Feature request: Add "send all" option to fungible tokens

[PiVortex]

It would be helpful to introduce a "send all" option for fungible tokens that determines your balance and sends exactly that making sure it leaves exactly 0 balance left.

Since this could be a critical operation I suggest instead of this popping up as an option button that the user types in "send all" when specifying how many tokens. This "send all" suggestion would appear in the examples.

Use case: I have a contract that needs to be initialized with a certain number of tokens. The amount of tokens changes when I use the contract. I want to redeploy the contract but it becomes difficult to get the exact number of tokens to reinitialize.

Slime gave my message in tools a thumbs up so it seems like it could be useful to others also.

Thanks

[frol]

The challenge here is that at the moment where you enter "send all" there is no information about the current balance since we have not yet asked for the network configuration, so we don't even have the RPC information yet. On the other hand, we can use a dedicated enum instead of just NearAmount:

/// "all" -> MaxAmount
/// "10 NEAR" -> ExactAmount(NearAmount(10 NEAR))
enum TransferAmount {
    MaxAmount,
    ExactAmount(NearAmount),
}

This way we will be able to resolve "all" to the specific number at the moment where we will have more information about the network.