Clean up amount label computation

Author: tanx

src/computed/invoice.js

@@ -1,13 +1,11 @@
 import { computed, extendObservable } from 'mobx';
-import { toSatoshis, toAmountLabel } from '../helper';
+import { toLabel } from '../helper';
 
 const ComputedInvoice = store => {
   extendObservable(store, {
-    invoiceAmountLabel: computed(() => {
-      const { invoice, settings } = store;
-      const satoshis = toSatoshis(invoice.amount, settings.unit);
-      return toAmountLabel(satoshis, store.settings);
-    }),
+    invoiceAmountLabel: computed(() =>
+      toLabel(store.invoice.amount, store.settings)
+    ),
   });
 };
 

src/computed/payment.js

@@ -1,18 +1,12 @@
 import { computed, extendObservable } from 'mobx';
-import { toSatoshis, toAmountLabel } from '../helper';
+import { toSatoshis, toAmountLabel, toLabel } from '../helper';
 
 const ComputedPayment = store => {
   extendObservable(store, {
-    paymentAmountLabel: computed(() => {
-      const { payment, settings } = store;
-      const satoshis = toSatoshis(payment.amount, settings.unit);
-      return toAmountLabel(satoshis, store.settings);
-    }),
-    paymentFeeLabel: computed(() => {
-      const { payment, settings } = store;
-      const satoshis = toSatoshis(payment.fee, settings.unit);
-      return toAmountLabel(satoshis, store.settings);
-    }),
+    paymentAmountLabel: computed(() =>
+      toLabel(store.payment.amount, store.settings)
+    ),
+    paymentFeeLabel: computed(() => toLabel(store.payment.fee, store.settings)),
     paymentTotalLabel: computed(() => {
       const { payment, settings } = store;
       const satAmount = toSatoshis(payment.amount, settings.unit);

src/helper.js

@@ -126,6 +126,18 @@ export const toAmountLabel = (satoshis, settings) => {
     : formatNumber(toAmount(satoshis, settings.unit));
 };
 
+/**
+ * Convert a string formatted BTC amount either to fiat or the selected BTC unit.
+ * The output should be used throughout the UI for value labels.
+ * @param  {string} amount The amount e.g. '0.0001'
+ * @param  {Object} settings Contains the current exchange rate
+ * @return {string}          The corresponding value label
+ */
+export const toLabel = (amount, settings) => {
+  const satoshis = toSatoshis(amount, settings.unit);
+  return toAmountLabel(satoshis, settings);
+};
+
 /**
  * Split '-' separated words and convert to uppercase
  * @param  {string} value     The input string