name: "Prune Renovate Branches"

on:
  workflow_dispatch:
  schedule:
    - cron: '0 3 * * *'   # daily at 03:00 UTC

permissions:
  contents: write       # required to delete branch refs
  pull-requests: read

jobs:
  prune:
    runs-on: ubuntu-latest
    concurrency:
      group: prune-renovate-branches
      cancel-in-progress: true

    env:
      BRANCH_PREFIX: "renovate/"  # adjust if you use a different prefix

    steps:
      - name: Choose GitHub Token
        run: |
          if [ -n "${{ secrets.GITHUB_TOKEN }}" ]; then
            echo "Using GITHUB_TOKEN" >&2
            echo "GITHUB_TOKEN=${{ secrets.GITHUB_TOKEN }}" >> "$GITHUB_ENV"
          else
            echo "Using CHARON_TOKEN fallback" >&2
            echo "GITHUB_TOKEN=${{ secrets.CHARON_TOKEN }}" >> "$GITHUB_ENV"
          fi
      - name: Prune renovate branches
        uses: actions/github-script@3a2844b7e9c422d3c10d287c895573f7108da1b3 # v9
        with:
          github-token: ${{ env.GITHUB_TOKEN }}
          script: |
            const owner = context.repo.owner;
            const repo = context.repo.repo;
            const branchPrefix = (process.env.BRANCH_PREFIX || 'renovate/').replace(/^refs\/heads\//, '');
            const refPrefix = `heads/${branchPrefix}`; // e.g. "heads/renovate/"

            core.info(`Searching for refs with prefix: ${refPrefix}`);

            // List matching refs (branches) under the prefix
            let refs;
            try {
              refs = await github.rest.git.listMatchingRefs({
                owner,
                repo,
                ref: refPrefix
              });
            } catch (err) {
              core.info(`No matching refs or API error: ${err.message}`);
              refs = { data: [] };
            }

            for (const r of refs.data) {
              const fullRef = r.ref; // "refs/heads/renovate/..."
              const branchName = fullRef.replace('refs/heads/', '');
              core.info(`Evaluating branch: ${branchName}`);

              // Find PRs for this branch (head = "owner:branch")
              const prs = await github.rest.pulls.list({
                owner,
                repo,
                head: `${owner}:${branchName}`,
                state: 'all',
                per_page: 100
              });

              let shouldDelete = false;
              if (!prs.data || prs.data.length === 0) {
                core.info(`No PRs found for ${branchName} — marking for deletion.`);
                shouldDelete = true;
              } else {
                // If none of the PRs are open, safe to delete
                const hasOpen = prs.data.some(p => p.state === 'open');
                if (!hasOpen) {
                  core.info(`All PRs for ${branchName} are closed — marking for deletion.`);
                  shouldDelete = true;
                } else {
                  core.info(`Open PR(s) exist for ${branchName} — skipping deletion.`);
                }
              }

              if (shouldDelete) {
                try {
                  await github.rest.git.deleteRef({
                    owner,
                    repo,
                    ref: `heads/${branchName}`
                  });
                  core.info(`Deleted branch: ${branchName}`);
                } catch (delErr) {
                  core.warning(`Failed to delete ${branchName}: ${delErr.message}`);
                }
              }
            }

      - name: Done
        run: echo "Prune run completed."