const Eris = require('eris');
const moment = require('moment');
const publicIp = require('public-ip');
const config = require('../config');
const utils = require('./utils');

let inboxGuild = null;
let mainGuild = null;
let logChannel = null;

function getInboxGuild(bot) {
  if (! inboxGuild) inboxGuild = bot.guilds.find(g => g.id === config.mailGuildId);
  return inboxGuild;
}

function getMainGuild(bot) {
  if (! mainGuild) mainGuild = bot.guilds.find(g => g.id === config.mainGuildId);
  return mainGuild;
}

function getLogChannel(bot) {
  const inboxGuild = getInboxGuild(bot);

  if (! config.logChannelId) {
    return inboxGuild.channels.get(inboxGuild.id);
  }

  if (! logChannel) {
    logChannel = inboxGuild.channels.get(config.logChannelId);
  }

  return logChannel;
}

const userMentionRegex = /^<@\!?([0-9]+?)>$/;

/**
 * Returns the user ID of the user mentioned in str, if any
 * @param {String} str
 * @returns {String|null}
 */
function getUserMention(str) {
  str = str.trim();

  if (str.match(/^[0-9]+$/)) {
    // User ID
    return str;
  } else {
    let mentionMatch = str.match(userMentionRegex);
    if (mentionMatch) return mentionMatch[1];
  }

  return null;
}

/**
 * Returns the current timestamp in an easily readable form
 * @param {String|Date|undefined} date
 * @returns {String}
 */
function getTimestamp(date) {
  return moment.utc(date).format('HH:mm');
}

/**
 * Disables link previews in the given string by wrapping links in < >
 * @param {String} str
 * @returns {String}
 */
function disableLinkPreviews(str) {
  return str.replace(/(^|[^<])(https?:\/\/\S+)/ig, '$1<$2>');
}

/**
 * Returns a URL to the bot's web server
 * @param {String} path
 * @returns {String}
 */
function getSelfUrl(path = '') {
  if (config.url) {
    return Promise.resolve(`${config.url}/${path}`);
  } else {
    const port = config.port || 8890;
    return publicIp.v4().then(ip => {
      return `http://${ip}:${port}/${path}`;
    });
  }
}

/**
 * Returns the highest hoisted role of the given member
 * @param {Eris.Member} member
 * @returns {Eris.Role}
 */
function getMainRole(member) {
  const roles = member.roles.map(id => member.guild.roles.get(id));
  roles.sort((a, b) => a.position > b.position ? -1 : 1);
  return roles.find(r => r.hoist);
}

/**
 * Splits array items into chunks of the specified size
 * @param {Array} items
 * @param {Number} chunkSize
 * @returns {Array}
 */
function chunk(items, chunkSize) {
  const result = [];

  for (let i = 0; i < items.length; i += chunkSize) {
    result.push(items.slice(i, i + chunkSize));
  }

  return result;
}

module.exports = {
  getInboxGuild,
  getMainGuild,
  getLogChannel,
  getUserMention,
  getTimestamp,
  disableLinkPreviews,
  getSelfUrl,
  getMainRole,
  chunk,
};