import colormap from "colormap";

import { Color, DoubleSide } from "three";
import { MapControls } from "three/examples/jsm/controls/MapControls.js";

import XYZ from "ol/source/XYZ.js";

import Extent from "@giro3d/giro3d/core/geographic/Extent.js";
import Instance from "@giro3d/giro3d/core/Instance.js";
import ElevationLayer from "@giro3d/giro3d/core/layer/ElevationLayer.js";
import Map from "@giro3d/giro3d/entities/Map.js";
import GeoTIFFFormat from "@giro3d/giro3d/formats/GeoTIFFFormat.js";
import ColorMap, { ColorMapMode } from "@giro3d/giro3d/core/layer/ColorMap.js";
import TiledImageSource from "@giro3d/giro3d/sources/TiledImageSource.js";
import Inspector from "@giro3d/giro3d/gui/Inspector.js";

function bindNumericalDropDown(id, onChange) {
  const element = document.getElementById(id);
  if (!(element instanceof HTMLSelectElement)) {
    throw new Error(
      "invalid binding element: expected HTMLSelectElement, got: " +
        element.constructor.name,
    );
  }

  element.onchange = () => {
    onChange(parseInt(element.value));
  };

  const callback = (v) => {
    element.value = v.toString();
    onChange(parseInt(element.value));
  };

  return [callback, parseInt(element.value), element];
}

function bindSlider(id, onChange) {
  const element = document.getElementById(id);
  if (!(element instanceof HTMLInputElement)) {
    throw new Error(
      "invalid binding element: expected HTMLInputElement, got: " +
        element.constructor.name,
    );
  }

  element.oninput = function oninput() {
    onChange(element.valueAsNumber);
  };

  const setValue = (v, min, max, step) => {
    if (min != null && max != null) {
      element.min = min.toString();
      element.max = max.toString();

      if (step != null) {
        element.step = step;
      }
    }
    element.valueAsNumber = v;
    onChange(element.valueAsNumber);
  };

  const initialValue = element.valueAsNumber;

  return [setValue, initialValue, element];
}

function bindToggle(id, onChange) {
  const element = document.getElementById(id);
  if (!(element instanceof HTMLInputElement)) {
    throw new Error(
      "invalid binding element: expected HTMLButtonElement, got: " +
        element.constructor.name,
    );
  }

  element.oninput = function oninput() {
    onChange(element.checked);
  };

  const callback = (v) => {
    element.checked = v;
    onChange(element.checked);
  };

  return [callback, element.checked, element];
}

const x = -13602000;
const y = 5812000;
const halfWidth = 2500;

const extent = new Extent(
  "EPSG:3857",
  x - halfWidth,
  x + halfWidth,
  y - halfWidth,
  y + halfWidth,
);

const instance = new Instance({
  target: "view",
  crs: extent.crs,
});

const map = new Map({
  extent,
  hillshading: {
    enabled: true,
    intensity: 0.5,
  },
  side: DoubleSide,
  backgroundColor: "white",
  contourLines: true,
});

instance.add(map);

const source = new TiledImageSource({
  source: new XYZ({
    minZoom: 10,
    maxZoom: 16,
    url: "https://3d.oslandia.com/dem/MtStHelens-tiles/{z}/{x}/{y}.tif",
  }),
  format: new GeoTIFFFormat(),
});

const floor = 1100;
const ceiling = 2500;

const values = colormap({ colormap: "viridis", nshades: 256 });
const colors = values.map((v) => new Color(v));

const dem = new ElevationLayer({
  name: "dem",
  source,
  extent,
  colorMap: new ColorMap(colors, floor, ceiling, ColorMapMode.Elevation),
});

map.addLayer(dem);

instance.view.camera.position.set(-13594700, 5819700, 7300);

const controls = new MapControls(instance.view.camera, instance.domElement);

controls.target.set(-13603000, 5811000, 0);

instance.view.setControls(controls);

instance.notifyChange();

Inspector.attach("inspector", instance);

bindToggle("contourLineCheckbox", (state) => {
  if (state) {
    document.getElementById("options").removeAttribute("disabled");
  } else {
    document.getElementById("options").setAttribute("disabled", "disabled");
  }
  map.contourLines.enabled = state;
  instance.notifyChange(map);
});

bindNumericalDropDown("mainInterval", (v) => {
  map.contourLines.interval = v;
  instance.notifyChange(map);
});
bindNumericalDropDown("secondaryInterval", (v) => {
  map.contourLines.secondaryInterval = v;
  instance.notifyChange(map);
});
bindSlider("opacitySlider", (v) => {
  map.contourLines.opacity = v;
  instance.notifyChange(map);
});
bindSlider("thicknessSlider", (v) => {
  map.contourLines.thickness = v;
  instance.notifyChange(map);
});

<!doctype html>
<html lang="en">
  <head>
    <title>Contour lines</title>
    <meta charset="UTF-8" />
    <meta name="name" content="contour_lines" />
    <meta
      name="description"
      content="Use contour lines to display elevation levels."
    />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />

    <link rel="icon" href="https://giro3d.org/images/favicon.svg" />
    <link
      href="https://giro3d.org/assets/bootstrap-custom.css"
      rel="stylesheet"
    />
    <script src="https://giro3d.org/assets/bootstrap.bundle.min.js"></script>
    <link
      rel="stylesheet"
      type="text/css"
      href="https://giro3d.org/latest/examples/css/example.css"
    />
  </head>

  <body>
    <div id="view" class="m-0 p-0 w-100 h-100"></div>
    <div
      id="inspector"
      class="position-absolute top-0 start-0 mh-100 overflow-auto"
    ></div>

    <div class="side-pane-with-status-bar">
      <div class="card">
        <div class="card-header">
          <div class="form-check form-switch">
            <input
              class="form-check-input"
              type="checkbox"
              checked="true"
              role="switch"
              id="contourLineCheckbox"
              autocomplete="off"
            />
            <label class="form-check-label" for="contourLineCheckbox"
              >Contour lines</label
            >
          </div>
        </div>

        <div class="card-body">
          <fieldset class="container" id="options">
            <div class="input-group my-2">
              <span class="input-group-text flex-grow-1"
                >Main interval (m)</span
              >
              <select
                class="btn btn-outline-primary btn-sm"
                id="mainInterval"
                autocomplete="off"
              >
                <option value="0">Disabled</option>
                <option selected value="100">100 m</option>
                <option value="200">200 m</option>
                <option value="400">400 m</option>
              </select>
            </div>

            <div class="input-group my-2">
              <span class="input-group-text flex-grow-1"
                >Secondary interval (m)</span
              >
              <select
                class="btn btn-outline-primary btn-sm"
                id="secondaryInterval"
                autocomplete="off"
              >
                <option value="0">Disabled</option>
                <option selected value="10">10 m</option>
                <option selected value="20">20 m</option>
                <option value="50">50 m</option>
              </select>
            </div>

            <label for="opacitySlider" class="form-label">Opacity</label>
            <div class="input-group">
              <input
                type="range"
                min="0"
                max="1"
                value="1"
                step="0.05"
                class="form-range"
                id="opacitySlider"
                autocomplete="off"
              />
            </div>

            <label for="thicknessSlider" class="form-label">Thickness</label>
            <div class="input-group">
              <input
                type="range"
                min="0"
                max="2"
                value="1"
                step="0.05"
                class="form-range"
                id="thicknessSlider"
                autocomplete="off"
              />
            </div>
          </fieldset>
        </div>
      </div>
    </div>

    <script type="module" src="index.js"></script>
    <script>
      /* activate popovers */
      const popoverTriggerList = [].slice.call(
        document.querySelectorAll('[data-bs-toggle="popover"]'),
      );
      popoverTriggerList.map(
        // bootstrap is used as script in the template, disable warning about undef
        // eslint-disable-next-line no-undef
        (popoverTriggerEl) =>
          new bootstrap.Popover(popoverTriggerEl, {
            trigger: "hover",
            placement: "left",
            content: document.getElementById(
              popoverTriggerEl.getAttribute("data-bs-content"),
            ).innerHTML,
            html: true,
          }),
      );
    </script>
  </body>
</html>

{
    "name": "contour_lines",
    "dependencies": {
        "colormap": "^2.3.2",
        "@giro3d/giro3d": "0.41.0"
    },
    "devDependencies": {
        "vite": "^3.2.3"
    },
    "scripts": {
        "start": "vite",
        "build": "vite build"
    }
}