UI: replace model selection screen's data stubbing; add empty view

examples/llama.android/app/src/main/java/com/example/llama/revamp/data/repository/ModelRepository.kt

@@ -51,6 +51,8 @@ interface ModelRepository {
         progressTracker: ImportProgressTracker? = null
     ): ModelInfo
 
+    suspend fun updateModelLastUsed(modelId: String)
+
     suspend fun deleteModel(modelId: String)
     suspend fun deleteModels(modelIds: List<String>)
 
@@ -230,16 +232,20 @@ class ModelRepositoryImpl @Inject constructor(
         input.close()
     }
 
-    override suspend fun deleteModel(modelId: String) {
+    override suspend fun updateModelLastUsed(modelId: String) = withContext(Dispatchers.IO) {
+        modelDao.updateLastUsed(modelId, System.currentTimeMillis())
+    }
+
+    override suspend fun deleteModel(modelId: String) = withContext(Dispatchers.IO) {
         modelDao.getModelById(modelId)?.let { model ->
             File(model.path).let {
                 if (it.exists()) { it.delete() }
             }
             modelDao.deleteModel(model)
-        }
+        } ?: Unit
     }
 
-    override suspend fun deleteModels(modelIds: List<String>) {
+    override suspend fun deleteModels(modelIds: List<String>) = withContext(Dispatchers.IO) {
         modelDao.getModelsByIds(modelIds).let { models ->
             models.forEach { model ->
                 File(model.path).let {

examples/llama.android/app/src/main/java/com/example/llama/revamp/ui/screens/ModelSelectionScreen.kt

@@ -1,24 +1,36 @@
 package com.example.llama.revamp.ui.screens
 
+import androidx.compose.foundation.layout.Arrangement
 import androidx.compose.foundation.layout.Column
 import androidx.compose.foundation.layout.Spacer
 import androidx.compose.foundation.layout.fillMaxSize
 import androidx.compose.foundation.layout.height
 import androidx.compose.foundation.layout.padding
+import androidx.compose.foundation.layout.size
+import androidx.compose.foundation.layout.width
 import androidx.compose.foundation.lazy.LazyColumn
 import androidx.compose.foundation.lazy.items
+import androidx.compose.material.icons.Icons
+import androidx.compose.material.icons.filled.Add
+import androidx.compose.material.icons.filled.FolderOpen
+import androidx.compose.material3.Button
 import androidx.compose.material3.ExperimentalMaterial3Api
+import androidx.compose.material3.Icon
+import androidx.compose.material3.MaterialTheme
 import androidx.compose.material3.Text
-import androidx.compose.material3.TextButton
 import androidx.compose.runtime.Composable
-import androidx.compose.runtime.remember
+import androidx.compose.runtime.collectAsState
+import androidx.compose.runtime.getValue
 import androidx.compose.ui.Alignment
 import androidx.compose.ui.Modifier
+import androidx.compose.ui.text.style.TextAlign
 import androidx.compose.ui.unit.dp
+import androidx.hilt.navigation.compose.hiltViewModel
 import com.example.llama.revamp.data.model.ModelInfo
 import com.example.llama.revamp.ui.components.ModelCard
 import com.example.llama.revamp.ui.components.ModelCardActions
 import com.example.llama.revamp.ui.components.PerformanceAppScaffold
+import com.example.llama.revamp.viewmodel.MainViewModel
 
 @OptIn(ExperimentalMaterial3Api::class)
 @Composable
@@ -26,9 +38,9 @@ fun ModelSelectionScreen(
     onModelSelected: (ModelInfo) -> Unit,
     onManageModelsClicked: () -> Unit,
     onMenuClicked: () -> Unit,
+    viewModel: MainViewModel = hiltViewModel(),
 ) {
-    // For demo purposes, we'll use sample models
+    val models by viewModel.availableModels.collectAsState()
-    val models = remember { ModelInfo.getSampleModels() }
 
     PerformanceAppScaffold(
         title = "Models",
@@ -41,15 +53,9 @@ fun ModelSelectionScreen(
                 .padding(paddingValues)
                 .padding(horizontal = 16.dp)
         ) {
-            TextButton(
+            if (models.isEmpty()) {
-                onClick = onManageModelsClicked,
+                EmptyModelsView(onManageModelsClicked)
-                modifier = Modifier
+            } else {
-                    .align(Alignment.End)
-                    .padding(top = 8.dp, bottom = 8.dp)
-            ) {
-                Text("Manage Models")
-            }
-
                 LazyColumn {
                     items(models) { model ->
                         ModelCard(
@@ -66,4 +72,51 @@ fun ModelSelectionScreen(
                 }
             }
         }
+    }
+}
+
+@Composable
+private fun EmptyModelsView(onManageModelsClicked: () -> Unit) {
+    Column(
+        modifier = Modifier
+            .fillMaxSize()
+            .padding(16.dp),
+        horizontalAlignment = Alignment.CenterHorizontally,
+        verticalArrangement = Arrangement.Center
+    ) {
+        Icon(
+            imageVector = Icons.Default.FolderOpen,
+            contentDescription = null,
+            modifier = Modifier.size(64.dp),
+            tint = MaterialTheme.colorScheme.primary.copy(alpha = 0.6f)
+        )
+
+        Spacer(modifier = Modifier.height(16.dp))
+
+        Text(
+            text = "No Models Available",
+            style = MaterialTheme.typography.headlineSmall
+        )
+
+        Spacer(modifier = Modifier.height(8.dp))
+
+        Text(
+            text = "Add models to get started with local LLM inference",
+            style = MaterialTheme.typography.bodyMedium,
+            textAlign = TextAlign.Center,
+            color = MaterialTheme.colorScheme.onSurfaceVariant
+        )
+
+        Spacer(modifier = Modifier.height(24.dp))
+
+        Button(onClick = onManageModelsClicked) {
+            Icon(
+                imageVector = Icons.Default.Add,
+                contentDescription = null,
+                modifier = Modifier.size(18.dp)
+            )
+            Spacer(modifier = Modifier.width(8.dp))
+            Text("Add Models")
+        }
+    }
 }

examples/llama.android/app/src/main/java/com/example/llama/revamp/viewmodel/MainViewModel.kt

@@ -1,17 +1,19 @@
 package com.example.llama.revamp.viewmodel
 
 import androidx.lifecycle.ViewModel
-import androidx.lifecycle.ViewModelProvider
 import androidx.lifecycle.viewModelScope
 import com.example.llama.revamp.data.model.ModelInfo
+import com.example.llama.revamp.data.repository.ModelRepository
 import com.example.llama.revamp.engine.InferenceEngine
 import dagger.hilt.android.lifecycle.HiltViewModel
 import kotlinx.coroutines.Job
 import kotlinx.coroutines.flow.MutableStateFlow
+import kotlinx.coroutines.flow.SharingStarted
 import kotlinx.coroutines.flow.StateFlow
 import kotlinx.coroutines.flow.asStateFlow
 import kotlinx.coroutines.flow.catch
 import kotlinx.coroutines.flow.onCompletion
+import kotlinx.coroutines.flow.stateIn
 import kotlinx.coroutines.launch
 import java.text.SimpleDateFormat
 import java.util.Date
@@ -23,7 +25,8 @@ import javax.inject.Inject
  */
 @HiltViewModel
 class MainViewModel @Inject constructor (
-    private val inferenceEngine: InferenceEngine
+    private val inferenceEngine: InferenceEngine,
+    private val modelRepository: ModelRepository,
 ) : ViewModel() {
 
     // Expose the engine state
@@ -32,6 +35,14 @@ class MainViewModel @Inject constructor (
     // Benchmark results
     val benchmarkResults: StateFlow<String?> = inferenceEngine.benchmarkResults
 
+    // Available models for selection
+    val availableModels: StateFlow<List<ModelInfo>> = modelRepository.getModels()
+        .stateIn(
+            scope = viewModelScope,
+            started = SharingStarted.WhileSubscribed(SUBSCRIPTION_TIMEOUT_MS),
+            initialValue = emptyList()
+        )
+
     // Selected model information
     private val _selectedModel = MutableStateFlow<ModelInfo?>(null)
     val selectedModel: StateFlow<ModelInfo?> = _selectedModel.asStateFlow()
@@ -52,6 +63,10 @@ class MainViewModel @Inject constructor (
      */
     fun selectModel(modelInfo: ModelInfo) {
         _selectedModel.value = modelInfo
+
+        viewModelScope.launch {
+            modelRepository.updateModelLastUsed(modelInfo.id)
+        }
     }
 
     /**
@@ -238,16 +253,14 @@ class MainViewModel @Inject constructor (
     }
 
     /**
-     * Unloads the currently loaded model.
+     * Unloads the currently loaded model after cleanup chores:
+     * - Cancel any ongoing token collection
+     * - Clear messages
      */
     suspend fun unloadModel() {
-        // Cancel any ongoing token collection
         tokenCollectionJob?.cancel()
-
-        // Clear messages
         _messages.value = emptyList()
 
-        // Unload model
         inferenceEngine.unloadModel()
     }
 
@@ -259,17 +272,10 @@ class MainViewModel @Inject constructor (
         super.onCleared()
     }
 
-    /**
+    companion object {
-     * Factory for creating MainViewModel instances.
+        private val TAG = MainViewModel::class.java.simpleName
-     */
+
-    class Factory(private val inferenceEngine: InferenceEngine) : ViewModelProvider.Factory {
+        private const val SUBSCRIPTION_TIMEOUT_MS = 5000L
-        @Suppress("UNCHECKED_CAST")
-        override fun <T : ViewModel> create(modelClass: Class<T>): T {
-            if (modelClass.isAssignableFrom(MainViewModel::class.java)) {
-                return MainViewModel(inferenceEngine) as T
-            }
-            throw IllegalArgumentException("Unknown ViewModel class")
-        }
     }
 }