draft-release.yml

name: Draft Release

on:
  workflow_dispatch:
    inputs:
      branch:
        description: "Branch to release from"
        required: false
        default: "main"
        type: string
      tag:
        description: "New tag (default: 'v' + version from pyproject.toml)"
        required: false
        type: string

permissions:
  contents: write

jobs:
  draft-release:
    runs-on: ubuntu-latest
    steps:
      - name: Checkout repo
        uses: actions/checkout@v4
        with:
          ref: ${{ inputs.branch }}
          fetch-depth: 0
          fetch-tags: true

      - name: Resolve tags and target SHA
        id: vars
        env:
          INPUT_TAG: ${{ inputs.tag }}
        run: |
          set -euo pipefail
          TARGET_SHA=$(git rev-parse HEAD)
          if ! PREV_TAG=$(git describe --tags --abbrev=0 2>/dev/null); then
            echo "::error::No previous tag found in history; cannot auto-bump. Pass 'tag' input explicitly."
            exit 1
          fi

          if [ -n "$INPUT_TAG" ]; then
            NEW_TAG="$INPUT_TAG"
          else
            VERSION=$(grep -E '^version[[:space:]]*=[[:space:]]*"' pyproject.toml | head -1 | sed -E 's/^version[[:space:]]*=[[:space:]]*"([^"]+)".*/\1/')
            if [ -z "$VERSION" ]; then
              echo "::error::Could not read version from pyproject.toml. Pass 'tag' input explicitly."
              exit 1
            fi
            NEW_TAG="v${VERSION}"
          fi

          if [ "$NEW_TAG" = "$PREV_TAG" ]; then
            echo "::error::New tag ($NEW_TAG) matches the latest existing tag ($PREV_TAG). Bump the version in pyproject.toml (or pass an explicit 'tag') before drafting a release."
            exit 1
          fi

          echo "Previous tag: $PREV_TAG"
          echo "New tag:      $NEW_TAG"
          echo "Target SHA:   $TARGET_SHA"
          {
            echo "PREV_TAG=$PREV_TAG"
            echo "NEW_TAG=$NEW_TAG"
            echo "TARGET_SHA=$TARGET_SHA"
          } >> "$GITHUB_OUTPUT"

      - name: Generate release notes
        env:
          PREV_TAG: ${{ steps.vars.outputs.PREV_TAG }}
        run: |
          set -euo pipefail
          {
            echo "# Changelog"
            git log --reverse --no-merges --pretty=format:"* %s (%H)" "${PREV_TAG}..HEAD" \
              | sed -E 's/ \(#[0-9]+\)( \([0-9a-f]{40}\))$/\1/'
          } > release-notes.md
          echo "::group::Generated release notes"
          cat release-notes.md
          echo "::endgroup::"

      - name: Create draft release
        env:
          GH_TOKEN: ${{ github.token }}
          NEW_TAG: ${{ steps.vars.outputs.NEW_TAG }}
          TARGET_SHA: ${{ steps.vars.outputs.TARGET_SHA }}
        run: |
          set -euo pipefail
          gh release create "$NEW_TAG" \
            --draft \
            --title "$NEW_TAG" \
            --target "$TARGET_SHA" \
            --notes-file release-notes.md