Merge pull request #529 from synonymdev/fix/lnurl-min-send-ceil

Fix/lnurl minSendable edge case when msats are not divisable by 1000

Author: ovitrif

app/src/main/java/to/bitkit/ext/Lnurl.kt

@@ -3,9 +3,26 @@ package to.bitkit.ext
 import com.synonym.bitkitcore.LnurlPayData
 import com.synonym.bitkitcore.LnurlWithdrawData
 
+private const val MSATS_PER_SAT: ULong = 1000u
+
+/**
+ * LNURL amounts are expressed in millisatoshis (msat).
+ *
+ * When converting a minimum bound to whole sats we must round up:
+ * `minSendable = 100500 msat` means the minimum payable amount is `101 sat` (not `100 sat`).
+ */
+private fun msatsToSatsCeil(msats: ULong): ULong {
+    val quotient = msats / MSATS_PER_SAT
+    val remainder = msats % MSATS_PER_SAT
+    return when (remainder) {
+        0uL -> quotient
+        else -> quotient + 1uL
+    }
+}
+
 fun LnurlPayData.commentAllowed(): Boolean = commentAllowed?.let { it > 0u } == true
-fun LnurlPayData.maxSendableSat(): ULong = maxSendable / 1000u
-fun LnurlPayData.minSendableSat(): ULong = minSendable / 1000u
+fun LnurlPayData.maxSendableSat(): ULong = maxSendable / MSATS_PER_SAT
+fun LnurlPayData.minSendableSat(): ULong = msatsToSatsCeil(minSendable)
 
-fun LnurlWithdrawData.minWithdrawableSat(): ULong = (minWithdrawable ?: 0u) / 1000u
-fun LnurlWithdrawData.maxWithdrawableSat(): ULong = maxWithdrawable / 1000u
+fun LnurlWithdrawData.minWithdrawableSat(): ULong = msatsToSatsCeil(minWithdrawable ?: 0u)
+fun LnurlWithdrawData.maxWithdrawableSat(): ULong = maxWithdrawable / MSATS_PER_SAT

app/src/main/java/to/bitkit/ui/screens/wallets/activity/ActivityDetailScreen.kt

@@ -249,7 +249,8 @@ fun ActivityDetailScreen(
                                 app.toast(
                                     type = Toast.ToastType.SUCCESS,
                                     title = context.getString(R.string.wallet__boost_success_title),
-                                    description = context.getString(R.string.wallet__boost_success_msg)
+                                    description = context.getString(R.string.wallet__boost_success_msg),
+                                    testTag = "BoostSuccessToast"
                                 )
                                 listViewModel.resync()
                                 onCloseClick()
@@ -258,7 +259,8 @@ fun ActivityDetailScreen(
                                 app.toast(
                                     type = Toast.ToastType.ERROR,
                                     title = context.getString(R.string.wallet__boost_error_title),
-                                    description = context.getString(R.string.wallet__boost_error_msg)
+                                    description = context.getString(R.string.wallet__boost_error_msg),
+                                    testTag = "BoostFailureToast"
                                 )
                                 detailViewModel.onDismissBoostSheet()
                             },

app/src/test/java/to/bitkit/ext/LnurlExtTest.kt

@@ -0,0 +1,77 @@
+package to.bitkit.ext
+
+import com.synonym.bitkitcore.LnurlPayData
+import com.synonym.bitkitcore.LnurlWithdrawData
+import org.junit.Test
+import to.bitkit.test.BaseUnitTest
+import kotlin.test.assertEquals
+
+class LnurlExtTest : BaseUnitTest() {
+
+    @Test
+    fun `minSendableSat rounds up when msats not divisible by 1000`() {
+        val data = LnurlPayData(
+            uri = "lnurl",
+            callback = "callback",
+            minSendable = 100_500u,
+            maxSendable = 200_000u,
+            metadataStr = "[]",
+            commentAllowed = null,
+            allowsNostr = false,
+            nostrPubkey = null,
+        )
+
+        assertEquals(101u, data.minSendableSat())
+    }
+
+    @Test
+    fun `minSendableSat keeps exact sat amounts`() {
+        val data = LnurlPayData(
+            uri = "lnurl",
+            callback = "callback",
+            minSendable = 100_000u,
+            maxSendable = 200_000u,
+            metadataStr = "[]",
+            commentAllowed = null,
+            allowsNostr = false,
+            nostrPubkey = null,
+        )
+
+        assertEquals(100u, data.minSendableSat())
+        assertEquals(0u, data.copy(minSendable = 0u).minSendableSat())
+    }
+
+    @Test
+    fun `maxSendableSat floors when msats not divisible by 1000`() {
+        val data = LnurlPayData(
+            uri = "lnurl",
+            callback = "callback",
+            minSendable = 1_000u,
+            maxSendable = 100_999u,
+            metadataStr = "[]",
+            commentAllowed = null,
+            allowsNostr = false,
+            nostrPubkey = null,
+        )
+
+        assertEquals(100u, data.maxSendableSat())
+        assertEquals(0u, data.copy(maxSendable = 0u).maxSendableSat())
+    }
+
+    @Test
+    fun `minWithdrawableSat rounds up and treats null as zero`() {
+        val nullMin = LnurlWithdrawData(
+            uri = "lnurl",
+            callback = "callback",
+            k1 = "k1",
+            defaultDescription = "desc",
+            minWithdrawable = null,
+            maxWithdrawable = 1_000u,
+            tag = "withdraw",
+        )
+        assertEquals(0u, nullMin.minWithdrawableSat())
+
+        val nonRoundMin = nullMin.copy(minWithdrawable = 1_500u)
+        assertEquals(2u, nonRoundMin.minWithdrawableSat())
+    }
+}