quotation rate display

frontend/pshared/lib/utils/currency.dart

@@ -1,22 +1,64 @@
-String currencyCodeToSymbol(String currencyCode) {
+import 'package:flutter/material.dart';
+
+import 'package:pshared/models/asset.dart';
+import 'package:pshared/models/currency.dart';
+
+
+String currencyCodeToSymbol(Currency currencyCode) {
   switch (currencyCode) {
-    case 'USD':
+    case Currency.usd:
       return '\$';
-    case 'PLN':
-      return 'zł';
-    case 'EUR':
-      return '€';
-    case 'GBP':
-      return '£';
-    case 'HUF':
-      return 'Ft';
-    case 'RUB':
+    case Currency.usdt:
+      return '₮';
+    case Currency.usdc:
+      return '\$';
+    case Currency.rub:
       return '₽';
-    default:
-      return currencyCode;
+    case Currency.eur:
+      return '€';
   }
 }
 
-String currencyToString(String currencyCode, double amount) {
-  return '${currencyCodeToSymbol(currencyCode)}\u00A0${amount.toStringAsFixed(2)}';
+String amountToString(double amount) {
+  return amount.toStringAsFixed(2);
+}
+
+String currencyToString(Currency currencyCode, double amount) {
+  return '${currencyCodeToSymbol(currencyCode)}\u00A0${amountToString(amount)}';
+}
+
+String assetToString(Asset asset) {
+  return currencyToString(asset.currency, asset.amount);
+}
+
+Currency currencyStringToCode(String currencyCode) {
+  switch (currencyCode) {
+    case 'USD':
+      return Currency.usd;
+    case 'USDT':
+      return Currency.usdt;
+    case 'USDC':
+      return Currency.usdc;
+    case 'RUB':
+      return Currency.rub;
+    case 'EUR':
+      return Currency.eur;
+    default:
+      throw ArgumentError('Unknown currency code: $currencyCode');
+  }
+}
+
+IconData iconForCurrencyType(Currency currencyCode) {
+  switch (currencyCode) {
+    case Currency.usd:
+      return Icons.currency_exchange;
+    case Currency.eur:
+      return Icons.currency_exchange;
+    case Currency.rub:
+      return Icons.currency_ruble;
+    case Currency.usdt:
+      return Icons.currency_exchange;
+    case Currency.usdc:
+      return Icons.money;
+  }
 }