Sort authors in onboarding by number of news resources

core/domain/src/main/java/com/google/samples/apps/nowinandroid/core/domain/GetPersistentSortedFollowableAuthorsStreamUseCase.kt

@@ -17,6 +17,7 @@
 package com.google.samples.apps.nowinandroid.core.domain
 
 import com.google.samples.apps.nowinandroid.core.data.repository.AuthorsRepository
+import com.google.samples.apps.nowinandroid.core.data.repository.NewsRepository
 import com.google.samples.apps.nowinandroid.core.data.repository.UserDataRepository
 import com.google.samples.apps.nowinandroid.core.domain.model.FollowableAuthor
 import javax.inject.Inject
@@ -29,11 +30,12 @@ import kotlinx.coroutines.flow.map
  * data.
  */
 class GetPersistentSortedFollowableAuthorsStreamUseCase @Inject constructor(
+    newsRepository: NewsRepository,
     authorsRepository: AuthorsRepository,
     private val userDataRepository: UserDataRepository
 ) {
     private val getSortedFollowableAuthorsStream =
-        GetSortedFollowableAuthorsStreamUseCase(authorsRepository)
+        GetSortedFollowableAuthorsStreamUseCase(newsRepository, authorsRepository)
 
     /**
      * Returns a list of authors with their associated followed state sorted alphabetically by name.

core/domain/src/main/java/com/google/samples/apps/nowinandroid/core/domain/GetSortedFollowableAuthorsStreamUseCase.kt

@@ -17,33 +17,40 @@
 package com.google.samples.apps.nowinandroid.core.domain
 
 import com.google.samples.apps.nowinandroid.core.data.repository.AuthorsRepository
+import com.google.samples.apps.nowinandroid.core.data.repository.NewsRepository
 import com.google.samples.apps.nowinandroid.core.domain.model.FollowableAuthor
 import javax.inject.Inject
 import kotlinx.coroutines.flow.Flow
-import kotlinx.coroutines.flow.map
+import kotlinx.coroutines.flow.combine
 
 /**
  * A use case which obtains a list of authors sorted alphabetically by name with their followed
  * state.
  */
 class GetSortedFollowableAuthorsStreamUseCase @Inject constructor(
+    private val newsRepository: NewsRepository,
     private val authorsRepository: AuthorsRepository
 ) {
     /**
      * Returns a list of authors with their associated followed state sorted alphabetically by name.
      *
-     * @param followedTopicIds - the set of topic ids which are currently being followed.
+     * @param followedAuthorIds - the set of topic ids which are currently being followed.
      */
     operator fun invoke(followedAuthorIds: Set<String>): Flow<List<FollowableAuthor>> {
-        return authorsRepository.getAuthorsStream().map { authors ->
+        return combine(
+            newsRepository.getNewsResourcesStream(),
+            authorsRepository.getAuthorsStream()
+        ) { resources, authors ->
+            val authorResourceCount =
+                resources.flatMap { it.authors }.groupingBy { it.id }.eachCount()
             authors
+                .sortedByDescending { authorResourceCount[it.id] }
                 .map { author ->
                     FollowableAuthor(
                         author = author,
                         isFollowed = author.id in followedAuthorIds
                     )
                 }
-                .sortedBy { it.author.name }
         }
     }
 }