buildFindPointInGeojson.mjs

import getKpFeatureFromGeojson from './getKpFeatureFromGeojson.mjs'
import findPointInKpFeature from './findPointInKpFeature.mjs'


/**
 * 判斷點陣列[x,y]或點物件{x,y}是否位於某一特徵(Feature)內之字典物件，若有則回傳該特徵之鍵名，若無則回傳def值
 *
 * Unit Test: {@link https://github.com/yuda-lyu/w-gis/blob/master/test/buildFindPointInGeojson.test.mjs Github}
 * @memberOf w-gis
 * @returns {Object} 回傳函數物件，包含init、isInit、getPoint函數。init為初始化，輸入geojson與opt，無輸出，功能詳見getKpFeatureFromGeojson。isInit為回傳是否初始化布林值，無輸入。getPoint為查詢點位於哪個特徵並回傳該鍵名，輸入p與opt，功能詳見findPointInKpFeature。
 * @example
 *
 * let geojson
 * let p
 * let r
 *
 * geojson = `
 * {
 *     'type': 'FeatureCollection',
 *     'name': 'pgs',
 *     'features': [
 *         {
 *             'type': 'Feature',
 *             'properties': {
 *                 'name': 'pgs1',
 *             },
 *             'geometry': {
 *                 'type': 'MultiPolygon',
 *                 'coordinates': [
 *                     [
 *                         [
 *                             [0, 0],
 *                             [0, 1],
 *                             [1, 1],
 *                             [1, 0],
 *                             [0, 0],
 *                         ]
 *                     ]
 *                 ]
 *             }
 *         },
 *         {
 *             'type': 'Feature',
 *             'properties': {
 *                 'name': 'pgs2',
 *             },
 *             'geometry': {
 *                 'type': 'MultiPolygon',
 *                 'coordinates': [
 *                     [
 *                         [
 *                             [1, 1],
 *                             [1, 2],
 *                             [2, 2],
 *                             [2, 1],
 *                             [1, 1],
 *                         ]
 *                     ]
 *                 ]
 *             }
 *         },
 *     ]
 * }
 * `
 * let BD = buildFindPointInGeojson
 * let bd = new BD()
 * await bd.init(geojson, { key: 'properties.name' })
 *
 * p = [0.5, 0.5]
 * r = await bd.getPoint(p)
 * console.log(r)
 * // => 'pgs1'
 *
 * p = [1.5, 1.5]
 * r = await bd.getPoint(p)
 * console.log(r)
 * // => 'pgs2'
 *
 * p = [1.5, 0.5]
 * r = await bd.getPoint(p)
 * console.log(r)
 * // => 'unknow'
 *
 * p = [1.5, 0.5]
 * r = await bd.getPoint(p, { def: '未知' })
 * console.log(r)
 * // => '未知'
 *
 */
function Build() {
    let bInit = false
    let kp = null

    async function init(geojson, opt = {}) {

        //getKpFeatureFromGeojson
        kp = getKpFeatureFromGeojson(geojson, opt)

        //bInit
        bInit = true

    }

    function isInit() {
        return bInit
    }

    async function getPoint(p, opt = {}) {

        //check
        if (!bInit) {
            throw new Error('no init')
        }

        //findPointInKpFeature
        let r = findPointInKpFeature(p, kp, opt)

        return r
    }

    return {
        init,
        isInit,
        getPoint,
    }
}


export default Build