slash-command-merge.yml

name: /merge handler

on:
  repository_dispatch:
    types: [merge-command]

permissions:
  pull-requests: write

concurrency: merge-handler-${{ github.event.client_payload.pull_request.node_id || github.run_id }}

jobs:
  merge:
    if: github.event.client_payload.pull_request != null
    name: Trim description and merge
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4
        with:
          sparse-checkout: |
            tools/ci_format_pr_description.js
      - id: pr-data
        name: Get PR data and trim PR body
        uses: actions/github-script@v7
        with:
          script: |
            const pull_id = context.payload.client_payload.pull_request.node_id;

            core.debug(`Pull request ID: ${pull_id}.`);
            const query = `query($id: ID!) {
              node(id: $id) {
                ... on PullRequest {
                  autoMergeRequest {
                    mergeMethod
                  }
                  mergeQueueEntry {
                    state
                  }
                  closed
                  body
                }
              }
            }`;

            const { node: pr_info } = await github.graphql(query, { id: pull_id });
            core.debug(`PR data: ${JSON.stringify(pr_info)}`);

            if (pr_info.closed) {
              core.notice('PR is already merged or closed.');
              return;
            }

            if (pr_info.autoMergeRequest || pr_info.mergeQueueEntry) {
              core.notice('PR is already queued for merging.');
              return;
            }

            const formatPR = require('./tools/ci_format_pr_description.js');

            let [ body, body_tail ] = pr_info.body.split(/^---\s*$/m, 2);
            body = formatPR.formatPRdescription(body, 72);
            body = body.trimEnd();
            body_tail = body_tail?.trimEnd() || '';
            // Only runs when the PR is still open and is not staged for merging.
            core.setOutput('run', 'true');
            core.setOutput('body', body);
            core.setOutput('body-tail', body_tail);
            if (pr_info.body !== body) {
              // Only attempt PR description update if there are changes to be made
              core.setOutput('update-body', 'true');
            }

      - if: steps.pr-data.outputs.run
        id: find-comment
        name: Find previously generated informational comment
        uses: peter-evans/find-comment@v3
        with:
          issue-number: ${{ github.event.client_payload.pull_request.number }}
          comment-author: github-actions[bot]
          body-includes: <!-- /merge info comment -->
          direction: last

        # Only update the comment if there's a tail. This prevents the
        # tail from being replaced due to multiple /merge calls.
      - if: >-
          steps.pr-data.outputs.run
          && !(steps.find-comment.outputs.comment-id
            && steps.pr-data.outputs.body-tail == '')
        name: Create or update informational comment
        uses: peter-evans/create-or-update-comment@v4
        with:
          comment-id: ${{ steps.find-comment.outputs.comment-id }}
          issue-number: ${{ github.event.client_payload.pull_request.number }}
          body: |
            <!-- /merge info comment -->
            <!-- Autogenerated by merge-command. DO NOT EDIT -->
            Merge requested by: @${{ github.event.client_payload.github.payload.comment.user.login }}

            Contents after the first section break of the PR description has been removed and preserved below:

            ---

            <blockquote>
            ${{ steps.pr-data.outputs.body-tail }}
            </blockquote>
          edit-mode: replace

      - if: steps.pr-data.outputs.run && steps.pr-data.outputs.update-body
        name: Update PR description
        env:
          PR_URL: ${{ github.event.client_payload.pull_request.html_url }}
          NEW_PR_BODY: ${{ steps.pr-data.outputs.body }}
          GH_TOKEN: ${{ github.token }}
        run: gh pr edit "$PR_URL" --body "$NEW_PR_BODY"

        # An app token is required for CI to trigger
      - if: steps.pr-data.outputs.run
        id: token
        name: Create app token for merges
        uses: actions/create-github-app-token@v1
        with:
          app-id: ${{ secrets.CHORE_APP_ID }}
          private-key: ${{ secrets.CHORE_APP_KEY }}

        # TODO: Switch to GitHub CLI once
        # https://github.com/cli/cli/issues/7213 is solved.
      - if: steps.pr-data.outputs.run
        name: Queue for merging
        uses: actions/github-script@v7
        with:
          script: |
            const pull_id = context.payload.client_payload.pull_request.node_id;
            const queue = `mutation ($input: EnablePullRequestAutoMergeInput!) {
              enablePullRequestAutoMerge(input: $input) {
                clientMutationId
              }
            }`;

            await github.graphql(queue, {
              input: {
                pullRequestId: pull_id
              }
            });
          github-token: ${{ steps.token.outputs.token }}