require('dotenv').config();
const axios = require('axios');
const xpath = require('xpath');
const Dom = require('xmldom').DOMParser;
const Snoowrap = require('snoowrap');

function rand(list) {
  return list[Math.floor((Math.random() * list.length))];
}

async function getHurricane() {
  const data = await axios.default.get(
    'http://www.prh.noaa.gov/cphc/gis-cp.xml'
  );
  const doc = new Dom().parseFromString(data.data);
  const select = xpath.useNamespaces({ nhc: 'http://www.nhc.noaa.gov' });

  const element = select('/rss/channel/item[1]/nhc:Cyclone', doc)[0];
  const type = element.getElementsByTagName('nhc:type')[0].textContent;
  const name = element.getElementsByTagName('nhc:name')[0].textContent;
  const datetime = element.getElementsByTagName('nhc:datetime')[0].textContent;
  const movement = element.getElementsByTagName('nhc:movement')[0].textContent;
  const windspeed = element.getElementsByTagName('nhc:wind')[0].textContent;
  const pressure = element.getElementsByTagName('nhc:pressure')[0].textContent;

  const element2 = select('/rss/channel/item[2]', doc)[0];
  const guid = element2.getElementsByTagName('guid')[0].textContent;

  let stormId, advisoryNumber, imgLink;

  try {
    stormId = guid.match(/ep\d{6}/);
    advisoryNumber = guid.match(/\d{2}A/);

    if (stormId && advisoryNumber) {
      imgLink = `http://www.prh.noaa.gov/cphc/tc_graphics/2018/graphics/${stormId[0].toUpperCase()}_3day_cone_with_line_${advisoryNumber}.png`;
    }
  } catch (e) {
    console.error(e);
  }

  return {
    type,
    name,
    datetime,
    movement,
    windspeed,
    pressure,
    stormId,
    imgLink,
    advisoryNumber,
    guid,
  };
}

const QUOTES = [
  'Brought to you by your friendly /u/vlt-bot',
  'Stay safe out there. /u/vlt-bot',
  'This automated message brought to you by /u/vlt-bot',
  'Up-to-date information from NOAA and /u/vlt-bot',
];

function promisifyGet(func) {
  return () => {
    return new Promise((resolve, reject) => {
      func((err, res) => {
        if (err) {
          reject(err);
        } else {
          resolve(res);
        }
      });
    });
  };
}

function promisifySet(func) {
  return args => {
    return new Promise((resolve, reject) => {
      func(...args, (err, res) => {
        if (err) {
          reject(err);
        } else {
          resolve(res);
        }
      });
    });
  };
}

module.exports = async (ctx, cb) => {
  try {
    ctx.storage.get(async function(err, data) {
      try {
        const { lastProcessed } = data;
        const r = new Snoowrap({
          clientId: ctx.secrets.REDDIT_ID,
          clientSecret: ctx.secrets.REDDIT_SECRET,
          username: ctx.secrets.REDDIT_USERNAME,
          password: ctx.secrets.REDDIT_PASSWORD,
          userAgent: ctx.secrets.REDDIT_USER_AGENT,
        });

        const {
          type,
          name,
          datetime,
          movement,
          windspeed,
          pressure,
          imgLink,
          guid,
        } = await getHurricane();

        if (guid === lastProcessed) {
          cb(null, 'Nothing to do.');
          return;
        }

        const msg = textOnly => `${type} ${name} is moving ${movement}. Winds at ${windspeed}, air pressure ${pressure}.

${!textOnly && imgLink ? imgLink : ''}

Data as of ${datetime}. *${rand(QUOTES)}*`;
        console.log(msg);
        await r.getLivethread(ctx.secrets.LIVE_THREAD_ID).addUpdate(msg(false));
        await r
          .getLivethread(ctx.secrets.TEXT_ONLY_THREAD_ID)
          .addUpdate(msg(true));
        ctx.storage.set({ lastProcessed: guid }, cb);
      } catch (e) {
        cb(e);
      }
    });
  } catch (e) {
    cb(e);
  }
};