import expect from '../../../expect.js';
import {interpolatePoint} from '../../../../../src/ol/geom/flat/interpolate.js';

describe('ol/geom/flat/interpolate.js', function () {
  describe('interpolatePoint', function () {
    it('returns the expected value for single points', function () {
      const flatCoordinates = [0, 1];
      const point = interpolatePoint(flatCoordinates, 0, 2, 2, 0.5);
      expect(point).to.eql([0, 1]);
    });

    it('returns the expected value for simple line segments', function () {
      const flatCoordinates = [0, 1, 2, 3];
      const point = interpolatePoint(flatCoordinates, 0, 4, 2, 0.5);
      expect(point).to.eql([1, 2]);
    });

    it(
      'returns the expected value when the mid point is an existing ' +
        'coordinate',
      function () {
        const flatCoordinates = [0, 1, 2, 3, 4, 5];
        const point = interpolatePoint(flatCoordinates, 0, 6, 2, 0.5);
        expect(point).to.eql([2, 3]);
      }
    );

    it('also when vertices are repeated', function () {
      const flatCoordinates = [0, 1, 2, 3, 2, 3, 4, 5];
      const point = interpolatePoint(flatCoordinates, 0, 8, 2, 0.5);
      expect(point).to.eql([2, 3]);
    });

    it(
      'returns the expected value when the midpoint falls halfway between ' +
        'two existing coordinates',
      function () {
        const flatCoordinates = [0, 1, 2, 3, 4, 5, 6, 7];
        const point = interpolatePoint(flatCoordinates, 0, 8, 2, 0.5);
        expect(point).to.eql([3, 4]);
      }
    );

    it('also when vertices are repeated', function () {
      const flatCoordinates = [0, 1, 2, 3, 2, 3, 4, 5, 6, 7];
      const point = interpolatePoint(flatCoordinates, 0, 10, 2, 0.5);
      expect(point).to.eql([3, 4]);
    });

    it('returns the expected value when the coordinates are not evenly spaced', function () {
      const flatCoordinates = [0, 1, 2, 3, 6, 7];
      const point = interpolatePoint(flatCoordinates, 0, 6, 2, 0.5);
      expect(point).to.eql([3, 4]);
    });

    it('also when vertices are repeated', function () {
      const flatCoordinates = [0, 1, 2, 3, 2, 3, 6, 7];
      const point = interpolatePoint(flatCoordinates, 0, 8, 2, 0.5);
      expect(point).to.eql([3, 4]);
    });

    it('returns the expected value when using opt_dest', function () {
      const flatCoordinates = [0, 1, 2, 3, 6, 7];
      const point = interpolatePoint(flatCoordinates, 0, 6, 2, 0.5, [0, 0]);
      expect(point).to.eql([3, 4]);
    });
  });
});
