Implement paging

This is currently breaking swipe to dismiss so it can't stay like this but it's probably better performance-wise

app/src/main/java/com/wbrawner/nanoflux/Utils.kt

@@ -19,5 +19,5 @@ suspend fun syncAll(
             iconRepository.getFeedIcon(it.feed.id)
         }
     }
-    entryRepository.getAll(true)
+    entryRepository.fetch()
 }

app/src/main/java/com/wbrawner/nanoflux/data/viewmodel/EntryListViewModel.kt

@@ -2,12 +2,14 @@ package com.wbrawner.nanoflux.data.viewmodel
 
 import androidx.lifecycle.ViewModel
 import androidx.lifecycle.viewModelScope
+import androidx.paging.Pager
+import androidx.paging.PagingConfig
+import androidx.paging.cachedIn
+import com.wbrawner.nanoflux.network.EntryAndFeedPagingSource
 import com.wbrawner.nanoflux.network.repository.*
 import com.wbrawner.nanoflux.storage.model.Entry
-import com.wbrawner.nanoflux.storage.model.EntryAndFeed
 import com.wbrawner.nanoflux.syncAll
 import kotlinx.coroutines.Dispatchers
-import kotlinx.coroutines.flow.Flow
 import kotlinx.coroutines.flow.MutableStateFlow
 import kotlinx.coroutines.flow.asStateFlow
 import kotlinx.coroutines.launch
@@ -24,7 +26,12 @@ abstract class EntryListViewModel(
     val loading = _loading.asStateFlow()
     private val _errorMessage = MutableStateFlow<String?>(null)
     val errorMessage = _errorMessage.asStateFlow()
-    abstract val entries: Flow<List<EntryAndFeed>>
+    protected open val entryStatus: EntryStatus? = null
+    private val pagingSource: EntryAndFeedPagingSource
+        get() = EntryAndFeedPagingSource(entryRepository, entryStatus)
+    val entries = Pager(PagingConfig(pageSize = 15)) {
+        pagingSource
+    }.flow.cachedIn(viewModelScope)
 
     fun dismissError() {
         _errorMessage.value = null
@@ -39,9 +46,10 @@ abstract class EntryListViewModel(
         return entry.url
     }
 
-    fun refresh(status: EntryStatus? = null) = viewModelScope.launch(Dispatchers.IO) {
+    fun refresh() = viewModelScope.launch(Dispatchers.IO) {
         _loading.emit(true)
         syncAll(categoryRepository, feedRepository, iconRepository, entryRepository)
+        pagingSource.invalidate()
         _loading.emit(false)
     }
 
@@ -51,9 +59,11 @@ abstract class EntryListViewModel(
         } else if (entry.status == Entry.Status.UNREAD) {
             entryRepository.markEntryRead(entry)
         }
+        pagingSource.invalidate()
     }
 
     fun toggleStar(entry: Entry) = viewModelScope.launch(Dispatchers.IO) {
         entryRepository.toggleStar(entry)
+        pagingSource.invalidate()
     }
 }

app/src/main/java/com/wbrawner/nanoflux/data/viewmodel/EntryViewModel.kt

@@ -36,7 +36,7 @@ class EntryViewModel @Inject constructor(
             _errorMessage.value = null
             try {
                 var markedRead = false
-                entryRepository.getEntry(id).collect {
+                entryRepository.observeEntry(id).collect {
                     _entry.value = it
                     _loading.value = false
                     if (!markedRead) {

app/src/main/java/com/wbrawner/nanoflux/data/viewmodel/HistoryViewModel.kt

@@ -1,9 +1,6 @@
 package com.wbrawner.nanoflux.data.viewmodel
 
-import com.wbrawner.nanoflux.network.repository.CategoryRepository
+import com.wbrawner.nanoflux.network.repository.*
-import com.wbrawner.nanoflux.network.repository.EntryRepository
-import com.wbrawner.nanoflux.network.repository.FeedRepository
-import com.wbrawner.nanoflux.network.repository.IconRepository
 import dagger.hilt.android.lifecycle.HiltViewModel
 import timber.log.Timber
 import javax.inject.Inject
@@ -22,5 +19,5 @@ class HistoryViewModel @Inject constructor(
     iconRepository,
     logger
 ) {
-    override val entries = entryRepository.observeRead()
+    override val entryStatus: EntryStatus = EntryStatus.HISTORY
 }

app/src/main/java/com/wbrawner/nanoflux/data/viewmodel/MainViewModel.kt

@@ -24,7 +24,7 @@ class MainViewModel @Inject constructor(
 
     init {
         viewModelScope.launch(Dispatchers.IO) {
-            if (entryRepository.getCount() == 0L) {
+            if (entryRepository.count() == 0L) {
                 syncAll(categoryRepository, feedRepository, iconRepository, entryRepository)
             }
         }

app/src/main/java/com/wbrawner/nanoflux/data/viewmodel/StarredViewModel.kt

@@ -1,9 +1,6 @@
 package com.wbrawner.nanoflux.data.viewmodel
 
-import com.wbrawner.nanoflux.network.repository.CategoryRepository
+import com.wbrawner.nanoflux.network.repository.*
-import com.wbrawner.nanoflux.network.repository.EntryRepository
-import com.wbrawner.nanoflux.network.repository.FeedRepository
-import com.wbrawner.nanoflux.network.repository.IconRepository
 import dagger.hilt.android.lifecycle.HiltViewModel
 import timber.log.Timber
 import javax.inject.Inject
@@ -22,5 +19,5 @@ class StarredViewModel @Inject constructor(
     iconRepository,
     logger
 ) {
-    override val entries = entryRepository.observeStarred()
+    override val entryStatus: EntryStatus = EntryStatus.STARRED
 }

app/src/main/java/com/wbrawner/nanoflux/data/viewmodel/UnreadViewModel.kt

@@ -1,9 +1,6 @@
 package com.wbrawner.nanoflux.data.viewmodel
 
-import com.wbrawner.nanoflux.network.repository.CategoryRepository
+import com.wbrawner.nanoflux.network.repository.*
-import com.wbrawner.nanoflux.network.repository.EntryRepository
-import com.wbrawner.nanoflux.network.repository.FeedRepository
-import com.wbrawner.nanoflux.network.repository.IconRepository
 import dagger.hilt.android.lifecycle.HiltViewModel
 import timber.log.Timber
 import javax.inject.Inject
@@ -22,5 +19,5 @@ class UnreadViewModel @Inject constructor(
     iconRepository,
     logger
 ) {
-    override val entries = entryRepository.observeUnread()
+    override val entryStatus: EntryStatus = EntryStatus.UNREAD
 }

app/src/main/java/com/wbrawner/nanoflux/ui/Entries.kt

@@ -1,5 +1,6 @@
 package com.wbrawner.nanoflux.ui
 
+import android.content.res.Configuration.UI_MODE_NIGHT_YES
 import android.graphics.BitmapFactory
 import android.util.Base64
 import androidx.compose.animation.ExperimentalAnimationApi
@@ -7,8 +8,9 @@ import androidx.compose.foundation.ExperimentalFoundationApi
 import androidx.compose.foundation.Image
 import androidx.compose.foundation.clickable
 import androidx.compose.foundation.layout.*
+import androidx.compose.foundation.layout.Arrangement.spacedBy
 import androidx.compose.foundation.lazy.LazyColumn
-import androidx.compose.foundation.lazy.itemsIndexed
+import androidx.compose.foundation.shape.RoundedCornerShape
 import androidx.compose.material.*
 import androidx.compose.material.icons.Icons
 import androidx.compose.material.icons.filled.Email
@@ -27,6 +29,8 @@ import androidx.compose.ui.text.font.FontWeight
 import androidx.compose.ui.tooling.preview.Preview
 import androidx.compose.ui.unit.dp
 import androidx.compose.ui.unit.sp
+import androidx.paging.compose.LazyPagingItems
+import androidx.paging.compose.itemsIndexed
 import com.google.accompanist.flowlayout.FlowCrossAxisAlignment
 import com.google.accompanist.flowlayout.FlowRow
 import com.google.accompanist.swiperefresh.SwipeRefresh
@@ -44,7 +48,7 @@ import kotlin.math.roundToInt
 )
 @Composable
 fun EntryList(
-    entries: List<EntryAndFeed>,
+    entries: LazyPagingItems<EntryAndFeed>,
     onEntryItemClicked: (entry: Entry) -> Unit,
     onFeedClicked: (feed: Feed) -> Unit,
     onCategoryClicked: (category: Category) -> Unit,
@@ -61,10 +65,16 @@ fun EntryList(
     ) {
         LazyColumn {
             itemsIndexed(entries, { _, entry -> entry.entry.id }) { index, entry ->
+                if (entry == null) {
+                    EntryListPlaceholder()
+                    return@itemsIndexed
+                }
                 val dismissState = rememberDismissState()
-                LaunchedEffect(key1 = dismissState.currentValue) {
+                LaunchedEffect(key1 = dismissState.currentValue, key2 = entry.entry.id) {
                     when (dismissState.currentValue) {
-                        DismissValue.DismissedToStart -> onToggleReadClicked(entry.entry)
+                        DismissValue.DismissedToStart -> {
+                            onToggleReadClicked(entry.entry)
+                        }
                         DismissValue.DismissedToEnd -> {
                             onStarClicked(entry.entry)
                             dismissState.reset()
@@ -113,7 +123,7 @@ fun EntryList(
                         onShareClicked = onShareClicked,
                     )
                 }
-                if (index < entries.lastIndex) {
+                if (index < entries.itemCount - 1) {
                     Divider()
                 }
             }
@@ -121,6 +131,40 @@ fun EntryList(
     }
 }
 
+@Composable
+fun EntryListPlaceholder() {
+    Surface(color = MaterialTheme.colors.surface) {
+        Column(
+            modifier = Modifier
+                .fillMaxWidth()
+                .padding(8.dp),
+            verticalArrangement = spacedBy(8.dp)
+        ) {
+            Surface(
+                modifier = Modifier
+                    .fillMaxWidth()
+                    .height(30.dp),
+                shape = RoundedCornerShape(4.dp),
+                color = MaterialTheme.colors.onSurface.copy(alpha = 0.2f)
+            ) {}
+            Surface(
+                modifier = Modifier
+                    .fillMaxWidth()
+                    .height(30.dp),
+                shape = RoundedCornerShape(4.dp),
+                color = MaterialTheme.colors.onSurface.copy(alpha = 0.2f)
+            ) {}
+            Surface(
+                modifier = Modifier
+                    .fillMaxWidth()
+                    .height(30.dp),
+                shape = RoundedCornerShape(4.dp),
+                color = MaterialTheme.colors.onSurface.copy(alpha = 0.2f)
+            ) {}
+        }
+    }
+}
+
 @Composable
 fun EntryListItem(
     entry: Entry,
@@ -245,6 +289,7 @@ fun CategoryButton(
 
 @Composable
 @Preview
+@Preview(uiMode = UI_MODE_NIGHT_YES)
 fun EntryListItem_Preview() {
     NanofluxApp {
         EntryListItem(
@@ -310,6 +355,15 @@ fun EntryListItem_Preview() {
     }
 }
 
+@Composable
+@Preview
+@Preview(uiMode = UI_MODE_NIGHT_YES)
+fun EntryListPlaceholder_Preview() {
+    NanofluxApp {
+        EntryListPlaceholder()
+    }
+}
+
 private const val MILLIS_IN_SECOND = 1000.0
 private const val MILLIS_IN_MINUTE = 60000.0
 private const val MILLIS_IN_HOUR = 3_600_000.0

app/src/main/java/com/wbrawner/nanoflux/ui/EntryListScreen.kt

@@ -10,6 +10,7 @@ import androidx.compose.runtime.getValue
 import androidx.compose.runtime.rememberCoroutineScope
 import androidx.compose.ui.platform.LocalContext
 import androidx.navigation.NavController
+import androidx.paging.compose.collectAsLazyPagingItems
 import com.wbrawner.nanoflux.data.viewmodel.EntryListViewModel
 import kotlinx.coroutines.launch
 
@@ -21,7 +22,7 @@ fun EntryListScreen(
 ) {
     val loading by entryListViewModel.loading.collectAsState()
     val errorMessage by entryListViewModel.errorMessage.collectAsState()
-    val entries by entryListViewModel.entries.collectAsState(emptyList())
+    val entries = entryListViewModel.entries.collectAsLazyPagingItems()
     val coroutineScope = rememberCoroutineScope()
     errorMessage?.let {
         coroutineScope.launch {

gradle/libs.versions.toml

@@ -13,7 +13,9 @@ ktor = "2.1.0"
 material = "1.3.0"
 maxSdk = "33"
 minSdk = "21"
+paging-compose = "1.0.0-alpha17"
 room = "2.4.3"
+room-paging = "2.5.0-beta02"
 versionCode = "1"
 versionName = "1.0"
 work = "2.7.1"
@@ -24,6 +26,7 @@ accompanist-swiperefresh = { module = "com.google.accompanist:accompanist-swiper
 accompanist-webview = { module = "com.google.accompanist:accompanist-webview", version.ref = "accompanist" }
 androidx-core = { module = "androidx.core:core-ktx", version.ref = "androidx-core" }
 androidx-appcompat = { module = "androidx.appcompat:appcompat", version.ref = "androidx-appcompat" }
+androidx-paging = { module = "androidx.paging:paging-compose", version.ref = "paging-compose" }
 material = { module = "com.google.android.material:material", version.ref = "material" }
 compose-compiler = { module = "androidx.compose.compiler:compiler", version.ref = "compose-compiler" }
 compose-ui = { module = "androidx.compose.ui:ui", version.ref = "compose-ui" }

network/src/main/java/com/wbrawner/nanoflux/network/EntryAndFeedPagingSource.kt

@@ -0,0 +1,50 @@
+package com.wbrawner.nanoflux.network
+
+import androidx.paging.PagingSource
+import androidx.paging.PagingState
+import com.wbrawner.nanoflux.network.repository.EntryRepository
+import com.wbrawner.nanoflux.network.repository.EntryStatus
+import com.wbrawner.nanoflux.storage.model.EntryAndFeed
+import timber.log.Timber
+
+class EntryAndFeedPagingSource(
+    private val entryRepository: EntryRepository,
+    private val entryStatus: EntryStatus? = null
+) : PagingSource<Int, EntryAndFeed>() {
+    init {
+        Timber.tag("Nanoflux").d("EntryAndFeedPagingSource created")
+    }
+
+    override fun getRefreshKey(state: PagingState<Int, EntryAndFeed>): Int? = state.anchorPosition
+        ?.let { anchorPosition ->
+            val anchorPage = state.closestPageToPosition(anchorPosition)
+            anchorPage?.prevKey?.plus(1) ?: anchorPage?.nextKey?.minus(1)
+        }
+
+    override suspend fun load(params: LoadParams<Int>): LoadResult<Int, EntryAndFeed> {
+        return try {
+            val nextPageNumber = params.key ?: 1
+            val offset = params.loadSize * (nextPageNumber - 1)
+            val nextKey = if (offset + params.loadSize < entryRepository.count()) {
+                nextPageNumber + 1
+            } else {
+                null
+            }
+            Timber.tag("Nanoflux").d("Loading data at page $nextPageNumber")
+            val loadFunction = when (entryStatus) {
+                EntryStatus.UNREAD -> entryRepository::loadUnread
+                EntryStatus.HISTORY -> entryRepository::loadRead
+                EntryStatus.STARRED -> entryRepository::loadStarred
+                else -> entryRepository::load
+            }
+            LoadResult.Page(
+                data = loadFunction(params.loadSize, offset),
+                prevKey = null,
+                nextKey = nextKey
+            )
+        } catch (e: Exception) {
+            Timber.e("Failed to load page", e)
+            LoadResult.Error(e)
+        }
+    }
+}

network/src/main/java/com/wbrawner/nanoflux/network/repository/EntryRepository.kt

@@ -8,7 +8,10 @@ import com.wbrawner.nanoflux.storage.model.Entry
 import com.wbrawner.nanoflux.storage.model.EntryAndFeed
 import io.ktor.http.*
 import io.ktor.util.network.*
+import kotlinx.coroutines.CoroutineScope
+import kotlinx.coroutines.Dispatchers
 import kotlinx.coroutines.flow.Flow
+import kotlinx.coroutines.launch
 import timber.log.Timber
 import java.io.IOException
 import javax.inject.Inject
@@ -20,41 +23,36 @@ class EntryRepository @Inject constructor(
     private val entryDao: EntryDao,
     private val logger: Timber.Tree
 ) {
-    fun observeRead(): Flow<List<EntryAndFeed>> = entryDao.observeRead()
+    fun observeRead() = entryDao.observeRead()
-    fun observeStarred(): Flow<List<EntryAndFeed>> = entryDao.observeStarred()
+    fun observeStarred() = entryDao.observeStarred()
-    fun observeUnread(): Flow<List<EntryAndFeed>> = entryDao.observeUnread()
+    fun observeUnread() = entryDao.observeUnread()
 
-    fun getCount(): Long = entryDao.getCount()
+    suspend fun count(): Long = entryDao.count()
 
-    suspend fun getAll(fetch: Boolean = false, afterId: Long? = null): List<EntryAndFeed> {
+    suspend fun fetch(afterId: Long? = null) {
-        if (fetch) {
+        getEntries { page ->
-            getEntries { page ->
+            apiService.getEntries(
-                apiService.getEntries(
+                order = Entry.Order.PUBLISHED_AT,
-                    order = Entry.Order.PUBLISHED_AT,
+                direction = Entry.SortDirection.DESC,
-                    direction = Entry.SortDirection.DESC,
+                offset = 100L * page,
-                    offset = 100L * page,
+                limit = 100,
-                    limit = 100,
+                afterEntryId = afterId
-                    afterEntryId = afterId
+            )
-                )
-            }
         }
-        return entryDao.getAll()
     }
 
-    suspend fun getAllUnread(fetch: Boolean = false): List<EntryAndFeed> {
+    suspend fun load(limit: Int, offset: Int) = entryDao.load(limit, offset)
-        if (fetch) {
+    suspend fun loadRead(limit: Int, offset: Int) = entryDao.loadRead(limit, offset)
-            getEntries { page ->
+    suspend fun loadUnread(limit: Int, offset: Int) = entryDao.loadUnread(limit, offset)
-                apiService.getEntries(
+    suspend fun loadStarred(limit: Int, offset: Int) = entryDao.loadStarred(limit, offset)
-                    offset = 100L * page,
-                    limit = 100,
-                    status = listOf(Entry.Status.UNREAD)
-                )
-            }
-        }
-        return entryDao.getAllUnread()
-    }
 
-    suspend fun getEntry(id: Long): Flow<EntryAndFeed> {
+    suspend fun getEntry(id: Long): EntryAndFeed? = entryDao.get(id)
+        ?: run {
+            entryDao.insertAll(apiService.getEntry(id))
+            entryDao.get(id)
+        }
+
+    suspend fun observeEntry(id: Long): Flow<EntryAndFeed> {
         val entry = entryDao.observe(id)
         if (entryDao.get(id) == null) {
             entryDao.insertAll(apiService.getEntry(id))

storage/build.gradle.kts

@@ -51,6 +51,7 @@ dependencies {
     implementation(libs.preference)
     implementation(libs.room.ktx)
     kapt(libs.room.kapt)
+    api(libs.androidx.paging)
     implementation(libs.bundles.coroutines)
     implementation(libs.kotlinx.serialization)
     implementation(libs.hilt.android.core)

storage/src/main/java/com/wbrawner/nanoflux/storage/dao/EntryDao.kt

@@ -8,7 +8,7 @@ import kotlinx.coroutines.flow.Flow
 @Dao
 interface EntryDao {
     @Query("SELECT COUNT(*) FROM Entry")
-    fun getCount(): Long
+    suspend fun count(): Long
 
     @Transaction
     @Query("SELECT * FROM Entry ORDER BY publishedAt DESC")
@@ -35,12 +35,20 @@ interface EntryDao {
     fun observeUnread(): Flow<List<EntryAndFeed>>
 
     @Transaction
-    @Query("SELECT * FROM Entry ORDER BY publishedAt DESC")
+    @Query("SELECT * FROM Entry ORDER BY publishedAt DESC LIMIT :limit OFFSET :offset")
-    fun getAll(): List<EntryAndFeed>
+    suspend fun load(limit: Int, offset: Int): List<EntryAndFeed>
 
     @Transaction
-    @Query("SELECT * FROM Entry WHERE status = \"UNREAD\" ORDER BY createdAt DESC")
+    @Query("SELECT * FROM Entry WHERE status = \"READ\" ORDER BY createdAt DESC LIMIT :limit OFFSET :offset")
-    fun getAllUnread(): List<EntryAndFeed>
+    suspend fun loadRead(limit: Int, offset: Int): List<EntryAndFeed>
+
+    @Transaction
+    @Query("SELECT * FROM Entry WHERE status = \"UNREAD\" ORDER BY createdAt DESC LIMIT :limit OFFSET :offset")
+    suspend fun loadUnread(limit: Int, offset: Int): List<EntryAndFeed>
+
+    @Transaction
+    @Query("SELECT * FROM Entry WHERE starred = 1 ORDER BY publishedAt DESC LIMIT :limit OFFSET :offset")
+    suspend fun loadStarred(limit: Int, offset: Int): List<EntryAndFeed>
 
     @Transaction
     @Query("SELECT * FROM Entry WHERE id = :id")