combine-prs.yaml

name: ci-combineprs

run-name: combine-prs [ ${{ inputs.branchPrefix }} ]

on:
  workflow_dispatch:
    inputs:
      branchPrefix:
        description: 'Branch prefix to find combinable PRs based on (ie, dependabot/ compose/ feat/ fix/ other)'
        required: true
        type: string
        default: 'dependabot/'
      mustBeGreen:
        description: 'Combine PRs that are green? (dependabot context.status is unreachable so set to false)'
        required: true
        type: boolean
        default: false
      combineBranchName:
        description: 'Name of the branch to combine PRs into'
        required: true
        default: 'combined-pr'
      ignoreLabel:
        description: 'Exclude PRs with this label'
        required: true
        default: 'nocombine'

jobs:

  combine-prs:

    runs-on: ubuntu-22.04
    permissions:
      contents: write
      pull-requests: write

    steps:
      - uses: actions/github-script@v6 # v7 needs testing
        id: fetch-branch-names
        name: fetch-branch-names
        with:
          github-token: ${{ secrets.GITHUB_TOKEN }}
          script: |
            const pulls = await github.paginate('GET /repos/:owner/:repo/pulls', {
              owner: context.repo.owner,
              repo: context.repo.repo
            });
            branches = [];
            prs = [];
            base_branch = null;
            for (const pull of pulls) {
              const branch = pull['head']['ref'];
              console.log('Pull for branch: ' + branch);
              if (branch.startsWith('${{ github.event.inputs.branchPrefix }}')) {
                console.log('Branch matched: ' + branch);
                statusOK = true;
                if(${{ github.event.inputs.mustBeGreen }}) {
                  console.log('Checking green status: ' + branch);
                  const statuses = await github.paginate('GET /repos/{owner}/{repo}/commits/{ref}/status', {
                    owner: context.repo.owner,
                    repo: context.repo.repo,
                    ref: branch
                  });
                  if(statuses.length > 0) {
                    const latest_status = statuses[0]['state'];
                    console.log('Validating status: ' + latest_status);
                    if(latest_status != 'success') {
                      console.log('Discarding ' + branch + ' with status ' + latest_status);
                      statusOK = false;
                    }
                  }
                }
                console.log('Checking labels: ' + branch);
                const labels = pull['labels'];
                for(const label of labels) {
                  const labelName = label['name'];
                  console.log('Checking label: ' + labelName);
                  if(labelName == '${{ github.event.inputs.ignoreLabel }}') {
                    console.log('Discarding ' + branch + ' with label ' + labelName);
                    statusOK = false;
                  }
                }
                if (statusOK) {
                  console.log('Adding branch to array: ' + branch);
                  branches.push(branch);
                  prs.push('#' + pull['number'] + ' ' + pull['title']);
                  base_branch = pull['base']['ref'];
                }
              }
            }

            if (branches.length == 0) {
              core.setFailed('No PRs/branches matched criteria');
              return;
            }

            core.setOutput('base-branch', base_branch);
            core.setOutput('prs-string', prs.join('\n'));
            
            combined = branches.join(' ')
            console.log('Combined: ' + combined);
            return combined

      - uses: actions/checkout@d632683dd7b4114ad314bca15554477dd762a938 # v4.2.0
        with:
          ref: ${{ steps.fetch-branch-names.outputs.base-branch }}
          fetch-depth: 0

      - name: create-combined-branch
        env:
          BASE_BRANCH: ${{ steps.fetch-branch-names.outputs.base-branch }}
          BRANCHES_TO_COMBINE: ${{ steps.fetch-branch-names.outputs.result }}
          COMBINE_BRANCH_NAME: ${{ github.event.inputs.combineBranchName }}
        run: |
          echo "Branches to combine: $BRANCHES_TO_COMBINE"

          sourcebranches="${BRANCHES_TO_COMBINE%\"}"
          sourcebranches="${sourcebranches#\"}"
          
          basebranch="${BASE_BRANCH%\"}"
          basebranch="${basebranch#\"}"

          git config pull.rebase false
          git config user.name github-actions
          git config user.email github-actions@github.com

          git branch $COMBINE_BRANCH_NAME $basebranch
          git checkout $COMBINE_BRANCH_NAME

          # merge all branches into the new branch
          git pull origin $sourcebranches --no-edit

          # push the new branch to the remote
          git push origin $COMBINE_BRANCH_NAME

      - uses: actions/github-script@v4 # v5-v6 have pulls.create problems that I couldn't resolve, have not tested v7 yet
        name: create-combined-pr
        env:
          PRS_STRING: ${{ steps.fetch-branch-names.outputs.prs-string }}
        with:
          github-token: ${{ secrets.GITHUB_TOKEN }}
          script: |
            const prString = process.env.PRS_STRING;
            const body = 'This PR was created by the Combine PRs action by combining the following PRs:\n' + prString;
            await github.pulls.create({
              owner: context.repo.owner,
              repo: context.repo.repo,
              title: 'Combined PR [${{ github.event.inputs.branchPrefix }}*]',
              head: '${{ github.event.inputs.combineBranchName }}',
              base: '${{ steps.fetch-branch-names.outputs.base-branch }}',
              body: body
            });