name: Label PRs needing rebase

on:
  push:
    branches: [main]

concurrency:
  group: label-rebase-prs
  cancel-in-progress: true

jobs:
  label-conflicting-prs:
    environment: ai-bots
    runs-on: ubuntu-latest
    steps:
      - uses: actions/github-script@v7
        with:
          github-token: ${{ secrets.PR_RW_GITHUB_TOKEN }}
          script: |
            const allowedAuthors = ['wwwillchen', 'wwwillchen-bot'];

            const prs = await github.paginate(github.rest.pulls.list, {
              owner: context.repo.owner,
              repo: context.repo.repo,
              state: 'open',
            });

            for (const pr of prs) {
              try {
                if (!allowedAuthors.includes(pr.user.login)) continue;
                if (pr.draft) continue;

                // mergeable status requires an individual GET call
                let latest = (await github.rest.pulls.get({
                  owner: context.repo.owner,
                  repo: context.repo.repo,
                  pull_number: pr.number,
                })).data;

                // GitHub may not have computed mergeability yet (null).
                // Retry with exponential backoff.
                if (latest.mergeable === null) {
                  for (let attempt = 0; attempt < 3 && latest.mergeable === null; attempt++) {
                    await new Promise(r => setTimeout(r, 3000 * (attempt + 1)));
                    latest = (await github.rest.pulls.get({
                      owner: context.repo.owner,
                      repo: context.repo.repo,
                      pull_number: pr.number,
                    })).data;
                  }
                  if (latest.mergeable === null) {
                    console.log(`PR #${pr.number}: mergeability still unknown after retries, skipping`);
                    continue;
                  }
                }

                if (latest.mergeable_state === 'dirty') {
                  const labels = latest.labels.map(l => l.name);
                  // Don't add if already labeled, actively rebasing, or previously failed
                  if (labels.includes('cc:rebase') || labels.includes('cc:rebasing') || labels.includes('cc:rebase-failed')) {
                    console.log(`PR #${pr.number} already has rebase label, skipping`);
                    continue;
                  }
                  console.log(`Adding cc:rebase to PR #${pr.number}: ${pr.title}`);
                  await github.rest.issues.addLabels({
                    owner: context.repo.owner,
                    repo: context.repo.repo,
                    issue_number: pr.number,
                    labels: ['cc:rebase'],
                  });
                } else {
                  console.log(`PR #${pr.number} is mergeable (state: ${latest.mergeable_state}), skipping`);
                }
              } catch (err) {
                console.log(`Error processing PR #${pr.number}: ${err.message}`);
              }
            }
