'use strict'

var fs = require('fs');
var downloader = require('./downloader');
var xml2js = require ('xml2js');
var dir = 'data/stations/';

module.exports = {
    /**
     * Add station IDs here, A-Z 0-9
     */
    stations: [
        'ANVC1',
        'BDXC1',
        'CECC1',
        'CPXC1',
        'HBYC1',
        'ICAC1',
        'NTBC1',
        'PRYC1',
        'PTGC1',
        '46011',
        '46012',
        '46013',
        '46014',
        '46022',
        '46025',
        '46027',
        '46028',
        '46042',
        '46053',
        '46054',
        '46092',
        '46213',
        '46214',
        '46215',
        '46216',
        '46217',
        '46221',
        '46223',
        '46225',
        '46232',
        '46234',
        '46237',
        '46239',
        '46240',
        '46242',
        '46244',
        '46253',
        '46254',
        '46256',
        '46257'
    ],

    /**
     * Downloads each station's data XML.
     */
    downloadAllMetadata: function() {
        var len = this.stations.length;
        var url;

        for (var i = 0; i < len; i++) {
            url = 'http://www.ndbc.noaa.gov/get_observation_as_xml.php?station=' + this.stations[i];
            downloader.download(url, dir + this.stations[i] + '.txt');
        }
    },

    /**
     *
     */
    parseAllMetadata: function() {
        function done() {
            if (data.length === len) {
                fs.writeFile(outfile, data.join('\n'), function(err) {
                    if (err) {
                        throw new Error(err)
                    }

                    console.log('Station data written to ' + outfile);
                });
            }
        };

        function next() {
            // Wait for other concurrent files to finish.
            if (count !== data.length) {
                return;
            }

            var concurrent = 3;
            var tmp;

            for (var i = 0; i < concurrent; i++) {
                tmp = count + i;

                if (tmp === len) {
                    break;
                }

                // console.log(tmp + "(" + count + ")" + " reading " + dir + module.exports.stations[tmp] + '.txt');
                fs.readFile(dir + module.exports.stations[tmp] + '.txt', 'utf8', thenParse);
            }

            count += concurrent;
        };

        function thenParse(err, xml) {
            if (err) {
                throw new Error(err)
            }

            xml2js.parseString(xml, thenReport);
        };

        function thenReport(err, json) {
            if (err) {
                throw new Error(err)
            }

            data.push(JSON.stringify(json.observation.$));
            next();
            done();
        };

        var outfile = 'data-stations.json';
        var len = module.exports.stations.length;
        var count = 0;
        var data = [];

        next();
    },
};