name: get-go-version

on:
  workflow_call:
    outputs:
      go-version:
        description: "The Go version detected by this workflow"
        value: ${{ jobs.get-go-version.outputs.go-version }}
      go-version-previous:
        description: "The Go version (MAJOR.MINOR) prior to the current one, used for backwards compatibility testing"
        value: ${{ jobs.get-go-version.outputs.go-version-previous }}

jobs:
  get-go-version:
    name: "Determine Go toolchain version"
    runs-on: ubuntu-latest
    outputs:
      go-version: ${{ steps.get-go-version.outputs.go-version }}
      go-version-previous: ${{ steps.get-go-version.outputs.go-version-previous }}
    steps:
      - uses: actions/checkout@0ad4b8fadaa221de15dcec353f45205ec38ea70b # v4.1.4
      - name: Determine Go version
        id: get-go-version
        # We use .go-version as our source of truth for current Go
        # version, because "goenv" can react to it automatically.
        #
        # In the future, we can transition from .go-version and goenv to
        # Go 1.21 `toolchain` directives by updating this workflow rather
        # than individually setting `go-version-file` in each `setup-go`
        # job (as of 2024-01-03, `setup-go` does not support `toolchain`).
        #
        # When changing the method of Go version detection, also update
        # GOLANG_VERSION detection in the root Makefile; this is used for
        # setting the Dockerfile Go version.
        run: |
          GO_VERSION=$(head -n 1 .go-version)
          echo "Building with Go ${GO_VERSION}"
          echo "go-version=${GO_VERSION}" >> $GITHUB_OUTPUT
          GO_MINOR_VERSION=${GO_VERSION%.*}
          GO_VERSION_PREVIOUS="${GO_MINOR_VERSION%.*}.$((${GO_MINOR_VERSION#*.}-1))"
          echo "Previous version ${GO_VERSION_PREVIOUS}"
          echo "go-version-previous=${GO_VERSION_PREVIOUS}" >> $GITHUB_OUTPUT