Made atomic and disk stored invoice numbers (UNTESTED)

src/sales_backend/address.cr

@@ -19,7 +19,7 @@ class Address
         country: Country,
         is_default: {type: Bool, default: false},
     )
-    def == (other : Address)
-        self.to_json==other.to_json
+    def <=> (other : Address)
+        self.to_json<=>other.to_json
     end
 end

src/sales_backend/http/product.cr

@@ -0,0 +1,9 @@
+require "kemal"
+require "../*"
+require "io"
+require "file"
+require "exception"
+require "crypto/bcrypt/password"
+require "uuid"
+require "uuid/json"
+require "../../config"

src/sales_backend/invoice.cr

@@ -1,11 +1,39 @@
 require "json"
 require "./invoice_line"
 require "./address"
+require "../config"
+require "atomic"
+require "file"
 
 class Invoice
+    @@last_invoice : Atomic(Int64)
+
+    def initialize
+        @@last_invoice = Atomic(Int64).new(1)
+        if(File.exists? Statics.data_path+"invoices_meta.json")
+            @@last_invoice.set Int64.from_json File.read Statics.data_path+"invoices_meta.json"
+        end
+    end
+
+    def get_new_id
+        ret : Int64 =-1
+        begin
+            metaf = File.open(Statics.data_path+"invoices_meta.json")
+            metaf.flock_exclusive do
+                metaf.truncate
+                ret = @@last_invoice.add(1)
+                metaf.write @@last_invoice.get.to_json
+            end
+        ensure
+            metaf.close
+        end
+        return ret
+    end
+
     JSON.mapping(
         items: Array(InvoiceLine),
         invoicing_address: Address,
-        delivery_address: Address
+        delivery_address: Address,
+        id: Int64
     )
   end

src/sales_backend/product.cr

@@ -1,5 +1,6 @@
 require "json"
-
+require "uuid"
+require "uuid/json"
 
 class Product
     JSON.mapping(
@@ -8,6 +9,6 @@ class Product
         name: {type: String, nilable: true},
         description: {type: String, nilable: true},
         pic_url: {type: String, nilable: true},
-        id: b">Int64,
+        id: o">UUID,
     )
   end