ci/github-script/merge: improve caching of team members

// Caching the list of committers saves API requests when running the bot on the schedule and

// Caching the list of team members saves API requests when running the bot on the schedule and

// processing many PRs at once.

let committers

const members = {}

async function runChecklist({ github, context, pull_request, maintainers }) {

  const pull_number = pull_request.number

  if (!committers) {

  function getTeamMembers(team_slug) {

    if (context.eventName === 'pull_request') {

      // We have no chance of getting a token in the pull_request context with the right

      // permissions to access the members endpoint below. Thus, we're pretending to have

      // no committers. This is OK; because this is only for the Test workflow, not for

      // no members. This is OK; because this is only for the Test workflow, not for

      // real use.

      committers = new Set()

    } else {

      committers = github

      return new Set()

    }

    if (!members[team_slug]) {

      members[team_slug] = github

        .paginate(github.rest.teams.listMembersInOrg, {

          org: context.repo.owner,

          team_slug: 'nixpkgs-committers',

          team_slug,

          per_page: 100,

        })

        .then((members) => new Set(members.map(({ id }) => id)))

    }

    return members[team_slug]

  }

  committers = await getTeamMembers('nixpkgs-committers')

  const files = await github.paginate(github.rest.pulls.listFiles, {

    ...context.repo,

    ),

    'PR authored by r-ryantm or committer.':

      pull_request.user.login === 'r-ryantm' ||

      (await committers).has(pull_request.user.id),

      committers.has(pull_request.user.id),

    'PR has maintainers eligible for merge.': eligible.size > 0,

  }