action.yml

name: Calculate the next incremental tag
description: |
  Action to calculate a lightweight incremental tag.
  
  Tag has specific format - `vYYYY.WW.INC` where:
    - YYYY - current year
    - WW - current week number
    - INC - incremental number to have unique tag names within a week
outputs:
  tag:
    description: "The calculated tag"
    value: ${{ steps.calculate_tag.outputs.tag }}
runs:
  using: "composite"
  steps:
    - name: Calculate tag
      id: calculate_tag
      shell: bash
      run: |
        tag_prefix="$(date +"v%G.%V.")"
        previous_version="$(git tag -l "${tag_prefix}*" --merged | cut -d. -f3 | sort -h | tail -n1 | grep '^[0-9]\+$' || echo '0')"
        version_number=$((previous_version + 1))
        tag="$tag_prefix$version_number"
        exists="$(git tag -l "$tag")"
        if [[ "$tag" == "$exists" ]]; then
          echo "Tag $tag already exists; skipping tag creation"
          exit 1
        fi
        echo tag="$tag" >> "$GITHUB_OUTPUT"