fix broken exchange logic + add network fee to calculation

mbw/src/main/java/com/mycelium/wallet/external/changelly/ChangellyAPIService.kt

@@ -1,7 +1,12 @@
 package com.mycelium.wallet.external.changelly
 
-import com.mycelium.wallet.external.changelly.model.*
-import org.jetbrains.annotations.TestOnly
+import com.mycelium.wallet.external.changelly.model.ChangellyCurrency
+import com.mycelium.wallet.external.changelly.model.ChangellyGetExchangeAmountResponse
+import com.mycelium.wallet.external.changelly.model.ChangellyListResponse
+import com.mycelium.wallet.external.changelly.model.ChangellyResponse
+import com.mycelium.wallet.external.changelly.model.ChangellyTransaction
+import com.mycelium.wallet.external.changelly.model.ChangellyTransactionOffer
+import com.mycelium.wallet.external.changelly.model.FixRate
 import retrofit2.Call
 import retrofit2.Response
 import retrofit2.http.POST
@@ -56,7 +61,17 @@ interface ChangellyAPIService {
         @Query("from") from: String,
         @Query("to") to: String,
         @Query("amountFrom") amount: BigDecimal = BigDecimal.ONE,
-    ): Response<ChangellyListResponse<FixRateForAmount>>
+    ): Response<ChangellyListResponse<FixRate>>
+
+    @Deprecated(
+        "To get the fixed rate, you need to use getFixRateForAmount, but the transaction amount must be within limits",
+        ReplaceWith("getFixRateForAmount")
+    )
+    @POST("getFixRate")
+    suspend fun getFixRate(
+        @Query("from") from: String,
+        @Query("to") to: String,
+    ): Response<ChangellyListResponse<FixRate>>
 
     @POST("createFixTransaction")
     suspend fun createFixTransaction(
@@ -70,21 +85,15 @@ interface ChangellyAPIService {
 
     @POST("getTransactions")
     suspend fun getTransaction(
-        @Query("id") id: String
+        @Query("id") id: String,
+        @Query("limit") limit: Int = 1,
     ): Response<ChangellyResponse<List<ChangellyTransaction>>>
 
     @POST("getTransactions")
     suspend fun getTransactions(
         @Query("id") id: List<String>,
     ): Response<ChangellyResponse<List<ChangellyTransaction>>>
 
-
-    @TestOnly
-    @POST("getFixRate")
-    suspend fun getFixRate(@Query("from") from: String,
-                                  @Query("to") to: String): Response<ChangellyResponse<FixRateForAmount>>
-
-
     companion object {
         const val BCH = "BCH"
         const val BTC = "BTC"

mbw/src/main/java/com/mycelium/wallet/external/changelly/model/FixRate.kt

@@ -11,6 +11,7 @@ data class FixRate(
     val maxTo: BigDecimal,
     val minFrom: BigDecimal,
     val minTo: BigDecimal,
-    val amountFrom: BigDecimal,
-    val amountTo: BigDecimal,
+    val amountFrom: BigDecimal?,
+    val amountTo: BigDecimal?,
+    val networkFee: BigDecimal?,
 )

mbw/src/main/java/com/mycelium/wallet/external/changelly2/ExchangeFragment.kt

@@ -22,7 +22,10 @@ import com.bumptech.glide.load.resource.bitmap.CircleCrop
 import com.bumptech.glide.request.RequestOptions
 import com.mrd.bitlib.model.BitcoinAddress
 import com.mycelium.view.RingDrawable
-import com.mycelium.wallet.*
+import com.mycelium.wallet.BuildConfig
+import com.mycelium.wallet.MbwManager
+import com.mycelium.wallet.R
+import com.mycelium.wallet.Utils
 import com.mycelium.wallet.activity.modern.ModernMain
 import com.mycelium.wallet.activity.modern.event.BackHandler
 import com.mycelium.wallet.activity.modern.event.BackListener
@@ -36,14 +39,19 @@ import com.mycelium.wallet.activity.util.toStringWithUnit
 import com.mycelium.wallet.activity.view.ValueKeyboard
 import com.mycelium.wallet.activity.view.loader
 import com.mycelium.wallet.databinding.FragmentChangelly2ExchangeBinding
-import com.mycelium.wallet.event.*
+import com.mycelium.wallet.event.ExchangeRatesRefreshed
+import com.mycelium.wallet.event.ExchangeSourceChanged
+import com.mycelium.wallet.event.PageSelectedEvent
+import com.mycelium.wallet.event.SelectedAccountChanged
+import com.mycelium.wallet.event.SelectedCurrencyChanged
+import com.mycelium.wallet.event.TransactionBroadcasted
 import com.mycelium.wallet.external.changelly.model.ChangellyResponse
 import com.mycelium.wallet.external.changelly.model.ChangellyTransactionOffer
 import com.mycelium.wallet.external.changelly.model.FixRate
-import com.mycelium.wallet.external.changelly.model.FixRateForAmount
 import com.mycelium.wallet.external.changelly2.remote.Changelly2Repository
 import com.mycelium.wallet.external.changelly2.viewmodel.ExchangeViewModel
 import com.mycelium.wallet.external.partner.openLink
+import com.mycelium.wallet.startCoroutineTimer
 import com.mycelium.wapi.wallet.AesKeyCipher
 import com.mycelium.wapi.wallet.BroadcastResultType
 import com.mycelium.wapi.wallet.Transaction
@@ -183,7 +191,7 @@ class ExchangeFragment : Fragment(), BackListener {
                         val exchangeInfoResult = viewModel.exchangeInfo.value?.result
                         if (friendlyDigits == null || exchangeInfoResult == null) N_A
                         else amount.toBigDecimal().setScale(friendlyDigits, RoundingMode.HALF_UP)
-                                ?.div(viewModel.exchangeInfo.value!!.getExpectedValue())
+                                ?.div(exchangeInfoResult)
                                 ?.stripTrailingZeros()
                                 ?.toPlainString() ?: N_A
                     } catch (e: NumberFormatException) {
@@ -358,13 +366,17 @@ class ExchangeFragment : Fragment(), BackListener {
 
     private fun computeBuyValue() {
         val amount = viewModel.sellValue.value
-        viewModel.buyValue.value = if (amount?.isNotEmpty() == true
-                && viewModel.exchangeInfo.value?.result != null) {
+        val info = viewModel.exchangeInfo.value
+        val rate = info?.result
+        val networkFee = info?.networkFee ?: BigDecimal.ZERO
+        viewModel.buyValue.value = if (amount?.isNotEmpty() == true && rate != null) {
             try {
-                (amount.toBigDecimal() * viewModel.exchangeInfo.value?.getExpectedValue()!!)
-                        .setScale(viewModel.toCurrency.value?.friendlyDigits!!, RoundingMode.HALF_UP)
-                        .stripTrailingZeros()
-                        .toPlainString()
+                val result = amount.toBigDecimal() * rate - networkFee
+                if (result <= BigDecimal.ZERO) null
+                else result
+                    .setScale(viewModel.toCurrency.value?.friendlyDigits!!, RoundingMode.HALF_UP)
+                    .stripTrailingZeros()
+                    .toPlainString()
             } catch (e: NumberFormatException) {
                 "N/A"
             }
@@ -439,7 +451,12 @@ class ExchangeFragment : Fragment(), BackListener {
                     { result ->
                         val data = result?.result?.firstOrNull()
                         if (data != null) {
-                            viewModel.exchangeInfo.value = data
+                            val info = viewModel.exchangeInfo.value
+                            viewModel.exchangeInfo.value = if (info == null) data else data.copy(
+                                amountFrom = info.amountFrom,
+                                amountTo = info.amountTo,
+                                networkFee = info.networkFee,
+                            )
                             viewModel.errorRemote.value = ""
                         } else {
                             viewModel.errorRemote.value = result?.error?.message ?: ""
@@ -485,8 +502,7 @@ class ExchangeFragment : Fragment(), BackListener {
                                 fromAmount,
                                 { result ->
                                     result?.result?.firstOrNull()?.let {
-                                        val info = viewModel.exchangeInfo.value
-                                        viewModel.exchangeInfo.postValue(it)
+                                        viewModel.exchangeInfo.value = it
                                         viewModel.errorRemote.value = ""
                                     } ?: run {
                                         viewModel.errorRemote.value = result?.error?.message ?: ""

mbw/src/main/java/com/mycelium/wallet/external/changelly2/remote/Changelly2Repository.kt

@@ -3,7 +3,12 @@ package com.mycelium.wallet.external.changelly2.remote
 import androidx.lifecycle.LifecycleCoroutineScope
 import com.mycelium.bequant.remote.doRequest
 import com.mycelium.wallet.external.changelly.ChangellyRetrofitFactory
-import com.mycelium.wallet.external.changelly.model.*
+import com.mycelium.wallet.external.changelly.model.ChangellyCurrency
+import com.mycelium.wallet.external.changelly.model.ChangellyListResponse
+import com.mycelium.wallet.external.changelly.model.ChangellyResponse
+import com.mycelium.wallet.external.changelly.model.ChangellyTransaction
+import com.mycelium.wallet.external.changelly.model.ChangellyTransactionOffer
+import com.mycelium.wallet.external.changelly.model.FixRate
 import kotlinx.coroutines.CoroutineScope
 import java.math.BigDecimal
 
@@ -26,23 +31,25 @@ object Changelly2Repository {
         from: String,
         to: String,
         amount: BigDecimal,
-        success: (ChangellyListResponse<FixRateForAmount>?) -> Unit,
+        success: (ChangellyListResponse<FixRate>?) -> Unit,
         error: (Int, String) -> Unit,
         finally: (() -> Unit)? = null
     ) =
         doRequest(scope, {
             api.getFixRateForAmount(exportSymbol(from), exportSymbol(to), amount)
         }, success, error, finally)
 
-    fun fixRate(scope: CoroutineScope,
-                from: String,
-                to: String,
-                success: (ChangellyListResponse<FixRateForAmount>?) -> Unit,
-                error: (Int, String) -> Unit,
-                finally: (() -> Unit)? = null) =
-            doRequest(scope, {
-                api.getFixRateForAmount(exportSymbol(from), exportSymbol(to))
-            }, success, error, finally)
+    fun fixRate(
+        scope: CoroutineScope,
+        from: String,
+        to: String,
+        success: (ChangellyListResponse<FixRate>?) -> Unit,
+        error: (Int, String) -> Unit,
+        finally: (() -> Unit)? = null
+    ) =
+        doRequest(scope, {
+            api.getFixRate(exportSymbol(from), exportSymbol(to))
+        }, success, error, finally)
 
     fun createFixTransaction(
         scope: CoroutineScope,

mbw/src/main/java/com/mycelium/wallet/external/changelly2/viewmodel/ExchangeViewModel.kt

@@ -14,7 +14,6 @@ import com.mycelium.wallet.WalletApplication
 import com.mycelium.wallet.activity.util.toStringFriendlyWithUnit
 import com.mycelium.wallet.activity.util.toStringWithUnit
 import com.mycelium.wallet.external.changelly.model.FixRate
-import com.mycelium.wallet.external.changelly.model.FixRateForAmount
 import com.mycelium.wapi.wallet.Address
 import com.mycelium.wapi.wallet.Transaction
 import com.mycelium.wapi.wallet.Util
@@ -35,7 +34,7 @@ class ExchangeViewModel(application: Application) : AndroidViewModel(application
     val mbwManager = MbwManager.getInstance(WalletApplication.getInstance())
     var currencies = setOf("BTC", "ETH")
     val fromAccount = MutableLiveData<WalletAccount<*>>()
-    val exchangeInfo = MutableLiveData<FixRateForAmount>()
+    val exchangeInfo = MutableLiveData<FixRate>()
     val sellValue = object : MutableLiveData<String>() {
         override fun setValue(value: String?) {
             if (this.value != value) {
@@ -59,7 +58,7 @@ class ExchangeViewModel(application: Application) : AndroidViewModel(application
             }
         }
     }
-    val swapEnableDelay = MutableLiveData<Boolean>(false)
+    val swapEnableDelay = MutableLiveData(false)
     val swapEnabled = MediatorLiveData<Boolean>().apply {
         value = false
         fun update() {
@@ -152,7 +151,7 @@ class ExchangeViewModel(application: Application) : AndroidViewModel(application
     }
 
     val exchangeRateToValue = Transformations.map(exchangeInfo) {
-        it.getExpectedValue().toPlainString()
+        it.result.toPlainString()
     }
 
     val exchangeRateToCurrency = Transformations.map(exchangeInfo) {