Hi there, I am building a simple in app virtual currency or gifts type of app, I have setup authentication, a main screen, we show send button, on clicking it, it opens up a list of all other registered users, upon clicking the user, a component (bottom sheet) opens up that shows the selected userid/display name and asks the amount they want to send in text field, with a button that says, Confirm and Send, what I want to know is how to build the logic for so that after clicking on the send and confirm we need to check if the from user has that required amount in their account, if it less, we show an error that you do not have required amount, if the user has the amount, then we will proceed with transaction, the amount will be subtracted from the sending user account and will be added to selected user account