name: Update Editors Picks

on:
    push:
        branches: [main]
        paths:
            - 'editors-picks-input.txt'

jobs:
    update:
        runs-on: ubuntu-latest
        permissions:
            contents: write

        steps:
            - name: Checkout
              uses: actions/checkout@v4
              with:
                  fetch-depth: 1

            - name: Check for backoff condition
              id: backoff
              run: |
                  CHANGED=$(git diff-tree --no-commit-id -r --name-only HEAD)
                  echo "Files changed in this commit:"
                  echo "$CHANGED"
                  if echo "$CHANGED" | grep -qE '^public/editors-picks\.json$|^public/editors-picks-old/'; then
                    echo "Detected changes to generated files in this commit — backing off to avoid overwriting manual edits."
                    echo "skip=true" >> "$GITHUB_OUTPUT"
                  else
                    echo "skip=false" >> "$GITHUB_OUTPUT"
                  fi

            - name: Setup Python
              if: steps.backoff.outputs.skip == 'false'
              uses: actions/setup-python@v5
              with:
                  python-version: '3.x'

            - name: Archive current editors picks
              if: steps.backoff.outputs.skip == 'false'
              run: |
                  python3 - << 'EOF'
                  import json, re
                  from datetime import date

                  today = date.today()
                  # Filename uses non-padded month/day to match existing convention
                  filename = f"{today.year}-{today.month}-{today.day}.json"
                  # Date field uses ISO format (zero-padded)
                  iso_date = today.strftime("%Y-%m-%d")
                  archive_path = f"public/editors-picks-old/{filename}"

                  # Read optional label from input file
                  label = iso_date
                  with open("editors-picks-input.txt") as f:
                      for line in f:
                          m = re.match(r"^#\s*label:\s*(.+)", line.strip())
                          if m:
                              label = m.group(1).strip()
                              break

                  # Copy current picks to archive
                  with open("public/editors-picks.json") as f:
                      current = json.load(f)
                  with open(archive_path, "w") as f:
                      json.dump(current, f, indent=4)

                  # Prepend to index so newest archived version appears first
                  with open("public/editors-picks-old/index.json") as f:
                      index = json.load(f)
                  index.insert(0, {
                      "file": filename,
                      "label": label,
                      "date": iso_date,
                  })
                  with open("public/editors-picks-old/index.json", "w") as f:
                      json.dump(index, f, indent=4)

                  print(f"Archived to {archive_path} with label '{label}'")
                  EOF

            - name: Generate new editors picks
              if: steps.backoff.outputs.skip == 'false'
              run: python3 gen-editors-picks.py

            - name: Commit and push
              if: steps.backoff.outputs.skip == 'false'
              run: |
                  git config user.name "github-actions[bot]"
                  git config user.email "github-actions[bot]@users.noreply.github.com"
                  git add public/editors-picks.json public/editors-picks-old/
                  git diff --staged --quiet && echo "No changes to commit." && exit 0
                  git commit -m "chore: update editors picks [skip ci]"
                  git push