app: wire in local persistence in LobstersViewModel

Signed-off-by: Harsh Shandilya <me@msfjarvis.dev>

app/src/main/java/dev/msfjarvis/lobsters/data/LobstersViewModel.kt

@@ -4,27 +4,44 @@ import androidx.hilt.lifecycle.ViewModelInject
 import androidx.lifecycle.ViewModel
 import androidx.lifecycle.viewModelScope
 import dev.msfjarvis.lobsters.api.LobstersApi
+import dev.msfjarvis.lobsters.data.source.PostsDatabase
 import dev.msfjarvis.lobsters.model.LobstersPost
+import kotlinx.coroutines.CoroutineExceptionHandler
 import kotlinx.coroutines.flow.MutableStateFlow
 import kotlinx.coroutines.flow.StateFlow
+import kotlinx.coroutines.flow.collectLatest
 import kotlinx.coroutines.launch
-
+import java.net.UnknownHostException
 
 class LobstersViewModel @ViewModelInject constructor(
   private val lobstersApi: LobstersApi,
+  database: PostsDatabase,
 ) : ViewModel() {
   private var apiPage = 1
   private val _posts = MutableStateFlow<List<LobstersPost>>(emptyList())
+  private val dao = database.postsDao()
+  private val coroutineExceptionHandler = CoroutineExceptionHandler { _, throwable ->
+    when (throwable) {
+      // Swallow UHE since that happens when there is no internet and we'll just rely on our cache
+      is UnknownHostException -> {}
+      else -> throw throwable
+    }
+  }
   val posts: StateFlow<List<LobstersPost>> get() = _posts
 
   init {
+    viewModelScope.launch {
+      dao.loadPosts().collectLatest { _posts.value = it }
+    }
     getMorePosts()
   }
 
   fun getMorePosts() {
-    viewModelScope.launch {
+    viewModelScope.launch(coroutineExceptionHandler) {
-      _posts.value += lobstersApi.getHottestPosts(apiPage)
+      val newPosts = lobstersApi.getHottestPosts(apiPage)
+      _posts.value += newPosts
       apiPage += 1
+      dao.insertPosts(*_posts.value.toTypedArray())
     }
   }
 }