Slack messages to text

slack2text.js

#!/usr/bin/env node
const { readFileSync } = require('fs');

function messageHeader(item) {
  const { user, ts, replies, user_profile } = item;
  const name = user_profile?.display_name
              || user_profile?.real_name
              || user_profile?.name
              || user;
  return { name, user, ts, replies };
}

function parseText(body, messages, users) {
  body.forEach((item) => {
    if (item.user && item.user_profile) {
      const profile = item.user_profile;
      users[item.user] = profile.display_name || profile.real_name || profile.name;
    }
    if (item.subtype) return;
    if (item.bot_id) return;
    if (!item.text) return;
    const header = messageHeader(item);
    let text = item.text;
    if (text.match(/<@U[0-9A-Z]+>/)) {
      Object.entries(users).forEach(([id, name]) => {
        const regex = new RegExp(`<@${id}>`, 'g');
        text = text.replaceAll(regex, `@${name}`);
      });
    }
    messages.push({ ...header, text });
  });
}

function message2string(message, isThread = false) {
  const time = new Date(parseFloat(message.ts) * 1000).toLocaleString();
  const pad = isThread ? '\t\t' : '';
  console.log(`${pad}------`);
  console.log(`${pad}[${message.name} ${time}]`);
  message.text.split('\n').forEach((line) => console.log(`${pad}${line}`));
}


const { messages } = process.argv.slice(2)
  .sort((a, b) => a.localeCompare(b))
  .reduce((acc, file) => {
    const jsonData = JSON.parse(readFileSync(file, 'utf8'));
    parseText(jsonData, acc.messages, acc.users);
    return acc;
  }, { messages: [], users: {} });

const messageTags = messages
  .sort((a, b) => parseFloat(a.ts) - parseFloat(b.ts))
  .map((message) => `${message.user}:${message.ts}`);
const messageHash = messages.reduce((acc, message) => {
  acc[`${message.user}:${message.ts}`] = message;
  return acc;
}, {});

messageTags.forEach((tag) => {
  const message = messageHash[tag];
  if (!message) return;
  message2string(message);
  delete messageHash[tag];
  if (message.replies) {
    message.replies.forEach((reply) => {
      const replyTag = `${reply.user}:${reply.ts}`;
      const replyMessage = messageHash[replyTag];
      if (!replyMessage) return;
      message2string(replyMessage, true);
      delete messageHash[replyTag];
    });
  }
});