Send notifications from Roam to Slack

roam-slack-notification.js

// PoC by @filipematossilv and @ViktorTabori
// Token for a Slack App.
var oauthToken = "TOKEN_HERE";
// Slack app must already have been invited to the channel.
// See https://api.slack.com/methods/channels.list on how to get the ID.
var notificationChannel = "CHANNEL_HERE";
// Email must be the one used in the Slack that contains the channel.
var tagToEmail = {
  "#[[!name]]": "someone@example.com",
}
function jsonEncode(baseUrl, json) {
  const url = new URL(baseUrl);
  Object.entries(json).map(([k, v]) => url.searchParams.set(k, v))
  return url.href;
}
async function callSlackAPI(url, data) {
  // Can only submit GET requests to the Slack API via web since they have CORS
  // setup to deny Authentication and Content-Type headers.
  const response = await fetch(jsonEncode(url, { token: oauthToken, ...data }));
  return response.json();
}
async function getUserId(email) {
  // Needs users:read.email permissions.
  const lookupByEmailURL = "https://slack.com/api/users.lookupByEmail";
  const response = await callSlackAPI(lookupByEmailURL, { email });
  return response.ok ? response.user.id : false;
}
async function postNotification(msg) {
  // Needs chat:write permissions.
  const postMessageURL = "https://slack.com/api/chat.postMessage";
  const response = await callSlackAPI(postMessageURL, {
    channel: notificationChannel,
    unfurl_links: false,
    link_names: true,
    text: msg
  });
  return response.ok;
}
async function notifyUserOfLink(email, link, msg) {
  const uid = await getUserId(email);
  if (!uid) {
    return false;
  }
  return await postNotification(`Ping <@${uid}> at ${link}\n${msg}`);
}
function blockLink(blockId) {
  const graph = document.location.href.match(/^.*?\/app\/([^\/]+)\/?/)[1];
  return `https://roamresearch.com/#/app/${graph}/page/${blockId}`;
}
function handleTag(tag, blockId, blockStr) {
  const email = tagToEmail[tag];
  if (email) {
    // console.log("sending notification");
    return notifyUserOfLink(email, blockLink(blockId), blockStr);
  }
}
function newTags(before, after) {
  const tagRegExp = /#(?:\[\[)?([^\s])*(?:\]\])?/g;
  const tagsBefore = before.match(tagRegExp) || [];
  const tagsAfter = after.match(tagRegExp) || [];
  return tagsAfter.filter(t => !tagsBefore.includes(t));
}
function watchBlocksForNewTags() {
  let lastBlockId = null;
  let lastBlockStr = null;
  const callback = function (mutationsList, _) {
    // Events aren't necessarily ordered.
    // First check all the blocks left from and handle new tags.
    for (var mutation of mutationsList) {
      if (mutation.type === 'childList' && mutation.removedNodes.length && mutation.removedNodes[0].childElementCount && mutation.removedNodes[0].children[0].classList.contains('rm-block-input')) {
        const blockId = mutation.target.children[1].id.match(/.{9}$/)[0];
        const str = mutation.removedNodes[0].children[0].textContent;
        // console.log("exit block", blockId, str)
        if (lastBlockId == blockId) {
          const tags = newTags(lastBlockStr, str);
          tags.forEach(t => handleTag(t, blockId, str));
        }
      }
    }
    // Then check what the new block is, if any.
    for (var mutation of mutationsList) {
      // Enter existing block.
      if (mutation.type === 'childList' && mutation.addedNodes.length && mutation.addedNodes[0].childElementCount && mutation.addedNodes[0].children[0].classList.contains('rm-block-input')) {
        const blockId = mutation.target.children[1].children[0].id.match(/.{9}$/)[0];
        const str = mutation.addedNodes[0].children[0].textContent;
        lastBlockId = blockId;
        lastBlockStr = str;
      }
      // Enter new block.
      if (mutation.type === 'childList' && mutation.addedNodes.length && mutation.addedNodes[0].childElementCount &&
        mutation.addedNodes[0].children[0] &&
        mutation.addedNodes[0].children[0].children[0] &&
        mutation.addedNodes[0].children[0].children[0].children[1] &&
        mutation.addedNodes[0].children[0].children[0].children[1].children[0] &&
        mutation.addedNodes[0].children[0].children[0].children[1].children[0].classList.contains('rm-block-input')
      ) {
        const el = mutation.addedNodes[0].children[0].children[0].children[1].children[0];
        const blockId = el.id.match(/.{9}$/)[0];
        const str = el.textContent;
        lastBlockId = blockId;
        lastBlockStr = str;
        // console.log("enter new block", blockId, str)
      }
    }
  };
  // Create an observer instance linked to the callback function
  const observer = new MutationObserver(callback);
  observer.observe(document.body, { childList: true, subtree: true });
}
watchBlocksForNewTags();