feature/ability to apply coupon for price

lib/monopay-ruby/configuration.rb

@@ -1,7 +1,8 @@
 class MonopayRuby::Configuration
-  attr_accessor :api_token
+  attr_accessor :api_token, :min_value
 
   def initialize
     @api_token = ENV["MONOBANK_API_TOKEN"] # note ability to use ENV variable in docs
+    @min_value = ENV["MIN_VALUE"] || 1 # 0.01 - minimun valid amount in Monobank
   end
 end

lib/monopay-ruby/invoices/simple_invoice.rb

@@ -30,12 +30,14 @@ def initialize(redirect_url = nil, webhook_url = nil)
       # @param [String] destination - additional info about payment
       # @param [String] reference - bill number or other reference
       # @return [Boolean] true if invoice was created successfully, false otherwise
-      def create(amount, destination: nil, reference: nil)
+      def create(amount, discount=1, destination: nil, reference: nil)
         begin
-          @amount = convert_to_cents(amount)
+          @amount = [convert_to_cents(amount), MonopayRuby.configuration.min_value].max
           @destination = destination
           @reference = reference
 
+          make_discount(discount) if discount < 1
+
           response = RestClient.post(API_CREATE_INVOICE_URL, request_body, headers)
           response_body = JSON.parse(response.body)
 
@@ -75,10 +77,18 @@ def request_body
       def convert_to_cents(amount)
         if amount.is_a?(BigDecimal)
           Money.from_amount(amount, DEFAULT_CURRENCY).cents
-        else
+        elsif amount.is_a?(Integer)
           amount
+        else
+          raise TypeError, "expected amount will be an Integer or BigDecimal, got #{amount.class}"
         end
       end
+
+      def make_discount(discount)
+        sum = (@amount * (1 - discount)).to_i
+
+        @amount = [sum, MonopayRuby.configuration.min_value].max
+      end
     end
   end
 end

lib/monopay-ruby/webhooks/public_key.rb

@@ -2,7 +2,6 @@
 require "base64"
 require "json"
 
-require "pry"
 module MonopayRuby
   module Webhooks
     class PublicKey < MonopayRuby::Base