semver-version.yml

# Reusable workflow that works out the version a pull request releases from its semver label (major,
# minor or patch): on a pull request, the pre-release X.Y.Z-PRE-<number>, asking for the label when
# it is missing; on a push to the main branch, X.Y.Z from the label of the merged pull request. See
# README.md for how to call it.
name: Semver version

on:
  workflow_call:
    inputs:
      tag-prefix:
        description: Text the release tags start with (default v); empty for tags like 1.2.3
        type: string
        default: v
    outputs:
      version:
        description: X.Y.Z on a push, X.Y.Z-PRE-<pull request number> on a pull request
        value: ${{ jobs.version.outputs.version }}
      bump:
        description: major, minor or patch, from the label
        value: ${{ jobs.version.outputs.bump }}

jobs:
  version:
    name: Semver version
    runs-on: ubuntu-latest
    permissions:
      contents: read
      pull-requests: write
    outputs:
      version: ${{ steps.version.outputs.version }}
      bump: ${{ steps.label.outputs.bump }}
    steps:
      # all the tags, to find the latest release
      - name: Check out the repository
        uses: actions/checkout@08c6903cd8c0fde910a37f88322edcfb5dd907a8 # v5.0.0
        with:
          fetch-depth: 0
          path: repo
          persist-credentials: false

      # the script from the same commit as this workflow, not from the caller's repository
      - name: Locate this workflow
        env:
          WORKFLOW_REPOSITORY: ${{ job.workflow_repository }}
          WORKFLOW_SHA: ${{ job.workflow_sha }}
        run: |
          if [ -z "$WORKFLOW_REPOSITORY" ] || [ -z "$WORKFLOW_SHA" ]; then
            echo "::error::job.workflow_repository and job.workflow_sha are empty: this workflow has to run as a reusable workflow on github.com"
            exit 1
          fi
          echo "Using $WORKFLOW_REPOSITORY@$WORKFLOW_SHA"

      - name: Check out the version script
        uses: actions/checkout@08c6903cd8c0fde910a37f88322edcfb5dd907a8 # v5.0.0
        with:
          repository: ${{ job.workflow_repository }}
          ref: ${{ job.workflow_sha }}
          path: semver-workflows
          persist-credentials: false

      # On a pull request, the labels it has now, not the ones of the event that started the run (see
      # chart-pr.yml). On a push, the labels of the pull request the pushed commit was merged from.
      - name: Read the semver label
        id: label
        env:
          GH_TOKEN: ${{ github.token }}
          EVENT: ${{ github.event_name }}
          PR: ${{ github.event.pull_request.number }}
          SHA: ${{ github.sha }}
        run: |
          if [ "$EVENT" = pull_request ]; then
            labels=$(gh api "repos/$GITHUB_REPOSITORY/pulls/$PR" --jq '[.labels[].name]')
          else
            pr=$(gh api "repos/$GITHUB_REPOSITORY/commits/$SHA/pulls" \
              --jq '[.[] | select(.merged_at != null)][0] // empty | {number, labels: [.labels[].name]}')
            if [ -z "$pr" ]; then
              echo "::error::No merged pull request contains $SHA, so there is no semver label to release it with"
              exit 1
            fi
            echo "Releasing pull request #$(jq -r .number <<< "$pr")"
            labels=$(jq -c .labels <<< "$pr")
          fi
          bumps=$(jq -r '[.[] | select(. == "major" or . == "minor" or . == "patch")] | join(" ")' <<< "$labels")
          if [ "$(wc -w <<< "$bumps")" -ne 1 ]; then
            echo "::error::The pull request needs exactly one of the labels major, minor or patch (found: ${bumps:-none})"
            exit 1
          fi
          echo "bump=$bumps" >> "$GITHUB_OUTPUT"

      - name: Ask for the label
        if: failure() && steps.label.outcome == 'failure' && github.event_name == 'pull_request'
        env:
          GH_TOKEN: ${{ github.token }}
          PR: ${{ github.event.pull_request.number }}
        run: |
          gh pr comment "$PR" --repo "$GITHUB_REPOSITORY" \
            --body "Please apply exactly one of the following labels to the PR: 'patch', 'minor', 'major'." \
            || echo "::warning::Could not comment on the pull request"

      - name: Work out the version
        id: version
        working-directory: repo
        env:
          BUMP: ${{ steps.label.outputs.bump }}
          TAG_PREFIX: ${{ inputs.tag-prefix }}
          EVENT: ${{ github.event_name }}
          PR: ${{ github.event.pull_request.number }}
        run: |
          version=$(../semver-workflows/scripts/next-version.sh)
          if [ "$EVENT" = pull_request ]; then
            version="$version-PRE-$PR"
          fi
          echo "version=$version" >> "$GITHUB_OUTPUT"
          echo "Version: $version"