import { LinearApproximation } from "../../Source/Cesium.js";

describe("Core/LinearApproximation", function () {
  it("should produce correct results", function () {
    var xTable = [2.0, 4.0];
    var yTable = [2.0, 3.0, 4.0, 34.0];

    var results = LinearApproximation.interpolateOrderZero(
      3.0,
      xTable,
      yTable,
      2
    );

    expect(results.length).toEqual(2);
    expect(results[0]).toEqual(3.0);
    expect(results[1]).toEqual(18.5);
  });

  it("should produce correct results with a result parameter", function () {
    var xTable = [2.0, 4.0];
    var yTable = [2.0, 3.0, 4.0, 34.0];

    var result = new Array(2);
    var results = LinearApproximation.interpolateOrderZero(
      3.0,
      xTable,
      yTable,
      2,
      result
    );

    expect(result).toBe(results);
    expect(results.length).toEqual(2);
    expect(results[0]).toEqual(3.0);
    expect(results[1]).toEqual(18.5);
  });

  it("should produce correct results 2", function () {
    var xTable2 = [40, 120];
    var yTable2 = [20, 40, 60, 80, 90, 100];

    var results = LinearApproximation.interpolateOrderZero(
      80.0,
      xTable2,
      yTable2,
      3
    );

    expect(results.length).toEqual(3);
    expect(results[0]).toEqual(50.0);
    expect(results[1]).toEqual(65.0);
    expect(results[2]).toEqual(80.0);
  });

  it("should produce correct results 3", function () {
    var xTable3 = [20, 30];
    var yTable3 = [10, 20, 30, 20, 30, 40, 20, 40, 60, 80, 90, 100];

    var results = LinearApproximation.interpolateOrderZero(
      40,
      xTable3,
      yTable3,
      1
    );

    expect(results.length).toEqual(1);
    expect(results[0]).toEqual(30.0);
  });

  it("should throw if length is greater than 2", function () {
    var xTable = [44.0, 99.0, 230.0];
    var yTable = [2.3, 4.5, 6.6, 3.2, 4.4, 12.23];

    expect(function () {
      LinearApproximation.interpolateOrderZero(2.3, xTable, yTable, 3);
    }).toThrowDeveloperError();
  });

  it("should throw when yStride equals zero indicating that there are no dependent variables for interpolation", function () {
    var xTable = [4.0, 8.0];
    var yTable = [4.0, 8.0];

    expect(function () {
      LinearApproximation.interpolateOrderZero(6.0, xTable, yTable, 0);
    }).toThrowDeveloperError();
  });

  it("getRequiredDataPoints returns 2", function () {
    expect(LinearApproximation.getRequiredDataPoints(1)).toEqual(2);
  });
});