name: Auto Release on Tag

on:
  push:
    tags:
      - 'v*'

permissions:
  contents: write

jobs:
  release:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4
        with:
          fetch-depth: 0
      - name: Extract version from tag
        id: ver
        run: echo "version=${GITHUB_REF#refs/tags/v}" >> $GITHUB_OUTPUT
      - name: Extract CHANGELOG section
        id: notes
        run: |
          set -euo pipefail
          VERSION="${{ steps.ver.outputs.version }}"
          NOTES=/tmp/release-notes.md
          # Extract section for this version from CHANGELOG.md
          # Pattern: "## v${VERSION}" through the next "## " or EOF
          if [ ! -f CHANGELOG.md ]; then
            echo "No CHANGELOG.md found; using minimal release notes"
            # MUST write the file, not just an output: the create step consumes a FILE, so an
            # early exit here used to leave --notes-file pointing at a path that never existed,
            # turning "degrade to minimal notes" into a failed release job (#202).
            echo "Release v${VERSION}" > "$NOTES"
            echo "notes_file=$NOTES" >> $GITHUB_OUTPUT
            exit 0
          fi
          awk -v ver="v${VERSION}" '
            $0 ~ "^## " ver { found=1; print; next }
            found && /^## v/ { exit }
            found { print }
          ' CHANGELOG.md > "$NOTES"
          if [ ! -s "$NOTES" ]; then
            echo "No matching section in CHANGELOG for v${VERSION}; using minimal notes"
            echo "Release v${VERSION}" > "$NOTES"
          fi
          echo "--- release notes (${VERSION}) ---"; cat "$NOTES"
          echo "notes_file=$NOTES" >> $GITHUB_OUTPUT
      - name: Create GitHub Release
        env:
          GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
        run: |
          if gh release view "v${{ steps.ver.outputs.version }}" >/dev/null 2>&1; then
            echo "Release v${{ steps.ver.outputs.version }} already exists — skipping"
            exit 0
          fi
          gh release create "v${{ steps.ver.outputs.version }}" \
            --title "v${{ steps.ver.outputs.version }}" \
            --notes-file "${{ steps.notes.outputs.notes_file }}" \
            --latest