Ruby Mancala

Kata.rb

class Well
  attr_accessor :next_well, :seeds, :game

  def initialize game
    self.seeds = 0
    self.game = game
    self.game.wells << self
  end
  
  def sow
    current_seeds = self.seeds
    self.seeds = 0
    self.next_well.take_seed current_seeds 
    self.game.determine_winner
  end

  def take_seed count
    self.seeds += 1
    count = count - 1
    self.next_well.take_seed count if count > 0
  end
end 

class GoalWell < Well
  attr_accessor :owner

  def take_seed count
    if game.turn == self.owner
      super
    else
      self.next_well.take_seed count
    end
  end
end

class Game
  attr_accessor :wells, :winner, :turn

  def initialize 
    self.wells = Array.new
  end

  def determine_winner
    if self.ended? 
      return if !self.player1_goal_well

      return if !self.player2_goal_well

      if self.player1_goal_well.seeds > self.player2_goal_well.seeds
        self.winner = :player1
        return
      end

      if self.player2_goal_well.seeds > self.player1_goal_well.seeds
        self.winner = :player2
        return
      end

      self.winner = :tie
    end
  end

  def ended?
      self.playable_wells
        .map { |w| w.seeds }
        .inject { |sum, n| sum + n } == 0
  end

  def playable_wells
    self.wells.find_all { |w| w.instance_of? Well }
  end

  def player1_goal_well
    self.goal_well_for :player1
  end

  def player2_goal_well
    self.goal_well_for :player2
  end

  def goal_well_for player
    self.wells.find { |w| w.instance_of? GoalWell and w.owner == player }
  end
end

kata_spec.rb

require './kata.rb'

describe "sowing" do
  before(:each) do
    @game = Game.new
    @well1 = Well.new @game
    @well2 =  Well.new @game
    @well1.next_well = @well2
    @well2.next_well = @well1
  end

  it "sowing 1 seed across 2 wells" do 
    @well1.seeds = 1
    @well1.sow
    @well2.seeds.should == 1
    @well1.seeds.should == 0
  end

  it "sowing 2 seed across 2 wells" do 
    @well1.seeds = 2
    @well1.sow
    @well2.seeds.should == 1
    @well1.seeds.should == 1
  end

  it "sowing 3 seed across 2 wells" do 
    @well1.seeds = 3
    @well1.sow
    @well2.seeds.should == 2
    @well1.seeds.should == 1
  end
end

describe "end game" do
  before(:each) do
    @game = Game.new
    @well1 = Well.new @game
    @goal_well = GoalWell.new @game
    @goal_well.owner = :player1
    @well2 =  Well.new @game
    @well1.next_well = @goal_well 
    @goal_well.next_well = @well2
    @well2.next_well = @well1
  end

  it "game ends if no one can sow seeds" do
  	@game.turn = :player1
    @well1.seeds = 1
    @well1.sow
    @well1.game.ended?.should be_true
  end

  it "game continues if there are seeds to sow" do
  	@game.turn = :player1
    @well1.seeds = 2
    @well1.sow
    @well1.game.ended?.should be_false
  end

  it "game continues if there are seeds to sow" do
  	@game.turn = :player1
    @well1.seeds = 3
    @well1.sow
    @well1.game.ended?.should be_false
  end
end

describe "winner" do
  before(:each) do
    @game = Game.new
    @well1 = Well.new @game
    @goal_well = GoalWell.new @game
    @goal_well.owner = :player1
    @well2 =  Well.new @game
    @goal_well_2 = GoalWell.new @game
    @goal_well_2.owner = :player2
    @well1.next_well = @goal_well 
    @goal_well.next_well = @well2
    @well2.next_well = @goal_well_2
    @goal_well_2.next_well = @well1
  end

  it "player one wins" do
  	@game.turn = :player1
    @well1.seeds = 1
    @well1.sow
    @well1.game.winner.should == :player1
  end

  it "player two wins" do
  	@game.turn = :player2
    @well2.seeds = 1
    @well2.sow
    @game.winner.should == :player2
  end

  it "tie" do
  	@game.turn = :player1
    @well1.seeds = 1
    @well2.seeds = 1
    @well1.sow
    @game.turn = :player2
    @well2.sow
    @game.winner.should == :tie 
  end
end


describe "goal well" do
  before(:each) do
    @game = Game.new
    @well1 = Well.new @game
    @goal_well = GoalWell.new @game
    @goal_well.owner = :player1
    @well2 =  Well.new @game
    @goal_well_2 = GoalWell.new @game
    @goal_well_2.owner = :player2
    @well1.next_well = @goal_well 
    @goal_well.next_well = @well2
    @well2.next_well = @goal_well_2
    @goal_well_2.next_well = @well1
  end

  it "player 2's well is skipped on player 1's turn" do
    @game.turn = :player1
    @well1.seeds = 3
    @well1.sow
    @goal_well_2.seeds.should == 0
    @well1.seeds.should == 1
  end
end