require_relative "../helper.rb"

# Values and their defaults. The deviations default to 0.
FLOATS_WITH_RANGE = {
    angular_velocity: 0.0..0.0,
    center_x: 0.5..0.5,
    center_y: 0.5..0.5,
    fade: 0.0..0.0,
    friction: 0.0..0.0,
    interval: Float::INFINITY..Float::INFINITY,
    scale: 1.0..1.0,
    speed: 0.0..0.0,
    time_to_live: Float::INFINITY..Float::INFINITY,
    zoom: 0.0..0.0,
}

describe Ashton::ParticleEmitter do
  before :all do
    $window ||= Gosu::Window.new 16, 16, false
    # Need not to create a large number of these.
    @emitter = described_class.new 1, 2, 3
  end

  let(:default_max) { 1000 }
  let(:subject) { @emitter }

  describe "initialize" do
    [:x, :y, :z].each.with_index(1) do |attr, value|
      it "should set #{attr}" do
        subject.send(attr).should be_kind_of Float
        subject.send(attr).should eq value
      end
    end

    FLOATS_WITH_RANGE.each_pair do |attr, expected|
      it "should set #{attr}" do
        subject.send(attr).should be_kind_of Range
        subject.send(attr).should eq expected
      end
    end

    it "should be set max_particles" do
      subject.max_particles.should be_kind_of Fixnum
      subject.max_particles.should eq default_max
    end

    it "should not have any particles" do
      subject.count.should eq 0
    end

    it "should have color set to white" do
      subject.color.should eq Gosu::Color::WHITE
    end
  end

  [:x, :y, :z].each.with_index(1) do |attr, value|
    describe "#{attr}=" do
      it "should set the value of #{attr}" do
        ->{ subject.send "#{attr}=", value + 5.0 }.should change(subject, attr).from(value).to(value + 5)
      end
    end
  end

  FLOATS_WITH_RANGE.keys.each do |attr|
    describe "#{attr}=" do
      it "should set #{attr} with a number" do
        subject.send("#{attr}=", 42.0).should eq 42.0
        subject.send("#{attr}").should eq 42.0..42.0
      end

      it "should set #{attr} with a range" do
        subject.send("#{attr}=", 42.0..99.0).should eq 42.0..99.0
        subject.send("#{attr}").should eq 42.0..99.0
      end
    end
  end

  describe "color=" do
    it "should set color" do
      (subject.color = Gosu::Color::BLACK).should eq Gosu::Color::BLACK
      subject.color.should eq Gosu::Color::BLACK
    end
  end

  describe "draw" do
    it "should respond to #draw" do
      subject.draw
    end
  end

  describe "emit" do
    it "should create one more particle" do
      ->{ subject.emit }.should change(subject, :count).from(0).to(1)
    end

    it "should replace a particle if we are already at max particles" do
      (default_max + 1).times { subject.emit }
      subject.count.should eq default_max
    end
  end

  describe "update" do
    it "should an appropriate number of particles" do
      subject = described_class.new 1, 2, 3, interval: 0.001
      mock(subject).emit.times 16
      subject.update 1.0 / 60.0 # 16.66667 ms
    end

    it "should not emit a particle if delta is less than interval" do
      subject = described_class.new 1, 2, 3, interval: 0.020
      dont_allow(subject).emit
      subject.update 1.0 / 60.0 # 16.66667 ms
    end

    it "should fail given a negative delta" do
      ->{ subject.update -1 }.should raise_error ArgumentError, "delta must be >= 0"
    end

    it "should fail for a bad delta type" do
      ->{ subject.update "fred" }.should raise_error TypeError
    end
  end
end