action.yml

# **what?**
# Add a changelog yaml file per changie expectation when a bot creates a PR.  The new yaml file 
# will be created if none already exists on the PR when the PR has a specifed label.  Once created,
# it will be committed by a specified bot and commit will be pushed to the PR.
#
# **why?**
# Automate changelog generation for more visability with automated bot changes.

# **when?**
# Once a PR is created and it has been correctly labeled.  
#
# An exampe use is for PRs created by dependabot.  You can also manually trigger this by adding the
# specified label at any time.
#
# Assumptions
#  1. You're using changie
#  2. Your changelogs live in the default `.changes. path, nothing custom
#  3. This action is called in the context of a PR
#  4. Not changelog yaml file already exists on this PR
#  5. This PR already exists and you just need to add a commit with the changelog to it
#
# A note on tokens:
# When using the GITHUB_TOKEN, the resulting commit will not trigger another GitHub Actions
# Workflow run. This is due to limitations set by GitHub.
# See: https://docs.github.com/en/actions/security-guides/automatic-token-authentication#using-the-github_token-in-a-workflow
# When you use the repository's GITHUB_TOKEN to perform tasks on behalf of the GitHub Actions
# app, events triggered by the GITHUB_TOKEN will not create a new workflow run. This prevents
# you from accidentally creating recursive workflow runs. To get around this, use a Personal
# Access Token to commit changes.

name: Automated Changelog Generation for changie
description: Generate a changelog yaml file in a format expected by changie for bot driven PRs.

inputs:
  GITHUB_TOKEN:
    description: Token to use to commit the file.  If you use the GITHUB_TOKEN this commit will not retrigger workflows.  Use a PAT to cause the commit to re-trigger workflows.
    required: true
  commit_author_name:
    description: Author name for the commit
    required: true
  commit_author_email:
    description: Author email for the commit
    required: true
  commit_message:
    description: Message to put on commit of new changelog file
    required: false
    default: "Add automated changelog yaml from template"
  changie_kind:
    description: Type of changelog file  # TODO: how does changie define this?
    required: true
  label:
    description: GitHub label to trigger off of
    required: true
  custom_changelog_string: # use changie commands once available
    description: The multi-line string containing the expected contents of the custom fields for a changelog entry.
    required: false

runs:
  using: "composite"

  steps:
    - name: Checkout Branch
      if: ${{ contains(github.event.pull_request.labels.*.name, inputs.label ) }}
      uses: actions/checkout@v3
      with:
        # specifying the ref avoids checking out the repository in a detached state
        ref: ${{ github.event.pull_request.head.ref }}
        token: ${{ inputs.GITHUB_TOKEN }}

    - name: Check if changelog file exists already
      # if there's already a changelog entry, don't add another one!
      if: ${{ contains(github.event.pull_request.labels.*.name, inputs.label ) }}
      shell: bash
      id: changelog_check
      run: |
        git fetch origin ${{ github.event.pull_request.base.ref }}
        declare RESULT=$(git diff --name-only ${{ github.event.pull_request.head.sha }} ${{ github.event.pull_request.base.sha }})
        echo $RESULT
        if echo $RESULT | grep '.changes/unreleased/.*.yaml'; then
          echo "exists=true" >> $GITHUB_OUTPUT
          echo "Changelog already exists for this PR, skip creating a new one"
        else
          echo "exists=false" >> $GITHUB_OUTPUT
          echo "No changelog exists for this PR, creating a new one"
        fi

    - name: Create file from template
      if: ${{ steps.changelog_check.outputs.exists == 'false'  && contains(github.event.pull_request.labels.*.name, inputs.label ) }}
      shell: bash
      run: |
        FILEPATH=.changes/unreleased/${{ inputs.changie_kind }}-$(date +%Y%m%d-%H%M%S).yaml
        echo 'kind: "${{ inputs.changie_kind }}"' > $FILEPATH
        echo 'body: "${{ github.event.pull_request.title }}"' >> $FILEPATH
        echo "time: $(date +%Y-%m-%dT%H:%M:%S.00000Z)" >> $FILEPATH
        echo "${{ inputs.custom_changelog_string }}" >> $FILEPATH

    - name: Commit & Push changes
      if: ${{ steps.changelog_check.outputs.exists == 'false' && contains(github.event.pull_request.labels.*.name, inputs.label ) }}
      shell: bash
      run: |
        git status
        git config user.name '${{ inputs.commit_author_name }}'
        git config user.email '${{ inputs.commit_author_email }}'
        git pull
        git add .
        git commit -m "${{ inputs.commit_message }}"
        git push