VendingMachineV3

VendingMachineV3

VendingMachineV3 is used to exchange tBTC v1 to tBTC v2 in a 1:1 ratio after the tBTC v1 bridge sunsetting is completed. Since tBTC v1 bridge is no longer working, tBTC v1 tokens can not be used to perform BTC redemptions. This contract allows tBTC v1 owners to upgrade to tBTC v2 without any deadline. This way, tBTC v1 tokens left on the market are always backed by Bitcoin. The governance will deposit tBTC v2 into the contract in the amount equal to tBTC v1 supply. The governance is allowed to withdraw tBTC v2 only if tBTC v2 left in this contract is enough to cover the upgrade of all tBTC v1 left on the market. This contract is owned by the governance.

tbtcV1

contract IERC20 tbtcV1

tbtcV2

contract TBTC tbtcV2

Exchanged

event Exchanged(address to, uint256 amount)

Deposited

event Deposited(address from, uint256 amount)

TbtcV2Withdrawn

event TbtcV2Withdrawn(address to, uint256 amount)

FundsRecovered

event FundsRecovered(address token, address to, uint256 amount)

constructor

constructor(contract IERC20 _tbtcV1, contract TBTC _tbtcV2) public

exchange

function exchange(uint256 amount) external

Exchange tBTC v1 for tBTC v2 in a 1:1 ratio. The caller needs to have at least amount of tBTC v1 balance approved for transfer to the VendingMachineV3 before calling this function.

Parameters

Name	Type	Description
amount	uint256	The amount of tBTC v1 to exchange for tBTC v2.

receiveApproval

function receiveApproval(address from, uint256 amount, address token, bytes) external

Exchange tBTC v1 for tBTC v2 in a 1:1 ratio. The caller needs to have at least amount of tBTC v1 balance approved for transfer to the VendingMachineV3 before calling this function.

This function is a shortcut for approve + exchange. Only tBTC v1 caller is allowed and only tBTC v1 is allowed as a token to transfer.

Parameters

Name	Type	Description
from	address	tBTC v1 token holder exchanging tBTC v1 to tBTC v2.
amount	uint256	The amount of tBTC v1 to exchange for tBTC v2.
token	address	tBTC v1 token address.
	bytes

depositTbtcV2

function depositTbtcV2(uint256 amount) external

Allows to deposit tBTC v2 tokens to the contract. VendingMachineV3 can not mint tBTC v2 tokens so tBTC v2 needs to be deposited into the contract so that tBTC v1 to tBTC v2 exchange can happen. The caller needs to have at least amount of tBTC v2 balance approved for transfer to the VendingMachineV3 before calling this function.

This function is for the redeemer and tBTC v1 operators. This is NOT a function for tBTC v1 token holders.

Parameters

Name	Type	Description
amount	uint256	The amount of tBTC v2 to deposit into the contract.

withdrawTbtcV2

function withdrawTbtcV2(address recipient, uint256 amount) external

Allows the governance to withdraw tBTC v2 deposited into this contract. The governance is allowed to withdraw tBTC v2 only if tBTC v2 left in this contract is enough to cover the upgrade of all tBTC v1 left on the market.

Parameters

Name	Type	Description
recipient	address	The address which should receive withdrawn tokens.
amount	uint256	The amount to withdraw.

recoverFunds

function recoverFunds(contract IERC20 token, address recipient, uint256 amount) external

Allows the governance to recover ERC20 sent to this contract by mistake or tBTC v1 locked in the contract to exchange to tBTC v2. No tBTC v2 can be withdrawn using this function.

Parameters

Name	Type	Description
token	contract IERC20	The address of a token to recover.
recipient	address	The address which should receive recovered tokens.
amount	uint256	The amount to recover.

_exchange

function _exchange(address tokenOwner, uint256 amount) internal