cesium-geoserverterrainprovider/src/plugin/wmtsParser.ts

plugin to create a Cesium terrain provider from Geoserver

import { basicAssignResult, CRS, FormatImage, ICRS, IDescription, IFormatImage, IResult } from "./utils";
const C: typeof import('cesium') = (window as any).Cesium
const { fetchXML: loadXML } = C.Resource;

export async function generate(description: IDescription) {
    let resultat: IResult;
    if (description.url) {
        let urlofServer = description.url;
        const index = urlofServer.lastIndexOf("?");
        if (index > -1) { urlofServer = urlofServer.substring(0, index) }
        let urlGetCapabilities = urlofServer + '/gwc/service/wmts?REQUEST=GetCapabilities';
        if (description.proxy) {
            urlGetCapabilities = description.proxy.getURL(urlGetCapabilities);
        }
        description.xml = await loadXML({ url: urlGetCapabilities });
        resultat = getMetaDatafromXML(description);
    } else if (description.xml) {
        resultat = getMetaDatafromXML(description);
    } else {
        throw new Error('either description.url or description.xml are required.');
    }
    return resultat;
};

function getMetaDatafromXML(description: IDescription): IResult {
    const xml = description.xml;
    if (!(xml instanceof XMLDocument)) { throw new Error('xml must be a XMLDocument'); }

    const resultat: Partial<IResult> = {};
    const layerName = description.layerName;
    basicAssignResult(description, resultat);
    const maxLevel = description.maxLevel;
    const proxy = description.proxy;
    let styleName = description.styleName;
    let template: string = null;
    let listTileMatrixSetLinkNode: Element[] = [];

    let urlKVP: string = null, urlRESTful: string = null;
    let formatImage: IFormatImage = null;
    //KVP support for now

    Array.from(xml.querySelectorAll('Operation[name="GetTile"] HTTP Get'))
        .map((elt) => ({ node: elt, type: elt.querySelector("Value").textContent }))
        .forEach(item => {
            if (item.type === "RESTful" && urlRESTful === null) {
                urlRESTful = item.node.getAttribute("xlink:href");
                if (proxy) { urlRESTful = proxy.getURL(urlRESTful); }
            }
            if (item.type === "KVP" && urlKVP === null) {
                urlKVP = item.node.getAttribute("xlink:href");
                if (proxy) { urlKVP = proxy.getURL(urlKVP); }
            }
        });


    const nodeIdentifiers = xml.querySelectorAll("Contents>Layer>Identifier");
    let layerNode: ParentNode = null;
    for (let i = 0; i < nodeIdentifiers.length && layerNode === null; i++) {
        if (layerName === nodeIdentifiers[i].textContent) {
            layerNode = nodeIdentifiers[i].parentNode;
        }
    }

    if (layerNode !== null) {
        //optionality of style in geoserver is not compliant with OGC requirements!!
        let defaultStyle: string;
        let selectedStyle: string;
        Array.from(layerNode.querySelectorAll("Style")).forEach(item => {
            const style = item.querySelector("Identifier").textContent;
            if (item.getAttribute("isDefault") != null) { defaultStyle = style; }
            if (style === styleName) { selectedStyle = style; }
        });
        //Work with attribute isDefault when no style was defined!!
        if (!styleName || styleName !== selectedStyle) { styleName = defaultStyle || ''; }

        //format
        const nodeFormats = Array.from(layerNode.querySelectorAll("Format"));
        for (let l = 0; l < FormatImage.length && formatImage === null; l++) {
            const validFormats = nodeFormats.filter(elt => elt.textContent === FormatImage[l].format);
            if (validFormats.length > 0) { formatImage = FormatImage[l]; }
        }
        //TileMatrixSetLink =>TileMatrixSet
        listTileMatrixSetLinkNode = Array.from(layerNode.querySelectorAll("TileMatrixSetLink"));
    }

    const nodeMatrixSetIds = Array.from(xml.querySelectorAll("TileMatrixSet>Identifier"));
    for (let a = 0; a < listTileMatrixSetLinkNode.length && !resultat.ready; a++) {
        const matrixSetLinkNode = listTileMatrixSetLinkNode[a];
        const tileMatrixSetLinkName = matrixSetLinkNode.querySelector("TileMatrixSet").textContent;
        let tileMatrixSetNode: ParentNode = null;
        let CRSSelected: ICRS = null;

        for (let i = 0; i < nodeMatrixSetIds.length && tileMatrixSetNode === null; i++) {
            if (nodeMatrixSetIds[i].textContent === tileMatrixSetLinkName) { tileMatrixSetNode = nodeMatrixSetIds[i].parentNode; }
        }

        const supportedCRS = tileMatrixSetNode.querySelector("SupportedCRS").textContent;
        for (let n = 0; n < CRS.length && CRSSelected === null; n++) {
            if (CRS[n].supportedCRS === supportedCRS) { CRSSelected = CRS[n]; }
        }

        if (CRSSelected !== null) {

            const tileSets: {
                id: string,
                maxWidth: number,
                maxHeight: number,
                scaleDenominator: number,
                complete: boolean,
                tileWidth: number,
                tileHeight: number,
                bbox?: {
                    minTileRow: number,
                    maxTileRow: number,
                    minTileCol: number,
                    maxTileCol: number
                }
            }[] = Array.from(tileMatrixSetNode.querySelectorAll("TileMatrix"))
                .map(function (noeud) {
                    let id = noeud.querySelector("Identifier").textContent;
                    let maxWidth = parseInt(noeud.querySelector("MatrixWidth").textContent, 10);
                    let maxHeight = parseInt(noeud.querySelector("MatrixHeight").textContent, 10);
                    let tileWidth = parseInt(noeud.querySelector("TileWidth").textContent, 10);
                    let tileHeight = parseInt(noeud.querySelector("TileHeight").textContent, 10);
                    let scaleDenominator = parseFloat(noeud.querySelector("ScaleDenominator").textContent);
                    return {
                        id,
                        maxWidth,
                        maxHeight,
                        scaleDenominator,
                        complete: false,
                        tileWidth,
                        tileHeight
                    };
                })
                .sort((a, b) => b.scaleDenominator - a.scaleDenominator);

            const listTileMatrixLimits = Array.from(matrixSetLinkNode.querySelectorAll("TileMatrixSetLimits>TileMatrixLimits"))
                .map(nodeLink => ({
                    id: nodeLink.querySelector("TileMatrix").textContent,
                    bbox: {
                        minTileRow: parseInt(nodeLink.querySelector("MinTileRow").textContent, 10),
                        maxTileRow: parseInt(nodeLink.querySelector("MaxTileRow").textContent, 10),
                        minTileCol: parseInt(nodeLink.querySelector("MinTileCol").textContent, 10),
                        maxTileCol: parseInt(nodeLink.querySelector("MaxTileCol").textContent, 10)
                    }
                }));
            tileSets.forEach(tile => {
                listTileMatrixLimits.forEach(nodeLink => {
                    if (tile.id === nodeLink.id) {
                        tile.bbox = nodeLink.bbox;
                        tile.complete = true;
                    }
                });
            });

            if (tileSets.length > 0) {
                resultat.tilingScheme = new CRSSelected.tilingScheme({
                    ellipsoid: CRSSelected.ellipsoid,
                    numberOfLevelZeroTilesX: tileSets[0].maxWidth,
                    numberOfLevelZeroTilesY: tileSets[0].maxHeight
                });
                const resourceURL = layerNode.querySelector("ResourceURL[format='" + formatImage.format + "']");

                if (resourceURL !== null) {
                    template = resourceURL.getAttribute("template").replace("{TileRow}", "{y}").replace("{TileCol}", "{x}").replace("{style}", styleName).replace("{Style}", styleName).
                        replace("{TileMatrixSet}", tileMatrixSetLinkName).replace("{layer}", layerName).replace("{infoFormatExtension}", formatImage.extension);
                } else if (urlKVP !== null) {
                    template = urlKVP + "service=WMTS&request=GetTile&version=1.0.0&layer=" + layerName + "&style=" + styleName + "&format=" + formatImage.format + "&TileMatrixSet=" + tileMatrixSetLinkName + "&TileMatrix={TileMatrix}&TileRow={y}&TileCol={x}"
                }

                if (template !== null) {
                    resultat.getTileDataAvailable = (x, y, level) => {
                        let retour = false;
                        if (level < maxLevel && level < tileSets.length) {
                            const tile = tileSets[level];
                            const bbox = tile.bbox;
                            if (tile.complete) {
                                retour = (y <= bbox.maxTileRow && y >= bbox.minTileRow) && (x <= bbox.maxTileCol && x >= bbox.minTileCol);
                            } else {
                                retour = x < tile.maxWidth && y < tile.maxHeight;
                            }
                        }
                        return retour;
                    };
                    resultat.URLtemplateImage = function (x, y, level) {
                        let retour = "";
                        if (resultat.getTileDataAvailable(x, y, level)) {
                            let tile = tileSets[level];
                            retour = template.replace("{TileMatrix}", tile.id);
                        }
                        return retour;
                    };

                    const imageSize = {
                        width: tileSets[0].tileWidth,
                        height: tileSets[0].tileHeight
                    };
                    const checkSize = tileSets.filter(elt => elt.tileWidth != imageSize.width || elt.tileHeight != imageSize.height);
                    if (checkSize.length === 0) {
                        resultat.imageSize = imageSize;
                    }
                    resultat.ready = true;
                }
            }

        }
    }

    return resultat as IResult;
};