Implement curated photos cache

SIKV · Jun 28, 2024 · 8516b29 · 8516b29
1 parent 8949b18
commit 8516b29
Show file tree

Hide file tree

Showing 6 changed files with 87 additions and 46 deletions.
diff --git a/data/src/main/java/com/github/sikv/photos/data/Result.kt b/data/src/main/java/com/github/sikv/photos/data/Result.kt
@@ -0,0 +1,6 @@
+package com.github.sikv.photos.data
+
+sealed class Result<out T : Any> {
+    data class Success<out T : Any>(val data: T) : Result<T>()
+    data class Error(val exception: Exception) : Result<Nothing>()
+}
diff --git a/data/src/main/java/com/github/sikv/photos/data/repository/PhotosRepository.kt b/data/src/main/java/com/github/sikv/photos/data/repository/PhotosRepository.kt
@@ -1,10 +1,11 @@
 package com.github.sikv.photos.data.repository
 
+import com.github.sikv.photos.data.Result
 import com.github.sikv.photos.domain.PhotoSource
 import com.github.sikv.photos.domain.Photo
 
 interface PhotosRepository {
     suspend fun getPhoto(id: String, source: PhotoSource): Photo?
-    suspend fun getCuratedPhotos(page: Int, perPage: Int): List<Photo>
+    suspend fun getCuratedPhotos(page: Int, perPage: Int): Result<List<Photo>>
     suspend fun searchPhotos(query: String, page: Int, perPage: Int, source: PhotoSource): List<Photo>
 }
diff --git a/data/src/main/java/com/github/sikv/photos/data/repository/impl/PhotosRepositoryImpl.kt b/data/src/main/java/com/github/sikv/photos/data/repository/impl/PhotosRepositoryImpl.kt
@@ -1,6 +1,7 @@
 package com.github.sikv.photos.data.repository.impl
 
 import com.github.sikv.photos.api.client.ApiClient
+import com.github.sikv.photos.data.Result
 import com.github.sikv.photos.data.repository.FavoritesRepository
 import com.github.sikv.photos.data.repository.PhotosRepository
 import com.github.sikv.photos.domain.Photo
@@ -23,13 +24,30 @@ class PhotosRepositoryImpl @Inject constructor(
         }
     }
 
-    override suspend fun getCuratedPhotos(page: Int, perPage: Int): List<Photo> {
-        return apiClient.pexelsClient
-            .getCuratedPhotos(page + getPageNumberComplement(PhotoSource.PEXELS), perPage)
-            .photos
-            .onEach { photo ->
-                favoritesRepository.populateFavorite(photo)
+    /**
+     * Uses Network First (stale-if-error) caching strategy (only for page 0).
+     */
+    override suspend fun getCuratedPhotos(page: Int, perPage: Int): Result<List<Photo>> {
+        try {
+            val photos = apiClient.pexelsClient
+                .getCuratedPhotos(page + getPageNumberComplement(PhotoSource.PEXELS), perPage)
+                .photos
+                .onEach { photo ->
+                    favoritesRepository.populateFavorite(photo)
+                }
+
+            if (page == 0) {
+                // TODO: Store in cache.
             }
+            return Result.Success(photos)
+        } catch (e: Exception) {
+            if (page == 0) {
+                // TODO: Read cache and return result.
+                return Result.Error(e)
+            } else {
+                return Result.Error(e)
+            }
+        }
     }
 
     override suspend fun searchPhotos(

diff --git a/.../curated-photos/src/main/java/com/github/sikv/photos/curated/CuratedPhotosPagingSource.kt b/.../curated-photos/src/main/java/com/github/sikv/photos/curated/CuratedPhotosPagingSource.kt
@@ -2,6 +2,7 @@ package com.github.sikv.photos.curated
 
 import androidx.paging.PagingSource
 import androidx.paging.PagingState
+import com.github.sikv.photos.data.Result
 import com.github.sikv.photos.data.repository.PhotosRepository
 import com.github.sikv.photos.domain.Photo
 
@@ -13,16 +14,20 @@ internal class CuratedPhotosPagingSource(
         val initialPosition = 0
         val position = params.key ?: initialPosition
 
-        return try {
-            val photos = photosRepository.getCuratedPhotos(position, params.loadSize)
+        val photosResult = photosRepository.getCuratedPhotos(position, params.loadSize)
 
-            LoadResult.Page(
-                data = photos,
-                prevKey = if (position == initialPosition) null else position - 1,
-                nextKey = if (photos.isEmpty()) null else position + 1
-            )
-        } catch (e: Exception) {
-            return LoadResult.Error(e)
+        return when (photosResult) {
+            is Result.Success -> {
+                LoadResult.Page(
+                    data = photosResult.data,
+                    prevKey = if (position == initialPosition) null else position - 1,
+                    nextKey = if (photosResult.data.isEmpty()) null else position + 1
+                )
+            }
+
+            is Result.Error -> {
+                LoadResult.Error(photosResult.exception)
+            }
         }
     }
 

diff --git a/feature/curated-photos/src/main/java/com/github/sikv/photos/curated/CuratedPhotosScreen.kt b/feature/curated-photos/src/main/java/com/github/sikv/photos/curated/CuratedPhotosScreen.kt
@@ -8,14 +8,13 @@ import androidx.compose.runtime.getValue
 import androidx.compose.ui.res.stringResource
 import androidx.hilt.navigation.compose.hiltViewModel
 import androidx.lifecycle.compose.collectAsStateWithLifecycle
+import androidx.paging.LoadState
 import androidx.paging.compose.collectAsLazyPagingItems
 import com.github.sikv.photos.compose.ui.DynamicPhotoItem
 import com.github.sikv.photos.compose.ui.Scaffold
 import com.github.sikv.photos.compose.ui.SwitchLayoutAction
 import com.github.sikv.photos.domain.Photo
 
-// TODO: Add loading indicator.
-
 @Composable
 internal fun CuratedPhotosScreen(
     onPhotoClick: (Photo) -> Unit,
@@ -25,7 +24,9 @@ internal fun CuratedPhotosScreen(
     onDownloadPhotoClick: (Photo) -> Unit,
     viewModel: CuratedPhotosViewModel = hiltViewModel(),
 ) {
-    val photos = viewModel.getCuratedPhotos().collectAsLazyPagingItems()
+    val photos = viewModel.curatedPhotos.collectAsLazyPagingItems()
+    val loadState = photos.loadState.refresh
+
     val listLayout by viewModel.listLayoutState.collectAsStateWithLifecycle()
 
     Scaffold(
@@ -37,24 +38,37 @@ internal fun CuratedPhotosScreen(
             )
         }
     ) {
-        LazyVerticalGrid(
-            columns = GridCells.Fixed(listLayout.spanCount)
-        ) {
-            items(photos.itemCount) { index ->
-                photos[index]?.let { photo ->
-                    val isFavorite by viewModel.isFavorite(photo).collectAsStateWithLifecycle(initialValue = false)
+        when (loadState) {
+            is LoadState.Loading -> {
+                // TODO: Implement.
+                Text(text = "Loading...")
+            }
+            is LoadState.Error -> {
+                // TODO: Implement.
+                Text(text = "Error!")
+            }
+            is LoadState.NotLoading -> {
+                LazyVerticalGrid(
+                    columns = GridCells.Fixed(listLayout.spanCount)
+                ) {
+                    items(photos.itemCount) { index ->
+                        photos[index]?.let { photo ->
+                            val isFavorite by viewModel.isFavorite(photo)
+                                .collectAsStateWithLifecycle(initialValue = false)
 
-                    DynamicPhotoItem(
-                        photo = photo,
-                        isFavorite = isFavorite,
-                        listLayout = listLayout,
-                        onPhotoClick = onPhotoClick,
-                        onPhotoAttributionClick = onPhotoAttributionClick,
-                        onPhotoActionsClick = onPhotoActionsClick,
-                        onToggleFavoriteClick = viewModel::toggleFavorite,
-                        onSharePhotoClick = onSharePhotoClick,
-                        onDownloadPhotoClick = onDownloadPhotoClick
-                    )
+                            DynamicPhotoItem(
+                                photo = photo,
+                                isFavorite = isFavorite,
+                                listLayout = listLayout,
+                                onPhotoClick = onPhotoClick,
+                                onPhotoAttributionClick = onPhotoAttributionClick,
+                                onPhotoActionsClick = onPhotoActionsClick,
+                                onToggleFavoriteClick = viewModel::toggleFavorite,
+                                onSharePhotoClick = onSharePhotoClick,
+                                onDownloadPhotoClick = onDownloadPhotoClick
+                            )
+                        }
+                    }
                 }
             }
         }

diff --git a/...ure/curated-photos/src/main/java/com/github/sikv/photos/curated/CuratedPhotosViewModel.kt b/...ure/curated-photos/src/main/java/com/github/sikv/photos/curated/CuratedPhotosViewModel.kt
@@ -4,7 +4,6 @@ import androidx.lifecycle.ViewModel
 import androidx.lifecycle.viewModelScope
 import androidx.paging.Pager
 import androidx.paging.PagingConfig
-import androidx.paging.PagingData
 import com.github.sikv.photos.common.PreferencesService
 import com.github.sikv.photos.config.ConfigProvider
 import com.github.sikv.photos.data.repository.FavoritesRepository2
@@ -27,6 +26,13 @@ internal class CuratedPhotosViewModel @Inject constructor(
     private val configProvider: ConfigProvider
 ) : ViewModel() {
 
+    val curatedPhotos = Pager(
+        config = configProvider.getPagingConfig(),
+        pagingSourceFactory = {
+            CuratedPhotosPagingSource(photosRepository)
+        }
+    ).flow
+
     private val mutableListLayoutState = MutableStateFlow(preferencesService.getCuratedListLayout())
     val listLayoutState: StateFlow<ListLayout> = mutableListLayoutState
 
@@ -55,15 +61,6 @@ internal class CuratedPhotosViewModel @Inject constructor(
             }
         }
     }
-
-    fun getCuratedPhotos(): Flow<PagingData<Photo>> {
-        return Pager(
-            config = configProvider.getPagingConfig(),
-            pagingSourceFactory = {
-                CuratedPhotosPagingSource(photosRepository)
-            }
-        ).flow
-    }
 }
 
 private fun ConfigProvider.getPagingConfig(): PagingConfig {