Make rate calculation scriptable

BTCPayServer/Models/StoreViewModels/RatesViewModel.cs

@@ -0,0 +1,66 @@
+using System;
+using System.Collections.Generic;
+using System.ComponentModel.DataAnnotations;
+using System.Linq;
+using System.Threading.Tasks;
+using BTCPayServer.Rating;
+using BTCPayServer.Services.Rates;
+using Microsoft.AspNetCore.Mvc.Rendering;
+
+namespace BTCPayServer.Models.StoreViewModels
+{
+    public class RatesViewModel
+    {
+        public class TestResultViewModel
+        {
+            public string CurrencyPair { get; set; }
+            public string Rule { get; set; }
+            public bool Error { get; set; }
+        }
+        class Format
+        {
+            public string Name { get; set; }
+            public string Value { get; set; }
+        }
+        public void SetExchangeRates(CoinAverageExchange[] supportedList, string preferredExchange)
+        {
+            var defaultStore = preferredExchange ?? CoinAverageRateProvider.CoinAverageName;
+            var choices = supportedList.Select(o => new Format() { Name = o.Display, Value = o.Name }).ToArray();
+            var chosen = choices.FirstOrDefault(f => f.Value == defaultStore) ?? choices.FirstOrDefault();
+            Exchanges = new SelectList(choices, nameof(chosen.Value), nameof(chosen.Name), chosen);
+            PreferredExchange = chosen.Value;
+        }
+
+        public List<TestResultViewModel> TestRateRules { get; set; }
+
+        public SelectList Exchanges { get; set; }
+
+        public bool ShowScripting { get; set; }
+
+        [Display(Name = "Rate rules")]
+        [MaxLength(2000)]
+        public string Script { get; set; }
+        public string DefaultScript { get; set; }
+        public string ScriptTest { get; set; }
+        public CoinAverageExchange[] AvailableExchanges { get; set; }
+
+        [Display(Name = "Multiply the original rate by ...")]
+        [Range(0.01, 10.0)]
+        public double RateMultiplier
+        {
+            get;
+            set;
+        }
+
+        [Display(Name = "Preferred price source (eg. bitfinex, bitstamp...)")]
+        public string PreferredExchange { get; set; }
+
+        public string RateSource
+        {
+            get
+            {
+                return PreferredExchange == CoinAverageRateProvider.CoinAverageName ? "https://apiv2.bitcoinaverage.com/indices/global/ticker/short" : $"https://apiv2.bitcoinaverage.com/exchanges/{PreferredExchange}";
+            }
+        }
+    }
+}