action.yml

name: 'Snippet Permalink Updater'
description: 'Updates a Markdown file with a permalink to a specific code snippet'

author: Tibor Schmidt <robitx@gmail.com>

inputs:
  snippet_file:
    description: 'Path to the file containing the snippet'
    required: true
  start_marker:
    description: 'Start marker for the snippet'
    required: true
  end_marker:
    description: 'End marker for the snippet'
    required: true
  markdown_file:
    description: 'Path to the Markdown file to update'
    default: 'README.md'
  replace_marker:
    description: 'Marker in Markdown file to identify where to replace the permalink'
    required: true
outputs:
  permalink:
    description: 'The generated permalink'
runs:
  using: 'composite'
  steps:
    - name: Get latest commit ID for snippet file
      id: get-commit
      shell: bash
      run: |
        COMMIT_ID=$(git log -n 1 --pretty=format:%H -- ${{ inputs.snippet_file }})
        echo "commit_id=$COMMIT_ID" >> $GITHUB_OUTPUT

    - name: Find line numbers and update Markdown file
      shell: bash
      run: |
        START_LINE=$(grep -n -- "${{ inputs.start_marker }}" "${{ inputs.snippet_file }}" | cut -d: -f1)
        END_LINE=$(grep -n -- "${{ inputs.end_marker }}" "${{ inputs.snippet_file }}" | cut -d: -f1)
        
        if [ -z "$START_LINE" ] || [ -z "$END_LINE" ]; then
          echo "Markers not found in snippet file"
          exit 1
        fi

        START_LINE=$((START_LINE + 1))
        END_LINE=$((END_LINE - 1))
        
        PERMALINK="https://github.com/${GITHUB_REPOSITORY}/blob/${{ steps.get-commit.outputs.commit_id }}/${{ inputs.snippet_file }}#L${START_LINE}-L${END_LINE}"
        
        echo "permalink=$PERMALINK" >> $GITHUB_OUTPUT
        
        sed "/${{ inputs.replace_marker }}/!b;n;c$PERMALINK" \
          "${{ inputs.markdown_file }}" > temp_file && \
        mv temp_file "${{ inputs.markdown_file }}"

    - name: Output diff for the changed file
      shell: bash
      run: |
        git diff "${{ inputs.markdown_file }}"