Condition on Button (Action)

Hi,

We are using Rule Based Workflow and have added a new Custom Step.

This step has 3 actions - Approve, Reject and Withdraw.

1. Now based on the Action selected by Processor we want to trigger an condition check if it fails then the Action should not complete. And ensure user provides the data as per condition then only the request should get completed.
2. And also based on action we have to hard-code some of the values.

Each action goes to a new step.

Please guide how I can achieve the two requirements.

Thanks,

Charan.