PolylineUtils.test.js

import { parsePolylineInput, calculatePolylineDistanceMeters } from "./PolylineUtils";
import { formatDistance } from "./Utils";

describe("PolylineUtils", () => {
  const EXPECTED_POINTS = [
    { latitude: 37.42213, longitude: -122.0848 },
    { latitude: 37.4152, longitude: -122.0627 },
    { latitude: 37.427, longitude: -122.0854 },
  ];

  test("decodes a GMP Encoded Polyline", () => {
    const encoded = "i_lcF~tchVhj@ciCwhAzlC";
    const decoded = parsePolylineInput(encoded);

    expect(decoded).toHaveLength(EXPECTED_POINTS.length);
    for (let i = 0; i < EXPECTED_POINTS.length; i++) {
      expect(decoded[i].latitude).toBeCloseTo(EXPECTED_POINTS[i].latitude, 5);
      expect(decoded[i].longitude).toBeCloseTo(EXPECTED_POINTS[i].longitude, 5);
    }
  });

  test("decodes an S2 Polyline", () => {
    const s2String =
      "AQMAAAA7_tIhjf_avysne_M5iOW__WHh1yJy4z9MIcUK8Pvav7QbiLMRiuW_SWY5Y1lx4z-CIIuaN__av1Eb3-fUh-W_iPpHZ7By4z8=";
    const decoded = parsePolylineInput(s2String);

    expect(decoded).toHaveLength(EXPECTED_POINTS.length);
    for (let i = 0; i < EXPECTED_POINTS.length; i++) {
      expect(decoded[i].latitude).toBeCloseTo(EXPECTED_POINTS[i].latitude, 5);
      expect(decoded[i].longitude).toBeCloseTo(EXPECTED_POINTS[i].longitude, 5);
    }
  });

  test("decodes a GMP Unencoded Polyline (Plain Text)", () => {
    const input =
      "{ latitude: 37.42213, longitude: -122.0848 }, { latitude: 37.4152, longitude: -122.0627 }, { latitude: 37.427, longitude: -122.0854 }";
    const decoded = parsePolylineInput(input);

    expect(decoded).toHaveLength(EXPECTED_POINTS.length);
    for (let i = 0; i < EXPECTED_POINTS.length; i++) {
      expect(decoded[i].latitude).toBe(EXPECTED_POINTS[i].latitude);
      expect(decoded[i].longitude).toBe(EXPECTED_POINTS[i].longitude);
    }
  });

  test("decodes a JSON Polyline", () => {
    const input = JSON.stringify(EXPECTED_POINTS);
    const decoded = parsePolylineInput(input);

    expect(decoded).toHaveLength(EXPECTED_POINTS.length);
    for (let i = 0; i < EXPECTED_POINTS.length; i++) {
      expect(decoded[i].latitude).toBe(EXPECTED_POINTS[i].latitude);
      expect(decoded[i].longitude).toBe(EXPECTED_POINTS[i].longitude);
    }
  });

  test("throws error on invalid input", () => {
    expect(() => parsePolylineInput("not a polyline")).toThrow();
  });
});

describe("calculatePolylineDistanceMeters", () => {
  test("returns 0 for empty or single point polylines", () => {
    expect(calculatePolylineDistanceMeters([])).toBe(0);
    expect(calculatePolylineDistanceMeters([{ latitude: 0, longitude: 0 }])).toBe(0);
  });

  test("calculates distance correctly", () => {
    // Mock window.google.maps
    global.window.google = {
      maps: {
        LatLng: class {
          constructor(lat, lng) {
            this.lat = lat;
            this.lng = lng;
          }
        },
        geometry: {
          spherical: {
            computeDistanceBetween: jest.fn().mockImplementation(() => 100), // Mock 100m for any two points
          },
        },
      },
    };

    const points = [
      { latitude: 0, longitude: 0 },
      { latitude: 1, longitude: 1 },
      { latitude: 2, longitude: 2 },
    ];
    // 2 segments, 100m each = 200m
    expect(calculatePolylineDistanceMeters(points)).toBe(200);

    // Cleanup
    delete global.window.google;
  });
});

describe("formatDistance", () => {
  test("formats under 1000 meters correctly", () => {
    const { metric, imperial } = formatDistance(500);
    expect(metric).toBe("500 m");
    expect(imperial).toBe("1640 ft");
  });

  test("formats over 1000 meters into km and miles", () => {
    const { metric, imperial } = formatDistance(2500);
    expect(metric).toBe("2.50 km");
    expect(imperial).toBe("1.55 mi");
  });
});