prepare-release-branch.yml

name: Prepare release branch
on:
  workflow_dispatch:
    inputs:
      prerelease_version:
        description: "Pre-release version number? (e.g. 1.9.0rc2)"
        required: False

jobs:
  prereqs:
    environment: GITHUB
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4

      - name: Install toml
        run: pip install toml

      - name: Verify prerequisites
        env:
          PRERELEASE_VERSION: ${{ github.event.inputs.prerelease_version }}
        run: |
          if [[ $GITHUB_REF_NAME != main ]]; then
            echo this workflow should only be run against main
            exit 1
          fi
          
          if ! grep --quiet "^## Unreleased$" CHANGELOG.md; then
            echo the change log is missing an \"Unreleased\" section
            exit 1
          fi
          chmod +x ./.github/scripts/get-version.sh
          if [[ ! -z $PRERELEASE_VERSION ]]; then
            stable_version=$(./.github/scripts/get-version.sh)
            if [[ $PRERELEASE_VERSION != ${stable_version}* ]]; then
              echo "$PRERELEASE_VERSION is not a prerelease for the version on main ($stable_version)"
              exit 1
            fi
          fi

  create-pull-request-against-release-branch:
    environment: GITHUB
    runs-on: ubuntu-latest
    needs: prereqs
    steps:
      - uses: actions/checkout@v4
      - name: Install toml
        run: pip install toml
      - name: Create release branch
        env:
          PRERELEASE_VERSION: ${{ github.event.inputs.prerelease_version }}
        run: |

          if [[ -z $PRERELEASE_VERSION ]]; then
            stable_version=$(./.github/scripts/get-version.sh)
          else
            stable_version=$PRERELEASE_VERSION
          fi


          if [[ $stable_version =~ ^([0-9]+)\.([0-9]+)\.0$ ]]; then
            stable_version_branch_part=$(echo $stable_version | sed -E 's/([0-9]+)\.([0-9]+)\.0/\1.\2.0/')
            release_branch_name="release/v${stable_version_branch_part}"
          elif [[ $stable_version =~ ^([0-9]+)\.([0-9]+)\.0 ]]; then
            # pre-release version, e.g. 1.9.0rc2
            release_branch_name="release/v$stable_version"
          else
            echo "unexpected version: $stable_version"
            exit 1
          fi
          git push origin HEAD:$release_branch_name

          echo "STABLE_VERSION=$stable_version" >> $GITHUB_ENV
          echo "RELEASE_BRANCH_NAME=$release_branch_name" >> $GITHUB_ENV

      - name: Update the change log with the approximate release date
        run: |
          date=$(date "+%Y-%m-%d")
          sed -Ei "s/^## Unreleased$/## Version ${STABLE_VERSION} ($date)/" CHANGELOG.md

      - name: Create pull request against the release branch
        env:
          PRERELEASE_VERSION: ${{ github.event.inputs.prerelease_version }}
          USER_EMAIL: ${{ secrets.GIT_USER_EMAIL }}
          USER_NAME: ${{ secrets.GIT_USER_NAME }}
          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
        run: |
          message="Prepare release ${STABLE_VERSION}"
          branch="monocle/prepare-release-${STABLE_VERSION}"
          git config --global user.email "$USER_EMAIL"
          git config --global user.name "$USER_NAME"
          git commit -a -m "$message"
          git push origin HEAD:$branch
          gh pr create --title "[$RELEASE_BRANCH_NAME] $message" \
                       --body "$message." \
                       --head $branch \
                       --base $RELEASE_BRANCH_NAME

  create-pull-request-against-main:
    environment: GITHUB
    runs-on: ubuntu-latest
    needs: [prereqs, create-pull-request-against-release-branch]
    steps:
      - uses: actions/checkout@v4

      - name: Install toml
        run: pip install toml

      - name: Set environment variables
        env:
          PRERELEASE_VERSION: ${{ github.event.inputs.prerelease_version }}
        run: |

          if [[ -z $PRERELEASE_VERSION ]]; then
            stable_version=$(./.github/scripts/get-version.sh)
          else
            stable_version=$PRERELEASE_VERSION
          fi

          if [[ $stable_version =~ ^([0-9]+)\.([0-9]+)\.0$ ]]; then
            stable_major="${BASH_REMATCH[1]}"
            stable_minor="${BASH_REMATCH[2]}"
            stable_next_version="$stable_major.$((stable_minor + 1)).0"
          elif [[ $stable_version =~ ^([0-9]+)\.([0-9]+)\.0 ]]; then
            # pre-release version, e.g. 1.9.0rc2
            stable_major="${BASH_REMATCH[1]}"
            stable_minor="${BASH_REMATCH[2]}"
            stable_next_version="$stable_major.$stable_minor.0"
          else
            echo "unexpected stable_version: $stable_version"
            exit 1
          fi

          echo "STABLE_VERSION=${stable_version}" >> $GITHUB_ENV
          echo "STABLE_NEXT_VERSION=${stable_next_version}" >> $GITHUB_ENV

      - name: Update version
        run: |
          chmod +x ./.github/scripts/update-version.sh
          .github/scripts/update-version.sh $STABLE_NEXT_VERSION

      - name: Update the change log on main
        run: |
          # the actual release date on main will be updated at the end of the release workflow
          date=$(date "+%Y-%m-%d")
          sed -Ei "s/^## Unreleased$/## Version ${STABLE_VERSION} ($date)/" CHANGELOG.md

      - name: Create pull request against main
        env:
          PRERELEASE_VERSION: ${{ github.event.inputs.prerelease_version }}
          USER_EMAIL: ${{ secrets.GIT_USER_EMAIL }}
          USER_NAME: ${{ secrets.GIT_USER_NAME }}
          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
        run: |
          message="Update version to ${STABLE_NEXT_VERSION}"
          body="Update version to ${STABLE_NEXT_VERSION}."
          branch="monocle/update-version-to-${STABLE_NEXT_VERSION}"
          git config --global user.email "$USER_EMAIL"
          git config --global user.name "$USER_NAME"
          git commit -a -m "$message"
          git push origin HEAD:$branch
          gh pr create --title "$message" \
                       --body "$body" \
                       --head $branch \
                       --base main