On `delete` mode new comment always will be created

[ViacheslavKudinov]

Hello, i have the situation when i change mode dynamically based on the result of another step, but on delete mode extra comment will be temporarily added all the time due to current logic.

I use this Action to add comment on PR in case if TFLinter finds some concerns based on exit code. When TFLinter finds concern, the Action adds comment as it runs based on

      - name: 'Set comment PR mode'
        run: |
          if [ "${{ steps.tflint.outputs.exitcode }}" != "0" ]; then
            echo "pr_comment_mode=recreate" >> $GITHUB_ENV 
          else
            echo "pr_comment_mode=delete" >>  $GITHUB_ENV
          fi

      - name: 'Comment PR'
        if: ${{ steps.tflint.outputs.exitcode != '0' || env.pr_comment_mode == 'delete'}}
        uses: thollander/actions-comment-pull-request@v2
        with:
          message: |
            ## :microscope: TFLint validation
            ```shell
            ${{ steps.tflint.outputs.stdout || 'TFLint is running...' }}

      pr_number: ${{ github.event.pull_request.number }}
      mode: ${{ env.pr_comment_mode }}
      comment_tag: "tflint_comment"
      GITHUB_TOKEN: ${{ secrets.SOME_TOKEN }}

so, if there is any concerns it will be `pr_comment_mode=recreate`  means comment will be added. Everything as expected. 
When there is a new commit with changes, but still some concerns from TFLinter, comment will be recreated and Action works as expected.
But if all the TFLint concerns were fixed, then mentioned step sets `pr_comment_mode=delete` .
In this situation there is a small side effect as `delete` mode always creates comment. The thing is, there is a situation when it will be two PR comments from this Action, one created when it was TFLint concerns and the new extra short living comment as `createComment` function will be executed before **post step**  which will remove both comments later.

It will be great if it  can be avoided the creation of new intermediate PR comment when `mode: delete` in the situation I've described. 

Maybe, it is kind of "new" mode (`cleanup` ?) when `delete` works just as delete, without creation of any comment before the deletion in the end during post step.  

[ghost]

Noticed same behavior as well ..

[mlahargou]

I think we are having the same (or similar) problem. I'd like to just be able to delete comments that have the specified comment_tag. It would be nice if this snippet would just delete the comment if it existed.

         - name: Delete comment if exists
           uses: thollander/actions-comment-pull-request@v2
           with:
              comment_tag: 'some_tag'
              mode: delete

Currently we get an error because either filePath or message is required by the action:

Error: Either "filePath" or "message" should be provided as input

---

To me, the current delete mode is more like a delete-on-completion mode. But for the sake of backwards compatibility, it might make sense to add a only-delete option which just does:

+++ b/src/main.ts
@@ -157,6 +157,12 @@ async function run() {
             body,
           });
           return;
+        } else if (mode === 'only-delete') {
+          await deleteComment({
+            ...context.repo,
+            comment_id: comment.id,
+          });
+          return;
         } else if (mode === 'delete') {
           core.debug('Registering this comment to be deleted.');

[mlahargou]

Here's a proof of concept with no backwards compatibility issues: https://github.com/iFixit/actions-comment-pull-request/compare/main...iFixit:actions-comment-pull-request:add-only-delete

I can open a PR if you'd like.