name: Optimize images

# **What it does**: Optimize images.
# **Why we have it**: Reduce bandwidth needs.
# **Who does it impact**: Docs engineering.

on:
  workflow_dispatch:
  pull_request:
    paths:
      - '**/*.png'

permissions:
  contents: write
  pull-requests: write

jobs:
  optimize-images-on-pr:
    # We can't make commits on forks
    if: github.repository == 'github/docs-internal'
    runs-on: ubuntu-latest
    steps:
      - name: Check out repo on head ref
        uses: actions/checkout@dcd71f646680f2efd8db4afa5ad64fdcba30e748
        with:
          ref: ${{ github.head_ref }}
          # Need to specify a PAT here because otherwise GITHUB_TOKEN is used
          # by default.  Workflows won't trigger in that case because actions
          # performed with GITHUB_TOKEN don't trigger other workflows.
          token: ${{ secrets.DOCUBOT_REPO_PAT }}

      - name: Check out base ref
        run: git fetch --no-tags --depth=1 origin $GITHUB_BASE_REF

      - name: Install the Optipng package
        run: sudo apt-get update && sudo apt-get -y install optipng

      - name: Run optipng on new or changed images
        run: |
          set -e # exit when any command fails

          echo "Ensure we can view $GITHUB_BASE_REF"
          git checkout $GITHUB_BASE_REF

          echo "Ensure we can view $GITHUB_HEAD_REF"
          git checkout $GITHUB_HEAD_REF

          echo "List the files that changed"
          git diff --name-only --diff-filter=d $GITHUB_BASE_REF $GITHUB_HEAD_REF

          echo "Run optipng on pngs in from the diff"
          git diff --name-only -z --diff-filter=d $GITHUB_BASE_REF $GITHUB_HEAD_REF -- '*.png' | xargs -0 optipng -nx

      - name: Make a commit and a push
        run: |
          echo "If there's no changes, exit"
          if [[ !  `git status --porcelain` ]]
          then
            echo "No changes found"
            exit 0
          fi

          echo "Make a commit"
          git config user.name github-actions
          git config user.email github-actions@github.com
          git add "*.png"
          git commit --message="Optimize images"

          echo "Push up changes"
          git push
        env:
          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}