Add lower limit of one satoshi on bids

Many Lightning wallets do not support payments below 1 sat (in
millisatoshis). For wider compliance, set a lower limit of 1 sat on orders,
while preserving the minimum bid per byte requirement for orders whose absolute
bid exceeds 1 sat.

constants.rb

@@ -17,6 +17,7 @@ CHARGE_API_TOKEN = ENV['CHARGE_API_TOKEN'] || 'mySecretToken'
 CHARGE_ROOT = ENV['CHARGE_ROOT'] || "http://api-token:#{CHARGE_API_TOKEN}@localhost:9112"
 
 MIN_PER_BYTE_BID = Integer(ENV['MIN_PER_BYTE_BID'] || 1) # minimum price per byte in millisatoshis
+MIN_BID = 1000 # minimum absolute bid in millisatoshis
 MIN_MESSAGE_SIZE = 1
 
 UDP_HDR_SIZE         = 8

helpers/order_helpers.rb

@@ -53,6 +53,10 @@ module Sinatra
       halt 400, error_object("Message upload problem", "Message too small. Minimum message size is #{MIN_MESSAGE_SIZE} byte", ERROR::CODES[:MESSAGE_FILE_TOO_SMALL])
     end
 
+    def bid_below_minimum_error()
+      halt 413, error_object("Bid too low", "Bid cannot be below #{MIN_BID} millisatoshis.", ERROR::CODES[:BID_TOO_SMALL])
+    end
+
     def bid_too_small_error(min_bid)
       halt 413, error_object("Bid too low", "Per byte bid cannot be below #{MIN_PER_BYTE_BID} millisatoshis per byte. The minimum bid for this message is #{min_bid} millisatoshis.", ERROR::CODES[:BID_TOO_SMALL])
     end

main.rb

@@ -182,7 +182,9 @@ post '/order' do
   order.message_size = message_size
   order.message_digest = sha256.to_s
 
-  if bid.to_f / order.message_size_with_overhead < MIN_PER_BYTE_BID
+  if bid.to_f < MIN_BID
+    bid_below_minimum_error()
+  elsif bid.to_f / order.message_size_with_overhead < MIN_PER_BYTE_BID
     bid_too_small_error(order.message_size_with_overhead * MIN_PER_BYTE_BID)
   end
 

models/orders.rb

@@ -112,7 +112,7 @@ class Order < ActiveRecord::Base
 
   def paid_enough?
     self.adjust_bids
-    self.bid_per_byte >= MIN_PER_BYTE_BID
+    self.bid_per_byte >= MIN_PER_BYTE_BID && self.bid.to_f >= MIN_BID
   end
   
   def message_size_with_overhead

tests/tests.rb

@@ -139,6 +139,17 @@ class MainAppTest < Minitest::Test
     assert_equal ERROR::CODES[:BID_TOO_SMALL], last_response_error_code
   end
 
+  def test_bid_below_min_bid
+    post '/order', params={"bid" => (4 + L2_OVERHEAD), "message" => "test"}
+    refute last_response.ok?
+    assert_equal ERROR::CODES[:BID_TOO_SMALL], last_response_error_code
+    post '/order', params={"bid" => (MIN_BID - 1), "message" => "test"}
+    refute last_response.ok?
+    assert_equal ERROR::CODES[:BID_TOO_SMALL], last_response_error_code
+    post '/order', params={"bid" => (MIN_BID), "message" => "test"}
+    assert last_response.ok?
+  end
+
   def test_bid_too_low
     post '/order', params={"bid" => 1, "file" => Rack::Test::UploadedFile.new(TEST_FILE, "image/png")}
     refute last_response.ok?