Accept Offer

After the offer is created, it can be accepted by the buyer. On this page, we'll go over the process of accepting the offer.

Accepting Process

1. Accept Offer Parameters.

First, the buyer must specify which offer to accept by providing the offer ID.

Additionally, the buyer must specify the source token amount to be purchased, as the Bakstag Protocol supports fractional offer acceptance. The amount should be expressed in shared decimals.

Finally, the buyer needs to provide the address of his account in source chain. The source tokens will be transferred into this account.

Namely, buyer must provide:

• Offer ID: The unique identifier of the offer
• Source Amount: The amount of source token to be purchased.
• Source Buyer Address: The address for receiving the purchased tokens.

The destination token will be transferred from the signer of the transaction.

2. Quote.

The next step is to call quote that provides:

• LayerZero Messaging Fee - the fee required by LayerZero.
• Accept Offer Receipt - includes protocol fee and the destination token amount.
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The quote is a view (read) function, so calling it incurs no cost. The Destination token amount is the total amount the buyer would spend, by accepting the offer. This amount is calculated automatically using the exchange rate stored in the offer. The Protocol fee would be taken from destination token amount and transferred to the treasury, while the remaining part would be transferred to the destination seller address.

function quoteAcceptOffer(
    bytes32 _dstBuyerAddress,
    AcceptOfferParams calldata _params,
    bool _payInLzToken
) external returns (MessagingFee memory fee, AcceptOfferReceipt memory acceptOfferReceipt);

• Pay in LayerZero Token: Decide whether to cover LayerZero fee in native or ZRO token.

3. Validation of Offer Accept Transaction

The quoteAcceptOffer validates the transaction.If the transaction is invalid, it will be reverted. Transaction is invalid in case of:

• InvalidEid: Buyer attempts to accept the offer from the wrong chain—i.e., from the source chain instead of the destination chain.
• ExcessiveAmount: Available Source token amount is exceeded
• NonexistentOffer: Invalid offerId is provided

4. Approve.

If the destination token is not native, e.g., USDC (Base), buyer has to approve the OTC Market to transfer the destination tokens. The approval amount is taken form the Accept Offer Receipt.

5. Accept.

Finally, invoke acceptOffer.

function acceptOffer(
    AcceptOfferParams calldata _params,
    MessagingFee calldata _fee
) external payable returns (MessagingReceipt memory msgReceipt, AcceptOfferReceipt memory acceptOfferReceipt);

Calling acceptOffer will return LayerZero Messaging Receipt and Create Offer Receipt.

Accepting monochain offer

In case of accepting monochain offer, the destination OTC market would be also the source OTC market. So it will:

• Validate Accept Offer: Verify if the transaction is valid
• Update Offer source amount: Update the source token amount available to accept for next buyers.
• Emit event: Log OfferAccepted event notifying offchain workers.
• Transfer destination token: Transfer protocol fee to treasury and remaining amount to destination seller address
• Transfer source token: Transfer source token amount to source buyer address

Accepting cross-chain offer

While accepting the cross-chain offer, OTC market will:

• Validate Accept Offer: Verify if the transaction is valid
• Update Offer source amount: Update the source token amount available to accept for next buyers.
• Emit event: Log OfferAccepted event notifying offchain workers.
• Transfer destination token: Transfer protocol fee to treasury and remaining amount to destination seller address
• Send cross-chain message: Build and send OfferAccepted message to the source chain OTC Market.

After the cross-chain message is delivered, the source chain OTC market will:

• Update Offer source amount: Update the source token amount available to accept.
• Emit event: Log OfferAccepted event notifying offchain workers.
• Transfer source tokens: Transfer the source token amount to source buyer address

Bakstag currently maintains a duplicate storage of offers, so the source token amount should be decreased on both source and destination chains.

Treasury

The Treasury is a multi signature account used to store all collected fees, managed by DAO in the future.