Estimate path payment rate two-way

[pacoccino]

Currently the Find Path method in horizon let us find a path from a source account to a destination account and destination asset.

Though it only allow us to set a destination amount, that allow us to know the sendMax amount to send.
This only permits to estimate an exchange rate on one way.

It would be very nice to have an endpoint, where we can set a source asset, source amount and destination asset and end up with an estimation of the amount of destination asset that will be received.

Maybe it would be a new endpoint because find path does not need to set the source asset.

[s-a-y]

Any plans to work on that? Would be really useful

[nullstyle]

There aren't any plans to work on this in the near term @s-a-y, but I will make sure it gets added onto the list of things to work on when I get around to doing another pass on pathfinding.

[s-a-y]

I could probably try to take a look at it with my team (we are not up to speed with golang) if you confirm there are no technical barriers for implementing this feature @nullstyle

[nullstyle]

There shouldn't be anything you can't work with @s-a-y, but I figure it will be a pain in the butt to implement... If you're not familiar with go, you'll probably run into a lot of pain. The pathfinding is meant to be pluggable and this will be the first big expansion of the interface so there will be some design questions to answer in addition to implementation.

The relevant interfaces are here: https://github.com/stellar/horizon/blob/master/src/github.com/stellar/horizon/paths/main.go

You'll want to expand that interface to incorporate this change to a two-way system.

[istrau2]

Just wanted to +1 this. I've had to use some really nasty hacks to get around this in lupoex.