version.yaml

---
# This workflow runs when PRs labeled `major`, `minor`, or `patch` are closed
# and increments version numbers. Then, it opens a PR labeled `release` for the
# changes. When that PR is merged, a release is created (see `release.yaml`).
#
# Are you here because I left Mercury and now my personal access token is
# invalid for workflows, breaking CI? You'll want to go to
#     https://github.com/MercuryTechnologies/nix-your-shell/settings/secrets/actions
# and update the `REPO_GITHUB_TOKEN` secret to a new, valid token.

on:
  pull_request_target:
    types:
      - closed
    branches:
      - main

name: Update versions and create release PR

jobs:
  # We make `if_merged` a `needs:` of the other jobs here to only run this
  # workflow on merged PRs.
  if_merged:
    name: Check that PR was merged and not closed
    if: github.event.pull_request.merged == true
      && ( contains(github.event.pull_request.labels.*.name, 'major')
        || contains(github.event.pull_request.labels.*.name, 'minor')
        || contains(github.event.pull_request.labels.*.name, 'patch')
      )
    runs-on: ubuntu-latest
    steps:
      - run: |
          echo "This is a canonical hack to run GitHub Actions on merged PRs"
          echo "See: https://docs.github.com/en/actions/using-workflows/events-that-trigger-workflows#running-your-pull_request-workflow-when-a-pull-request-merges"

  bump_type:
    name: Determine version bump type
    needs: if_merged
    runs-on: ubuntu-latest
    outputs:
      bump_type: ${{ steps.bump_type.outputs.bump_type }}
    steps:
      - name: Set output
        id: bump_type
        env:
          is_major: ${{ contains(github.event.pull_request.labels.*.name, 'major') }}
          is_minor: ${{ contains(github.event.pull_request.labels.*.name, 'minor') }}
          is_patch: ${{ contains(github.event.pull_request.labels.*.name, 'patch') }}
        run: |
          if [[ "$is_major" == "true" ]]; then
            echo "bump_type=major" >> "$GITHUB_OUTPUT"
          elif [[ "$is_minor" == "true" ]]; then
            echo "bump_type=minor" >> "$GITHUB_OUTPUT"
          elif [[ "$is_patch" == "true" ]]; then
            echo "bump_type=patch" >> "$GITHUB_OUTPUT"
          fi

  version:
    name: Bump version and create release PR
    permissions:
      pull-requests: write
    needs:
      - if_merged
      - bump_type
    runs-on: ubuntu-latest
    steps:
      - name: Checkout
        uses: actions/checkout@v3
        with:
          # Fetch all history/tags (needed to compute versions)
          fetch-depth: 0

      - uses: cachix/install-nix-action@v22
        with:
          github_access_token: ${{ secrets.GITHUB_TOKEN }}
          extra_nix_config: |
            extra-experimental-features = nix-command flakes
            accept-flake-config = true

      - name: Get old version number
        id: old_cargo_metadata
        run: echo "version=$(nix run .#get-crate-version)" >> "$GITHUB_OUTPUT"

      - name: Increment `Cargo.toml` version
        run: nix run .#make-release-commit -- ${{ needs.bump_type.outputs.bump_type }}

      - name: Get new version number
        id: new_cargo_metadata
        run: echo "version=$(nix run .#get-crate-version)" >> "$GITHUB_OUTPUT"

      - name: Create release PR
        id: release_pr
        uses: peter-evans/create-pull-request@v5
        with:
          # We push with the repo-scoped GitHub token to avoid branch
          # protections. This token is tied to my account (@9999years) which is
          # excluded from branch protection restrictions.
          #
          # I'd love a better way of implementing this but GitHub doesn't have
          # one: https://github.com/github-community/community/discussions/13836
          token: ${{ secrets.REPO_GITHUB_TOKEN }}
          branch: release/${{ steps.new_cargo_metadata.outputs.version }}
          delete-branch: true
          base: main
          title: Release version ${{ steps.new_cargo_metadata.outputs.version }}
          body: |
            Update version to ${{ steps.new_cargo_metadata.outputs.version }} with [cargo-release](https://github.com/crate-ci/cargo-release).
            Merge this PR to build and publish a new release.
          labels: release

      - name: Comment on PR with link to release PR
        uses: peter-evans/create-or-update-comment@v3
        with:
          issue-number: ${{ github.event.pull_request.number }}
          body: |
            [A PR to release these changes has been created, bumping the version from ${{ steps.old_cargo_metadata.outputs.version }} to ${{ steps.new_cargo_metadata.outputs.version }}.][pr]

            [pr]: ${{ steps.release_pr.outputs.pull-request-url }}