A couple proposed improvements to search.

The UX and performance of search is relatively poor because each keystroke triggers a search & update. With this changes:

1. Search queries are moved into an IO thread so that typing is smooth and data sends happend in the background.

2. Text changed are debounced by 300 millis, meaning search will not be fired off on every keystroke, but rather only when we the user stops typing for 300 millis.

app/src/main/java/com/vitorpamplona/amethyst/ui/screen/loggedIn/SearchScreen.kt

@@ -8,13 +8,10 @@ import androidx.compose.foundation.layout.Row
 import androidx.compose.foundation.layout.defaultMinSize
 import androidx.compose.foundation.layout.fillMaxHeight
 import androidx.compose.foundation.layout.fillMaxWidth
-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.itemsIndexed
-import androidx.compose.foundation.shape.CircleShape
 import androidx.compose.foundation.shape.RoundedCornerShape
 import androidx.compose.foundation.text.KeyboardOptions
 import androidx.compose.material.Divider
@@ -34,20 +31,18 @@ import androidx.compose.runtime.getValue
 import androidx.compose.runtime.livedata.observeAsState
 import androidx.compose.runtime.mutableStateOf
 import androidx.compose.runtime.remember
+import androidx.compose.runtime.rememberCoroutineScope
+import androidx.compose.runtime.setValue
 import androidx.compose.ui.Alignment
 import androidx.compose.ui.Modifier
-import androidx.compose.ui.draw.clip
 import androidx.compose.ui.graphics.Color
 import androidx.compose.ui.res.painterResource
 import androidx.compose.ui.text.font.FontWeight
 import androidx.compose.ui.text.input.KeyboardCapitalization
-import androidx.compose.ui.text.input.TextFieldValue
 import androidx.compose.ui.text.style.TextOverflow
 import androidx.compose.ui.unit.dp
 import androidx.lifecycle.viewmodel.compose.viewModel
 import androidx.navigation.NavController
-import coil.compose.AsyncImage
-import coil.compose.rememberAsyncImagePainter
 import com.vitorpamplona.amethyst.R
 import com.vitorpamplona.amethyst.model.Account
 import com.vitorpamplona.amethyst.model.Channel
@@ -55,13 +50,21 @@ import com.vitorpamplona.amethyst.model.LocalCache
 import com.vitorpamplona.amethyst.model.Note
 import com.vitorpamplona.amethyst.model.User
 import com.vitorpamplona.amethyst.service.NostrSearchEventOrUserDataSource
-import com.vitorpamplona.amethyst.service.NostrThreadDataSource
 import com.vitorpamplona.amethyst.ui.note.ChannelName
 import com.vitorpamplona.amethyst.ui.note.NoteCompose
 import com.vitorpamplona.amethyst.ui.note.UserCompose
 import com.vitorpamplona.amethyst.ui.note.UserPicture
 import com.vitorpamplona.amethyst.ui.note.UsernameDisplay
 import com.vitorpamplona.amethyst.ui.screen.loggedIn.AccountViewModel
+import kotlinx.coroutines.Dispatchers
+import kotlinx.coroutines.FlowPreview
+import kotlinx.coroutines.flow.debounce
+import kotlinx.coroutines.flow.distinctUntilChanged
+import kotlinx.coroutines.flow.filter
+import kotlinx.coroutines.flow.receiveAsFlow
+import kotlinx.coroutines.channels.Channel as CoroutineChannel
+import kotlinx.coroutines.launch
+import kotlinx.coroutines.withContext
 
 @Composable
 fun SearchScreen(accountViewModel: AccountViewModel, navController: NavController) {
@@ -81,21 +84,47 @@ fun SearchScreen(accountViewModel: AccountViewModel, navController: NavControlle
     }
 }
 
+@OptIn(FlowPreview::class)
 @Composable
 private fun SearchBar(accountViewModel: AccountViewModel, navController: NavController) {
-    val searchValue = remember { mutableStateOf(TextFieldValue("")) }
+    var searchValue by remember { mutableStateOf("") }
     val searchResults = remember { mutableStateOf<List<User>>(emptyList()) }
     val searchResultsNotes = remember { mutableStateOf<List<Note>>(emptyList()) }
     val searchResultsChannels = remember { mutableStateOf<List<Channel>>(emptyList()) }
+    val scope = rememberCoroutineScope()
 
     val onlineSearch = NostrSearchEventOrUserDataSource
 
     val isTrailingIconVisible by remember {
         derivedStateOf {
-            searchValue.value.text.isNotBlank()
+            searchValue.isNotBlank()
         }
     }
 
+    // Create a channel for processing search queries.
+    val searchTextChanges = remember {
+        CoroutineChannel<String>(CoroutineChannel.CONFLATED)
+    }
+
+    LaunchedEffect(Unit) {
+        // Wait for text changes to stop for 300 ms before firing off search.
+        withContext(Dispatchers.IO){
+            searchTextChanges.receiveAsFlow()
+                .filter { it.isNotBlank() }
+                .distinctUntilChanged()
+                .debounce(300)
+                .collect {
+                    if (it.removePrefix("npub").removePrefix("note").length >= 4)
+                        onlineSearch.search(it)
+
+                    searchResults.value = LocalCache.findUsersStartingWith(it)
+                    searchResultsNotes.value = LocalCache.findNotesStartingWith(it)
+                    searchResultsChannels.value = LocalCache.findChannelsStartingWith(it)
+                }
+        }
+
+    }
+
     DisposableEffect(Unit) {
         onDispose {
             NostrSearchEventOrUserDataSource.clear()
@@ -111,16 +140,12 @@ private fun SearchBar(accountViewModel: AccountViewModel, navController: NavCont
         verticalAlignment = Alignment.CenterVertically
     ) {
         TextField(
-            value = searchValue.value,
+            value = searchValue,
             onValueChange = {
-                searchValue.value = it
+                searchValue = it
-
+                scope.launch(Dispatchers.IO) {
-                if (it.text.removePrefix("npub").removePrefix("note").length >= 4)
+                    searchTextChanges.trySend(it)
-                    onlineSearch.search(it.text)
+                }
-
-                searchResults.value = LocalCache.findUsersStartingWith(it.text)
-                searchResultsNotes.value = LocalCache.findNotesStartingWith(it.text)
-                searchResultsChannels.value = LocalCache.findChannelsStartingWith(it.text)
             },
             shape = RoundedCornerShape(25.dp),
             keyboardOptions = KeyboardOptions.Default.copy(
@@ -147,7 +172,7 @@ private fun SearchBar(accountViewModel: AccountViewModel, navController: NavCont
                 if (isTrailingIconVisible) {
                     IconButton(
                         onClick = {
-                            searchValue.value = TextFieldValue("")
+                            searchValue = ""
                             searchResults.value = emptyList()
                             searchResultsChannels.value = emptyList()
                             searchResultsNotes.value = emptyList()
@@ -169,7 +194,8 @@ private fun SearchBar(accountViewModel: AccountViewModel, navController: NavCont
         )
     }
 
-    if (searchValue.value.text.isNotBlank()) {
+
+    if (searchValue.isNotBlank()) {
         LazyColumn(
             modifier = Modifier.fillMaxHeight(),
             contentPadding = PaddingValues(