Step.05-Solution-Build-a-Repository

Author: Jill Heske

app/src/main/java/com/example/android/devbyteviewer/repository/VideosRepository.kt

@@ -17,9 +17,39 @@
 
 package com.example.android.devbyteviewer.repository
 
-// TODO (01) Create a VideosRepository class that takes a VideosDatabase argument.
+import androidx.lifecycle.LiveData
+import androidx.lifecycle.Transformations
+import com.example.android.devbyteviewer.database.VideosDatabase
+import com.example.android.devbyteviewer.database.asDomainModel
+import com.example.android.devbyteviewer.domain.Video
+import com.example.android.devbyteviewer.network.Network
+import com.example.android.devbyteviewer.network.asDatabaseModel
+import kotlinx.coroutines.Dispatchers
+import kotlinx.coroutines.withContext
 
-// TODO (02) Define a suspend refreshVideos() function that gets data from the network and
-// inserts it into the database.
+class VideosRepository(private val database: VideosDatabase) {
 
-// TODO (03) Define a Transformations.map  to convert the DatabaseVideo list to a list of Video.
+    /**
+     * A playlist of videos that can be shown on the screen.
+     */
+    val videos: LiveData<List<Video>> =
+            Transformations.map(database.videoDao.getVideos()) {
+        it.asDomainModel()
+    }
+
+    /**
+     * Refresh the videos stored in the offline cache.
+     *
+     * This function uses the IO dispatcher to ensure the database insert database operation
+     * happens on the IO dispatcher. By switching to the IO dispatcher using `withContext` this
+     * function is now safe to call from any thread including the Main thread.
+     *
+     * To actually load the videos for use, observe [videos]
+     */
+    suspend fun refreshVideos() {
+        withContext(Dispatchers.IO) {
+            val playlist = Network.devbytes.getPlaylist().await()
+            database.videoDao.insertAll(*playlist.asDatabaseModel())
+        }
+    }
+}