[#776] Enable ZIP 317 fees support

* [#776] Enable ZIP 317 fees support

* Deprecate ZcashSdk.MINERS_FEE

* Replace MINERS_FEE with Proposal API in Demo app

* Changelog update

* Bump SDK to 2.0.8 to produce snapshot version

CHANGELOG.md

@@ -6,6 +6,10 @@ and this library adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+### Changed
+- The SDK uses ZIP-317 fee system internally
+- `ZcashSdk.MINERS_FEE` has been deprecated, and will be removed in 2.1.0
+
 ## [2.0.7] - 2024-03-08
 
 ### Fixed

backend-lib/src/main/java/cash/z/ecc/android/sdk/internal/jni/RustBackend.kt

@@ -376,7 +376,7 @@ class RustBackend private constructor(
      */
     companion object {
         internal val rustLibraryLoader = NativeLibraryLoader("zcashwalletsdk")
-        private const val IS_USE_ZIP_317_FEES = false
+        private const val IS_USE_ZIP_317_FEES = true
 
         suspend fun loadLibrary() {
             rustLibraryLoader.load {

demo-app/src/main/java/cash/z/ecc/android/sdk/demoapp/Navigation.kt

@@ -40,6 +40,7 @@ import cash.z.ecc.android.sdk.demoapp.ui.screen.transactions.view.Transactions
 import cash.z.ecc.android.sdk.demoapp.util.AndroidApiVersion
 import cash.z.ecc.android.sdk.demoapp.util.fromResources
 import cash.z.ecc.android.sdk.internal.Twig
+import cash.z.ecc.android.sdk.model.Proposal
 import cash.z.ecc.android.sdk.model.ZcashNetwork
 import cash.z.ecc.android.sdk.type.ServerValidation
 import kotlinx.coroutines.CoroutineScope
@@ -131,6 +132,9 @@ internal fun ComposeActivity.Navigation() {
             val synchronizer = walletViewModel.synchronizer.collectAsStateWithLifecycle().value
             val walletSnapshot = walletViewModel.walletSnapshot.collectAsStateWithLifecycle().value
             val spendingKey = walletViewModel.spendingKey.collectAsStateWithLifecycle().value
+
+            val sendTransactionProposal = remember { mutableStateOf<Proposal?>(null) }
+
             if (null == synchronizer || null == walletSnapshot || null == spendingKey) {
                 // Display loading indicator
             } else {
@@ -140,10 +144,14 @@ internal fun ComposeActivity.Navigation() {
                     onSend = {
                         walletViewModel.send(it)
                     },
+                    onGetProposal = {
+                        sendTransactionProposal.value = walletViewModel.getSendProposal(it)
+                    },
                     onBack = {
                         walletViewModel.clearSendOrShieldState()
                         navController.popBackStackJustOnce(SEND)
-                    }
+                    },
+                    sendTransactionProposal = sendTransactionProposal.value
                 )
             }
         }

demo-app/src/main/java/cash/z/ecc/android/sdk/demoapp/demos/getbalance/GetBalanceFragment.kt

@@ -14,7 +14,6 @@ import cash.z.ecc.android.sdk.demoapp.databinding.FragmentGetBalanceBinding
 import cash.z.ecc.android.sdk.demoapp.ext.requireApplicationContext
 import cash.z.ecc.android.sdk.demoapp.util.SyncBlockchainBenchmarkTrace
 import cash.z.ecc.android.sdk.demoapp.util.fromResources
-import cash.z.ecc.android.sdk.ext.ZcashSdk
 import cash.z.ecc.android.sdk.ext.convertZatoshiToZecString
 import cash.z.ecc.android.sdk.internal.Twig
 import cash.z.ecc.android.sdk.model.Account
@@ -138,10 +137,10 @@ class GetBalanceFragment : BaseDemoFragment<FragmentGetBalanceBinding>() {
         }
 
         binding.shield.apply {
-            // TODO [#776]: Support variable fees
-            // TODO [#776]: https://github.com/zcash/zcash-android-wallet-sdk/issues/776
+            // This check is not entirely correct - it does not calculate the resulting fee with the new Proposal API
+            // Note that the entire fragment-based old Demo app will be removed as part of [#973]
             visibility =
-                if ((transparentBalance ?: Zatoshi(0)) > ZcashSdk.MINERS_FEE) {
+                if ((transparentBalance ?: Zatoshi(0)).value > 0L) {
                     View.VISIBLE
                 } else {
                     View.GONE

demo-app/src/main/java/cash/z/ecc/android/sdk/demoapp/ui/screen/balance/view/BalanceView.kt

@@ -26,12 +26,11 @@ import cash.z.ecc.android.sdk.demoapp.R
 import cash.z.ecc.android.sdk.demoapp.fixture.WalletSnapshotFixture
 import cash.z.ecc.android.sdk.demoapp.ui.screen.home.viewmodel.SendState
 import cash.z.ecc.android.sdk.demoapp.ui.screen.home.viewmodel.WalletSnapshot
-import cash.z.ecc.android.sdk.ext.ZcashSdk
 import cash.z.ecc.android.sdk.model.toZecString
 
 @Preview(name = "Balance")
-@Composable
 @Suppress("ktlint:standard:function-naming")
+@Composable
 private fun ComposablePreview() {
     MaterialTheme {
         Balance(
@@ -152,10 +151,8 @@ private fun BalanceMainContent(
             )
         )
 
-        // TODO [#776]: Support variable fees
-        // TODO [#776]: https://github.com/zcash/zcash-android-wallet-sdk/issues/776
-        // This check will not be correct with variable fees
-        if (walletSnapshot.transparentBalance > ZcashSdk.MINERS_FEE) {
+        // This check is not entirely correct - it does not calculate the resulting fee with the new Proposal API
+        if (walletSnapshot.transparentBalance.value > 0L) {
             // Note this implementation does not guard against multiple clicks
             Button(onClick = onShieldFunds) {
                 Text(stringResource(id = R.string.action_shield))

demo-app/src/main/java/cash/z/ecc/android/sdk/demoapp/ui/screen/home/viewmodel/WalletSnapshot.kt

@@ -2,7 +2,6 @@ package cash.z.ecc.android.sdk.demoapp.ui.screen.home.viewmodel
 
 import cash.z.ecc.android.sdk.Synchronizer
 import cash.z.ecc.android.sdk.block.processor.CompactBlockProcessor
-import cash.z.ecc.android.sdk.ext.ZcashSdk
 import cash.z.ecc.android.sdk.model.PercentDecimal
 import cash.z.ecc.android.sdk.model.WalletBalance
 import cash.z.ecc.android.sdk.model.Zatoshi
@@ -16,13 +15,11 @@ data class WalletSnapshot(
     val progress: PercentDecimal,
     val synchronizerError: SynchronizerError?
 ) {
-    // TODO [#776]: Support variable fees
-    // TODO [#776]: https://github.com/zcash/zcash-android-wallet-sdk/issues/776
     // Note: the wallet is effectively empty if it cannot cover the miner's fee
-    val hasFunds =
-        saplingBalance.available.value >
-            (ZcashSdk.MINERS_FEE.value.toDouble() / Zatoshi.ZATOSHI_PER_ZEC) // 0.0001
-    val hasSaplingBalance = saplingBalance.total.value > 0
+    // This check is not entirely correct - it does not calculate the resulting fee with the new Proposal API
+    val hasFunds = saplingBalance.available.value > 0L
+
+    val hasSaplingBalance = saplingBalance.total.value > 0L
 
     val isSendEnabled: Boolean get() = status == Synchronizer.Status.SYNCED && hasFunds
 }

demo-app/src/main/java/cash/z/ecc/android/sdk/demoapp/ui/screen/home/viewmodel/WalletViewModel.kt

@@ -22,12 +22,14 @@ import cash.z.ecc.android.sdk.model.Account
 import cash.z.ecc.android.sdk.model.BlockHeight
 import cash.z.ecc.android.sdk.model.PercentDecimal
 import cash.z.ecc.android.sdk.model.PersistableWallet
+import cash.z.ecc.android.sdk.model.Proposal
 import cash.z.ecc.android.sdk.model.TransactionSubmitResult
 import cash.z.ecc.android.sdk.model.WalletAddresses
 import cash.z.ecc.android.sdk.model.WalletBalance
 import cash.z.ecc.android.sdk.model.Zatoshi
 import cash.z.ecc.android.sdk.model.ZcashNetwork
 import cash.z.ecc.android.sdk.model.ZecSend
+import cash.z.ecc.android.sdk.model.proposeSend
 import cash.z.ecc.android.sdk.model.send
 import cash.z.ecc.android.sdk.tool.DerivationTool
 import co.electriccoin.lightwallet.client.model.LightWalletEndpoint
@@ -50,6 +52,7 @@ import kotlinx.coroutines.flow.map
 import kotlinx.coroutines.flow.stateIn
 import kotlinx.coroutines.flow.toList
 import kotlinx.coroutines.launch
+import kotlinx.coroutines.runBlocking
 import kotlinx.coroutines.sync.Mutex
 import kotlinx.coroutines.sync.withLock
 import kotlinx.coroutines.withContext
@@ -57,6 +60,7 @@ import kotlin.time.Duration.Companion.seconds
 
 // To make this more multiplatform compatible, we need to remove the dependency on Context
 // for loading the preferences.
+@Suppress("TooManyFunctions")
 class WalletViewModel(application: Application) : AndroidViewModel(application) {
     private val walletCoordinator = WalletCoordinator.getInstance(application)
 
@@ -212,12 +216,36 @@ class WalletViewModel(application: Application) : AndroidViewModel(application)
         }
     }
 
+    /**
+     * Synchronously provides proposal object for the given [spendingKey] and [zecSend] objects
+     */
+    fun getSendProposal(zecSend: ZecSend): Proposal? {
+        if (sendState.value is SendState.Sending) {
+            return null
+        }
+
+        val synchronizer = synchronizer.value
+
+        return if (null != synchronizer) {
+            // Calling the proposal API within a blocking coroutine should be fine for the showcase purpose
+            runBlocking {
+                val spendingKey = spendingKey.filterNotNull().first()
+                kotlin.runCatching {
+                    synchronizer.proposeSend(spendingKey, zecSend)
+                }.onFailure {
+                    Twig.error(it) { "Failed to get transaction proposal" }
+                }.getOrNull()
+            }
+        } else {
+            error("Unable to send funds because synchronizer is not loaded.")
+        }
+    }
+
     /**
      * Asynchronously shields transparent funds.  Note that two shielding operations cannot occur at the same time.
      *
      * Observe the result via [sendState].
      */
-    @Suppress("MagicNumber")
     fun shieldFunds() {
         if (sendState.value is SendState.Sending) {
             return
@@ -230,6 +258,7 @@ class WalletViewModel(application: Application) : AndroidViewModel(application)
             viewModelScope.launch {
                 val spendingKey = spendingKey.filterNotNull().first()
                 kotlin.runCatching {
+                    @Suppress("MagicNumber")
                     synchronizer.proposeShielding(spendingKey.account, Zatoshi(100000))?.let {
                         synchronizer.createProposedTransactions(
                             it,

demo-app/src/main/java/cash/z/ecc/android/sdk/demoapp/ui/screen/send/view/SendView.kt

@@ -7,6 +7,7 @@ import androidx.compose.foundation.layout.Row
 import androidx.compose.foundation.layout.Spacer
 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.rememberScrollState
@@ -43,6 +44,7 @@ import cash.z.ecc.android.sdk.demoapp.util.fromResources
 import cash.z.ecc.android.sdk.fixture.WalletFixture
 import cash.z.ecc.android.sdk.model.Memo
 import cash.z.ecc.android.sdk.model.MonetarySeparators
+import cash.z.ecc.android.sdk.model.Proposal
 import cash.z.ecc.android.sdk.model.ZcashNetwork
 import cash.z.ecc.android.sdk.model.ZecSend
 import cash.z.ecc.android.sdk.model.ZecSendExt
@@ -60,18 +62,22 @@ private fun ComposablePreview() {
             walletSnapshot = WalletSnapshotFixture.new(),
             sendState = SendState.None,
             onSend = {},
-            onBack = {}
+            onGetProposal = {},
+            onBack = {},
+            sendTransactionProposal = null
         )
     }
 }
 
 @Composable
-@Suppress("ktlint:standard:function-naming")
+@Suppress("ktlint:standard:function-naming", "LongParameterList")
 fun Send(
     walletSnapshot: WalletSnapshot,
     sendState: SendState,
     onSend: (ZecSend) -> Unit,
-    onBack: () -> Unit
+    onGetProposal: (ZecSend) -> Unit,
+    onBack: () -> Unit,
+    sendTransactionProposal: Proposal?,
 ) {
     Scaffold(topBar = {
         SendTopAppBar(onBack)
@@ -80,7 +86,9 @@ fun Send(
             paddingValues = paddingValues,
             walletSnapshot = walletSnapshot,
             sendState = sendState,
-            onSend = onSend
+            onSend = onSend,
+            onGetProposal = onGetProposal,
+            sendTransactionProposal = sendTransactionProposal
         )
     }
 }
@@ -105,12 +113,14 @@ private fun SendTopAppBar(onBack: () -> Unit) {
 }
 
 @Composable
-@Suppress("LongMethod", "ktlint:standard:function-naming")
+@Suppress("LongMethod", "ktlint:standard:function-naming", "LongParameterList")
 private fun SendMainContent(
     paddingValues: PaddingValues,
     walletSnapshot: WalletSnapshot,
     sendState: SendState,
-    onSend: (ZecSend) -> Unit
+    onSend: (ZecSend) -> Unit,
+    onGetProposal: (ZecSend) -> Unit,
+    sendTransactionProposal: Proposal?,
 ) {
     val context = LocalContext.current
     val monetarySeparators = MonetarySeparators.current(locale = Locale.US)
@@ -229,6 +239,36 @@ private fun SendMainContent(
             Text(validation.joinToString(", "))
         }
 
+        Spacer(modifier = Modifier.height(16.dp))
+
+        Button(
+            onClick = {
+                val zecSendValidation =
+                    ZecSendExt.new(
+                        context,
+                        recipientAddressString,
+                        amountZecString,
+                        memoString,
+                        monetarySeparators
+                    )
+
+                when (zecSendValidation) {
+                    is ZecSendExt.ZecSendValidation.Valid -> onGetProposal(zecSendValidation.zecSend)
+                    is ZecSendExt.ZecSendValidation.Invalid -> validation = zecSendValidation.validationErrors
+                }
+            },
+            // Needs actual validation
+            enabled = amountZecString.isNotBlank() && recipientAddressString.isNotBlank()
+        ) {
+            Text(stringResource(id = R.string.send_proposal_button))
+        }
+
+        if (sendTransactionProposal != null) {
+            Text(stringResource(id = R.string.send_proposal_status, sendTransactionProposal.toPrettyString()))
+
+            Spacer(modifier = Modifier.height(16.dp))
+        }
+
         Button(
             onClick = {
                 val zecSendValidation =

demo-app/src/main/res/values/strings.xml

@@ -73,6 +73,9 @@
     <string name="send_memo">Memo</string>
     <string name="send_button">Send</string>
 
+    <string name="send_proposal_button">Get Proposal</string>
+    <string name="send_proposal_status">Proposal:\n<xliff:g id="proposal" example="Fee:0.001...">%1$s</xliff:g></string>
+
     <string name="server_textfield_value"><xliff:g id="host" example="example.com">%1$s</xliff:g>:<xliff:g id="port" example="508">%2$d</xliff:g></string>
     <string name="server_textfield_hint">&lt;host&gt;:&lt;port&gt;</string>
     <string name="server_textfield_error">Invalid server</string>

gradle.properties

@@ -26,7 +26,7 @@ ZCASH_ASCII_GPG_KEY=
 # Configures whether release is an unstable snapshot, therefore published to the snapshot repository.
 IS_SNAPSHOT=true
 
-LIBRARY_VERSION=2.0.7
+LIBRARY_VERSION=2.0.8
 
 # Kotlin compiler warnings can be considered errors, failing the build.
 ZCASH_IS_TREAT_WARNINGS_AS_ERRORS=true

sdk-incubator-lib/src/main/java/cash/z/ecc/android/sdk/model/ZecSend.kt

@@ -18,3 +18,13 @@ suspend fun Synchronizer.send(
     ),
     spendingKey
 )
+
+suspend fun Synchronizer.proposeSend(
+    spendingKey: UnifiedSpendingKey,
+    send: ZecSend
+) = proposeTransfer(
+    spendingKey.account,
+    send.destination.address,
+    send.amount,
+    send.memo.value
+)

sdk-lib/src/androidTest/java/cash/z/ecc/android/sdk/integration/TestnetIntegrationTest.kt

@@ -5,7 +5,6 @@ import androidx.test.platform.app.InstrumentationRegistry
 import cash.z.ecc.android.sdk.Synchronizer
 import cash.z.ecc.android.sdk.Synchronizer.Status.SYNCED
 import cash.z.ecc.android.sdk.WalletInitMode
-import cash.z.ecc.android.sdk.ext.ZcashSdk
 import cash.z.ecc.android.sdk.ext.onFirst
 import cash.z.ecc.android.sdk.internal.Twig
 import cash.z.ecc.android.sdk.model.Account
@@ -116,7 +115,7 @@ class TestnetIntegrationTest : ScopedTest() {
             synchronizer.proposeTransfer(
                 spendingKey.account,
                 toAddress,
-                ZcashSdk.MINERS_FEE,
+                Zatoshi(10_000L),
                 "first mainnet tx from the SDK"
             ),
             spendingKey

sdk-lib/src/androidTest/java/cash/z/ecc/android/sdk/sample/TransparentRestoreSample.kt

@@ -3,7 +3,6 @@
 package cash.z.ecc.android.sdk.sample
 
 import androidx.test.filters.LargeTest
-import cash.z.ecc.android.sdk.ext.ZcashSdk
 import cash.z.ecc.android.sdk.model.BlockHeight
 import cash.z.ecc.android.sdk.model.Zatoshi
 import cash.z.ecc.android.sdk.model.ZcashNetwork
@@ -20,7 +19,7 @@ import org.junit.Test
  * the same data.
  */
 class TransparentRestoreSample {
-    val txValue = Zatoshi(ZcashSdk.MINERS_FEE.value / 2)
+    val txValue = Zatoshi(Zatoshi(10_000L).value / 2)
 
 //    val walletA = SimpleWallet(SEED_PHRASE, "WalletA")
 

sdk-lib/src/main/java/cash/z/ecc/android/sdk/ext/ZcashSdk.kt

@@ -8,11 +8,19 @@ import cash.z.ecc.android.sdk.model.Zatoshi
  * becomes easier to reduce privacy by segmenting the anonymity set of users, particularly as it
  * relates to network requests.
  */
-@Suppress("MagicNumber")
 object ZcashSdk {
     /**
      * Miner's fee in zatoshi.
      */
+    @Suppress("MagicNumber")
+    @Deprecated(
+        message = "Upcoming SDK 2.1 will create multiple transactions at once for some recipients.",
+        replaceWith =
+            ReplaceWith(
+                "proposeTransfer(usk.account, toAddress, amount, memo) OR " +
+                    "proposeShielding(usk.account, shieldingThreshold, memo)"
+            )
+    )
     val MINERS_FEE = Zatoshi(10_000L)
 
     /**

sdk-lib/src/main/java/cash/z/ecc/android/sdk/fixture/TransactionOverviewFixture.kt

@@ -1,12 +1,12 @@
 package cash.z.ecc.android.sdk.fixture
 
-import cash.z.ecc.android.sdk.ext.ZcashSdk
 import cash.z.ecc.android.sdk.model.BlockHeight
 import cash.z.ecc.android.sdk.model.FirstClassByteArray
 import cash.z.ecc.android.sdk.model.TransactionOverview
 import cash.z.ecc.android.sdk.model.TransactionState
 import cash.z.ecc.android.sdk.model.Zatoshi
 
+@Suppress("MagicNumber")
 object TransactionOverviewFixture {
     const val ID: Long = 1
     val RAW_ID: FirstClassByteArray get() = FirstClassByteArray("rawId".toByteArray())
@@ -16,9 +16,8 @@ object TransactionOverviewFixture {
     val RAW: FirstClassByteArray get() = FirstClassByteArray("raw".toByteArray())
     const val IS_SENT_TRANSACTION: Boolean = false
 
-    @Suppress("MagicNumber")
     val NET_VALUE: Zatoshi = Zatoshi(10_000)
-    val FEE_PAID: Zatoshi = ZcashSdk.MINERS_FEE
+    val FEE_PAID: Zatoshi = Zatoshi(10_000)
     const val IS_CHANGE: Boolean = false
     const val RECEIVED_NOTE_COUNT: Int = 1
     const val SENT_NOTE_COUNT: Int = 0

sdk-lib/src/main/java/cash/z/ecc/android/sdk/model/Proposal.kt

@@ -51,4 +51,8 @@ class Proposal(
     fun totalFeeRequired(): Zatoshi {
         return Zatoshi(inner.totalFeeRequired())
     }
+
+    fun toPrettyString(): String {
+        return "Transaction count: ${transactionCount()}, Total fee required: ${totalFeeRequired()}"
+    }
 }