From 3c9df13beb85d176f766a8d7e3d0e18aa873660b Mon Sep 17 00:00:00 2001
From: Vitalii Elenhaupt <velenhaupt@gmail.com>
Date: Fri, 17 Nov 2017 19:07:39 +0200
Subject: [PATCH] New option: LargeNumbers#int_min_digits (default: 5)

---
 config/ameba.yml                      |  1 +
 spec/ameba/rule/large_numbers_spec.cr | 18 ++++++++++--------
 src/ameba/rule/large_numbers.cr       | 19 +++++++++++++++----
 3 files changed, 26 insertions(+), 12 deletions(-)

diff --git a/config/ameba.yml b/config/ameba.yml
index f2dab120..66043bf8 100644
--- a/config/ameba.yml
+++ b/config/ameba.yml
@@ -21,6 +21,7 @@ EmptyExpression:
 LargeNumbers:
   # A rule that disallows usage of large numbers without underscore.
   Enabled: true
+  IntMinDigits: 5 # i.e. integers higher than 9999
 
 LineLength:
   # Disallows lines longer that MaxLength number of symbols.
diff --git a/spec/ameba/rule/large_numbers_spec.cr b/spec/ameba/rule/large_numbers_spec.cr
index 39302d30..6af4643d 100644
--- a/spec/ameba/rule/large_numbers_spec.cr
+++ b/spec/ameba/rule/large_numbers_spec.cr
@@ -17,7 +17,11 @@ module Ameba
         1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
         16 17 18 19 20 30 40 50 60 70 80 90
         100
+        999
+        1000
         1_000
+        9999
+        9_999
         10_000
         100_000
         200_000
@@ -79,15 +83,13 @@ module Ameba
 
     it_transforms "1_00000", "100_000"
 
-    it_transforms "1_23_i8", "123_i8"
-    it_transforms "1000_i16", "1_000_i16"
-    it_transforms "1000_i32", "1_000_i32"
-    it_transforms "1000_i64", "1_000_i64"
+    it_transforms "10000_i16", "10_000_i16"
+    it_transforms "10000_i32", "10_000_i32"
+    it_transforms "10000_i64", "10_000_i64"
 
-    it_transforms "1_23_u8", "123_u8"
-    it_transforms "1000_u16", "1_000_u16"
-    it_transforms "1000_u32", "1_000_u32"
-    it_transforms "1000_u64", "1_000_u64"
+    it_transforms "10000_u16", "10_000_u16"
+    it_transforms "10000_u32", "10_000_u32"
+    it_transforms "10000_u64", "10_000_u64"
 
     it_transforms "123456_f32", "123_456_f32"
     it_transforms "123456_f64", "123_456_f64"
diff --git a/src/ameba/rule/large_numbers.cr b/src/ameba/rule/large_numbers.cr
index 2d1a611f..b0144c1c 100644
--- a/src/ameba/rule/large_numbers.cr
+++ b/src/ameba/rule/large_numbers.cr
@@ -24,14 +24,19 @@ module Ameba::Rule
   # ```
   # LargeNumbers:
   #   Enabled: true
+  #   IntMinDigits: 5 # i.e. integers higher than 9999
   # ```
   #
   struct LargeNumbers < Base
+    prop int_min_digits = 5
+
     def test(source)
       Tokenizer.new(source).run do |token|
         next unless token.type == :NUMBER && decimal?(token.raw)
 
-        if (expected = underscored token.raw) != token.raw
+        parsed = parse_number token.raw
+
+        if allowed?(*parsed) && (expected = underscored *parsed) != token.raw
           source.error self, token.location,
             "Large numbers should be written with underscores: #{expected}"
         end
@@ -42,8 +47,14 @@ module Ameba::Rule
       value !~ /^0(x|b|o)/
     end
 
-    private def underscored(raw_number)
-      sign, value, fraction, suffix = parse_number raw_number
+    private def allowed?(_sign, value, fraction, _suffix)
+      return true unless fraction.nil?
+
+      digits = value.chars.select &.to_s.=~ /[0-9]/
+      digits.size >= int_min_digits
+    end
+
+    private def underscored(sign, value, fraction, suffix)
       value = slice_digits(value.reverse) { |slice| slice }.reverse
       fraction = "." + slice_digits(fraction) { |slice| slice } if fraction
 
@@ -75,7 +86,7 @@ module Ameba::Rule
     end
 
     private def parse_suffix(value)
-      if pos = (value =~ /e/ || value =~ /_(i|u|f)/)
+      if pos = (value =~ /e/ || value =~ /_?(i|u|f)/)
         suffix = value[pos..-1]
         value = value[0..pos - 1]
       end