iTowns / itowns / 27004518448

import { Extent, CRS } from '@itowns/geographic';

import GeoJsonParser from 'Parser/GeoJsonParser';

import KMLParser from 'Parser/KMLParser';

import GeotiffParser from 'Parser/GeotiffParser';

import GDFParser from 'Parser/GDFParser';

import GpxParser from 'Parser/GpxParser';

import GTXParser from 'Parser/GTXParser';

import ISGParser from 'Parser/ISGParser';

import VectorTileParser from 'Parser/VectorTileParser';

import Fetcher from 'Provider/Fetcher';

import { LRUCache } from 'lru-cache';

/** @private */

export const supportedParsers = new Map([

    ['application/geo+json', GeoJsonParser.parse],

    ['application/json', GeoJsonParser.parse],

    ['application/kml', KMLParser.parse],

    ['application/gpx', GpxParser.parse],

    ['application/x-protobuf;type=mapbox-vector', VectorTileParser.parse],

    ['application/gtx', GTXParser.parse],

    ['application/isg', ISGParser.parse],

    ['application/gdf', GDFParser.parse],

    ['image/geotiff', GeotiffParser.parse],

]);

const noCache = { get: () => {}, set: a => a, clear: () => {} };

/**

 * This interface describes parsing options.

 * @typedef {object} ParsingOptions

 * @property {Source} in - data informations contained in the file.

 * @property {FeatureBuildingOptions|Layer} out - options indicates how the features should be built.

 */

let uid = 0;

/**

 * Sources are object containing informations on how to fetch resources, from a

 * set source.

 *

 * To extend a Source, it is necessary to implement two functions:

 * `urlFromExtent` and `extentInsideLimit`.

 *

 * @extends InformationsData

 *

 * @property {boolean} isSource - Used to checkout whether this source is a

 * Source. Default is true. You should not change this, as it is used internally

 * for optimisation.

 * @property {number} uid - Unique uid mainly used to store data linked to this

 * source into Cache.

 * @property {string} url - The url of the resources that are fetched.

 * @property {string} format - The format of the resources that are fetched.

 * @property {Function} fetcher - The method used to fetch the resources from

 * the source. iTowns provides some methods in {@link Fetcher}, but it can be

 * specified a custom one. This method should return a `Promise` containing the

 * fetched resource. If this property is set, it overrides the chosen fetcher

 * method with `format`.

 * @property {object} networkOptions - Fetch options (passed directly to

 * `fetch()`), see [the syntax for more information](

 * https://developer.mozilla.org/en-US/docs/Web/API/WindowOrWorkerGlobalScope/fetch#Syntax).

 * By default, set to `{ crossOrigin: 'anonymous' }`.

 * @property {string} crs - The crs projection of the resources.

 * @property {string} attribution - The intellectual property rights for the

 * resources.

 * @property {Extent} extent - The extent of the resources.

 * @property {Function} parser - The method used to parse the resources attached

 * to the layer. iTowns provides some parsers, visible in the `Parser/` folder.

 * If the method is custom, it should return a `Promise` containing the parsed

 * resource. If this property is set, it overrides the default selected parser

 * method with `source.format`. If `source.format` is also empty, no parsing

 * action is done.

 * <br><br>

 * When calling this method, two parameters are passed:

 * <ul>

 *  <li>the fetched data, i.e. the data to parse</li>

 *  <li>an {@link ParsingOptions}  containing severals properties, set when this method is

 *  called: it is specific to each call, so the value of each property can vary

 *  depending on the current fetched tile for example</li>

 * </ul>

 */

class Source {

    /**

     * @param {object} source - An object that can contain all properties of a

     * Source. Only the `url` property is mandatory.

     */

    constructor(source) {

        if (source.projection) {

            console.warn('Source projection parameter is deprecated, use crs instead.');

            source.crs = source.crs || source.projection;

        }

        if (source.crs) {

            CRS.isValid(source.crs);

        }

        this.crs = source.crs;

        this.isSource = true;

        if (!source.url) {

            throw new Error('New Source: url is required');

        }

        this.uid = uid++;

        this.url = source.url;

        this.format = source.format;

        this.fetcher = source.fetcher || Fetcher.get(source.format);

        this.parser = source.parser || supportedParsers.get(source.format) || ((d, opt) => { d.extent = opt.extent; return d; });

        this.isVectorSource = (source.parser || supportedParsers.get(source.format)) != undefined;

        this.networkOptions = source.networkOptions || { crossOrigin: 'anonymous' };

        this.attribution = source.attribution;

        /** @type {Promise<any>} */

        this.whenReady = Promise.resolve();

        this._featuresCaches = {};

        if (source.extent && !(source.extent.isExtent)) {

            this.extent = new Extent(this.crs).setFromExtent(source.extent);

        } else {

            this.extent = source.extent;

        }

    }

    handlingError(err) {

    /**

     * Generates an url from an extent. This url is a link to fetch the

     * resources inside the extent.

     *

     * @param {Extent} extent - Extent to convert in url.

     * @returns {string} The URL constructed from the extent.

     */

    // eslint-disable-next-line

    urlFromExtent(extent) {

        throw new Error('In extended Source, you have to implement the method urlFromExtent!');

    }

    getDataKey(extent) {

        return `z${extent.zoom}r${extent.row}c${extent.col}`;

    }

    /**

     * Load  data from cache or Fetch/Parse data.

     * The loaded data is a Feature or Texture.

     *

     * @param      {Extent}  extent   extent requested parsed data.

     * @param      {FeatureBuildingOptions|Layer}  out     The feature returned options

     * @returns     {FeatureCollection|Texture}  The parsed data.

     */

    loadData(extent, out) {

        const cache = this._featuresCaches[out.crs];

        const key = this.getDataKey(extent);

        // try to get parsed data from cache

        let features = cache.get(key);

        if (!features) {

            // otherwise fetch/parse the data

            features = this.fetcher(this.urlFromExtent(extent), this.networkOptions)

                .then(file => this.parser(file, { out, in: this, extent }))

                .catch(err => this.handlingError(err));

            cache.set(key, features);

        }

        return features;

    }

    /**

     * Called when layer added.

     *

     * @param {object} options

     */

    onLayerAdded(options) {

        // Added new cache by crs

        if (!this._featuresCaches[options.out.crs]) {

            // Cache feature only if it's vector data, the feature are cached in source.

            // It's not necessary to cache raster in Source,

            // because it's already cached on layer.

            this._featuresCaches[options.out.crs] = this.isVectorSource ? new LRUCache({ max: 500 }) : noCache;

        }

    }

    /**

     * Called when layer removed.

     *

     * @param {options}  [options={}] options

     */

    onLayerRemoved(options = {}) {

        // delete unused cache

        const unusedCache = this._featuresCaches[options.unusedCrs];

        if (unusedCache) {

            unusedCache.clear();

            delete this._featuresCaches[options.unusedCrs];

        }

    }

    /**

     * Determines whether this source has data intersecting the given extent.

     *

     * If the source has no defined extent, it is assumed to cover all areas and

     * this method always returns `true`. Otherwise, the source's extent is

     * tested for intersection with the provided extent.

     *

     * @param {Extent|Tile} extentOrTile - The extent or tile to test against.

     *

     * @returns {boolean} `true` if the source has data for the

     * given extent, `false` otherwise.

     */

    hasData(extentOrTile) {

    }

}

export default Source;