From c900787aa7838d2c708c6c0e92f9da9f7c9121d2 Mon Sep 17 00:00:00 2001
From: David Gay <eapoems@riseup.net>
Date: Sat, 13 Apr 2024 21:21:01 -0400
Subject: Dice lib

---
 app/lib/dice.rb        | 29 +++++++++++++++++++++++++++++
 app/lib/dice/result.rb | 32 ++++++++++++++++++++++++++++++++
 app/lib/dice/roll.rb   | 14 ++++++++++++++
 test/lib/dice_test.rb  | 34 ++++++++++++++++++++++++++++++++++
 4 files changed, 109 insertions(+)
 create mode 100644 app/lib/dice.rb
 create mode 100644 app/lib/dice/result.rb
 create mode 100644 app/lib/dice/roll.rb
 create mode 100644 test/lib/dice_test.rb

diff --git a/app/lib/dice.rb b/app/lib/dice.rb
new file mode 100644
index 0000000..3b6df48
--- /dev/null
+++ b/app/lib/dice.rb
@@ -0,0 +1,29 @@
+module Dice
+  # @param sides [Integer]
+  # @return [Dice::Result]
+  def self.roll(sides)
+    result = Dice::Result.new
+    result.add_roll Dice::Roll.new(sides)
+    result
+  end
+
+  # @param formula [String]
+  def self.roll_formula(formula)
+    # Will add other delimiters later.
+    parts = formula.split("d")
+
+    if parts.length < 2
+      raise "Invalid formula: #{formula}"
+    end
+
+    num_dice = parts[0].empty? ? 1 : parts[0].to_i
+    sides = parts[1].to_i
+
+    result = Dice::Result.new
+    num_dice.times do
+      result.add_roll Dice::Roll.new(sides)
+    end
+
+    result
+  end
+end
diff --git a/app/lib/dice/result.rb b/app/lib/dice/result.rb
new file mode 100644
index 0000000..103a282
--- /dev/null
+++ b/app/lib/dice/result.rb
@@ -0,0 +1,32 @@
+class Dice::Result
+  attr_reader :rolls
+
+  def initialize
+    @rolls = []
+  end
+
+  # @param other [Dice::Result]
+  def ==(other)
+    sides == other.sides && face == other.face
+  end
+
+  # @param roll [Dice::Roll]
+  def add_roll(roll)
+    @rolls << roll
+  end
+
+  # @return [Integer]
+  def total
+    @rolls.sum(&:face)
+  end
+
+  def increase_sides_below_max(max_value, increase_by)
+    @rolls.each do |roll|
+      roll.increase_side_below_max(max_value, increase_by)
+    end
+  end
+
+  def to_s
+    "#{total} (#{@rolls.map(&:face).join(', ')})"
+  end
+end
diff --git a/app/lib/dice/roll.rb b/app/lib/dice/roll.rb
new file mode 100644
index 0000000..dd4788b
--- /dev/null
+++ b/app/lib/dice/roll.rb
@@ -0,0 +1,14 @@
+class Dice::Roll
+  attr_reader :sides, :face
+
+  # @param sides [Integer]
+  # @param face [Integer] (Optional) Rolled if not provided.
+  def initialize(sides, face = nil)
+    @sides = sides
+    @face = face || rand(1..sides)
+  end
+
+  def increase_side_below_max(max_value, increase_by)
+    @face += increase_by if @face < max_value
+  end
+end
diff --git a/test/lib/dice_test.rb b/test/lib/dice_test.rb
new file mode 100644
index 0000000..1f36f30
--- /dev/null
+++ b/test/lib/dice_test.rb
@@ -0,0 +1,34 @@
+require "test_helper"
+
+class DiceTest < ActiveSupport::TestCase
+  test "rolls fomula" do
+    result = Dice.roll_formula("4d6+2")
+
+    assert_equal 4, result.rolls.count
+    assert_equal 6, result.rolls.first&.sides
+  end
+
+  test "rolls single die" do
+    result = Dice.roll(10)
+
+    assert_equal 1, result.rolls.count
+    assert_equal 10, result.rolls.first&.sides
+  end
+
+  test "increases sides below max" do
+    original_result = Dice::Result.new
+    original_result.add_roll Dice::Roll.new(6, 5)
+    original_result.add_roll Dice::Roll.new(6, 6)
+    original_result.add_roll Dice::Roll.new(6, 2)
+
+    new_result = original_result.dup
+
+    assert_equal 13, new_result.total
+    new_result.increase_sides_below_max(6, 1)
+    assert_equal 15, new_result.total
+
+    new_result.rolls.each_with_index do |roll, index|
+      assert_equal roll, original_result.rolls[index]
+    end
+  end
+end
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