app: add support for refreshing hottest posts list

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

app/src/main/java/dev/msfjarvis/lobsters/ui/main/LobstersApp.kt

@@ -1,11 +1,14 @@
 package dev.msfjarvis.lobsters.ui.main
 
+import androidx.compose.animation.ExperimentalAnimationApi
+import androidx.compose.foundation.clickable
 import androidx.compose.foundation.layout.padding
 import androidx.compose.foundation.lazy.rememberLazyListState
 import androidx.compose.material.BottomNavigation
 import androidx.compose.material.BottomNavigationItem
 import androidx.compose.material.Scaffold
 import androidx.compose.material.Text
+import androidx.compose.material.TopAppBar
 import androidx.compose.runtime.Composable
 import androidx.compose.runtime.collectAsState
 import androidx.compose.runtime.getValue
@@ -13,6 +16,7 @@ import androidx.compose.runtime.rememberCoroutineScope
 import androidx.compose.ui.Modifier
 import androidx.compose.ui.platform.testTag
 import androidx.compose.ui.res.stringResource
+import androidx.compose.ui.unit.dp
 import androidx.lifecycle.viewmodel.compose.viewModel
 import androidx.navigation.compose.KEY_ROUTE
 import androidx.navigation.compose.NavHost
@@ -21,6 +25,7 @@ import androidx.navigation.compose.currentBackStackEntryAsState
 import androidx.navigation.compose.navigate
 import androidx.navigation.compose.rememberNavController
 import androidx.paging.compose.collectAsLazyPagingItems
+import dev.msfjarvis.lobsters.R
 import dev.msfjarvis.lobsters.ui.navigation.Destination
 import dev.msfjarvis.lobsters.ui.posts.HottestPosts
 import dev.msfjarvis.lobsters.ui.posts.SavedPosts
@@ -51,6 +56,12 @@ fun LobstersApp() {
   }
 
   Scaffold(
+    topBar = {
+      LobstersTopBar(
+        currentDestination = currentDestination,
+        reloadPosts = { viewModel.reloadPosts() },
+      )
+    },
     bottomBar = {
       LobstersBottomNav(
         currentDestination,
@@ -80,6 +91,33 @@ fun LobstersApp() {
   }
 }
 
+@OptIn(ExperimentalAnimationApi::class)
+@Composable
+fun LobstersTopBar(
+  currentDestination: Destination,
+  reloadPosts: () -> Unit,
+) {
+  TopAppBar(
+    title = {
+      Text(
+        text = stringResource(id = R.string.app_name),
+        modifier = Modifier.padding(vertical = 8.dp),
+      )
+    },
+    actions = {
+      if (currentDestination == Destination.Hottest) {
+        IconResource(
+          resourceId = R.drawable.ic_refresh_24px,
+          contentDescription = stringResource(id = R.string.refresh_posts_content_description),
+          modifier = Modifier
+            .padding(horizontal = 8.dp, vertical = 8.dp)
+            .clickable { reloadPosts() },
+        )
+      }
+    }
+  )
+}
+
 @Composable
 fun LobstersBottomNav(
   currentDestination: Destination,

app/src/main/java/dev/msfjarvis/lobsters/ui/viewmodel/LobstersViewModel.kt

@@ -35,6 +35,10 @@ class LobstersViewModel @Inject constructor(
     }.launchIn(viewModelScope)
   }
 
+  fun reloadPosts() {
+    pagingSource.invalidate()
+  }
+
   fun toggleSave(post: SavedPost) {
     viewModelScope.launch {
       val isSaved = lobstersRepository.isPostSaved(post.shortId)

app/src/main/res/drawable/ic_refresh_24px.xml

@@ -0,0 +1,9 @@
+<vector xmlns:android="http://schemas.android.com/apk/res/android"
+  android:width="24dp"
+  android:height="24dp"
+  android:viewportWidth="24"
+  android:viewportHeight="24">
+  <path
+    android:fillColor="#FF000000"
+    android:pathData="M17.65,6.35C16.2,4.9 14.21,4 12,4c-4.42,0 -7.99,3.58 -7.99,8s3.57,8 7.99,8c3.73,0 6.84,-2.55 7.73,-6h-2.08c-0.82,2.33 -3.04,4 -5.65,4 -3.31,0 -6,-2.69 -6,-6s2.69,-6 6,-6c1.66,0 3.14,0.69 4.22,1.78L13,11h7V4l-2.35,2.35z" />
+</vector>

app/src/main/res/values/strings.xml

@@ -8,4 +8,5 @@
   <string name="avatar_content_description">%1$s\'s avatar</string>
   <string name="add_to_saved_posts">Add to saved posts</string>
   <string name="remove_from_saved_posts">Remove from saved posts</string>
+  <string name="refresh_posts_content_description">Refresh posts</string>
 </resources>