feat: add transaction filter for zaps vs non-zaps on wallet screen

Adds filter chips (All / Zaps / Non-Zaps) to the transactions list.
Zap transactions are identified by having nostr metadata. The filter
is applied client-side via a combined Flow in WalletViewModel.

https://claude.ai/code/session_01CdNY7qYDRHJr1jhAFvVgzj

amethyst/src/main/java/com/vitorpamplona/amethyst/ui/screen/loggedIn/wallet/WalletTransactionsScreen.kt

@@ -40,6 +40,7 @@ import androidx.compose.material.icons.filled.ArrowUpward
 import androidx.compose.material.icons.filled.Refresh
 import androidx.compose.material3.CircularProgressIndicator
 import androidx.compose.material3.ExperimentalMaterial3Api
+import androidx.compose.material3.FilterChip
 import androidx.compose.material3.HorizontalDivider
 import androidx.compose.material3.Icon
 import androidx.compose.material3.IconButton
@@ -86,10 +87,11 @@ fun WalletTransactionsScreen(
         walletViewModel.fetchTransactions()
     }
 
-    val transactions by walletViewModel.transactions.collectAsState()
+    val transactions by walletViewModel.filteredTransactions.collectAsState(emptyList())
     val isLoading by walletViewModel.isLoading.collectAsState()
     val isLoadingMore by walletViewModel.isLoadingMore.collectAsState()
     val hasMore by walletViewModel.hasMoreTransactions.collectAsState()
+    val currentFilter by walletViewModel.transactionFilter.collectAsState()
 
     val listState = rememberLazyListState()
 
@@ -166,6 +168,9 @@ fun WalletTransactionsScreen(
                 modifier = Modifier.padding(padding),
                 state = listState,
             ) {
+                item {
+                    TransactionFilterRow(currentFilter) { walletViewModel.setTransactionFilter(it) }
+                }
                 items(transactions) { tx ->
                     TransactionItem(tx, accountViewModel, nav)
                     HorizontalDivider()
@@ -188,6 +193,36 @@ fun WalletTransactionsScreen(
     }
 }
 
+@Composable
+private fun TransactionFilterRow(
+    currentFilter: TransactionFilter,
+    onFilterSelected: (TransactionFilter) -> Unit,
+) {
+    Row(
+        modifier =
+            Modifier
+                .fillMaxWidth()
+                .padding(horizontal = 16.dp, vertical = 8.dp),
+        horizontalArrangement = Arrangement.spacedBy(8.dp),
+    ) {
+        FilterChip(
+            selected = currentFilter == TransactionFilter.ALL,
+            onClick = { onFilterSelected(TransactionFilter.ALL) },
+            label = { Text(stringRes(R.string.wallet_filter_all)) },
+        )
+        FilterChip(
+            selected = currentFilter == TransactionFilter.ZAPS,
+            onClick = { onFilterSelected(TransactionFilter.ZAPS) },
+            label = { Text(stringRes(R.string.wallet_filter_zaps)) },
+        )
+        FilterChip(
+            selected = currentFilter == TransactionFilter.NON_ZAPS,
+            onClick = { onFilterSelected(TransactionFilter.NON_ZAPS) },
+            label = { Text(stringRes(R.string.wallet_filter_non_zaps)) },
+        )
+    }
+}
+
 @Composable
 private fun TransactionItem(
     tx: NwcTransaction,

amethyst/src/main/java/com/vitorpamplona/amethyst/ui/screen/loggedIn/wallet/WalletViewModel.kt

@@ -39,6 +39,8 @@ import com.vitorpamplona.quartz.nip47WalletConnect.PayInvoiceSuccessResponse
 import kotlinx.coroutines.Dispatchers
 import kotlinx.coroutines.flow.MutableStateFlow
 import kotlinx.coroutines.flow.asStateFlow
+import kotlinx.coroutines.flow.combine
+import kotlinx.coroutines.flow.stateIn
 import kotlinx.coroutines.launch
 
 sealed class SendState {
@@ -70,6 +72,12 @@ sealed class ReceiveState {
     ) : ReceiveState()
 }
 
+enum class TransactionFilter {
+    ALL,
+    ZAPS,
+    NON_ZAPS,
+}
+
 class WalletViewModel : ViewModel() {
     private var account: Account? = null
 
@@ -83,7 +91,18 @@ class WalletViewModel : ViewModel() {
     val walletAlias = _walletAlias.asStateFlow()
 
     private val _transactions = MutableStateFlow<List<NwcTransaction>>(emptyList())
-    val transactions = _transactions.asStateFlow()
+
+    private val _transactionFilter = MutableStateFlow(TransactionFilter.ALL)
+    val transactionFilter = _transactionFilter.asStateFlow()
+
+    val filteredTransactions =
+        combine(_transactions, _transactionFilter) { txs, filter ->
+            when (filter) {
+                TransactionFilter.ALL -> txs
+                TransactionFilter.ZAPS -> txs.filter { it.parsedMetadata()?.nostr != null }
+                TransactionFilter.NON_ZAPS -> txs.filter { it.parsedMetadata()?.nostr == null }
+            }
+        }
 
     private val _isLoading = MutableStateFlow(false)
     val isLoading = _isLoading.asStateFlow()
@@ -336,4 +355,8 @@ class WalletViewModel : ViewModel() {
     fun clearError() {
         _error.value = null
     }
+
+    fun setTransactionFilter(filter: TransactionFilter) {
+        _transactionFilter.value = filter
+    }
 }

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

@@ -1260,6 +1260,9 @@
     <string name="wallet_incoming">Received</string>
     <string name="wallet_outgoing">Sent</string>
     <string name="wallet_refresh">Refresh</string>
+    <string name="wallet_filter_all">All</string>
+    <string name="wallet_filter_zaps">Zaps</string>
+    <string name="wallet_filter_non_zaps">Non-Zaps</string>
     <string name="route_security_filters">Security Filters</string>
     <string name="route_import_follows">Import Follows</string>