action.yml

name: 'Get Next Version'
description: 'Calculates the next semantic version from GitHub releases'
author: 'Eric Veenendaal'

inputs:
  version-prefix:
    description: 'Prefix for version tags (e.g., v). Leave empty for no prefix.'
    required: false
    default: ''
  bump-type:
    description: 'Which part to bump: major, minor, or patch'
    required: false
    default: 'patch'

outputs:
  next-version:
    description: 'The calculated next version number'
    value: ${{ steps.calculate_version.outputs.next_version }}
  current-version:
    description: 'The current/latest version found (empty if no releases)'
    value: ${{ steps.calculate_version.outputs.current_version }}

runs:
  using: 'composite'
  steps:
    - name: Ensure access to releases
      shell: bash
      run: |
        set -e
        echo "Testing access to GitHub releases..."
        if ! gh release list --limit 1 > /dev/null 2>&1; then
          echo "Error: Unable to access GitHub releases. Ensure the GITHUB_TOKEN has appropriate permissions and the repository has releases enabled." >&2
          exit 1
        fi
        echo "GitHub releases are accessible."
    - id: calculate_version
      shell: bash
      run: |
        set -e
        
        prefix="${{ inputs.version-prefix }}"
        bump_type="${{ inputs.bump-type }}"
        
        echo "Fetching latest release version..."
        
        # Get the latest release tag, handle case when no releases exist
        latest_tag=$(gh release list --limit 1 --json tagName \
          -q '.[0].tagName' 2>/dev/null || echo "")
        
        if [[ -z "$latest_tag" ]]; then
          echo "Error: No tags found. At least one release tag is required to proceed.\nMake sure you set 'fetch-depth: 0' on the actions/checkout step so all tags are available." >&2
          exit 1
        elif [[ $latest_tag =~ ^${prefix}([0-9]+)\.([0-9]+)\.([0-9]+)$ ]]; then
          # Parse semantic version (with or without prefix)
          major=${BASH_REMATCH[1]}
          minor=${BASH_REMATCH[2]}
          patch=${BASH_REMATCH[3]}
          
          # Remove prefix from current version for output
          current_version="${latest_tag#$prefix}"
          
          # Calculate next version based on bump type
          case "$bump_type" in
            major)
              major=$((major + 1))
              minor=0
              patch=0
              ;;
            minor)
              minor=$((minor + 1))
              patch=0
              ;;
            *)
              patch=$((patch + 1))
              ;;
          esac
          
          next_version="$major.$minor.$patch"
          echo "Found latest release: $latest_tag, next version: $next_version"
        else
          # Invalid version format, start over with appropriate version
          case "$bump_type" in
            major)
              next_version="1.0.0" ;;
            minor)
              next_version="0.1.0" ;;
            *)
              next_version="0.0.1" ;;
          esac
          echo "Invalid version format in latest release: $latest_tag, resetting to $next_version"
          current_version="$latest_tag"
        fi
        
        # Output results
        echo "next_version=$next_version" >> "$GITHUB_OUTPUT"
        echo "current_version=$current_version" >> "$GITHUB_OUTPUT"
        
        echo "✅ Version calculation complete:"
        echo "   Current version: ${current_version:-'(none)'}"
        echo "   Next version: $next_version"

branding:
  icon: 'tag'
  color: 'green'