android: refactor and extract things from LobstersApp

android/src/main/kotlin/dev/msfjarvis/claw/android/ui/ColorUtils.kt

@@ -1,29 +0,0 @@
-package dev.msfjarvis.claw.android.ui
-
-import android.content.Context
-import android.os.Build
-import androidx.compose.foundation.isSystemInDarkTheme
-import androidx.compose.material3.ColorScheme
-import androidx.compose.material3.dynamicDarkColorScheme
-import androidx.compose.material3.dynamicLightColorScheme
-import androidx.compose.runtime.Composable
-import dev.msfjarvis.claw.common.theme.DarkThemeColors
-import dev.msfjarvis.claw.common.theme.LightThemeColors
-
-@Composable
-fun decideColorScheme(context: Context): ColorScheme {
-  val isDarkTheme = isSystemInDarkTheme()
-  return if (Build.VERSION.SDK_INT >= 31) {
-    if (isDarkTheme) {
-      dynamicDarkColorScheme(context)
-    } else {
-      dynamicLightColorScheme(context)
-    }
-  } else {
-    if (isDarkTheme) {
-      DarkThemeColors
-    } else {
-      LightThemeColors
-    }
-  }
-}

android/src/main/kotlin/dev/msfjarvis/claw/android/ui/LobstersApp.kt

@@ -12,10 +12,7 @@ import androidx.compose.runtime.mutableStateOf
 import androidx.compose.runtime.remember
 import androidx.compose.runtime.setValue
 import androidx.compose.ui.Modifier
-import androidx.compose.ui.geometry.Offset
 import androidx.compose.ui.graphics.Color
-import androidx.compose.ui.input.nestedscroll.NestedScrollConnection
-import androidx.compose.ui.input.nestedscroll.NestedScrollSource
 import androidx.compose.ui.input.nestedscroll.nestedScroll
 import androidx.compose.ui.platform.LocalContext
 import androidx.compose.ui.platform.LocalUriHandler
@@ -35,8 +32,6 @@ import dev.msfjarvis.claw.common.comments.LocalHTMLConverter
 import dev.msfjarvis.claw.common.theme.LobstersTheme
 import dev.msfjarvis.claw.common.urllauncher.UrlLauncher
 
-private const val ScrollDelta = 50
-
 @OptIn(ExperimentalMaterial3Api::class)
 @Composable
 fun LobstersApp(
@@ -45,34 +40,19 @@ fun LobstersApp(
   htmlConverter: HTMLConverter,
   setWebUri: (String) -> Unit,
 ) {
+  var isFabVisible by remember { mutableStateOf(false) }
+
   val systemUiController = rememberSystemUiController()
   val networkListState = rememberLazyListState()
   val savedListState = rememberLazyListState()
   val navController = rememberNavController()
   val postActions = rememberPostActions(urlLauncher, navController, viewModel)
-  // The destination needs to be tracked here rather than used directly since
+  val currentDestination by currentNavigationDestination(navController)
-  // `NavController#currentDestination` is not a Composable state.
+  val nestedScrollConnection = rememberNestedScrollConnection { isFabVisible = it }
-  var currentDestination by remember { mutableStateOf<String?>(null) }
-  var isFabVisible by remember { mutableStateOf(false) }
-  val nestedScrollConnection = remember {
-    object : NestedScrollConnection {
-      override fun onPreScroll(available: Offset, source: NestedScrollSource): Offset {
-        val delta = available.y
 
-        if (delta > ScrollDelta) {
+  val networkPosts = viewModel.pagerFlow.collectAsLazyPagingItems()
-          isFabVisible = true
+  val savedPosts by viewModel.savedPosts.collectAsState(emptyList())
-        } else if (delta < -ScrollDelta) {
-          isFabVisible = false
-        }
 
-        // We didn't consume any offset here so return Offset.Zero
-        return Offset.Zero
-      }
-    }
-  }
-  navController.addOnDestinationChangedListener { _, destination, _ ->
-    currentDestination = destination.route ?: Destinations.Hottest.getRoute()
-  }
   LobstersTheme(
     LocalUriHandler provides urlLauncher,
     LocalHTMLConverter provides htmlConverter,
@@ -85,8 +65,6 @@ fun LobstersApp(
         systemUiController.setStatusBarColor(color = statusBarColor)
         systemUiController.setNavigationBarColor(color = Color.Transparent)
       }
-      val networkPosts = viewModel.pagerFlow.collectAsLazyPagingItems()
-      val savedPosts by viewModel.savedPosts.collectAsState(emptyList())
 
       Scaffold(
         topBar = { ClawAppBar(modifier = Modifier.statusBarsPadding()) },

android/src/main/kotlin/dev/msfjarvis/claw/android/ui/PostActions.ext.kt

@@ -1,36 +0,0 @@
-package dev.msfjarvis.claw.android.ui
-
-import androidx.compose.runtime.Composable
-import androidx.compose.runtime.remember
-import androidx.navigation.NavController
-import dev.msfjarvis.claw.android.viewmodel.ClawViewModel
-import dev.msfjarvis.claw.common.posts.PostActions
-import dev.msfjarvis.claw.common.urllauncher.UrlLauncher
-import dev.msfjarvis.claw.database.local.SavedPost
-
-@Composable
-fun rememberPostActions(
-  urlLauncher: UrlLauncher,
-  navController: NavController,
-  viewModel: ClawViewModel,
-): PostActions {
-  return remember {
-    object : PostActions {
-      override fun viewPost(postUrl: String, commentsUrl: String) {
-        urlLauncher.openUri(postUrl.ifEmpty { commentsUrl })
-      }
-
-      override fun viewComments(postId: String) {
-        navController.navigate(Destinations.Comments.getRoute(postId))
-      }
-
-      override fun viewCommentsPage(commentsUrl: String) {
-        urlLauncher.openUri(commentsUrl)
-      }
-
-      override fun toggleSave(post: SavedPost) {
-        viewModel.toggleSave(post)
-      }
-    }
-  }
-}

android/src/main/kotlin/dev/msfjarvis/claw/android/ui/ext.kt

@@ -0,0 +1,100 @@
+package dev.msfjarvis.claw.android.ui
+
+import android.content.Context
+import android.os.Build
+import androidx.compose.foundation.isSystemInDarkTheme
+import androidx.compose.material3.ColorScheme
+import androidx.compose.material3.dynamicDarkColorScheme
+import androidx.compose.material3.dynamicLightColorScheme
+import androidx.compose.runtime.Composable
+import androidx.compose.runtime.State
+import androidx.compose.runtime.mutableStateOf
+import androidx.compose.runtime.remember
+import androidx.compose.ui.geometry.Offset
+import androidx.compose.ui.input.nestedscroll.NestedScrollConnection
+import androidx.compose.ui.input.nestedscroll.NestedScrollSource
+import androidx.navigation.NavController
+import dev.msfjarvis.claw.android.viewmodel.ClawViewModel
+import dev.msfjarvis.claw.common.posts.PostActions
+import dev.msfjarvis.claw.common.theme.DarkThemeColors
+import dev.msfjarvis.claw.common.theme.LightThemeColors
+import dev.msfjarvis.claw.common.urllauncher.UrlLauncher
+import dev.msfjarvis.claw.database.local.SavedPost
+
+// The destination needs to be tracked like this rather than used directly since
+// `NavController#currentDestination` is not a Composable state.
+@Composable
+fun currentNavigationDestination(navController: NavController): State<String?> {
+  val currentDestination = remember { mutableStateOf<String?>(null) }
+  navController.addOnDestinationChangedListener { _, destination, _ ->
+    currentDestination.value = destination.route
+  }
+  return currentDestination
+}
+
+@Composable
+fun decideColorScheme(context: Context): ColorScheme {
+  val isDarkTheme = isSystemInDarkTheme()
+  return if (Build.VERSION.SDK_INT >= 31) {
+    if (isDarkTheme) {
+      dynamicDarkColorScheme(context)
+    } else {
+      dynamicLightColorScheme(context)
+    }
+  } else {
+    if (isDarkTheme) {
+      DarkThemeColors
+    } else {
+      LightThemeColors
+    }
+  }
+}
+
+@Composable
+fun rememberPostActions(
+  urlLauncher: UrlLauncher,
+  navController: NavController,
+  viewModel: ClawViewModel,
+): PostActions {
+  return remember {
+    object : PostActions {
+      override fun viewPost(postUrl: String, commentsUrl: String) {
+        urlLauncher.openUri(postUrl.ifEmpty { commentsUrl })
+      }
+
+      override fun viewComments(postId: String) {
+        navController.navigate(Destinations.Comments.getRoute(postId))
+      }
+
+      override fun viewCommentsPage(commentsUrl: String) {
+        urlLauncher.openUri(commentsUrl)
+      }
+
+      override fun toggleSave(post: SavedPost) {
+        viewModel.toggleSave(post)
+      }
+    }
+  }
+}
+
+private const val ScrollDelta = 50
+
+@Composable
+fun rememberNestedScrollConnection(setVisibility: (Boolean) -> Unit): NestedScrollConnection {
+  return remember {
+    object : NestedScrollConnection {
+      override fun onPreScroll(available: Offset, source: NestedScrollSource): Offset {
+        val delta = available.y
+
+        if (delta > ScrollDelta) {
+          setVisibility(true)
+        } else if (delta < -ScrollDelta) {
+          setVisibility(false)
+        }
+
+        // We didn't consume any offset here so return Offset.Zero
+        return Offset.Zero
+      }
+    }
+  }
+}