action.yml

name: 'Stacked PR Update Action'
description: 'Automatically fixes stacked PRs after a base PR is squash-merged'
author: 'GitHub Actions'

inputs:
  github-token:
    description: >
      Token for git push and GitHub API calls. The default GITHUB_TOKEN will NOT
      trigger CI on upstack PRs (GitHub deliberately suppresses workflow runs from
      pushes made with that token). Use a GitHub App installation token if you need
      checks to run on the updated PRs.
    required: true
    default: ${{ github.token }}

runs:
  using: 'composite'
  steps:
    - name: Check if action should run
      id: check
      shell: bash
      env:
        EVENT_ACTION: ${{ github.event.action }}
        PR_LABELS: ${{ join(github.event.pull_request.labels.*.name, ',') }}
        PR_MERGED: ${{ github.event.pull_request.merged }}
        MERGE_COMMIT_SHA: ${{ github.event.pull_request.merge_commit_sha }}
      run: |
        if [[ "$EVENT_ACTION" == "closed" && "$PR_MERGED" == "true" && -n "$MERGE_COMMIT_SHA" ]]; then
          echo "mode=squash-merge" >> $GITHUB_OUTPUT
        elif [[ "$EVENT_ACTION" == "synchronize" && "$PR_LABELS" == *autorestack-needs-conflict-resolution* ]]; then
          echo "mode=conflict-resolved" >> $GITHUB_OUTPUT
        else
          echo "Event does not match any action trigger (action=$EVENT_ACTION, merged=$PR_MERGED, labels=$PR_LABELS)"
          echo "mode=skip" >> $GITHUB_OUTPUT
        fi

    - name: Checkout repository
      if: steps.check.outputs.mode != 'skip'
      uses: actions/checkout@v4
      with:
        fetch-depth: 0
        token: ${{ inputs.github-token }}

    - name: Update PR stack
      if: steps.check.outputs.mode != 'skip'
      shell: bash
      env:
        GITHUB_TOKEN: ${{ inputs.github-token }}
        GIT_AUTHOR_NAME: github-actions
        GIT_AUTHOR_EMAIL: github-actions@github.com
        GIT_COMMITTER_NAME: github-actions
        GIT_COMMITTER_EMAIL: github-actions@github.com
        ACTION_MODE: ${{ steps.check.outputs.mode }}
        SQUASH_COMMIT: ${{ github.event.pull_request.merge_commit_sha }}
        MERGED_BRANCH: ${{ github.event.pull_request.head.ref }}
        TARGET_BRANCH: ${{ github.event.pull_request.base.ref }}
        PR_BRANCH: ${{ github.event.pull_request.head.ref }}
      run: |
        echo "Running in $ACTION_MODE mode"
        ${{ github.action_path }}/update-pr-stack.sh

branding:
  icon: 'git-pull-request'
  color: 'blue'