Contract: Bridge fees collection and claiming implementation

[keyleu]

Description

• Implemented fee collection and claiming for all tokens.
  How it works: Every time a user sends a token it will collect fees into the contract (part of the amount). The truncated amount counts towards the fee (so that users can choose what they want to receive on the other side).
  For claiming, any relayer can claim when ever he wants and the fees will be proportionally distributed to all of them.

Reviewers checklist:

• Try to write more meaningful comments with clear actions to be taken.
• Nit-picking should be unblocking. Focus on core issues.

Authors checklist

• Provide a concise and meaningful description
• Review the code yourself first, before making the PR.
• Annotate your PR in places that require explanation.
• Think and try to split the PR to smaller PR if it is big.

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This change is 

[miladz68]

Reviewed 6 of 34 files at r1, 28 of 28 files at r2, all commit messages.
Reviewable status: complete! all files reviewed, all discussions resolved (waiting on @dzmitryhil, @wojtek-coreum, and @ysv)

[dzmitryhil]

Reviewable status: all files reviewed, 3 unresolved discussions (waiting on @keyleu, @wojtek-coreum, and @ysv)

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contract/src/contract.rs line 63 at r2 (raw file):

const XRP_DEFAULT_MAX_HOLDING_AMOUNT: u128 =
    10u128.pow(16 - XRP_DEFAULT_SENDING_PRECISION as u32 + XRP_DECIMALS);
const XRP_DEFAULT_FEE: Uint128 = Uint128::zero();

Add please the TODO to update it.

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contract/src/contract.rs line 433 at r2 (raw file):

                    amount_after_fees(amount_truncated, token.bridging_fee, truncated_portion)?;

                if amount_to_send

We should include the fees for the MaximumBridgedAmount as well

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contract/src/contract.rs line 1003 at r2 (raw file):

    let truncated_amount =
        amount_to_send.checked_mul(Uint128::new(10u128.pow(exponent.unsigned_abs())))?;
    let truncated = amount.checked_sub(truncated_amount)?;

Probably call it truncation_remainder or remainder, same for the placed where you use it?

[keyleu]

Reviewable status: all files reviewed, 3 unresolved discussions (waiting on @dzmitryhil, @wojtek-coreum, and @ysv)

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contract/src/contract.rs line 63 at r2 (raw file):

Previously, dzmitryhil (Dzmitry Hil) wrote…

Add please the TODO to update it.

Added it.

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contract/src/contract.rs line 433 at r2 (raw file):

Previously, dzmitryhil (Dzmitry Hil) wrote…

We should include the fees for the MaximumBridgedAmount as well

Right,
But actually there was a bigger problem and was different (and more important one that I did not consider and that my tests did not detect).
I was only minting the amount to send to the user and not the fees, and since I only claimed at the end of the tests I didn't realize that I was taking the amount that was being bridged back (and not confirmed).

I added the minting for the fees into the contract and also modified tests to detect this.

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contract/src/contract.rs line 1003 at r2 (raw file):

Previously, dzmitryhil (Dzmitry Hil) wrote…

Probably call it truncation_remainder or remainder, same for the placed where you use it?

Sure, no problem. Changed it.

[dzmitryhil]

Reviewable status: 6 of 34 files reviewed, 1 unresolved discussion (waiting on @miladz68, @wojtek-coreum, and @ysv)

[miladz68]

Reviewed 28 of 28 files at r3, all commit messages.
Reviewable status: all files reviewed, 1 unresolved discussion (waiting on @wojtek-coreum and @ysv)