session-desktop/ts/session/apis/open_group_api/sogsv3/sogsV3MutationCache.ts

/**
 * This is strictly use to resolve conflicts between local state and the opengroup poll updates
 * Currently only supports message reactions 26/08/2022
 */

import { filter, findIndex, remove } from 'lodash';
import { handleOpenGroupMessageReactions } from '../../../../util/reactions';
import { OpenGroupMessageV4 } from '../opengroupV2/OpenGroupServerPoller';

export enum ChangeType {
  REACTIONS = 0,
}

type ReactionAction = 'ADD' | 'REMOVE';

type ReactionChange = {
  messageId: number; // will be serverId of the reacted message
  emoji: string;
  action: ReactionAction;
};

export type SogsV3Mutation = {
  seqno: number | null; // null until mutating API request returns
  server: string; // serverUrl
  room: string; // roomId
  changeType: ChangeType;
  metadata: ReactionChange; // For now we only support message reactions
};

// we don't want to export this, we want to export functions that manipulate it
const sogsMutationCache: Array<SogsV3Mutation> = [];

function verifyEntry(entry: SogsV3Mutation): boolean {
  return Boolean(
    !entry.server ||
      !entry.room ||
      entry.seqno !== null ||
      entry.metadata.messageId ||
      entry.metadata.emoji ||
      entry.metadata.action === 'ADD' ||
      entry.metadata.action === 'REMOVE'
  );
}

export function addToMutationCache(entry: SogsV3Mutation) {
  if (!verifyEntry(entry)) {
    window.log.error('SOGS Mutation Cache: Entry verification on add failed!', entry);
  } else {
    sogsMutationCache.push(entry);
    window.log.info('SOGS Mutation Cache: Entry added!', entry);
  }
}

export function updateMutationCache(entry: SogsV3Mutation, seqno: number) {
  if (!verifyEntry(entry)) {
    window.log.error('SOGS Mutation Cache: Entry verification on update failed!');
  } else {
    const entryIndex = findIndex(sogsMutationCache, entry);
    if (entryIndex >= 0) {
      const updatedEntry = entry;
      updatedEntry.seqno = seqno;
      sogsMutationCache[entryIndex] = updatedEntry;
      window.log.info('SOGS Mutation Cache: Entry updated!', updatedEntry);
    } else {
      window.log.error('SOGS Mutation Cache: Updated failed! Cannot find entry', entry);
    }
  }
}

export async function processMessagesUsingCache(
  server: string,
  room: string,
  message: OpenGroupMessageV4
) {
  const updatedReactions = message.reactions;
  const matches: Array<SogsV3Mutation> = filter(sogsMutationCache, { server, room });

  if (matches?.length) {
    for (const match of matches) {
      if (message.seqno && match.seqno && match.seqno <= message.seqno) {
        const removedEntry = remove(sogsMutationCache, match);
        window.log.info('SOGS Mutation Cache: Entry ignored and removed!', removedEntry);
      } else if (!message.seqno || (message.seqno && match.seqno && match.seqno > message.seqno)) {
        for (const reaction of Object.keys(message.reactions)) {
          const _matches = filter(sogsMutationCache, {
            server,
            room,
            changeType: ChangeType.REACTIONS,
            metadata: {
              messageId: message.id,
              emoji: reaction,
            },
          });
          if (_matches?.length) {
            for (const match of _matches) {
              switch (match.metadata.action) {
                case 'ADD':
                  updatedReactions[reaction].you = true;
                  updatedReactions[reaction].count += 1;
                  window.log.info(
                    'SOGS Mutation Cache: Added our reaction based on the cache',
                    updatedReactions[reaction]
                  );
                  break;
                case 'REMOVE':
                  updatedReactions[reaction].you = false;
                  updatedReactions[reaction].count -= 1;
                  window.log.info(
                    'SOGS Mutation Cache: Removed our reaction based on the cache',
                    updatedReactions[reaction]
                  );
                  break;
                default:
                  window.log.warn(
                    'SOGS Mutation Cache: Unsupported metadata action in OpenGroupMessageV4',
                    match
                  );
                  break;
              }
            }

            const removedMatches = remove(sogsMutationCache, ...matches);
            window.log.info(
              'SOGS Mutation Cache: Removed processed entries from cache!',
              removedMatches
            );
          }
        }
      }
    }
  }

  message.reactions = updatedReactions;
  await handleOpenGroupMessageReactions(message.reactions, message.id);
}