require 'spec_helper'
require 'enumerable/statistics'

RSpec.describe Array, '#histogram' do
  let(:ary) { [] }
  let(:args) { [] }
  let(:kwargs) { {} }

  subject(:histogram) { ary.histogram(*args, **kwargs) }

  with_array [] do
    context 'default' do
      specify do
        expect(histogram.edges).to eq([0.0])
        expect(histogram.weights).to eq([])
        expect(histogram.closed).to eq(:left)
        expect(histogram.density?).to eq(false)
      end
    end

    context 'closed: :right' do
      let(:kwargs) { {closed: :right} }

      specify do
        expect(histogram.edges).to eq([0.0])
        expect(histogram.weights).to eq([])
        expect(histogram.closed).to eq(:right)
        expect(histogram.density?).to eq(false)
      end
    end
  end

  with_array [1] do
    context 'default' do
      specify do
        expect(histogram.edges).to eq([1.0, 2.0])
        expect(histogram.weights).to eq([1])
        expect(histogram.closed).to eq(:left)
        expect(histogram.density?).to eq(false)
      end
    end

    context 'nbins: 5' do
      let(:args) { [5] }

      specify do
        expect(histogram.edges).to eq([1.0, 2.0])
        expect(histogram.weights).to eq([1])
        expect(histogram.closed).to eq(:left)
        expect(histogram.density?).to eq(false)
      end
    end
  end

  with_array [1, 2] do
    context 'closed: :left' do
      let(:kwargs) { {closed: :left} }

      specify do
        expect(histogram.edges).to eq([1.0, 1.5, 2.0, 2.5])
        expect(histogram.weights).to eq([1, 0, 1])
        expect(histogram.closed).to eq(:left)
        expect(histogram.density?).to eq(false)
      end
    end
  end

  with_array [1, 2, 3, 4, 5, 6, 7, 8, 9] do
    context 'default' do
      specify do
        expect(histogram.edges).to eq([0.0, 2.0, 4.0, 6.0, 8.0, 10.0])
        expect(histogram.weights).to eq([1, 2, 2, 2, 2])
        expect(histogram.closed).to eq(:left)
        expect(histogram.density?).to eq(false)
      end
    end

    context 'nbins: :auto' do
      let(:args) { [:auto] }

      specify do
        expect(histogram.edges).to eq([0.0, 2.0, 4.0, 6.0, 8.0, 10.0])
        expect(histogram.weights).to eq([1, 2, 2, 2, 2])
        expect(histogram.closed).to eq(:left)
        expect(histogram.density?).to eq(false)
      end
    end

    context 'closed: :right' do
      let(:kwargs) { {closed: :right} }

      specify do
        expect(histogram.edges).to eq([0.0, 2.0, 4.0, 6.0, 8.0, 10.0])
        expect(histogram.weights).to eq([2, 2, 2, 2, 1])
        expect(histogram.closed).to eq(:right)
        expect(histogram.density?).to eq(false)
      end
    end

    context 'nbins: 3' do
      let(:args) { [3] }

      specify do
        expect(histogram.edge).to eq([0.0, 5.0, 10.0])
        expect(histogram.weights).to eq([4, 5])
        expect(histogram.closed).to eq(:left)
        expect(histogram.density?).to eq(false)
      end
    end

    context 'weights: [3, 3, 3, 2, 2, 2, 1, 1, 1]' do
      let(:kwargs) { {weights: [3, 3, 3, 2, 2, 2, 1, 1, 1]} }

      specify do
        expect(histogram.edge).to eq([0.0, 2.0, 4.0, 6.0, 8.0, 10.0])
        expect(histogram.weights).to eq([3, 6, 4, 3, 2])
        expect(histogram.closed).to eq(:left)
        expect(histogram.density?).to eq(false)
      end
    end

    context 'weights: [3, 3i, 3, 2, 2, 2, 1, 1, 1]' do
      let(:kwargs) { {weights: [3, 3i, 3, 2, 2, 2, 1, 1, 1]} }

      specify do
        expect { histogram }.to raise_error(TypeError)
      end
    end

    context 'edges: [0.0, 3.0, 6.0, 9.0, 12.0]' do
      let(:kwargs) { {edges: [0.0, 3.0, 6.0, 9.0, 12.0]} }

      specify do
        expect(histogram.edge).to eq([0.0, 3.0, 6.0, 9.0, 12.0])
        expect(histogram.weights).to eq([2, 3, 3, 1])
        expect(histogram.closed).to eq(:left)
        expect(histogram.density?).to eq(false)
      end
    end

    context 'edges: [3.0, 6.0, 9.0]' do
      let(:kwargs) { {edges: [3.0, 6.0, 9.0]} }

      specify do
        expect(histogram.edge).to eq([3.0, 6.0, 9.0])
        expect(histogram.weights).to eq([3, 3])
        expect(histogram.closed).to eq(:left)
        expect(histogram.density?).to eq(false)
      end
    end
  end

  context "with 10,000 normal random values" do
    let(:ary) do
      random = Random.new(13)
      Array.new(10000) do
        # Box-Muller method
        x, y = random.rand, random.rand
        Math.sqrt(-2 * Math.log(x)) * Math.cos(2 * Math::PI * y)
      end
    end

    context "default" do
      specify do
        expect(histogram.edge).to eq([-4.0, -3.5, -3.0, -2.5, -2.0, -1.5,
                                      -1.0, -0.5,  0.0,  0.5,  1.0,  1.5,
                                       2.0,  2.5,  3.0,  3.5])
        expect(histogram.weights).to eq([2, 14, 50, 161, 451,
                                         884, 1508, 1880, 1966, 1538,
                                         893, 432, 160, 51, 10])
        expect(histogram.closed).to eq(:left)
        expect(histogram.density?).to eq(false)
      end
    end

    context "closed: :right" do
      let(:kwargs) { {closed: :right} }

      specify do
        expect(histogram.edge).to eq([-4.0, -3.5, -3.0, -2.5, -2.0, -1.5,
                                      -1.0, -0.5,  0.0,  0.5,  1.0,  1.5,
                                       2.0,  2.5,  3.0,  3.5])
        expect(histogram.weights).to eq([2, 14, 50, 161, 451,
                                         884, 1508, 1880, 1966, 1538,
                                         893, 432, 160, 51, 10])
        expect(histogram.closed).to eq(:right)
        expect(histogram.density?).to eq(false)
      end
    end

    context "nbins: 5" do
      let(:args) { [5] }

      specify do
        expect(histogram.edge).to eq([-4.0, -2.0, 0.0, 2.0, 4.0])
        expect(histogram.weights).to eq([227, 4723, 4829, 221])
        expect(histogram.closed).to eq(:left)
        expect(histogram.density?).to eq(false)
      end
    end
  end
end