name: "👽 Atmos Pro Determine Affected Stacks"
run-name: "👽 Atmos Pro Determine Affected Stacks"
 
# Atmos Pro reacts to events defined in the Atmos stack settings
# and will trigger the appropriate workflows for the given event.
#
# For example, pull requests opened, synchronize, and reopened will trigger plan workflows.
# Whereas pull requests merged will trigger apply workflows
on:
  pull_request:
    types:
      - opened
      - synchronize
      - reopened
      - closed
    branches:
      - main
 
# Avoid conflicting workflow triggers.
# For example, wait to trigger apply until plan has been triggered
concurrency:
  group: "${{ github.ref }}"
  cancel-in-progress: false
 
permissions:
  id-token: write # This is required for requesting the JWT (OIDC) token
  contents: read # This is required for actions/checkout
 
jobs:
  affected:
    name: Trigger Affected Stacks
 
    runs-on:
      - "ubuntu-latest"
 
    # Trigger Atmos Pro for Pull Request plan events and specifically closed PRs that have been merged (not just closed)
    if: github.event.action != 'closed' || (github.event.action == 'closed' && github.event.pull_request.merged == true)
 
    steps:
      - name: Checkout
        # For merged PRs, we will need to checkout the base branch to get the correct base branch SHA.
        # This isn't necessary for other events.
        if: github.event.action == 'closed'
        uses: actions/checkout@v4
        with:
          fetch-depth: 0 # Fetch all history for all branches and tags
 
      # For merged PRs, we want to use 1 previous commit from the base branch SHA
      # This is because by the time this workflow runs, the PR branch has already been merged.
      # It's critical to use the base branch SHA to get the correct changes, not the previous commit from the PR branch.
      - name: Determine previous commit on base branch
        id: get_parent
        if: github.event.action == 'closed'
        shell: bash
        run: |
          # For squash merges, github.event.pull_request.base.sha represents the state of the base branch
          # when the PR was created (or last updated). This may be stale compared to the actual commit
          # on the main branch at the time of the merge. Using 'HEAD~1' after the merge ensures we get
          # the commit that was the tip of main immediately before the squash merge commit was added.
          echo "Merge commit: $(git rev-parse HEAD)"
          PARENT=$(git rev-parse HEAD~1)
          echo "Parent (base) commit: $PARENT"
          echo "merge_commit=$MERGE_COMMIT" >> "$GITHUB_OUTPUT"
          echo "parent_commit=$PARENT" >> "$GITHUB_OUTPUT"
 
      - name: Determine Affected Stacks
        id: affected
        uses: cloudposse/github-action-atmos-affected-stacks@v6
        env:
          ATMOS_PRO_WORKSPACE_ID: ${{ vars.ATMOS_PRO_WORKSPACE_ID }}
        with:
          atmos-version: ${{ vars.ATMOS_VERSION }} # >= 1.180.0
          atmos-config-path: ${{ vars.ATMOS_CONFIG_PATH }}
          atmos-pro-upload: true
          # Compare the head of the PR to the base of the PR if the PR is not merged.
          # If the PR is merged, compare the head of the PR to 1 previous commit on the base branch.
          head-ref: ${{ github.event.pull_request.head.sha }}
          base-ref: ${{ github.event.action == 'closed' && steps.get_parent.outputs.parent_commit || github.event.pull_request.base.sha }}