# frozen_string_literal: true

RSpec.describe GameOfLife::Universe do
  describe ".new" do
    it "creates a @current 2D array (Plane) of height * width" do
      universe = described_class.new(width: 10, height: 1)
      current_generation = universe.instance_variable_get(:@current)

      expect(current_generation).to be_a GameOfLife::Plane
      expect(current_generation[0]).to be_a GameOfLife::Plane

      expect(current_generation.size).to eq 1
      expect(current_generation[0].size).to eq 10
    end

    it "creates a @future 2D array (Plane) of height * width" do
      universe = described_class.new(width: 10, height: 1)
      future_generation = universe.instance_variable_get(:@future)

      expect(future_generation).to be_a GameOfLife::Plane
      expect(future_generation[0]).to be_a GameOfLife::Plane

      expect(future_generation.size).to eq 1
      expect(future_generation[0].size).to eq 10
    end
  end

  describe "#to_s" do
    subject(:universe) { described_class.new(width: 3, height: 3) }

    before do
      universe[0] = [1, 2, 3]
      universe[1] = [4, 5, 6]
      universe[2] = [7, 8, 9]
    end

    it "prints out the universe 2D @current array" do
      expect(universe.to_s).to eq "123\n456\n789"
    end
  end

  describe "#evolve!" do
    subject(:universe) { described_class.new(width: 3, height: 3) }

    before do
      # quick way to initialize the whole universe with living cells
      9.times { |i| universe[i / 3][i % 3] = GameOfLife::Cell.new(y: i / 3, x: i % 3, alive: true) }
    end

    it "calls Cell#evolve! on every cell" do
      9.times { |i| expect(universe[i / 3][i % 3]).to receive(:evolve!) }
      universe.evolve!
    end

    it "updates the universe current state" do
      9.times { |i| expect(universe[i / 3][i % 3]).to be_alive }
      universe.evolve!
      9.times { |i| expect(universe[i / 3][i % 3]).to be_dead }
    end
  end

  describe "#neighbors" do
    subject(:universe) { described_class.new(width: 5, height: 5) }

    it "returns surronding neighbors" do
      current = GameOfLife::Plane.new(
        [
          GameOfLife::Plane.new(%w[. . . . .]),
          GameOfLife::Plane.new(%w[. x x x .]),
          GameOfLife::Plane.new(%w[. x C x .]),
          GameOfLife::Plane.new(%w[. x x x .]),
          GameOfLife::Plane.new(%w[. . . . .]),
        ],
      )
      universe.instance_variable_set(:@current, current)
      cell = GameOfLife::Cell.new(y: 2, x: 2, alive: "C")

      expect(universe.send(:neighbors, cell)).to eq %w[x x x x x x x x]
    end

    it "returns surronding neighbors (beyond top edge)" do
      current = GameOfLife::Plane.new(
        [
          GameOfLife::Plane.new(%w[. x C x .]),
          GameOfLife::Plane.new(%w[. x x x .]),
          GameOfLife::Plane.new(%w[. . . . .]),
          GameOfLife::Plane.new(%w[. . . . .]),
          GameOfLife::Plane.new(%w[. x x x .]),
        ],
      )
      universe.instance_variable_set(:@current, current)
      cell = GameOfLife::Cell.new(y: 0, x: 2, alive: "C")

      expect(universe.send(:neighbors, cell)).to eq %w[x x x x x x x x]
    end

    it "returns surronding neighbors (beyond left edge)" do
      current = GameOfLife::Plane.new(
        [
          GameOfLife::Plane.new(%w[. . . . .]),
          GameOfLife::Plane.new(%w[. . . . .]),
          GameOfLife::Plane.new(%w[x x . . x]),
          GameOfLife::Plane.new(%w[C x . . x]),
          GameOfLife::Plane.new(%w[x x . . x]),
        ],
      )
      universe.instance_variable_set(:@current, current)
      cell = GameOfLife::Cell.new(y: 3, x: 0, alive: "C")

      expect(universe.send(:neighbors, cell)).to eq %w[x x x x x x x x]
    end

    it "returns surronding neighbors (beyond diagonal edges)" do
      current = GameOfLife::Plane.new(
        [
          GameOfLife::Plane.new(%w[C x . . x]),
          GameOfLife::Plane.new(%w[x x . . x]),
          GameOfLife::Plane.new(%w[. . . . .]),
          GameOfLife::Plane.new(%w[. . . . .]),
          GameOfLife::Plane.new(%w[x x . . x]),
        ],
      )
      universe.instance_variable_set(:@current, current)
      cell = GameOfLife::Cell.new(y: 0, x: 0, alive: "C")

      expect(universe.send(:neighbors, cell)).to eq %w[x x x x x x x x]
    end

    it "returns surronding neighbors (beyond reversed diagonal edges)" do
      current = GameOfLife::Plane.new(
        [
          GameOfLife::Plane.new(%w[x . . x x]),
          GameOfLife::Plane.new(%w[. . . . .]),
          GameOfLife::Plane.new(%w[. . . . .]),
          GameOfLife::Plane.new(%w[x . . x x]),
          GameOfLife::Plane.new(%w[x . . x C]),
        ],
      )

      universe.instance_variable_set(:@current, current)
      cell = GameOfLife::Cell.new(y: 4, x: 4, alive: "C")

      expect(universe.send(:neighbors, cell)).to eq %w[x x x x x x x x]
    end
  end
end