metar-decoder/lib/index.js

Convert METAR weather reports to JavaScript objects

"use strict";
var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, P, generator) {
    function adopt(value) { return value instanceof P ? value : new P(function (resolve) { resolve(value); }); }
    return new (P || (P = Promise))(function (resolve, reject) {
        function fulfilled(value) { try { step(generator.next(value)); } catch (e) { reject(e); } }
        function rejected(value) { try { step(generator["throw"](value)); } catch (e) { reject(e); } }
        function step(result) { result.done ? resolve(result.value) : adopt(result.value).then(fulfilled, rejected); }
        step((generator = generator.apply(thisArg, _arguments || [])).next());
    });
};
Object.defineProperty(exports, "__esModule", { value: true });
exports.decode = void 0;
const axios_1 = require("axios");
const constants_1 = require("./constants");
const utils_1 = require("./utils");
function decode(metar) {
    const data = {};
    const sections = metar.split(' ');
    if (sections.length === 0)
        return null;
    data.rvr = [];
    data.clouds = [];
    data.weather = [];
    data.auto = sections[1] === 'AUTO';
    data.cavok = metar.includes('CAVOK');
    if (data.cavok) {
        data.visibility = 9999;
        sections.splice(sections.indexOf('CAVOK'), 1);
    }
    // WEATHER
    for (let i = sections.length - 1; i >= 0; i--) {
        if (constants_1.weather[sections[i]]) {
            const uncodedWeather = sections[i];
            data.weather.push({
                abbreviation: uncodedWeather,
                meaning: constants_1.weather[uncodedWeather],
            });
            sections.splice(i, 1);
        }
    }
    // AIRPORT
    data.airport = sections.shift();
    // TIME
    const timeSection = sections.shift();
    const now = new Date();
    data.recorded_at = new Date(Date.UTC(now.getFullYear(), now.getMonth(), Number(timeSection.slice(0, 2)), Number(timeSection.slice(2, 4)), Number(timeSection.slice(4, 6))));
    // WIND
    const windSection = sections.shift();
    data.wind = {};
    data.wind.direction = windSection.slice(0, 3);
    data.wind.speed = Number(windSection.slice(3, 5));
    if (windSection[5] === 'G') {
        data.wind.guest = Number(windSection.slice(5, 7));
        data.wind.unit = windSection.slice(7, 9);
    }
    else {
        data.wind.guest = null;
        data.wind.unit = windSection.slice(5, 7);
    }
    // VARIATION
    if (/(\d){3}V(\d){3}/g.test(sections[0])) {
        const [min, max] = sections.shift().split('V').map(Number);
        data.wind.variation = {
            min,
            max,
        };
    }
    // VISIBILITY
    if (!data.cavok) {
        data.visibility = Number(sections.shift());
        // MIN VISIBILITY
        if ((0, utils_1.matchExact)(/(\d){4}(W|E|N|S|(NE)|(NW)|(SE)|(SW))?/, sections[0])) {
            const min_visibility = sections.shift();
            data.min_visibility = {
                visibility: Number(min_visibility.slice(0, 4)),
                direction: min_visibility.slice(4, min_visibility.length),
            };
        }
    }
    // RVR
    while (sections[0].startsWith('R')) {
        const [runway, visibility] = sections.shift().substring(1).split('/');
        const isVariable = visibility.includes('V');
        data.rvr.push({
            runway,
            visibility: !isVariable
                ? visibility.slice(0, visibility.length - 1)
                : {
                    min: visibility.slice(0, 4),
                    max: visibility.slice(5, 9),
                },
            trend: constants_1.rvrTrend[visibility.slice(-1)],
        });
    }
    // CLOUDS
    if (/((SCT)|(BKN)|(FEW)|(OVC))(\d{3})((CB)|(TCB))?/.test(sections[0])) {
        while (constants_1.clouds.map((c) => c.code).includes(sections[0].slice(0, 3))) {
            const uncodedCloud = sections.shift();
            const cloud = constants_1.clouds.find((c) => c.code === uncodedCloud.slice(0, 3));
            if (!cloud)
                continue;
            data.clouds.push(Object.assign(Object.assign({}, cloud), { cumulonimbus: uncodedCloud.includes('CB'), altitude: Number(uncodedCloud.slice(3, 6)) * 100 }));
        }
    }
    if (sections[0].startsWith('VV')) {
        const vv = sections.shift();
        data.vertical_visibility = vv.substring(2);
    }
    // TEMP
    if (/(\d){2}\/(\d){2}/.test(sections[0])) {
        const [temperature, dewpoint] = sections.shift().split('/').map(Number);
        data.dewpoint = dewpoint,
            data.temperature = temperature;
    }
    // BARO
    if ((0, utils_1.matchExact)(/(Q|A)(\d){4}/, sections[0])) {
        const baro = sections.shift();
        data.qnh = baro.startsWith('A')
            ? (0, utils_1.inHgtoHpa)(Number(`${baro.slice(1, 3)}.${baro.slice(2, 5)}`))
            : Number(baro.slice(1, 5));
    }
    // TREND
    if (constants_1.trends[sections[0]]) {
        data.trend = {
            type: constants_1.trends[sections[0]],
            full: sections.join(' '),
        };
    }
    data.fetchAirport = () => __awaiter(this, void 0, void 0, function* () {
        if (typeof data.airport === 'object')
            return data.airport;
        try {
            const { data: json } = yield axios_1.default.get(`https://airports.larrrssss.workers.dev/${data.airport}`);
            if (json.status && json.status === 404)
                return null;
            data.airport = json;
            return data.airport;
        }
        catch (e) {
            return null;
        }
    });
    return data;
}
exports.decode = decode;