refactor/checkout (#8)

Co-authored-by: matst80 <mats.tornberg@gmail.com>
Reviewed-on: #8
Co-authored-by: Mats Törnberg <mats@tornberg.me>
Co-committed-by: Mats Törnberg <mats@tornberg.me>

proto/cart.proto

@@ -0,0 +1,96 @@
+syntax = "proto3";
+package cart_messages;
+option go_package = "git.k6n.net/go-cart-actor/proto/cart;cart_messages";
+
+import "google/protobuf/any.proto";
+import "google/protobuf/timestamp.proto";
+
+message ClearCartRequest {}
+
+message AddItem {
+  uint32 item_id = 1;
+  int32 quantity = 2;
+  int64 price = 3;
+  int64 orgPrice = 9;
+  string sku = 4;
+  string name = 5;
+  string image = 6;
+  int32 stock = 7;
+  int32 tax = 8;
+  string brand = 13;
+  string category = 14;
+  string category2 = 15;
+  string category3 = 16;
+  string category4 = 17;
+  string category5 = 18;
+  string disclaimer = 10;
+  string articleType = 11;
+  string sellerId = 19;
+  string sellerName = 20;
+  string country = 21;
+  string saleStatus = 24;
+  optional string outlet = 12;
+  optional string storeId = 22;
+  optional uint32 parentId = 23;
+  string cgm = 25;
+  optional google.protobuf.Timestamp reservationEndTime = 26;
+}
+
+message RemoveItem { uint32 Id = 1; }
+
+message ChangeQuantity {
+  uint32 Id = 1;
+  int32 quantity = 2;
+}
+
+message SetUserId {
+  string userId = 1;
+}
+
+message LineItemMarking {
+  uint32 id = 1;
+  uint32 type = 2;
+  string marking = 3;
+}
+
+message RemoveLineItemMarking {
+  uint32 id = 1;
+}
+
+message SubscriptionAdded {
+    uint32 itemId = 1;
+    string detailsId = 3;
+    string orderReference = 4;
+}
+
+message AddVoucher {
+  string code = 1;
+  int64 value = 2;
+  repeated string voucherRules = 3;
+  string description = 4;
+}
+
+message RemoveVoucher { uint32 id = 1; }
+
+message UpsertSubscriptionDetails {
+  optional string id = 1;
+  string offeringCode = 2;
+  string signingType = 3;
+  google.protobuf.Any data = 4;
+}
+
+message Mutation {
+  oneof type {
+    ClearCartRequest clear_cart = 1;
+    AddItem add_item = 2;
+    RemoveItem remove_item = 3;
+    ChangeQuantity change_quantity = 4;
+    SetUserId set_user_id = 5;
+    LineItemMarking line_item_marking = 6;
+    RemoveLineItemMarking remove_line_item_marking = 7;
+    SubscriptionAdded subscription_added = 8;
+    AddVoucher add_voucher = 20;
+    RemoveVoucher remove_voucher = 21;
+    UpsertSubscriptionDetails upsert_subscription_details = 22;
+  }
+}