$: << '../lib'

require 'geo_graf/polygon'

describe GeoGraf::Polygon do
  let(:polygon) { described_class.new(input, factory) }
  let(:factory) { double("Factory", polygon: rgeo_polygon, point: rgeo_point, linear_ring: rgeo_linear_ring, line: line_180) }
  let(:rgeo_polygon) { double("RGeoPolygon") } 
  let(:rgeo_point) { double("RGeoPoint") }
  let(:rgeo_linear_ring) { double("LinearRing") }
  let(:line_180) { double("Line", intersects?: false) }
  let(:input) { [[-2, -2], [2, -2], [-2, 1], [-2, -2]] }

  describe ".new" do
    subject(:create_new_polygon) { polygon }

    context "when the polygon doesn't span across 180th meridian" do
      it "creates a point for each coordinate" do
        factory.should_receive(:point).exactly(8).times # 4 + 4 used for creation of 180 and -180 lines

        create_new_polygon
      end

      it "creates a linear ring out of the points" do
        factory.should_receive(:linear_ring).with([rgeo_point] * 4)

        create_new_polygon
      end

      it "creates the polygon using the linear ring" do
        factory.should_receive(:polygon).with(rgeo_linear_ring)

        create_new_polygon
      end
    end

    context "when the polygon spans across 180th meridian" do
      let(:line_180) { double("Line", intersects?: true) }

      it "creates two polygons using the linear rings" do
        factory.should_receive(:polygon).with(rgeo_linear_ring).twice

        create_new_polygon
      end
    end
  end

  describe "#area" do
    subject(:get_area) { polygon.area }

    it "delegates to the internal RGeo polygon" do
      rgeo_polygon.should_receive(:area)

      get_area
    end
  end

  describe "#intersection_area" do
    let(:other_polygon) { double('OtherPolygon', rgeo_polygons: [others_rgeo_polygon_1]) }
    let(:others_rgeo_polygon_1) { double('OtherRgeoPolygon1') }
    let(:intersection) { double('Intersection', is_empty?: false, area: 1234.5) }
    let(:no_intersection) { double('NoIntersection', is_empty?: true) }

    context "when the polygon doesn't span across 180th meridian" do
      context "when it intersects the other polygon" do
        before do
          rgeo_polygon.stub(:intersection).with(others_rgeo_polygon_1).and_return(intersection)
        end

        it "returns the area of the intersection" do
          expect(polygon.intersection_area(other_polygon)).to eq(1234.5)
        end

        context "when the intersection spans over multiple polygons and points" do
          let(:intersection) { [double('Point'), double('Polygon', area: 123.67), double('Polygon', area: 3.12)] }

          before do
            intersection.stub(:is_empty?).and_return(false)
          end

          it "returns the sum of areas of the intersection" do
            expect(polygon.intersection_area(other_polygon)).to eq(126.79)
          end
        end
      end

      context "when it doesn't intersect the other polygon" do
        before do
          rgeo_polygon.stub(:intersection).with(others_rgeo_polygon_1).and_return(no_intersection)
        end

        it "returns 0.0" do
          expect(polygon.intersection_area(other_polygon)).to eq(0.0)
        end
      end
    end

    context "when the polygon spans across 180th meridian" do
      let(:other_polygon) {
        double('OtherPolygon', rgeo_polygons: [others_rgeo_polygon_1, others_rgeo_polygon_2])
      }
      let(:others_rgeo_polygon_2) { double('OtherRgeoPolygon2') }
      let(:shadow_rgeo_polygon) { double("ShadowRgeoPolygon") } 
      let(:line_180) { double("Line", intersects?: true) }

      before do
        factory.stub(:polygon).and_return(rgeo_polygon, shadow_rgeo_polygon)
        rgeo_polygon.stub(:intersection).with(others_rgeo_polygon_1).and_return(no_intersection)
        rgeo_polygon.stub(:intersection).with(others_rgeo_polygon_2).and_return(no_intersection)
        shadow_rgeo_polygon.stub(:intersection).with(others_rgeo_polygon_2).and_return(no_intersection)
      end

      context "when it intersects the other polygon" do
        before do
          shadow_rgeo_polygon.stub(:intersection).with(others_rgeo_polygon_1).and_return(intersection)
        end

        it "returns the area of the intersection" do
          expect(polygon.intersection_area(other_polygon)).to eq(1234.5)
        end

        context "when the intersection spans over multiple polygon" do
          let(:intersection) { [double('Point'), double('Polygon', area: 123.67), double('Polygon', area: 3.12)] }

          before do
            intersection.stub(:is_empty?).and_return(false)
          end

          it "returns the sum of areas of the intersection" do
            expect(polygon.intersection_area(other_polygon)).to eq(126.79)
          end
        end
      end

      context "when it doesn't intersect the other polygon" do
        before do
          shadow_rgeo_polygon.stub(:intersection).with(others_rgeo_polygon_1).and_return(no_intersection)
        end

        it "returns 0.0" do
          expect(polygon.intersection_area(other_polygon)).to eq(0.0)
        end
      end
    end
  end
end