feat: add new task to remind about open merge requests

import {Api} from '@openstapps/gitlab-api';

import {

  AccessLevel,

  MembershipScope,

  MergeRequestMergeStatus,

  MergeRequestState,

  Scope,

  User,

} from '@openstapps/gitlab-api/lib/types';

import {WebClient} from '@slack/client';

import {asyncPool} from 'async-pool-native/dist/async-pool';

import {logger} from '../common';

import {GROUPS} from '../configuration';

export async function remind(api: Api): Promise<void> {

  // get list of open merge requests

  const mergeRequests = await api.getMergeRequests(MembershipScope.GROUPS, GROUPS[0], MergeRequestState.OPENED);

  logger.info(`Found ${mergeRequests.length} open merge requests.`);

  // instantiate slack client

  const client = new WebClient(process.env.SLACK_API_TOKEN);

  // get members of main group

  const members = await api.getMembers(MembershipScope.GROUPS, GROUPS[0]);

  // filter members with at least maintainer status

  const maintainers = members.filter((member) => member.access_level >= AccessLevel.Maintainer);

  // extract maintainer's usernames

  const maintainerUsernames = maintainers.map((maintainer) => maintainer.username);

  // sort maintainer's usernames alphabetically

  maintainerUsernames.sort((a, b) => {

    return a.localeCompare(b);

  });

  logger.info(`Found ${maintainers.length} maintainer(s).`);

  await asyncPool(2, mergeRequests, async (mergeRequest) => {

    // check if merge request is WIP

    if (mergeRequest.work_in_progress) {

      logger.info(`Merge request '${mergeRequest.title}' is WIP.`);

      return;

    }

    // get merge request approval

    const approval = await api.getMergeRequestApproval(mergeRequest.project_id, mergeRequest.iid);

    if (approval.merge_status === MergeRequestMergeStatus.CAN_BE_MERGED) {

      if (approval.approvals_left > 0) {

        logger.warn(`Merge request '${mergeRequest.title}' needs more approvals!`);

        // get possible appropers, prefixed with '@' and joined with commas

        const possibleApprovers = maintainerUsernames

          .filter((username) => {

            if (approval.approved_by.length === 0) {

              return true;

            }

            return approval.approved_by.find((approver: { user: User }) => {

              return approver.user.username !== username;

            });

          })

          .map((username) => '@' + username)

          .join(', ');

        // send message to slack

        await client.chat.postMessage({

          channel: 'C762UG76Z',

          text: `Merge request '${mergeRequest.title}' needs more approvals! See ${mergeRequest.web_url}!`,

        });

        // create note in merge request

        await api.createNote(

          mergeRequest.project_id,

          Scope.MERGE_REQUESTS,

          mergeRequest.iid,

          `Please review, ${possibleApprovers}!`,

        );

      } else {

        logger.log(`Merge request '${mergeRequest.title}' is ready to be merged!`);

        // send message to slack

        await client.chat.postMessage({

          channel: 'C762UG76Z',

          text: `Merge request '${mergeRequest.title}' is ready to be merged! See ${mergeRequest.web_url}!`,

        });

        // prefix maintainers with '@' and join with commas

        const possibleMergers = maintainerUsernames

          .map((username) => '@' + username)

          .join(', ');

        // create note in merge request

        await api.createNote(

          mergeRequest.project_id,

          Scope.MERGE_REQUESTS,

          mergeRequest.iid,

          `Merge request is ready to be merged, ${possibleMergers}!`,

        );

      }

    }

  });

}