import colormap from "colormap";

import { Vector3, Color, DoubleSide } from "three";
import { MapControls } from "three/examples/jsm/controls/MapControls.js";

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

import * as FunctionCurveEditor from "function-curve-editor";

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 MapboxTerrainFormat from "@giro3d/giro3d/formats/MapboxTerrainFormat.js";
import Map from "@giro3d/giro3d/entities/Map.js";
import Inspector from "@giro3d/giro3d/gui/Inspector.js";
import ColorMap from "@giro3d/giro3d/core/layer/ColorMap.js";
import ColorMapMode from "@giro3d/giro3d/core/layer/ColorMapMode.js";
import TiledImageSource from "@giro3d/giro3d/sources/TiledImageSource.js";
import ColorLayer from "@giro3d/giro3d/core/layer/ColorLayer.js";

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];
}

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 bindDropDown(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(element.value);
  };

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

  const setOptions = (options) => {
    const items = options.map(
      (opt) =>
        `<option value=${opt.id} ${opt.selected ? "selected" : ""}>${opt.name}</option>`,
    );
    element.innerHTML = items.join("\n");
  };

  return [callback, element.value, element, setOptions];
}

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

  element.onclick = () => {
    onClick(element);
  };

  return element;
}

function makeColorRamp(
  preset,
  discrete = false,
  invert = false,
  mirror = false,
) {
  let nshades = discrete ? 10 : 256;

  const values = colormap({ colormap: preset, nshades });

  const colors = values.map((v) => new Color(v));

  if (invert) {
    colors.reverse();
  }

  if (mirror) {
    const mirrored = [...colors, ...colors.reverse()];
    return mirrored;
  }

  return colors;
}

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

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

  const lower = min;
  const upper = max;

  callback(lower.valueAsNumber, upper.valueAsNumber);

  function updateLabels() {
    document.getElementById("minLabel").innerText =
      `Lower bound: ${Math.round(lower.valueAsNumber)}m`;
    document.getElementById("maxLabel").innerText =
      `Upper bound: ${Math.round(upper.valueAsNumber)}m`;
  }

  lower.oninput = function oninput() {
    const rawValue = lower.valueAsNumber;
    const clampedValue = MathUtils.clamp(
      rawValue,
      Number.parseFloat(lower.min),
      upper.valueAsNumber - 1,
    );
    lower.valueAsNumber = clampedValue;
    callback(lower.valueAsNumber, upper.valueAsNumber);
    updateLabels();
  };

  upper.oninput = function oninput() {
    const rawValue = upper.valueAsNumber;
    const clampedValue = MathUtils.clamp(
      rawValue,
      lower.valueAsNumber + 1,
      Number.parseFloat(upper.max),
    );
    upper.valueAsNumber = clampedValue;
    callback(lower.valueAsNumber, upper.valueAsNumber);
    updateLabels();
  };

  const externalInput = (min, max) => {
    lower.min = min;
    lower.max = max;
    upper.min = min;
    upper.max = max;
    lower.valueAsNumber = min;
    upper.valueAsNumber = max;
    callback(lower.valueAsNumber, upper.valueAsNumber);
    updateLabels();
  };

  return externalInput;
}

const extent = Extent.fromCenterAndSize(
  "EPSG:3857",
  { x: 697313, y: 5591324 },
  30000,
  30000,
);

const instance = new Instance({
  target: "view",
  crs: extent.crs,
  backgroundColor: null, // To make the canvas transparent
});

const cameraPosition = new Vector3(697119, 5543639, 53043);

instance.view.camera.position.copy(cameraPosition);

const controls = new MapControls(instance.view.camera, instance.domElement);
controls.target = extent.centerAsVector3();
controls.enableDamping = true;
controls.dampingFactor = 0.2;
controls.saveState();
instance.view.setControls(controls);

const elevationMin = 780;
const elevationMax = 3574;

let parameters = {
  ramp: "viridis",
  discrete: false,
  invert: false,
  mirror: false,
  backgroundOpacity: 1,
  transparencyCurveKnots: [
    { x: 0, y: 1 },
    { x: 1, y: 1 },
  ],
  enableColorMap: true,
  layerType: "elevation",
  colors: makeColorRamp("viridis", false, false, false),
  min: elevationMin,
  max: elevationMax,
  mode: ColorMapMode.Elevation,
};

function updatePreview(colors) {
  const canvas = document.getElementById("gradient");
  const ctx = canvas.getContext("2d");

  canvas.width = colors.length;
  canvas.height = 1;

  for (let i = 0; i < colors.length; i++) {
    const color = colors[i];
    ctx.fillStyle = `#${color.getHexString()}`;
    ctx.fillRect(i, 0, 1, canvas.height);
  }
}

updatePreview(parameters.colors);

// Adds the map that will contain the layers.
const map = new Map({
  extent,
  backgroundColor: "cyan",
  side: DoubleSide,
  hillshading: {
    enabled: true,
    elevationLayersOnly: true,
  },
});
instance.add(map);

const key =
  "pk.eyJ1IjoidG11Z3VldCIsImEiOiJjbGJ4dTNkOW0wYWx4M25ybWZ5YnpicHV6In0.KhDJ7W5N3d1z3ArrsDjX_A";
const source = new TiledImageSource({
  format: new MapboxTerrainFormat(),
  source: new XYZ({
    url: `https://api.mapbox.com/v4/mapbox.terrain-rgb/{z}/{x}/{y}.pngraw?access_token=${key}`,
    projection: extent.crs,
    crossOrigin: "anonymous",
  }),
});

const backgroundLayer = new ColorLayer({
  name: "background",
  extent,
  source: new TiledImageSource({
    source: new XYZ({
      url: `https://api.mapbox.com/v4/mapbox.satellite/{z}/{x}/{y}.webp?access_token=${key}`,
      projection: extent.crs,
      crossOrigin: "anonymous",
    }),
  }),
});

const elevationLayer = new ElevationLayer({
  name: "elevation",
  extent,
  source,
  colorMap: new ColorMap(
    parameters.colors,
    elevationMin,
    elevationMax,
    ColorMapMode.Elevation,
  ),
});

const colorLayer = new ColorLayer({
  name: "color",
  extent,
  source,
  colorMap: new ColorMap(
    parameters.colors,
    elevationMin,
    elevationMax,
    ColorMapMode.Elevation,
  ),
});

map.addLayer(elevationLayer);

let activeLayer = elevationLayer;

function updateColorRamp() {
  parameters.colors = makeColorRamp(
    parameters.ramp,
    parameters.discrete,
    parameters.invert,
    parameters.mirror,
  );
  activeLayer.colorMap.colors = parameters.colors;
  activeLayer.colorMap.min = parameters.min;
  activeLayer.colorMap.max = parameters.max;
  activeLayer.colorMap.mode = parameters.mode;

  updateTransparency();

  updatePreview(parameters.colors);

  instance.notifyChange(map);
}

const [setEnableColorMap] = bindToggle("enable", (v) => {
  elevationLayer.visible = true;
  colorLayer.visible = true;
  backgroundLayer.visible = true;

  if (activeLayer.type === "ColorLayer") {
    activeLayer.visible = v;
  } else {
    activeLayer.colorMap.active = v;
  }
  instance.notifyChange(map);
});
const [setDiscrete] = bindToggle("discrete", (v) => {
  parameters.discrete = v;
  updateColorRamp();
});
const [setInvert] = bindToggle("invert", (v) => {
  parameters.invert = v;
  updateColorRamp();
});
const [setMirror] = bindToggle("mirror", (v) => {
  parameters.mirror = v;
  updateColorRamp();
});
const [setRamp] = bindDropDown("ramp", (v) => {
  parameters.ramp = v;
  updateColorRamp();
});
function setActiveLayers(...layers) {
  map.removeLayer(colorLayer);
  map.removeLayer(elevationLayer);
  map.removeLayer(backgroundLayer);

  for (const layer of layers) {
    map.addLayer(layer);
  }
  activeLayer = layers[layers.length - 1];
}
const [setLayerType] = bindDropDown("layerType", (v) => {
  switch (v) {
    case "elevation":
      setActiveLayers(elevationLayer);
      break;
    case "color":
      setActiveLayers(colorLayer);
      break;
    case "color+background":
      setActiveLayers(backgroundLayer, colorLayer);
      break;
    case "color+background+elevation":
      setActiveLayers(elevationLayer, backgroundLayer, colorLayer);
      break;
  }
  updateColorRamp();
  instance.notifyChange(map);
});
const [setBackgroundOpacity] = bindSlider("backgroundOpacity", (v) => {
  map.backgroundOpacity = v;
  instance.notifyChange(map);
});
const updateBounds = bindColorMapBounds((min, max) => {
  parameters.min = min;
  parameters.max = max;
  activeLayer.colorMap.min = min;
  activeLayer.colorMap.max = max;
  instance.notifyChange(map);
});

const [setMode] = bindDropDown("mode", (v) => {
  const numerical = Number.parseInt(v);
  switch (numerical) {
    case ColorMapMode.Elevation:
      parameters.mode = ColorMapMode.Elevation;
      updateBounds(elevationMin, elevationMax);
      break;
    case ColorMapMode.Slope:
      parameters.mode = ColorMapMode.Slope;
      updateBounds(0, 90);
      break;
    case ColorMapMode.Aspect:
      parameters.mode = ColorMapMode.Aspect;
      updateBounds(0, 360);
      break;
  }

  updateColorRamp();
  instance.notifyChange(map);
});

const canvas = document.getElementById("curve");

const widget = new FunctionCurveEditor.Widget(canvas);

function updateTransparency() {
  const length = parameters.colors.length;
  const f = widget.getFunction();
  const opacities = new Array(length);
  for (let i = 0; i < length; i++) {
    const t = i / length;
    opacities[i] = f(t);
  }
  activeLayer.colorMap.opacity = opacities;
}

function setupTransparencyCurve(knots = undefined) {
  // Curve editor
  const initialKnots = knots ?? [
    { x: 0, y: 1 },
    { x: 1, y: 1 },
  ];

  widget.setEditorState({
    knots: initialKnots,
    xMin: -0.2,
    xMax: 1.2,
    yMin: -0.2,
    yMax: 1.2,
    interpolationMethod: "linear",
    extendedDomain: true,
    relevantXMin: 0,
    relevantXMax: 1,
    gridEnabled: true,
  });

  widget.addEventListener("change", () => {
    updateColorRamp();
  });
}

setupTransparencyCurve();

function applyPreset(preset) {
  parameters = { ...preset };

  setupTransparencyCurve(preset.transparencyCurveKnots);
  setBackgroundOpacity(preset.backgroundOpacity);
  setRamp(preset.ramp);
  setEnableColorMap(preset.enableColorMap);
  setDiscrete(preset.discrete);
  setInvert(preset.invert);
  setMirror(preset.mirror);
  setMode(preset.mode);
  setLayerType(preset.layerType);
  updateBounds(preset.min, preset.max);
  updateColorRamp();

  instance.notifyChange(map);
}

const [setPreset] = bindDropDown("preset", (preset) => {
  switch (preset) {
    case "elevation":
      applyPreset({
        ramp: "viridis",
        transparencyCurveKnots: [
          { x: 0, y: 1 },
          { x: 1, y: 1 },
        ],
        backgroundOpacity: 1,
        enableColorMap: true,
        discrete: false,
        mirror: false,
        invert: false,
        layerType: "elevation",
        colors: makeColorRamp("viridis", false, false, false),
        opacity: new Array(256).fill(1),
        min: elevationMin,
        max: elevationMax,
        mode: ColorMapMode.Elevation,
      });
      break;

    case "elevation+transparency":
      applyPreset({
        ramp: "jet",
        transparencyCurveKnots: [
          { x: 0, y: 0.5 },
          { x: 0.4, y: 0.5 },
          { x: 0.401, y: 0 },
          { x: 1, y: 0 },
        ],
        backgroundOpacity: 1,
        enableColorMap: true,
        discrete: false,
        mirror: false,
        invert: false,
        layerType: "color+background+elevation",
        colors: makeColorRamp("jet", false, false, false),
        min: elevationMin,
        max: elevationMax,
        mode: ColorMapMode.Elevation,
      });
      break;

    case "southern-slope":
      applyPreset({
        ramp: "rdbu",
        transparencyCurveKnots: [
          { x: 0, y: 0 },
          { x: 0.4, y: 0 },
          { x: 0.401, y: 1 },
          { x: 0.6, y: 1 },
          { x: 0.601, y: 0 },
          { x: 1, y: 0 },
        ],
        backgroundOpacity: 1,
        enableColorMap: true,
        discrete: false,
        mirror: true,
        invert: false,
        layerType: "color+background+elevation",
        colors: makeColorRamp("rdbu", false, false, false),
        min: 0,
        max: 360,
        mode: ColorMapMode.Aspect,
      });
      break;

    case "flat-terrain":
      applyPreset({
        ramp: "jet",
        transparencyCurveKnots: [
          { x: 0, y: 1 },
          { x: 0.3, y: 1 },
          { x: 0.6, y: 0 },
          { x: 1, y: 0 },
        ],
        backgroundOpacity: 1,
        enableColorMap: true,
        discrete: false,
        mirror: false,
        invert: true,
        layerType: "color+background+elevation",
        colors: makeColorRamp("jet", false, false, false),
        min: 0,
        max: 35,
        mode: ColorMapMode.Slope,
      });
      break;
  }
});

function resetToDefaults() {
  setPreset("elevation");
}

bindButton("reset", resetToDefaults);

Inspector.attach("inspector", instance);

// For some reason, not waiting a bit causes the curve editor to be blank on Firefox
setTimeout(resetToDefaults, 100);

<!doctype html>
<html lang="en">
  <head>
    <title>Color maps</title>
    <meta charset="UTF-8" />
    <meta name="name" content="colormaps" />
    <meta
      name="description"
      content="Use colormaps to emphasize elevation and terrain features."
    />
    <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/next/examples/css/example.css"
    />

    <style>
      #view canvas {
        background: rgb(132, 170, 182);
        background: radial-gradient(
          circle,
          rgba(132, 170, 182, 1) 0%,
          rgba(37, 44, 48, 1) 100%
        );
      }
    </style>
  </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" style="width: 20rem">
      <!--Parameters -->
      <div class="card">
        <div class="card-header">
          Parameters
          <button
            type="button"
            id="reset"
            class="btn btn-sm btn-primary rounded float-end"
          >
            reset
          </button>
        </div>

        <div class="card-body" id="top-options">
          <!-- Preset -->
          <div class="input-group mb-3">
            <label class="input-group-text" for="preset">Preset</label>
            <select class="form-select" id="preset" autocomplete="off">
              <option value="elevation" selected>
                Simple elevation layer with color map
              </option>
              <option value="elevation+transparency">
                Elevation layer with color map visible only on the 780-2000m
                range.
              </option>
              <option value="southern-slope">
                Show the southern slopes of the mountains with a
                semi-transparent colormap.
              </option>
              <option value="flat-terrain">
                Shows flat areas of the terrain.
              </option>
            </select>
          </div>

          <!-- Layer type -->
          <div class="input-group mb-3">
            <label class="input-group-text" for="layerType">Layers</label>
            <select class="form-select" id="layerType" autocomplete="off">
              <option value="elevation" selected>Elevation</option>
              <option value="color">Color</option>
              <option value="color+background">Color + Background</option>
              <option value="color+background+elevation">
                Color + Background + Elevation
              </option>
            </select>
          </div>

          <!-- Activate color map -->
          <div class="form-check form-switch mb-1">
            <input
              class="form-check-input"
              checked
              type="checkbox"
              role="switch"
              id="enable"
              autocomplete="off"
            />
            <label class="form-check-label" for="enable"
              >Enable color map</label
            >
          </div>

          <!-- Reverse color map -->
          <div class="form-check form-switch mb-1">
            <input
              class="form-check-input"
              type="checkbox"
              role="switch"
              id="invert"
              autocomplete="off"
            />
            <label class="form-check-label" for="invert"
              >Invert color map</label
            >
          </div>

          <!-- Mirror color map -->
          <div class="form-check form-switch mb-1">
            <input
              class="form-check-input"
              type="checkbox"
              role="switch"
              id="mirror"
              autocomplete="off"
            />
            <label class="form-check-label" for="mirror"
              >Mirror color map</label
            >
          </div>

          <!-- Discrete color map -->
          <div class="form-check form-switch mb-3">
            <input
              class="form-check-input"
              type="checkbox"
              role="switch"
              id="discrete"
              autocomplete="off"
            />
            <label class="form-check-label" for="discrete"
              >Discrete color map</label
            >
          </div>

          <!-- Color ramp selector -->
          <div class="input-group mb-3">
            <label class="input-group-text" for="ramp">Colors</label>
            <select class="form-select" id="ramp" autocomplete="off">
              <option value="viridis" selected>Viridis</option>
              <option value="jet">Jet</option>
              <option value="greys">Greys</option>
              <option value="blackbody">Blackbody</option>
              <option value="earth">Earth</option>
              <option value="bathymetry">Bathymetry</option>
              <option value="magma">Magma</option>
              <option value="par">Par</option>
              <option value="rdbu">RdBu</option>
            </select>
          </div>

          <!-- Gradient preview -->
          <div class="mb-3 w-100">
            <canvas
              id="gradient"
              height="32"
              class="w-100 border rounded"
              style="height: 32px; image-rendering: pixelated"
            ></canvas>
          </div>

          <!-- Opacity curve -->
          <div class="mb-3 w-100">
            <label for="curve" class="mb-2">Opacity curve</label>
            <canvas
              id="curve"
              height="128"
              class="w-100"
              style="height: 128px"
            ></canvas>
          </div>

          <!-- Mode selector -->
          <div class="input-group mb-3">
            <label class="input-group-text" for="mode">Mode</label>
            <select class="form-select" id="mode" autocomplete="off">
              <option value="1" selected>Elevation</option>
              <option value="2">Slope</option>
              <option value="3">Aspect</option>
            </select>
          </div>

          <!-- Background opacity slider -->
          <div class="input-group border rounded p-2 mb-3">
            <label
              for="backgroundOpacity"
              id="backgroundOpacityLabel"
              class="form-label"
              >Map background opacity</label
            >
            <div class="input-group">
              <input
                type="range"
                min="0"
                max="1"
                step="0.01"
                value="1"
                class="form-range"
                id="backgroundOpacity"
                autocomplete="off"
              />
            </div>
          </div>

          <!-- Bound sliders -->
          <div class="input-group border rounded p-2" id="bounds">
            <label for="min" id="minLabel" class="form-label"
              >Lower bound: 780m</label
            >
            <div class="input-group">
              <input
                type="range"
                min="780"
                max="3574"
                value="0"
                class="form-range"
                id="min"
                autocomplete="off"
              />
            </div>

            <label for="max" id="maxLabel" class="form-label"
              >Upper bound: 3574m</label
            >
            <div class="input-group">
              <input
                type="range"
                min="780"
                max="3574"
                value="3574"
                class="form-range"
                id="max"
                autocomplete="off"
              />
            </div>
          </div>
        </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": "colormaps",
    "dependencies": {
        "colormap": "^2.3.2",
        "function-curve-editor": "^1.0.16",
        "@giro3d/giro3d": "git+https://gitlab.com/giro3d/giro3d.git"
    },
    "devDependencies": {
        "vite": "^3.2.3"
    },
    "scripts": {
        "start": "vite",
        "build": "vite build"
    }
}