refactor: handle selected contacts in a local variable

app/src/main/java/com/geeksville/mesh/model/ContactsViewModel.kt

@@ -11,12 +11,9 @@ import com.geeksville.mesh.database.entity.Packet
 import com.geeksville.mesh.repository.datastore.ChannelSetRepository
 import dagger.hilt.android.lifecycle.HiltViewModel
 import kotlinx.coroutines.Dispatchers
-import kotlinx.coroutines.flow.MutableStateFlow
 import kotlinx.coroutines.flow.SharingStarted.Companion.WhileSubscribed
-import kotlinx.coroutines.flow.asStateFlow
 import kotlinx.coroutines.flow.combine
 import kotlinx.coroutines.flow.stateIn
-import kotlinx.coroutines.flow.updateAndGet
 import kotlinx.coroutines.launch
 import java.text.DateFormat
 import java.util.Date
@@ -53,21 +50,6 @@ class ContactsViewModel @Inject constructor(
     private val packetRepository: PacketRepository,
 ) : ViewModel(), Logging {
 
-    private val _selectedContacts = MutableStateFlow(emptySet<String>())
-    val selectedContacts get() = _selectedContacts.asStateFlow()
-
-    fun updateSelectedContacts(contact: String) = _selectedContacts.updateAndGet {
-        if (it.contains(contact)) {
-            it.minus(contact)
-        } else {
-            it.plus(contact)
-        }
-    }
-
-    fun clearSelectedContacts() {
-        _selectedContacts.value = emptySet()
-    }
-
     val contactList = combine(
         nodeDB.myNodeInfo,
         packetRepository.getContacts(),
@@ -124,4 +106,4 @@ class ContactsViewModel @Inject constructor(
     fun deleteContacts(contacts: List<String>) = viewModelScope.launch(Dispatchers.IO) {
         packetRepository.deleteContacts(contacts)
     }
-}
+}

app/src/main/java/com/geeksville/mesh/ui/ContactItem.kt

@@ -1,6 +1,5 @@
 package com.geeksville.mesh.ui
 
-import android.content.res.Configuration
 import androidx.compose.animation.AnimatedVisibility
 import androidx.compose.foundation.background
 import androidx.compose.foundation.layout.Arrangement
@@ -27,7 +26,7 @@ import androidx.compose.ui.res.vectorResource
 import androidx.compose.ui.text.font.FontWeight
 import androidx.compose.ui.text.style.TextAlign
 import androidx.compose.ui.text.style.TextOverflow
-import androidx.compose.ui.tooling.preview.Preview
+import androidx.compose.ui.tooling.preview.PreviewLightDark
 import androidx.compose.ui.unit.dp
 import com.geeksville.mesh.R
 import com.geeksville.mesh.model.Contact
@@ -122,8 +121,7 @@ fun ContactItem(
     }
 }
 
-@Preview(showBackground = true)
-@Preview(showBackground = true, uiMode = Configuration.UI_MODE_NIGHT_YES)
+@PreviewLightDark
 @Composable
 private fun ContactItemPreview() {
     AppTheme {

app/src/main/java/com/geeksville/mesh/ui/ContactsFragment.kt

@@ -18,13 +18,13 @@ import androidx.compose.foundation.lazy.LazyColumn
 import androidx.compose.material.MaterialTheme
 import androidx.compose.runtime.Composable
 import androidx.compose.runtime.getValue
+import androidx.compose.runtime.toMutableStateList
 import androidx.compose.ui.Modifier
 import androidx.compose.ui.graphics.Color
 import androidx.compose.ui.platform.ComposeView
 import androidx.compose.ui.platform.ViewCompositionStrategy
 import androidx.compose.ui.unit.dp
 import androidx.fragment.app.viewModels
-import androidx.hilt.navigation.compose.hiltViewModel
 import androidx.lifecycle.compose.collectAsStateWithLifecycle
 import com.geeksville.mesh.android.Logging
 import com.geeksville.mesh.R
@@ -43,7 +43,7 @@ class ContactsFragment : ScreenFragment("Messages"), Logging {
     private val model: ContactsViewModel by viewModels()
 
     private val contacts get() = model.contactList.value
-    private val selectedList get() = model.selectedContacts.value.toList()
+    private val selectedList = emptyList<String>().toMutableStateList()
 
     private val selectedContacts get() = contacts.filter { it.contactKey in selectedList }
     private val isAllMuted get() = selectedContacts.all { it.isMuted }
@@ -63,13 +63,15 @@ class ContactsFragment : ScreenFragment("Messages"), Logging {
             actionMode = (activity as AppCompatActivity).startSupportActionMode(actionModeCallback)
         }
 
-        val selected = model.updateSelectedContacts(contact.contactKey)
-        if (selected.isEmpty()) {
+        selectedList.apply {
+            if (!remove(contact.contactKey)) add(contact.contactKey)
+        }
+        if (selectedList.isEmpty()) {
             // finish action mode when no items selected
             actionMode?.finish()
         } else {
             // show total items selected on action mode title
-            actionMode?.title = selected.size.toString()
+            actionMode?.title = selectedList.size.toString()
         }
     }
 
@@ -86,8 +88,15 @@ class ContactsFragment : ScreenFragment("Messages"), Logging {
         return ComposeView(requireContext()).apply {
             setViewCompositionStrategy(ViewCompositionStrategy.DisposeOnViewTreeLifecycleDestroyed)
             setContent {
+                val contacts by model.contactList.collectAsStateWithLifecycle()
+
                 AppTheme {
-                    ContactsScreen(model, ::onClick, ::onLongClick)
+                    ContactListView(
+                        contacts = contacts,
+                        selectedList = selectedList,
+                        onClick = ::onClick,
+                        onLongClick = ::onLongClick,
+                    )
                 }
             }
         }
@@ -171,14 +180,12 @@ class ContactsFragment : ScreenFragment("Messages"), Logging {
                 R.id.selectAllButton -> {
                     // if all selected -> unselect all
                     if (selectedList.size == contacts.size) {
-                        model.clearSelectedContacts()
+                        selectedList.clear()
                         mode.finish()
                     } else {
                         // else --> select all
-                        model.clearSelectedContacts()
-                        contacts.forEach {
-                            model.updateSelectedContacts(it.contactKey)
-                        }
+                        selectedList.clear()
+                        selectedList.addAll(contacts.map { it.contactKey })
                         actionMode?.title = contacts.size.toString()
                     }
                 }
@@ -187,7 +194,7 @@ class ContactsFragment : ScreenFragment("Messages"), Logging {
         }
 
         override fun onDestroyActionMode(mode: ActionMode) {
-            model.clearSelectedContacts()
+            selectedList.clear()
             actionMode = null
         }
     }
@@ -195,26 +202,25 @@ class ContactsFragment : ScreenFragment("Messages"), Logging {
 
 @OptIn(ExperimentalFoundationApi::class)
 @Composable
-fun ContactsScreen(
-    model: ContactsViewModel = hiltViewModel(),
+fun ContactListView(
+    contacts: List<Contact>,
+    selectedList: List<String>,
     onClick: (Contact) -> Unit,
     onLongClick: (Contact) -> Unit,
 ) {
-    val contacts by model.contactList.collectAsStateWithLifecycle(emptyList())
-    val selectedKeys by model.selectedContacts.collectAsStateWithLifecycle()
-    // val inSelectionMode by remember { derivedStateOf { selectedContacts.isNotEmpty() } }
-
     LazyColumn(
         modifier = Modifier
             .fillMaxSize()
             .padding(6.dp),
     ) {
         items(contacts, key = { it.contactKey }) { contact ->
-            val selected = selectedKeys.contains(contact.contactKey)
+            val selected = selectedList.contains(contact.contactKey)
+            val selectedColor = if (selected) Color.Gray else MaterialTheme.colors.background
+
             ContactItem(
                 contact = contact,
                 modifier = Modifier
-                    .background(color = if (selected) Color.Gray else MaterialTheme.colors.background)
+                    .background(color = selectedColor)
                     .combinedClickable(
                         onClick = { onClick(contact) },
                         onLongClick = { onLongClick(contact) },