ruby/clock: 1st iteration

README.md

@@ -20,7 +20,7 @@ Exercism Workspace
 |   July        |  Jurassic          |  C            (5/5),  C++   (5/5),  Fortran  (0/5)  |
 |   August      |  Apps              |  Dart         (5/5),  Java  (0/5),  Kotlin   (0/5)  |
 |   September   |  Slimline          |  Awk          (5/5),  Bash\*  (5/5),  jq       (0/5),  Perl  (0/5)  |
-|   October     |  Object-Oriented   |  Ruby         (1/5),  Java  (0/5)  |
+|   October     |  Object-Oriented   |  Ruby         (2/5),  Java  (0/5)  |
 |   November    |  Nibbly            |  |
 |   December    |  Diversions        |  |
 

ruby/README.md

@@ -68,3 +68,4 @@
 - [word-count](./word-count/README.md)
 - [allergies](./allergies/README.md)
 - [simple-cipher](./simple-cipher/README.md)
+- [clock](./clock/README.md)

ruby/clock/README.md

@@ -36,4 +36,9 @@ Two clocks that represent the same time should be equal to each other.
 
 ### Based on
 
-Pairing session with Erin Drummond - https://twitter.com/ebdrummond
+Pairing session with Erin Drummond - https://twitter.com/ebdrummond
+
+### My Solution
+
+- [my solution](./clock.rb)
+- [run-tests](./run-tests-ruby.txt)

ruby/clock/clock.rb

@@ -1,7 +1,37 @@
-=begin
-Write your code for the 'Clock' exercise in this file. Make the tests in
-`clock_test.rb` pass.
+# frozen_string_literal: false
 
-To get started with TDD, see the `README.md` file in your
-`ruby/clock` directory.
-=end
+# https://exercism.org/tracks/ruby/exercises/clock
+# Clock exercise
+class Clock
+  attr_reader :hour, :minute
+
+  MINUTES_IN_HOUR = 60
+  HOURS_IN_DAY = 24
+
+  def initialize(hour: 0, minute: 0)
+    @hour, @minute = normalize(hour, minute)
+  end
+
+  def normalize(hour, minute)
+    total_minutes = hour * MINUTES_IN_HOUR + minute
+    total_hours = total_minutes / MINUTES_IN_HOUR
+
+    [total_hours.modulo(HOURS_IN_DAY), total_minutes.modulo(MINUTES_IN_HOUR)]
+  end
+
+  def to_s
+    "#{@hour.to_s.rjust(2, '0')}:#{@minute.to_s.rjust(2, '0')}"
+  end
+
+  def +(other)
+    Clock.new(hour: @hour + other.hour, minute: @minute + other.minute)
+  end
+
+  def -(other)
+    Clock.new(hour: @hour - other.hour, minute: @minute - other.minute)
+  end
+
+  def ==(other)
+    @hour == other.hour && @minute == other.minute
+  end
+end