Add Opt

Fixes #69

lib/magic/cards/opt.rb

@@ -0,0 +1,19 @@
+module Magic
+  module Cards
+    Opt = Instant("Opt") do
+      cost blue: 1
+    end
+
+    class Opt < Instant
+      def resolve!(_controller)
+        game.add_effect(
+          Effects::Scry.new(source: self, amount: 1, then_do: -> do
+            game.add_effect(Effects::DrawCards.new(source: self, player: controller))
+          end)
+        )
+
+        super
+      end
+    end
+  end
+end

lib/magic/effect.rb

@@ -1,20 +1,25 @@
 module Magic
   class Effect
-    attr_reader :source, :targets, :choices
+    attr_reader :source, :targets, :choices, :then_do
 
     class InvalidTarget < StandardError; end;
 
-    def initialize(source:, targets: [], choices: [])
+    def initialize(source:, targets: [], choices: [], then_do: nil)
       @source = source
       @targets = targets
       @choices = choices.select { |choice| choice.can_be_targeted_by?(source) }
       @resolved = false
+      @then_do = then_do
     end
 
     def multiple_targets?
       targets > 1
     end
 
+    def single_choice?
+      requires_choices? && choices.count == 1
+    end
+
     def requires_choices?
       false
     end
@@ -29,6 +34,10 @@ def multiple_targets?
 
     def resolve(*)
       @resolved = true
+
+      if then_do
+        then_do.call
+      end
     end
 
     def skip!

lib/magic/effects/scry.rb

@@ -0,0 +1,25 @@
+module Magic
+  module Effects
+    class Scry < Effect
+      attr_reader :player, :amount
+
+      def initialize(source:, amount:, then_do:)
+        @source = source
+        @amount = amount
+        super(source: source, then_do: then_do)
+
+      end
+
+      def requires_choices?
+        true
+      end
+
+      def resolve(top: [], bottom: [])
+        source.controller.scry(amount:, top:, bottom:)
+
+        super
+
+      end
+    end
+  end
+end

lib/magic/events/scry.rb

@@ -0,0 +1,17 @@
+module Magic
+  module Events
+    class Scry
+      attr_reader :player, :top, :bottom
+
+      def initialize(player:, top:, bottom:)
+        @player = player
+        @top = top
+        @bottom = bottom
+      end
+
+      def inspect
+        "#<Events::Scry player: #{player}, top: #{top}, bottom: #{bottom}>"
+      end
+    end
+  end
+end

lib/magic/player.rb

@@ -126,6 +126,19 @@ def mill(amount)
       end
     end
 
+    def scry(amount:, top:, bottom:)
+      cards = library.shift(amount)
+      library.unshift(*top)
+      library.push(*bottom)
+      game.notify!(
+        Events::Scry.new(
+          player: self,
+          top: top.count,
+          bottom: bottom.count,
+        )
+      )
+    end
+
     def tap!(card)
       card.tap!
     end

lib/magic/zone.rb

@@ -3,7 +3,7 @@ class Zone
     extend Forwardable
     include Enumerable
 
-    def_delegators :@cards, :each, :<<, :by_name, :creatures, :by_any_type, :basic_lands, :controlled_by, :cmc_lte, :by_card
+    def_delegators :@cards, :each, :last, :shift, :unshift, :push, :<<, :by_name, :creatures, :by_any_type, :basic_lands, :controlled_by, :cmc_lte, :by_card
 
     attr_reader :owner, :cards
 

spec/cards/opt_spec.rb

@@ -0,0 +1,55 @@
+require 'spec_helper'
+
+RSpec.describe Magic::Cards::Opt do
+  include_context "two player game"
+
+  let(:opt) { described_class.new(game: game) }
+
+  def p1_library
+    [
+      Card("Forest"),
+      Card("Forest"),
+      Card("Forest"),
+      Card("Forest"),
+      Card("Forest"),
+      Card("Forest"),
+      Card("Forest"),
+      # End initial card draw
+      Card("Sol Ring"),
+      Card("Forest"),
+    ]
+  end
+
+  it "scries to the top" do
+    top_card = p1.library.first
+    p1.add_mana(blue: 1)
+    action = cast_action(player: p1, card: opt)
+    action.pay_mana(blue: 1)
+    game.take_action(action)
+    game.tick!
+    effect = game.effects.first
+    expect(effect).to be_a(Magic::Effects::Scry)
+    game.resolve_pending_effect(top: [top_card])
+
+    expect(opt.zone).to be_graveyard
+    expect(p1.library.first.name).to eq("Forest")
+    expect(p1.hand.map(&:name)).to include("Sol Ring")
+  end
+
+  it "scries to the bottom" do
+    top_card = p1.library.first
+    p1.add_mana(blue: 1)
+    action = cast_action(player: p1, card: opt)
+    action.pay_mana(blue: 1)
+    game.take_action(action)
+    game.tick!
+    effect = game.effects.first
+    expect(effect).to be_a(Magic::Effects::Scry)
+    game.resolve_pending_effect(bottom: [top_card])
+
+    expect(opt.zone).to be_graveyard
+    expect(p1.library.last).to eq(top_card)
+
+    expect(p1.hand.map(&:name)).not_to include("Sol Ring")
+  end
+end