const Eris = require('eris');
const moment = require('moment');
const Queue = require('./queue');
const config = require('./config');

const bot = new Eris.CommandClient(config.token, {}, {
  prefix: config.prefix || '!',
  ignoreSelf: true,
  ignoreBots: true,
  defaultHelpCommand: false,
});

let modMailGuild;
const modMailChannels = {};
const messageQueue = new Queue();

bot.on('ready', () => {
  modMailGuild = bot.guilds.find(g => g.id === config.mailGuildId);

  if (! modMailGuild) {
    console.error('You need to set and invite me to the mod mail guild first!');
    process.exit(0);
  }
});

function getModmailChannelInfo(channel) {
  if (! channel.topic) return null;

  const match = channel.topic.match(/^MODMAIL\|([0-9]+)\|(.*)$/);
  if (! match) return null;

  return {
    userId: match[1],
    name: match[2],
  };
}

function getModmailChannel(user) {
  if (modMailChannels[user.id]) {
    // Cached
    const channel = modMailGuild.channels.get(modMailChannels[user.id]);
    if (channel) {
      return Promise.resolve(channel);
    } else {
      // If the cache value was invalid, remove it
      delete modMailChannels[user.id];
    }
  }

  // Try to find a matching channel
  let candidate = modMailGuild.channels.find(c => {
    const info = getModmailChannelInfo(c);
    return info && info.userId === user.id;
  });

  if (candidate) {
    return Promise.resolve(candidate);
  } else {
    // If one is not found, create and cache it
    return modMailGuild.createChannel(`${user.username}-${user.discriminator}`)
      .then(channel => {
        // This is behind a timeout because Discord was telling me the channel didn't exist after creation even though it clearly did
        // ¯\_(ツ)_/¯
        return new Promise(resolve => {
          const topic = `MODMAIL|${user.id}|${user.username}#${user.discriminator}`;
          setTimeout(() => resolve(channel.edit({topic: topic})), 200);
        });
      })
      .then(channel => {
        modMailChannels[user.id] = channel.id;
        channel._wasCreated = true;
        return channel;
      });
  }
}

bot.on('messageCreate', (msg) => {
  if (! (msg.channel instanceof Eris.PrivateChannel)) return;
  if (msg.author.id === bot.user.id) return;

  // This needs to be queued as otherwise, if a user sent a bunch of messages initially and the createChannel endpoint is delayed, we might get duplicate channels
  messageQueue.add(() => {
    return getModmailChannel(msg.author).then(channel => {
      channel.createMessage(`« **${msg.author.username}#${msg.author.discriminator}:** ${msg.content}`);

      if (channel._wasCreated) {
        msg.channel.createMessage("Thank you for your message! Our mod team will reply to you here as soon as possible.");
      }
    });
  });
});

bot.registerCommand('reply', (msg, args) => {
  if (msg.channel.guild.id !== modMailGuild.id) return;
  if (! msg.member.permission.has('manageRoles')) return;

  const channelInfo = getModmailChannelInfo(msg.channel);
  if (! channelInfo) return;

  bot.getDMChannel(channelInfo.userId).then(channel => {
    const message = `**${msg.author.username}:** ${args.join(' ')}`;

    channel.createMessage(message);
    msg.channel.createMessage(`» ${message}`);
    msg.delete();
  });
});

bot.registerCommandAlias('r', 'reply');

bot.registerCommand('close', (msg, args) => {
  if (msg.channel.guild.id !== modMailGuild.id) return;
  if (! msg.member.permission.has('manageRoles')) return;

  const channelInfo = getModmailChannelInfo(msg.channel);
  if (! channelInfo) return;

  msg.channel.createMessage('Saving logs and closing channel...');
  msg.channel.getMessages(10000).then(messages => {
    const log = messages.reverse().map(message => {
      const date = moment.utc(message.timestamp, 'x').format('YYYY-MM-DD HH:mm:ss');
      return `[${date}] ${message.author.username}#${message.author.discriminator}: ${message.content}`;
    }).join('\n') + '\n';

    bot.createMessage(modMailGuild.id, `Log of modmail thread with ${channelInfo.name}:`, {
      file: new Buffer(log),
      name: 'log.txt',
    });

    delete modMailChannels[channelInfo.userId];
    msg.channel.delete();
  });
});

bot.connect();