# Nathan Hinton 2 Oct 2025

# Test file for the ship object

require './ship'

RSpec.describe Ship do
  let(:initial_x) { 0 }
  let(:initial_y) { 0 }
  subject(:ship) { Ship.new(initial_x, initial_y) }

  describe '#initialize' do
    it 'stores the given position' do
      expect(ship.instance_variable_get(:@position)).to eq([initial_x, initial_y])
    end

    it 'sets the speed to 0.1' do
      expect(ship.instance_variable_get(:@speed)).to eq(0.1)
    end

    it 'does not set @moving until a direction is chosen' do
      expect(ship.instance_variable_get(:@moving)).to be_nil
    end
  end

  describe '#tick' do
    it 'does nothing (but does not raise an exception)' do
      expect { ship.tick }.not_to raise_error
    end
  end

  describe '#move' do
    context 'when coordinates are valid' do
      it 'accepts adjacent moves whose sum is even' do
        # adjacent positions that satisfy the rules
        expect { ship.move(1, 1) }.not_to raise_error   # sum = 2
        expect { ship.move(2, 0) }.not_to raise_error   # sum = 2
        expect { ship.move(0, 2) }.not_to raise_error   # sum = 2
        expect { ship.move(-1, -1) }.not_to raise_error # sum = -2
      end
    end

    context 'when the x + y sum is odd' do
      it 'raises an ArgumentError' do
        expect { ship.move(0, 1) }.to raise_error(
          ArgumentError,
          /must add to be even/
        )
      end
    end

    context 'when the target is not adjacent' do
      it 'raises an ArgumentError' do
        # distance > 1: difference of sums != 2
        expect { ship.move(3, 3) }.to raise_error(
          ArgumentError,
          /must be to an adjcent space/
        )
        expect { ship.move(0, 0) }.to raise_error(
          ArgumentError,
          /must be to an adjcent space/
        )
      end
    end
  end

  describe '#move_direction' do
    it 'accepts direction values between 0 and 5' do
      (0..5).each do |direction|
        expect { ship.move_direction(direction) }.not_to raise_error
        # verify the @moving vector matches the spec
        expected = case direction
                   when 0 then [2, 0]
                   when 1 then [1, 1]
                   when 2 then [-1, 1]
                   when 3 then [-2, 0]
                   when 4 then [-1, -1]
                   when 5 then [1, -1]
                   end
        expect(ship.instance_variable_get(:@moving)).to eq(expected)
      end
    end

    it 'raises an ArgumentError for invalid directions' do
      expect { ship.move_direction(-1) }.to raise_error(
        ArgumentError,
        /must be between \(0..5\)/
      )
      expect { ship.move_direction(6) }.to raise_error(
        ArgumentError,
        /must be between \(0..5\)/
      )
    end
  end
end