sync-labels.yml

name: Sync Labels from Issue to PR

on:
  pull_request:
    types: [edited, opened, reopened]

permissions:
  pull-requests: write

jobs:
  sync-labels:
    runs-on: ubuntu-latest
    steps:
      - name: Get associated issue number
        id: get_issue_number
        run: |
          ISSUE_NUMBERS=$(echo "${{ github.event.pull_request.body }}" | grep -oE "#[0-9]+" | tr -d "#" | tr '\n' ',')
          ISSUE_NUMBERS=$(echo $ISSUE_NUMBERS | sed 's/,$//')
          echo "ISSUE_NUMBERS=$ISSUE_NUMBERS" >> $GITHUB_ENV
          echo "Issue numbers are $ISSUE_NUMBERS"

      - name: Get labels from issue
        uses: actions/github-script@60a0d83039c74a4aee543508d2ffcb1c3799cdea #v7
        id: get_issue_labels
        with:
          script: |
            const issueNumbers = process.env.ISSUE_NUMBERS.split(",");
            let allLabels = new Set();
            for (const issueNumber of issueNumbers) {
              try {
                const { data: { labels } } = await github.rest.issues.get({
                  issue_number: issueNumber,
                  owner: context.repo.owner,
                  repo: context.repo.repo,
                });
                labels.forEach(label => allLabels.add(label.name));
              } catch (error) {
                console.error(`Error fetching labels for issue #${issueNumber}: `, error);
              }
            }
            if (allLabels.size === 0) {
              core.setOutput('labels', '');
            } else {
              const sortedLabels = Array.from(allLabels).sort().join(",");
              core.setOutput('labels', sortedLabels);
            }

      - name: Check if labels are the same
        id: check_labels_are_same
        uses: actions/github-script@60a0d83039c74a4aee543508d2ffcb1c3799cdea #v7
        with:
          script: |
            const issueLabels = "${{ steps.get_issue_labels.outputs.labels }}";
            const prLabels = await github.rest.issues.listLabelsOnIssue({
              owner: context.repo.owner,
              repo: context.repo.repo,
              issue_number: context.issue.number,
            });
            const prLabelsNames = prLabels.data.map(label => label.name).sort();
            const isSame = issueLabels === prLabelsNames.join(",");
            core.setOutput('isSame', isSame.toString());
            core.setOutput('labels', issueLabels);

      - name: Apply labels to PR
        if: steps.check_labels_are_same.outputs.isSame == 'false'
        uses: actions/github-script@60a0d83039c74a4aee543508d2ffcb1c3799cdea #v7
        with:
          script: |
            const isSame = "${{ steps.check_labels_are_same.outputs.isSame }}";
            const labels = "${{ steps.check_labels_are_same.outputs.labels }}" === "" ? [] : "${{ steps.check_labels_are_same.outputs.labels }}".split(",");
            const owner = context.repo.owner;
            const repo = context.repo.repo;
            const issue_number = context.issue.number;

            if (labels.length === 0) {
              const prLabels = await github.rest.issues.listLabelsOnIssue({
                owner: owner,
                repo: repo,
                issue_number: issue_number,
              });
              for (const label of prLabels.data) {
                await github.rest.issues.removeLabel({
                  owner: owner,
                  repo: repo,
                  issue_number: issue_number,
                  name: label.name,
                });
              }
            } else {
              await github.rest.issues.setLabels({
                owner: owner,
                repo: repo,
                issue_number: issue_number,
                labels: labels,
              });
            }