import colormap from 'colormap';

import { MathUtils, Vector3, Color } 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/index.js';

/**
 * Binds a toggle switch or checkbox.
 * @param {string} id The id of the <input> element.
 * @param {(v: boolean) => void} onChange The callback when the dropdown value changes.
 * @returns {(v: boolean) => void} The function to update the value from outside.
 */
function bindToggle(id, onChange) {
    /** @type {HTMLInputElement} */
    const toggle = document.getElementById(id);

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

    return v => {
        toggle.checked = v;
        onChange(toggle.checked);
    };
}

/**
 * Binds a {@link HTMLInputElement} in slider mode.
 * @param {string} id The id of the <input> element.
 * @param {(v: number) => void} onChange The callback when the slider value changes.
 * @returns {(v: number) => void} The function to update the value from outside.
 */
function bindSlider(id, onChange) {
    /** @type {HTMLInputElement} */
    const slider = document.getElementById(id);
    slider.oninput = function oninput() {
        onChange(slider.valueAsNumber);
    };

    return v => {
        slider.valueAsNumber = v;
        onChange(slider.valueAsNumber);
    };
}

/**
 * Binds a text-value dropdown.
 * @param {string} id The id of the <input> element.
 * @param {(v: string) => void} onChange The callback when the dropdown value changes.
 * @returns {(v: string) => void} The function to update the value from outside.
 */
function bindDropDown(id, onChange) {
    /** @type {HTMLInputElement} */
    const mode = document.getElementById(id);
    mode.onchange = () => {
        onChange(mode.value);
    };

    return v => {
        mode.value = v;
        onChange(mode.value);
    };
}

/**
 * Binds a button.
 * @param {string} id The id of the <button> element.
 * @param {() => void} onClick The click handler.
 */
function bindButton(id, onClick) {
    document.getElementById(id).onclick = () => {
        onClick();
    };
}

/**
 * Create an array of {@link Color}s from the specified colormap preset.
 * @param {string} preset The name of the colormap preset.
 * @param {boolean} [discrete=false] If `true`, the color array will have 10 steps, otherwise 256.
 * @param {boolean} [invert=false] If `true`, the color array will be reversed.
 * @returns {Color[]} The color array.
 */
function makeColorRamp(preset, discrete = false, invert = false, mirror = false) {
    let nshades = discrete ? 10 : 256;

    // eslint-disable-next-line no-undef
    const values = colormap({ colormap: preset, nshades });
    // eslint-disable-next-line no-undef
    const colors = values.map(v => new Color(v));

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

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

    return colors;
}

// Defines geographic extent: CRS, min/max X, min/max Y
const extent = Extent.fromCenterAndSize('EPSG:3857', { x: 697313, y: 5591324 }, 30000, 30000);

// `viewerDiv` will contain Giro3D' rendering area (the canvas element)
const viewerDiv = document.getElementById('viewerDiv');

// Creates the Giro3D instance
const instance = new Instance(viewerDiv, {
    crs: extent.crs(),
    renderer: {
        // To display the background style
        clearColor: false,
    },
});

// Sets the camera position
const cameraPosition = new Vector3(697119, 5543639, 53043);
instance.camera.camera3D.position.copy(cameraPosition);

// Creates controls
const controls = new MapControls(instance.camera.camera3D, instance.domElement);

// Then looks at extent's center
controls.target = extent.centerAsVector3();
controls.saveState();

controls.enableDamping = true;
controls.dampingFactor = 0.2;

instance.useTHREEControls(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('planar', {
    extent,
    backgroundColor: 'cyan',
    doubleSided: true,
    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.materialOptions.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);
});

let suffix = 'm';

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

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

function bindColorMapBounds(callback) {
    /** @type {HTMLInputElement} */
    const lower = document.getElementById('lower');

    /** @type {HTMLInputElement} */
    const upper = document.getElementById('upper');

    callback(lower.valueAsNumber, upper.valueAsNumber);

    function updateLabels() {
        document.getElementById('minLabel').innerText =
            `Lower bound: ${lower.valueAsNumber}${suffix}`;
        document.getElementById('maxLabel').innerText =
            `Upper bound: ${upper.valueAsNumber}${suffix}`;
    }

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

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

    return (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();
    };
}

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(document.getElementById('panelDiv'), 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/latest/css/example.css"
        />

        <style>
        #viewerDiv 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="viewerDiv" class="m-0 p-0 w-100 h-100"></div>
        <div id="panelDiv" 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="lower" 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="lower"
                                autocomplete="off"
                            />
                        </div>

                        <label for="upper" 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="upper"
                                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": "0.37.3"
    },
    "devDependencies": {
        "vite": "^3.2.3"
    },
    "scripts": {
        "start": "vite",
        "build": "vite build"
    }
}