Moves cashu processing to a state class to account for errors.

vitorpamplona · Jun 27, 2023 · 833e6bc · 833e6bc
1 parent 9bed6fd
commit 833e6bc
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Showing 3 changed files with 42 additions and 18 deletions.
diff --git a/app/src/main/java/com/vitorpamplona/amethyst/service/CashuProcessor.kt b/app/src/main/java/com/vitorpamplona/amethyst/service/CashuProcessor.kt
@@ -6,6 +6,7 @@ import com.google.gson.JsonArray
 import com.google.gson.JsonObject
 import com.google.gson.JsonParser
 import com.vitorpamplona.amethyst.service.lnurl.LightningAddressResolver
+import com.vitorpamplona.amethyst.ui.components.GenericLoadable
 import okhttp3.MediaType.Companion.toMediaType
 import okhttp3.Request
 import okhttp3.RequestBody.Companion.toRequestBody
@@ -21,21 +22,25 @@ data class CashuToken(
 )
 
 class CashuProcessor {
-    fun parse(cashutoken: String): CashuToken {
-        val base64token = cashutoken.replace("cashuA", "")
-        val cashu = JsonParser.parseString(String(Base64.getDecoder().decode(base64token)))
-        val token = cashu.asJsonObject.get("token").asJsonArray[0].asJsonObject
-        val proofs = token["proofs"].asJsonArray
-        val mint = token["mint"].asString
+    fun parse(cashuToken: String): GenericLoadable<CashuToken> {
+        try {
+            val base64token = cashuToken.replace("cashuA", "")
+            val cashu = JsonParser.parseString(String(Base64.getDecoder().decode(base64token)))
+            val token = cashu.asJsonObject.get("token").asJsonArray[0].asJsonObject
+            val proofs = token["proofs"].asJsonArray
+            val mint = token["mint"].asString
 
-        var totalAmount = 0L
-        for (proof in proofs) {
-            totalAmount += proof.asJsonObject["amount"].asLong
-        }
-        val fees = Math.max(((totalAmount * 0.02).toInt()), 2)
-        val redeemInvoiceAmount = totalAmount - fees
+            var totalAmount = 0L
+            for (proof in proofs) {
+                totalAmount += proof.asJsonObject["amount"].asLong
+            }
+            val fees = Math.max(((totalAmount * 0.02).toInt()), 2)
+            val redeemInvoiceAmount = totalAmount - fees
 
-        return CashuToken(mint, totalAmount, fees, redeemInvoiceAmount, proofs)
+            return GenericLoadable.Loaded(CashuToken(mint, totalAmount, fees, redeemInvoiceAmount, proofs))
+        } catch (e: Exception) {
+            return GenericLoadable.Error<CashuToken>("Could not parse this cashu token")
+        }
     }
 
     fun melt(token: CashuToken, lud16: String, onSuccess: (String) -> Unit, onError: (String) -> Unit) {

diff --git a/app/src/main/java/com/vitorpamplona/amethyst/ui/components/CashuRedeem.kt b/app/src/main/java/com/vitorpamplona/amethyst/ui/components/CashuRedeem.kt
@@ -35,7 +35,7 @@ import kotlinx.coroutines.launch
 
 @Composable
 fun CashuPreview(cashutoken: String, accountViewModel: AccountViewModel) {
-    var cachuData by remember { mutableStateOf<CashuToken?>(null) }
+    var cachuData by remember { mutableStateOf<GenericLoadable<CashuToken>>(GenericLoadable.Loading<CashuToken>()) }
 
     LaunchedEffect(key1 = cashutoken) {
         launch(Dispatchers.IO) {
@@ -44,13 +44,13 @@ fun CashuPreview(cashutoken: String, accountViewModel: AccountViewModel) {
     }
 
     Crossfade(targetState = cachuData) {
-        if (it != null) {
-            CashuPreview(it, accountViewModel)
-        } else {
-            Text(
+        when (it) {
+            is GenericLoadable.Loaded<CashuToken> -> CashuPreview(it.loaded, accountViewModel)
+            is GenericLoadable.Error<CashuToken> -> Text(
                 text = "$cashutoken ",
                 style = LocalTextStyle.current.copy(textDirection = TextDirection.Content)
             )
+            else -> {}
         }
     }
 }

diff --git a/app/src/main/java/com/vitorpamplona/amethyst/ui/components/GenericLoadable.kt b/app/src/main/java/com/vitorpamplona/amethyst/ui/components/GenericLoadable.kt
@@ -0,0 +1,19 @@
+package com.vitorpamplona.amethyst.ui.components
+
+import androidx.compose.runtime.Immutable
+
+@Immutable
+sealed class GenericLoadable<T> {
+
+    @Immutable
+    class Loading<T> : GenericLoadable<T>()
+
+    @Immutable
+    class Loaded<T>(val loaded: T) : GenericLoadable<T>()
+
+    @Immutable
+    class Empty<T> : GenericLoadable<T>()
+
+    @Immutable
+    class Error<T>(val errorMessage: String) : GenericLoadable<T>()
+}