Billing: Add BillingData and JSON schema validation

Elwig/Helpers/Billing/BillingData.cs

@@ -0,0 +1,44 @@
+using Newtonsoft.Json;
+using NJsonSchema;
+using System;
+using System.Reflection;
+using System.Text.Json.Nodes;
+using System.Threading.Tasks;
+
+namespace Elwig.Helpers.Billing {
+    public class BillingData {
+
+        public static JsonSchema? Schema { get; private set; }
+
+        public static async Task Init() {
+            var stream = Assembly.GetExecutingAssembly().GetManifestResourceStream("Elwig.Schemas.payment_variant.json");
+            Schema = await JsonSchema.FromJsonAsync(stream ?? throw new ArgumentException("JSON schema not found"));
+        }
+
+        private JsonObject Data;
+
+        public BillingData(JsonObject data) {
+            Data = data;
+
+        }
+
+        public static JsonObject ParseJson(string json) {
+            if (Schema == null) throw new InvalidOperationException("Schema has to be initialized first");
+            try {
+                var errors = Schema.Validate(json);
+                if (errors.Count != 0) throw new ArgumentException("Invalid JSON data");
+                return JsonNode.Parse(json)?.AsObject() ?? throw new ArgumentException("Invalid JSON data");
+            } catch (JsonReaderException) {
+                throw new ArgumentException("Invalid JSON data");
+            }
+        }
+
+        public static BillingData FromJson(string json) {
+            return new(ParseJson(json));
+        }
+
+        public decimal CalculatePrice(string sortId, string? attrid, string qualId, bool gebunden, double oe, double kmw, bool minQuw) {
+            return 0m;
+        }
+    }
+}