check-kalium-commitish.yml

name: "Validate Kalium References"

on:
  pull_request:
    types: [ opened, synchronize ] # Don't rerun on `edited` to save time
    paths:
      - 'kalium'

jobs:
  validate-kalium-ref:
    runs-on: ubuntu-20.04

    steps:
      - name: Checkout
        uses: actions/checkout@v4
        with:
          submodules: recursive # Needed in order to fetch Kalium sources for building
          fetch-depth: 0

      - name: Run git merge-base
        id: validate_kalium
        env:
          GH_BASE_REF: ${{github.base_ref}}
        continue-on-error: true
        # git merge-base --is-ancestor A B returns 0 when A is ancestor of B
        # In our case, if FROM is not an ancestor of TO, then it returns 1
        run: |
          KALIUM_TO_REF="$(git rev-parse HEAD:kalium)"
          git fetch
          git checkout "$GH_BASE_REF"
          git pull
          git submodule update
          KALIUM_FROM_REF="$(git rev-parse HEAD:kalium)"
          echo "kalium_from=$KALIUM_FROM_REF" >> $GITHUB_OUTPUT
          echo "kalium_to=$KALIUM_TO_REF" >> $GITHUB_OUTPUT
          cd kalium
          git merge-base --is-ancestor "$KALIUM_FROM_REF" "$KALIUM_TO_REF" || echo "is_kalium_rollback=$?" >> $GITHUB_OUTPUT
          unset KALIUM_TO_REF
          unset KALIUM_FROM_REF

      - name: Leave a comment
        if: ${{ steps.validate_kalium.outputs.is_kalium_rollback == 1 }}
        env:
            GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
            PR_AUTHOR: ${{ github.event.pull_request.user.login }}
            KALIUM_FROM: ${{ steps.validate_kalium.outputs.kalium_from }}
            KALIUM_TO: ${{ steps.validate_kalium.outputs.kalium_to }}
            GH_BASE_REF: ${{github.base_ref}}
            GH_HEAD_REF: ${{github.head_ref}}
        run: |
          gh pr comment "$GH_HEAD_REF" --body "@$PR_AUTHOR looks like you are rolling back kalium to a previous commitish.

          This means that the PR's target branch ($GH_BASE_REF) is using a newer version of Kalium, and the changes in this PR will rollback Kalium to an older version.

          | $GH_BASE_REF | This PR |
          | ------------ | ------- |
          | [$KALIUM_FROM](https://github.com/wireapp/kalium/tree/$KALIUM_FROM) | [$KALIUM_TO](https://github.com/wireapp/kalium/tree/$KALIUM_TO) |

          Is this intentional?"