ATM low level design

[codeimmortal]

This design Consist of,

1. Different state of ATM (insertCard , insertpin , select-account, cash dispatcher).
2. State design pattern for different state of ATM.
3. Chain of responsibility principle for withdrawing cash.
4. Template pattern for handling error of each place in one place.
5. Concurrency control, preventing atm to conflict.

[thesaltree]

@codeimmortal thank you for the implementation. I added few potential issues and suggested changes. Please make improvements accordingly.

[codeimmortal]

Updated the change provided. @thesaltree

[codeimmortal]

@thesaltree , Just Reminder

[thesaltree]

@codeimmortal thanks for addressing the feedback.
Another question, are we actually using InsertPin in the flow and validating the pin using this logic?

        if pin == "1111" {
		return nil
	} else {
		return errors.New("Pin is not valid")
	}

[codeimmortal]

@thesaltree , code was added there. But now it has been added to flow also. ATM will ask for pin also.

[codeimmortal]

Let me know if validation is done.