.lifecycle.viewModelScope
 import androidx.paging.Pager
 import androidx.paging.PagingConfig
-import androidx.paging.PagingData
 import androidx.paging.cachedIn
-import androidx.paging.map
 import com.deliveryhero.whetstone.app.ApplicationScope
 import com.deliveryhero.whetstone.viewmodel.ContributesViewModel
 import com.slack.eithernet.ApiResult.Failure
@@ -35,10 +33,8 @@ import dev.msfjarvis.claw.api.LobstersApi
 import dev.msfjarvis.claw.core.injection.IODispatcher
 import dev.msfjarvis.claw.core.injection.MainDispatcher
 import dev.msfjarvis.claw.model.Comment
-import dev.msfjarvis.claw.model.LobstersPost
 import dev.msfjarvis.claw.model.UIPost
 import dev.msfjarvis.claw.model.fromSavedPost
-import dev.msfjarvis.claw.model.toSavedPost
 import dev.msfjarvis.claw.model.toUIPost
 import java.io.IOException
 import java.io.InputStream
@@ -79,7 +75,6 @@ constructor(
         pagingSourceFactory = { pagingSourceFactory.create(api::getHottestPosts) },
       )
       .flow
-      .map(::mapToUIPost)
       .cachedIn(viewModelScope)
   val newestPosts =
     Pager(
@@ -88,7 +83,6 @@ constructor(
         pagingSourceFactory = { pagingSourceFactory.create(api::getNewestPosts) },
       )
       .flow
-      .map(::mapToUIPost)
       .cachedIn(viewModelScope)
   val searchResults =
     Pager(
@@ -97,7 +91,6 @@ constructor(
         pagingSourceFactory = { searchPagingSourceFactory.create { searchQuery } },
       )
       .flow
-      .map(::mapToUIPost)
   val savedPosts = savedPostsRepository.savedPosts.map { it.map(UIPost.Companion::fromSavedPost) }
   val savedPostsByMonth
     get() = savedPosts.map(::groupSavedPosts)
@@ -112,13 +105,6 @@ constructor(
     viewModelScope.launch { readPostsRepository.readPosts.collectLatest { _readPosts = it } }
   }
 
-  private fun mapToUIPost(pagingData: PagingData<LobstersPost>): PagingData<UIPost> {
-    return pagingData.map { post ->
-      val uiPost = post.toUIPost()
-      uiPost.copy(isSaved = isPostSaved(uiPost), isRead = isPostRead(uiPost))
-    }
-  }
-
   private fun groupSavedPosts(items: List<UIPost>): ImmutableMap<String, List<UIPost>> {
     val sorted =
       items.sortedWith { post1, post2 ->
@@ -140,22 +126,9 @@ constructor(
       .toImmutableMap()
   }
 
-  private fun isPostSaved(post: UIPost): Boolean {
-    return _savedPosts.contains(post.shortId)
-  }
-
-  private fun isPostRead(post: UIPost): Boolean {
-    return _readPosts.contains(post.shortId)
-  }
-
   fun toggleSave(post: UIPost) {
-    viewModelScope.launch(ioDispatcher) {
+    viewModelScope.launch {
-      val saved = isPostSaved(post)
+      savedPostsRepository.toggleSave(post)
-      if (saved) {
-        savedPostsRepository.removePost(post.toSavedPost())
-      } else {
-        savedPostsRepository.savePost(post.toSavedPost())
-      }
       withContext(mainDispatcher) { SavedPostsWidget(savedPosts).updateAll(getApplication()) }
     }
   }

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

@@ -25,4 +25,8 @@ constructor(
   suspend fun markRead(postId: String) {
     withContext(dbDispatcher) { readPostsQueries.markRead(postId) }
   }
+
+  suspend fun isPostRead(shortId: String): Boolean {
+    return withContext(dbDispatcher) { readPostsQueries.isPostRead(shortId).executeAsOne() }
+  }
 }

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

@@ -1,5 +1,5 @@
 /*
- * Copyright © 2021-2023 Harsh Shandilya.
+ * Copyright © 2021-2024 Harsh Shandilya.
  * Use of this source code is governed by an MIT-style
  * license that can be found in the LICENSE file or at
  * https://opensource.org/licenses/MIT.
@@ -11,6 +11,8 @@ import app.cash.sqldelight.coroutines.mapToList
 import dev.msfjarvis.claw.core.injection.DatabaseDispatcher
 import dev.msfjarvis.claw.database.local.SavedPost
 import dev.msfjarvis.claw.database.local.SavedPostQueries
+import dev.msfjarvis.claw.model.UIPost
+import dev.msfjarvis.claw.model.toSavedPost
 import io.github.aakira.napier.Napier
 import javax.inject.Inject
 import kotlinx.coroutines.CoroutineDispatcher
@@ -24,9 +26,14 @@ constructor(
 ) {
   val savedPosts = savedPostQueries.selectAllPosts().asFlow().mapToList(dbDispatcher)
 
-  suspend fun savePost(post: SavedPost) {
+  suspend fun toggleSave(post: UIPost) {
-    Napier.d(tag = TAG) { "Saving post: ${post.shortId}" }
+    if (post.isSaved) {
-    withContext(dbDispatcher) { savedPostQueries.insertOrReplacePost(post) }
+      Napier.d(tag = TAG) { "Removing post: ${post.shortId}" }
+      withContext(dbDispatcher) { savedPostQueries.deletePost(post.shortId) }
+    } else {
+      Napier.d(tag = TAG) { "Saving post: ${post.shortId}" }
+      withContext(dbDispatcher) { savedPostQueries.insertOrReplacePost(post.toSavedPost()) }
+    }
   }
 
   suspend fun savePosts(posts: List<SavedPost>) {
@@ -38,9 +45,8 @@ constructor(
     }
   }
 
-  suspend fun removePost(post: SavedPost) {
+  suspend fun isPostSaved(postId: String): Boolean {
-    Napier.d(tag = TAG) { "Removing post: ${post.shortId}" }
+    return withContext(dbDispatcher) { savedPostQueries.isPostSaved(postId).executeAsOne() }
-    withContext(dbDispatcher) { savedPostQueries.deletePost(post.shortId) }
   }
 
   private companion object {

database/core/src/main/sqldelight/dev/msfjarvis/claw/database/local/ReadPosts.sq

@@ -2,6 +2,13 @@ CREATE TABLE ReadPosts(
   id TEXT NOT NULL PRIMARY KEY
 );
 
+isPostRead:
+SELECT EXISTS(
+  SELECT 1
+  FROM ReadPosts
+  WHERE id = ?
+) AS isRead;
+
 selectAllPosts:
 SELECT *
 FROM ReadPosts;

database/core/src/main/sqldelight/dev/msfjarvis/claw/database/local/SavedPost.sq

@@ -14,6 +14,13 @@ CREATE TABLE IF NOT EXISTS SavedPost(
   description TEXT NOT NULL DEFAULT ""
 );
 
+isPostSaved:
+SELECT EXISTS(
+  SELECT 1
+  FROM SavedPost
+  WHERE shortId = ?
+) AS isSaved;
+
 insertOrReplacePost:
 INSERT OR REPLACE
 INTO SavedPost