fmt: shared number formatting for HTML and PDF

asxpio.rb

@@ -17,6 +17,7 @@ $root   = __dir__
 $logger = Logger.new($stdout)
 $env    = ENV.fetch('RACK_ENV', 'development')
 
+require_relative 'lib/fmt'
 require_relative 'lib/mailer'
 require_relative 'lib/rate_limit'
 require_relative 'lib/db'
@@ -73,18 +74,12 @@ class AsxpioWeb < Sinatra::Base
         request.ip
     end
 
-    # Exchange rate for display: full captured precision (up to 8 dp), trailing
-    # zeros trimmed, padded to at least min_dp. Mirrors InvoicePdf#fmt_rate so
-    # the HTML and PDF agree. (4 dp matches the NBG's GEL quoting.)
     def fmt_rate(value, min_dp = 4)
-      frac = BigDecimal(value.to_s).round(8).to_s('F').split('.').last.sub(/0+$/, '')
+      Fmt.rate(value, min_dp: min_dp)
-      whole = BigDecimal(value.to_s).to_i
-      "#{whole}.#{frac.ljust(min_dp, '0')}"
     end
 
-    # LTC amount: up to 8 dp, trailing zeros trimmed, no padding.
     def fmt_ltc(value)
-      BigDecimal(value.to_s).round(8).to_s('F').sub(/(\.\d*?)0+$/, '\1').sub(/\.$/, '')
+      Fmt.ltc(value)
     end
   end
 

lib/fmt.rb

@@ -0,0 +1,25 @@
+require 'bigdecimal'
+
+# Number formatting shared by the HTML views and the PDF so they can't drift.
+module Fmt
+  module_function
+
+  # Exchange rate: full captured precision (up to 8 dp), trailing zeros
+  # trimmed, padded to at least min_dp so it reads as a rate. (4 dp matches
+  # the NBG's GEL quoting.)
+  def rate(value, min_dp: 4)
+    int, frac = BigDecimal(value.to_s).round(8).to_s('F').split('.')
+    frac = (frac || '').sub(/0+$/, '').ljust(min_dp, '0')
+    "#{group(int)}.#{frac}"
+  end
+
+  # LTC amount: up to 8 dp, trailing zeros trimmed, no padding.
+  def ltc(value)
+    BigDecimal(value.to_s).round(8).to_s('F').sub(/(\.\d*?)0+$/, '\1').sub(/\.$/, '')
+  end
+
+  # "1234567" -> "1,234,567"
+  def group(int)
+    int.reverse.gsub(/(\d{3})(?=\d)/, '\1,').reverse
+  end
+end

lib/invoice_pdf.rb

@@ -2,6 +2,7 @@ require 'prawn'
 require 'prawn/table'
 require 'bigdecimal'
 require 'stringio'
+require_relative 'fmt'
 
 class InvoicePdf
   FONTS_DIR = File.join($root, 'public', 'fonts')
@@ -333,18 +334,11 @@ class InvoicePdf
   end
 
   def fmt_ltc(value)
-    BigDecimal(value.to_s).round(8).to_s('F').sub(/(\.\d*?)0+$/, '\\1').sub(/\.$/, '')
+    Fmt.ltc(value)
   end
 
-  # Exchange rate: keep full captured precision (up to 8 dp), trim trailing
-  # zeros, but pad to at least `min_dp` so it reads as a rate. GEL/USD rates are
-  # quoted to 4 dp by the NBG, so the default min is 4.
   def fmt_rate(value, min_dp: 4)
-    s = BigDecimal(value.to_s).round(8).to_s('F')
+    Fmt.rate(value, min_dp: min_dp)
-    int, frac = s.split('.')
-    frac = (frac || '').sub(/0+$/, '')
-    frac = frac.ljust(min_dp, '0')
-    "#{with_thousands("#{int}.00").split('.').first}.#{frac}"
   end
 
   def fmt_qty(value)
@@ -354,7 +348,7 @@ class InvoicePdf
 
   def with_thousands(numstr)
     int, frac = numstr.split('.')
-    int = int.reverse.gsub(/(\d{3})(?=\d)/, '\\1,').reverse
+    int = Fmt.group(int)
     frac ? "#{int}.#{frac.ljust(2, '0')[0, 2]}" : "#{int}.00"
   end
 end

test/fmt_test.rb

@@ -0,0 +1,22 @@
+require_relative 'test_helper'
+
+class FmtTest < Minitest::Test
+  def test_rate_pads_to_min_dp
+    assert_equal '2.9500', Fmt.rate('2.95')
+    assert_equal '3.0000', Fmt.rate(3)
+  end
+
+  def test_rate_keeps_captured_precision
+    assert_equal '2.95123456', Fmt.rate('2.95123456')
+  end
+
+  def test_rate_groups_thousands
+    assert_equal '1,050.2500', Fmt.rate('1050.25')
+  end
+
+  def test_ltc_trims_trailing_zeros
+    assert_equal '1.25', Fmt.ltc('1.250000')
+    assert_equal '2', Fmt.ltc('2.0')
+    assert_equal '0.00123456', Fmt.ltc('0.00123456')
+  end
+end