Bid with DAI logic

[valiafetisov]

Contributes to #160

In order to test:

1. Restart an auction, note down the id, eg ETH-A:120
2. Make sure you have enough DAI in the VAT (more than Auction Price Total)
   • open wallet modal via $nuxt.$store.dispatch("modals/setWalletModalAndFetchData", true)
   • deposit enough DAI
3. Participate using correct auction id

   id = 'ETH-A:120'; $nuxt.$store.dispatch("auctions/bidWithDai", { id, bidAmountDai: $nuxt.$store.state.auctions.auctionStorage[id].totalPrice.toFixed() })
   

Note: this will bid total amount.

[LukSteib]

• I was able to bid on an auction the way described in the initial comment. See: https://kovan.etherscan.io/tx/0xa626deff5b45a71a3210e75514e48d27d00883ed8dd06f4cec81bfb8763cd107
• Dai was withdrawn from VAT
• However, I was expecting to receive the 0.1 ETH (= Auction amount) in my wallet. This is not true. AFAIK the ETH wallet balance did not change
  • Same for execution of a BAL auction -> BAL funds did not end up in wallet

[valiafetisov]

According to the execution trace it seems like the collateral ended up in the VAT, using flux function, which simply moves collateral from one user to another within VAT:

Therefore, we may actually need initially proposed "collateral withdrawal" step 🙁
(or should make a callee which does it one step)

[valiafetisov]

Anyway, take input data is correct: who has your address, therefore I suppose this functionality is implemented correctly on our side:

[LukSteib]

Therefore, we may actually need initially proposed "collateral withdrawal" step 🙁

:( yes, seems like it. So we definitely need a solution for a user to get the funds in the wallet

Anyway, take input data is correct: who has your address, therefore I suppose this functionality is implemented correctly on our side

Yes. Is there an easy command to fetch VAT balance for a certain collateral? Similar to the one we use for Dai. Just in order to doublecheck that collateral ends up in VAT associated with wallet address

[valiafetisov]

Is there an easy command to fetch VAT balance for a certain collateral?

Not really. Here is where they are stored in vat contract. So in order to get this number, you need to:

• open vat contract https://kovan.etherscan.io/address/0xba987bdb501d131f766fee8180da5d81b34b69d9#readContract
• execute gem read function, passing
  • ilk, bytes32 encoded collateral type according to the source code
    • can be found in the clipper contract https://kovan.etherscan.io/address/0x7dd1fb6b9afdba9f28db89c81723b8c6b27a2fbe#readContract
    • for ETH-A it's 0x4554482d41000000000000000000000000000000000000000000000000000000
  • address – your wallet address 0x4f3b7fb6204c614b28f0e1f50dc1c99175631678
• convert returned number (59083106099127643) from wad (ie move 18 decimal points left) via new BigNumber('59083106099127643').shiftedBy(-18).toFixed()
  • the result is 0.059083106099127643

So it's actually less than 0.1, most probably because you don't actually get the whole amount (just like with the swap) and profit calculation should be done depending on the debt:

unified-auctions-ui/core/src/price.ts

Lines 44 to 55 in 5494c08

	export const calculateTransactionGrossProfit = function (auction: Auction): BigNumber {
	if (!auction.marketUnitPrice) {
	return new BigNumber(0);
	}
	const totalMarketPrice = auction.collateralAmount.multipliedBy(auction.marketUnitPrice);
	if (totalMarketPrice <= auction.debtDAI) {
	return totalMarketPrice.minus(auction.totalPrice);
	}
	const collateralAmountLimitedByDebt = auction.debtDAI.dividedBy(auction.approximateUnitPrice);
	const totalMarketPriceLimitedByDebt = collateralAmountLimitedByDebt.multipliedBy(auction.marketUnitPrice);
	return totalMarketPriceLimitedByDebt.minus(auction.debtDAI);
	};

But I think we should open another PR for both implementing gem fetching and fixing "profit" calculation

[LukSteib]

So it's actually less than 0.1, most probably because you don't actually get the whole amount (just like with the swap) and profit calculation should be done depending on the debt

Yes, with the caveat that in the case of Dai bidding it also affects to amount to bid. So I assume the total amount to bid is not always auction amount * auction price :(

So going to approve this PR and we need to figure out gem and profit / total amount to bid related parts in other PRs

[valiafetisov]

So I assume the total amount to bid is not always auction amount * auction price

No, that's impossible because take actually accepts amt: Upper limit on amount of collateral to buy (and not DAI that user enters). In other words, user can only take auction partially, but can not ask for more collateral than there is. The actual amount to be transferred to the user (slice) is calculated based on the tab, amt and current price here: https://github.com/makerdao/dss/blob/60690042965500992490f695cf259256cc94c140/src/clip.sol#L357-L380