conv_churn.js

import { oldToNewConversationMessageComparator } from 'gelam/db/comparators';

/**
 * Churn up our application-specific summary stuff:
 * - A list of all messages in the conversation with index references to their
 *   parent (as we best understand it) for threading purposes.  (We could use
 *   direct references which survive structured clone transit, but will fail
 *   to JSON happily, and that makes us sad.)  We also include other attributes
 *   for a brief overview visualization of the conversation.
 *
 *
 */
export default function churnConversation(convInfo, messages, oldConvInfo, convType, convMeta) {
  // Ensure the messages are sorted oldest to newest.  We do this because for
  // simplicity for gaia mail's UX decisions we initially opted to do
  // NEW-TO-OLD.  A more rigorous treatment and rationale is needed, however.
  messages = messages.concat();
  messages.sort(oldToNewConversationMessageComparator);

  // ## TIDBITS
  // This previously was just brief coverage of the first N unread messages but
  // now powers time based visualizations.  It should likely go back to being
  // the first N unread, but the time digests could be their own thing.
  let tidbits = convInfo.app.tidbits = [];

  let midToIndex = new Map();
  let findClosestAncestor = (references) => {
    // We might not have references available.  This is the case for ActiveSync,
    // but it's also the case we don't have any useful threading in that case.
    if (!references) {
      return 0;
    }

    for (let i = references.length; i >= 0; i--) {
      let ref = references[i];
      if (midToIndex.has(ref)) {
        return midToIndex.get(ref);
      }
    }
    // If we couldn't find any, then assume that it's just a reply to the root.
    return 0;
  };

  for (let message of messages) {
    let isRead = message.flags.indexOf('\\Seen') !== -1;
    let isStarred = message.flags.indexOf('\\Flagged') !== -1;
    tidbits.push({
      id: message.id,
      date: message.date,
      isRead,
      isStarred,
      author: message.author,
      parent: findClosestAncestor(message.references)
    });
    midToIndex.set(message.guid, tidbits.length - 1);
  }

  if (tidbits.length === 1) {
    convInfo.height = 1;
  } else {
    convInfo.height = 2;
  }

  // ## Phabricator Revision stuff
  if (convType === 'phab-drev') {
    convInfo.app.drevInfo = convMeta.drevInfo;

    const patchInfo = convInfo.app.patchInfo = convMeta.patchInfo;
    for (const folderId of patchInfo.virtFolderIds) {
      convInfo.folderIds.add(folderId);
    }
  }
}