fiat ux

app/src/main/java/com/bitcointxoko/gudariwallet/ui/send/LnurlPayForm.kt

@@ -1,15 +1,20 @@
 package com.bitcointxoko.gudariwallet.ui.send
 
+import androidx.compose.foundation.layout.Arrangement
 import androidx.compose.foundation.layout.Column
+import androidx.compose.foundation.layout.Row
 import androidx.compose.foundation.layout.Spacer
 import androidx.compose.foundation.layout.fillMaxWidth
 import androidx.compose.foundation.layout.height
+import androidx.compose.foundation.layout.offset
 import androidx.compose.foundation.layout.size
+import androidx.compose.foundation.layout.width
 import androidx.compose.foundation.text.KeyboardOptions
 import androidx.compose.material.icons.Icons
 import androidx.compose.material.icons.filled.PersonAdd
 import androidx.compose.material3.Button
 import androidx.compose.material3.Icon
+import androidx.compose.material3.LocalTextStyle
 import androidx.compose.material3.MaterialTheme
 import androidx.compose.material3.OutlinedTextField
 import androidx.compose.material3.SuggestionChip
@@ -20,13 +25,18 @@ import androidx.compose.runtime.getValue
 import androidx.compose.runtime.mutableStateOf
 import androidx.compose.runtime.remember
 import androidx.compose.runtime.setValue
+import androidx.compose.ui.Alignment
 import androidx.compose.ui.Modifier
+import androidx.compose.ui.text.font.FontFamily
+import androidx.compose.ui.text.input.ImeAction
 import androidx.compose.ui.text.input.KeyboardType
+import androidx.compose.ui.text.style.TextAlign
 import androidx.compose.ui.unit.dp
 import androidx.lifecycle.compose.collectAsStateWithLifecycle
 import com.bitcointxoko.gudariwallet.LocalAppStrings
 import com.bitcointxoko.gudariwallet.ui.SendState
 import com.bitcointxoko.gudariwallet.ui.WalletViewModel
+import com.bitcointxoko.gudariwallet.ui.common.UnitWheelPicker
 import com.bitcointxoko.gudariwallet.util.WalletConstants
 import com.bitcointxoko.gudariwallet.util.fiatLabel
 import com.bitcointxoko.gudariwallet.util.formatFiat
@@ -37,6 +47,8 @@ import com.bitcointxoko.gudariwallet.ui.contacts.CreateContactSheet
 import com.bitcointxoko.gudariwallet.util.SendInputDetector
 import com.bitcointxoko.gudariwallet.util.SendInputType
 
+private enum class AmountUnit { SATS, FIAT }
+
 @Composable
 internal fun LnurlPayForm(
     state       : SendState.LnurlReady,
@@ -47,13 +59,34 @@ internal fun LnurlPayForm(
 ) {
     val strings = LocalAppStrings.current
 
-    var amount  by remember { mutableStateOf(state.minSats.toString()) }
-    var comment by remember { mutableStateOf("") }
-    val isFixed = state.minSats == state.maxSats
+    var amountText by remember { mutableStateOf(state.minSats.toString()) }
+    var comment    by remember { mutableStateOf("") }
+    val isFixed    = state.minSats == state.maxSats
 
-    val sats: Long? = amount.toLongOrNull()
+    val showFiatToggle = fiatRate != null && fiatCurrency != null
+    var activeUnit     by remember { mutableStateOf(AmountUnit.SATS) }
+
+    // ── Always compute sats from whatever the user typed ─────────────────
+    val parsedInput = amountText.trim().toDoubleOrNull()
+    val sats: Long? = when {
+        parsedInput == null -> null
+        activeUnit == AmountUnit.SATS -> parsedInput.toLong()
+        else /* FIAT */               -> (parsedInput * (fiatRate ?: 1.0)).toLong()
+    }
     val isAmountValid = sats != null && sats in state.minSats..state.maxSats
-    val fiatLabel: String? = fiatLabel(sats, fiatRate, fiatCurrency)
+
+    // ── Button labels — always sats + fiat, regardless of active unit ────
+    val satsLabelForButton: String  = sats?.toString() ?: ""
+    val fiatLabelForButton: String? = if (sats != null) fiatLabel(sats, fiatRate, fiatCurrency) else null
+
+    // ── Conversion label (the opposite unit) for supporting text ─────────
+    val conversionLabel: String? = remember(amountText, activeUnit, fiatRate, fiatCurrency) {
+        if (!showFiatToggle || parsedInput == null) return@remember null
+        when (activeUnit) {
+            AmountUnit.SATS -> fiatLabel(parsedInput.toLong(), fiatRate, fiatCurrency)
+            AmountUnit.FIAT -> "≈ ${(parsedInput * (fiatRate ?: 1.0)).toLong()} sats"
+        }
+    }
 
     // ── Contact lookup — reactive, sourced from WalletViewModel ──────────
     val existingContact by vm.contactForCurrentLnurl.collectAsStateWithLifecycle()
@@ -67,10 +100,14 @@ internal fun LnurlPayForm(
         }
     }
 
+    // ── The supporting-text height the picker must not center against ─────
+    //    OutlinedTextFieldDefaults counts: input area ~56 dp, supporting
+    //    text ~16 dp with 4 dp internal padding ≈ 20 dp extra below.
+    val supportingTextHeight = 20.dp
+
     Column {
         // ── Recipient header ──────────────────────────────────────────────
         if (existingContact != null) {
-            // Known contact — show their name instead of the raw address
             val contactName = existingContact!!.localAlias
                 ?: existingContact!!.displayName
                 ?: existingContact!!.name
@@ -80,7 +117,6 @@ internal fun LnurlPayForm(
                 style = MaterialTheme.typography.titleMedium
             )
         } else {
-            // Unknown — show domain/address as before
             Text(
                 text  = strings.payingTo(payingToLabel(state.lnurl, state.domain)),
                 style = MaterialTheme.typography.titleMedium
@@ -108,45 +144,106 @@ internal fun LnurlPayForm(
             )
         }
 
-        Spacer(Modifier.height(12.dp))
+        // ── Headroom above amount row — the picker has a 32 dp ghost item
+        //    above the selected item; this offsets so the visual centre of
+        //    the picker lines up with the title text above rather than the
+        //    Row's top edge.
+        Spacer(Modifier.height(16.dp))
 
-        // ── Amount field — unchanged ──────────────────────────────────────
-        OutlinedTextField(
-            value = amount,
-            onValueChange = { if (it.all(Char::isDigit)) amount = it },
-            label = { Text(strings.receive.amountInSats) },
-            isError = amount.isNotBlank() && !isAmountValid,
-            supportingText = {
-                when {
-                    amount.isNotBlank() && !isAmountValid -> {
-                        Text(
-                            text  = strings.lnurlAmountError(state.minSats, state.maxSats),
-                            color = MaterialTheme.colorScheme.error
-                        )
-                    }
-                    fiatRate != null && fiatCurrency != null -> {
-                        val minFiat = formatFiat(satsToFiat(state.minSats, fiatRate), fiatCurrency)
-                        val maxFiat = formatFiat(satsToFiat(state.maxSats, fiatRate), fiatCurrency)
-                        if (isFixed) Text(strings.lnurlFiatRange(minFiat, maxFiat))
-                        else Text(strings.lnurlSatsAndFiatRange(state.minSats, state.maxSats, minFiat, maxFiat))
-                    }
-                    !isFixed -> Text(strings.receive.satsRange(state.minSats, state.maxSats))
-                    else -> {}
-                }
-            },
-            enabled = !isFixed,
-            singleLine = true,
-            modifier = Modifier.fillMaxWidth(),
-            keyboardOptions = KeyboardOptions(keyboardType = KeyboardType.Number)
-        )
-
-        // ── Comment field — unchanged ─────────────────────────────────────
-        if (state.commentAllowed > 0) {
-            Spacer(Modifier.height(8.dp))
+        // ── Amount field with currency switcher ───────────────────────────
+        Row(
+            modifier          = Modifier.fillMaxWidth(),
+            verticalAlignment = Alignment.CenterVertically,
+            horizontalArrangement = Arrangement.spacedBy(8.dp)
+        ) {
             OutlinedTextField(
-                value = comment,
-                onValueChange  = { if (it.length <= state.commentAllowed) comment = it },
-                label = { Text(strings.commentOptional(state.commentAllowed)) },
+                value         = amountText,
+                onValueChange = {
+                    val allowed = if (activeUnit == AmountUnit.SATS)
+                        it.all(Char::isDigit)
+                    else
+                        it.all { c -> c.isDigit() || c == '.' } &&
+                                it.count { c -> c == '.' } <= 1
+                    if (allowed) amountText = it
+                },
+                placeholder = {
+                    Text(
+                        if (activeUnit == AmountUnit.SATS || !showFiatToggle) "0" else "0.00",
+                        modifier   = Modifier.fillMaxWidth(),
+                        textAlign  = TextAlign.End,
+                        fontFamily = FontFamily.Monospace
+                    )
+                },
+                isError = amountText.isNotBlank() && !isAmountValid,
+                supportingText = {
+                    when {
+                        amountText.isNotBlank() && !isAmountValid -> {
+                            Text(
+                                text  = strings.lnurlAmountError(state.minSats, state.maxSats),
+                                color = MaterialTheme.colorScheme.error
+                            )
+                        }
+                        conversionLabel != null -> {
+                            Text(
+                                text  = conversionLabel,
+                                color = MaterialTheme.colorScheme.onSurfaceVariant
+                            )
+                        }
+                        fiatRate != null && fiatCurrency != null -> {
+                            val minFiat = formatFiat(satsToFiat(state.minSats, fiatRate), fiatCurrency)
+                            val maxFiat = formatFiat(satsToFiat(state.maxSats, fiatRate), fiatCurrency)
+                            if (isFixed) Text(strings.lnurlFiatRange(minFiat, maxFiat))
+                            else Text(strings.lnurlSatsAndFiatRange(state.minSats, state.maxSats, minFiat, maxFiat))
+                        }
+                        !isFixed -> Text(strings.receive.satsRange(state.minSats, state.maxSats))
+                        else -> {}
+                    }
+                },
+                enabled    = !isFixed,
+                singleLine = true,
+                textStyle  = LocalTextStyle.current.copy(
+                    textAlign  = TextAlign.End,
+                    fontFamily = FontFamily.Monospace
+                ),
+                keyboardOptions = KeyboardOptions(
+                    keyboardType = if (activeUnit == AmountUnit.SATS) KeyboardType.Number else KeyboardType.Decimal,
+                    imeAction    = ImeAction.Done
+                ),
+                modifier = Modifier.weight(1f)
+            )
+
+            // ── Offset the picker upward by half the supporting-text height
+            //    so its selected item aligns with the text field's input
+            //    area (the visible text) rather than the geometric centre of
+            //    the entire OutlinedTextField including the sub-label below.
+            UnitWheelPicker(
+                units = if (showFiatToggle) listOf(strings.sats, fiatCurrency) else listOf(strings.sats),
+                selectedIndex = if (activeUnit == AmountUnit.SATS) 0 else 1,
+                onIndexSelected = { newIndex ->
+                    val newUnit = if (newIndex == 0) AmountUnit.SATS else AmountUnit.FIAT
+                    if (newUnit != activeUnit) {
+                        activeUnit = newUnit
+                        amountText = ""
+                    }
+                },
+                modifier = Modifier
+                    .width(64.dp)
+                    .offset(y = -supportingTextHeight / 2)
+            )
+        }
+
+        // ── Gap after amount row — accounts for the picker extending below
+        //    (picker is 96 dp, text field input area ~56 dp → ~40 dp
+        //    overhang below, minus the offset above). Keep this compact so
+        //    all inputs + title + button feel evenly spaced.
+        Spacer(Modifier.height(21.dp))
+
+        // ── Comment field ─────────────────────────────────────────────────
+        if (state.commentAllowed > 0) {
+            OutlinedTextField(
+                value         = comment,
+                onValueChange = { if (it.length <= state.commentAllowed) comment = it },
+                label         = { Text(strings.commentOptional(state.commentAllowed)) },
                 supportingText = { Text(strings.commentCounter(comment.length, state.commentAllowed)) },
                 modifier = Modifier.fillMaxWidth()
             )
@@ -154,17 +251,17 @@ internal fun LnurlPayForm(
 
         Spacer(Modifier.height(16.dp))
 
-        // ── Pay button — unchanged ────────────────────────────────────────
+        // ── Pay button ────────────────────────────────────────────────────
         Button(
             onClick = {
                 if (sats != null && isAmountValid) {
                     vm.fetchLnurlInvoice(
-                        rawRes    = state.rawRes,
-                        lnurl     = state.lnurl,
-                        domain    = state.domain,
+                        rawRes     = state.rawRes,
+                        lnurl      = state.lnurl,
+                        domain     = state.domain,
                         amountMsat = sats * WalletConstants.MSAT_PER_SAT,
-                        comment   = comment.takeIf { it.isNotBlank() },
-                        strings   = sendStrings,
+                        comment    = comment.takeIf { it.isNotBlank() },
+                        strings    = sendStrings,
                         contactId  = existingContact?.id
                     )
                 }
@@ -173,8 +270,8 @@ internal fun LnurlPayForm(
             modifier = Modifier.fillMaxWidth()
         ) {
             Text(
-                if (fiatLabel != null) strings.lnurlPayButtonWithFiat(amount, fiatLabel)
-                else strings.lnurlPayButton(amount)
+                if (fiatLabelForButton != null) strings.lnurlPayButtonWithFiat(satsLabelForButton, fiatLabelForButton)
+                else strings.lnurlPayButton(satsLabelForButton)
             )
         }
     }
@@ -192,4 +289,3 @@ internal fun LnurlPayForm(
         )
     }
 }
-

app/src/main/java/com/bitcointxoko/gudariwallet/util/CurrencyFormatter.kt

@@ -1,90 +1,81 @@
 package com.bitcointxoko.gudariwallet.util
 
-/**
- * Converts a satoshi amount to its fiat equivalent.
- *
- * @param sats         Amount in satoshis.
- * @param satsPerFiat  How many sats equal 1 fiat unit (e.g. if BTC = $100,000 then
- *                     satsPerFiat = 100,000,000 / 100,000 = 1,000 sats per dollar).
- * @return             Fiat amount as a Double.
- */
+import java.text.DecimalFormatSymbols
+import java.util.Locale
+
+// ── Public API ────────────────────────────────────────────────────────────────
+
 fun satsToFiat(sats: Long, satsPerFiat: Double): Double =
     sats / satsPerFiat
 
-/**
- * Formats a fiat amount for display with a currency symbol prefix.
- *
- * Tiers (bitcoin.design rules):
- *  - amount >= 1.00          → 2 dp,  e.g.  "$43.25"
- *  - 0.01 <= amount < 1.00   → 4 dp,  e.g.  "$0.0043"
- *  - amount < 0.01 (sub-cent)→ dynamic precision with "~" prefix,
- *                               e.g.  "~$0.0039"  (2 significant digits after leading zeros)
- *  - amount == 0.0           → "$0.00"
- *
- * @param amount    Fiat amount to format (always pass a positive value; sign is handled by caller).
- * @param currency  ISO 4217 currency code (e.g. "USD", "EUR").
- * @return          Formatted string with symbol, e.g. "$43.25" or "~$0.0039".
- */
 fun formatFiat(amount: Double, currency: String): String {
     val symbol = currencySymbol(currency)
 
     return when {
-        amount == 0.0      -> "${symbol}0.00"
-        amount >= 1.0      -> "$symbol${"%.2f".format(amount)}"
-        amount >= 0.01     -> "$symbol${"%.4f".format(amount)}"
-        else               -> formatSubCent(amount, symbol)
+        amount == 0.0  -> "${symbol}${localiseDecimal("0.00")}"
+        amount >= 1.0  -> {
+            val formatted = "%.2f".format(Locale.US, amount)
+            val isExact = formatted.toDouble() == amount
+            val prefix = if (isExact) "" else "~"
+            "$prefix$symbol${localiseDecimal(formatted)}"
+        }
+        amount >= 0.01 -> formatWithSigDigits(amount, symbol, minDecimals = 2)
+        else           -> formatWithSigDigits(amount, symbol, minDecimals = 0)
     }
 }
 
-/**
- * Converts sats → fiat and formats in one call, applying bitcoin.design display rules.
- *
- * Use this everywhere you display a sat amount alongside a fiat equivalent.
- *
- * @param sats         Absolute satoshi count (always positive; caller adds +/− sign).
- * @param satsPerFiat  Exchange rate: sats per 1 fiat unit.
- * @param currency     ISO 4217 currency code.
- * @return             Formatted fiat string, e.g. "$12.50", "~$0.0039", or "$0.00".
- */
 fun formatFiatForSats(sats: Long, satsPerFiat: Double, currency: String): String =
     formatFiat(satsToFiat(sats, satsPerFiat), currency)
 
+fun fiatLabel(
+    sats: Long?,
+    fiatRate: Double?,
+    fiatCurrency: String?,
+    minSats: Long = 1L
+): String? =
+    if (sats != null && sats >= minSats && fiatRate != null && fiatCurrency != null)
+        formatFiat(satsToFiat(sats, fiatRate), fiatCurrency)
+    else null
+
 // ── Internal helpers ──────────────────────────────────────────────────────────
 
-/**
- * Handles the sub-cent case (0 < amount < 0.01).
- *
- * Finds the first two significant (non-zero) digits after the decimal point
- * and rounds to that precision, prefixing with "~" to signal approximation.
- *
- * Examples:
- *   0.003887  →  "~$0.0039"
- *   0.000038  →  "~$0.000038"
- *   0.0000431 →  "~$0.000043"
- */
-private fun formatSubCent(amount: Double, symbol: String): String {
-    // Render with enough decimal places to capture at least 2 significant digits
-    val raw      = "%.10f".format(amount)          // e.g. "0.0000431000"
-    val dotIdx   = raw.indexOf('.')
-    if (dotIdx == -1) return "~$symbol$raw"
+private fun formatWithSigDigits(amount: Double, symbol: String, minDecimals: Int): String {
+    // Use Locale.US so "." is always the decimal char — safe for arithmetic & comparison
+    val raw = "%.15f".format(Locale.US, amount)
+    val dotIdx = raw.indexOf('.')
+    if (dotIdx == -1) return "$symbol${localiseDecimal(raw)}"
 
-    val decimals     = raw.substring(dotIdx + 1)   // e.g. "0000431000"
-    val firstSigIdx  = decimals.indexOfFirst { it != '0' }
-    if (firstSigIdx == -1) return "${symbol}0.00"  // effectively zero
+    val decimals    = raw.substring(dotIdx + 1)
+    val firstSigIdx = decimals.indexOfFirst { it != '0' }
 
-    // Keep all leading zeros + 2 significant digits
-    val precision = firstSigIdx + 2
-    val rounded   = "%.${precision}f".format(amount)
+    if (firstSigIdx == -1) return "${symbol}${localiseDecimal("0.00")}"
 
-    // Only add "~" if rounding actually changed the value
-    val isExact = "%.${precision}f".format(amount).toDoubleOrNull() == amount
-    return if (isExact) "$symbol$rounded" else "~$symbol$rounded"
+    val sigPrecision = firstSigIdx + 2
+    val precision    = maxOf(sigPrecision, minDecimals)
+
+    val rounded = "%.${precision}f".format(Locale.US, amount)
+    val isExact = rounded.toDouble() == amount   // safe: dot separator guaranteed
+
+    val prefix = if (isExact) "" else "~"
+    return "$prefix$symbol${localiseDecimal(rounded)}"
 }
 
 /**
- * Returns the display symbol for a given ISO 4217 currency code.
- * Falls back to the currency code + space for unlisted currencies.
+ * Converts a US-formatted decimal string (dot separator, no grouping)
+ * into the user's current locale format.
+ *
+ * "155.57"  →  "155,57"  (DE locale)
+ * "0.0039"  →  "0,0039"  (DE locale)
+ * "155.57"  →  "155.57"  (US locale)
  */
+private fun localiseDecimal(usFormatted: String): String {
+    val symbols = DecimalFormatSymbols.getInstance() // uses device default locale
+    val localeDecimalSep = symbols.decimalSeparator
+    // Only substitute if the locale actually uses a different separator
+    return if (localeDecimalSep == '.') usFormatted
+    else usFormatted.replace('.', localeDecimalSep)
+}
+
 private fun currencySymbol(currency: String): String = when (currency) {
     "USD" -> "$"
     "EUR" -> "€"
@@ -96,12 +87,3 @@ private fun currencySymbol(currency: String): String = when (currency) {
     "CHF" -> "Fr"
     else  -> "$currency "
 }
-
-/**
- * Returns a formatted fiat string for [sats] at the given rate, or null if
- * rate or currency is unavailable. Suppresses display for zero/null amounts.
- */
-fun fiatLabel(sats: Long?, fiatRate: Double?, fiatCurrency: String?, minSats: Long = 1L): String? =
-    if (sats != null && sats >= minSats && fiatRate != null && fiatCurrency != null)
-        formatFiat(satsToFiat(sats, fiatRate), fiatCurrency)
-    else null