name: Check merge to master

on:
    pull_request_target:
        types: [ opened, synchronize, reopened ]
        branches:
            - 3.3.x

jobs:
    merge-check:
        if: github.event_name == 'pull_request_target' && github.event.pull_request.base.ref == '3.3.x'
        runs-on: ubuntu-latest
        steps:
            -   name: Checkout the repository
                uses: actions/checkout@v3
                with:
                    fetch-depth: 0  # Ensure full history is fetched

            -   name: Set up Git user
                run: |
                    git config --global user.name "github-actions"
                    git config --global user.email "github-actions@github.com"

            -   name: Fetch all branches
                run: git fetch origin

            -   name: Simulate merging PR into 3.3.x
                id: simulate_merge
                run: |
                    git checkout 3.3.x
                    git fetch origin pull/${{ github.event.pull_request.number }}/head
                    git merge --no-ff FETCH_HEAD || exit 1

            -   name: Attempt to merge updated 3.3.x into master
                id: merge_master
                run: |
                    git checkout master
                    if git merge --no-ff 3.3.x --no-commit; then
                      echo "mergeable=true" >> $GITHUB_OUTPUT
                    else
                      echo "mergeable=false" >> $GITHUB_OUTPUT
                      git merge --abort
                    fi

            - name: Find Comment
              uses: peter-evans/find-comment@v3
              id: fc
              with:
                  issue-number: ${{ github.event.pull_request.number }}
                  comment-author: 'github-actions[bot]'
                  body-includes: The attempt to merge branch `3.3.x` into `master` has completed

            -   name: Post comment on PR
                if: always()  # Ensure this step always runs, regardless of merge result
                uses: peter-evans/create-or-update-comment@v4
                with:
                    token: ${{ secrets.GITHUB_TOKEN }}
                    issue-number: ${{ github.event.pull_request.number }}
                    comment-id: ${{ steps.fc.outputs.comment-id }}
                    edit-mode: replace
                    body: |
                        The attempt to merge branch `3.3.x` into `master` has completed after considering the changes in this PR.

                        - Merge result: ${{ steps.merge_master.outputs.mergeable == 'true' && 'Success ✅' || 'Conflict ❌' }}

                        ${{ steps.merge_master.outputs.mergeable == 'true' && 'This PR is ready to be merged.' || 'A separate PR will be needed to merge `3.3.x` into `master`.' }}

            -   name: Mark job as succeeded
                if: always()
                run: echo "Merge check completed. Ignoring the result to avoid failed status."