VendingMachine

VendingMachine

The Vending Machine is the owner of TBTC v2 token and can mint TBTC v2 tokens in 1:1 ratio from TBTC v1 tokens with TBTC v1 deposited in the contract as collateral. TBTC v2 can be unminted back to TBTC v1 with or without a fee - fee parameter is controlled by the Governance. This implementation acts as a bridge between TBTC v1 and TBTC v2 token, allowing to mint TBTC v2 before the system is ready and fully operational without sacrificing any security guarantees and decentralization of the project. Vending Machine can be upgraded in a two-step, governance-controlled process. The new version of the Vending Machine will receive the ownership of TBTC v2 token and entire TBTC v1 balance stored as collateral. It is expected that this process will be executed before the v2 system launch. There is an optional unmint fee with a value that can be updated in a two-step, governance-controlled process. All governable parameters are controlled by two roles: update initiator and finalizer. There is a separate initiator role for unmint fee update and vending machine upgrade. The initiator proposes the change by initiating the update and the finalizer (contract owner) may approve it by finalizing the change after the governance delay passes.

GOVERNANCE_DELAY

uint256 GOVERNANCE_DELAY

The time delay that needs to pass between initializing and finalizing update of any governable parameter in this contract.

FLOATING_POINT_DIVISOR

uint256 FLOATING_POINT_DIVISOR

Divisor for precision purposes. Used to represent fractions in parameter values.

tbtcV1

contract IERC20 tbtcV1

tbtcV2

contract TBTC tbtcV2

unmintFee

uint256 unmintFee

The fee for unminting TBTC v2 back into TBTC v1 represented as 1e18 precision fraction. The fee is proportional to the amount being unminted and added on the top of the amount being unminted. To calculate the fee value, the amount being unminted needs to be multiplied by unmintFee and divided by 1e18. For example, unmintFee set to 1000000000000000 means that 0.001 of the amount being unminted needs to be paid to the VendingMachine as an unminting fee on the top of the amount being unminted.

newUnmintFee

uint256 newUnmintFee

unmintFeeUpdateInitiatedTimestamp

uint256 unmintFeeUpdateInitiatedTimestamp

unmintFeeUpdateInitiator

address unmintFeeUpdateInitiator

newVendingMachine

address newVendingMachine

The address of a new vending machine. Set only when the upgrade process is pending. Once the upgrade gets finalized, the new vending machine will become an owner of TBTC v2 token.

vendingMachineUpgradeInitiatedTimestamp

uint256 vendingMachineUpgradeInitiatedTimestamp

vendingMachineUpgradeInitiator

address vendingMachineUpgradeInitiator

UnmintFeeUpdateInitiated

event UnmintFeeUpdateInitiated(uint256 newUnmintFee, uint256 timestamp)

UnmintFeeUpdated

event UnmintFeeUpdated(uint256 newUnmintFee)

VendingMachineUpgradeInitiated

event VendingMachineUpgradeInitiated(address newVendingMachine, uint256 timestamp)

VendingMachineUpgraded

event VendingMachineUpgraded(address newVendingMachine)

Minted

event Minted(address recipient, uint256 amount)

Unminted

event Unminted(address recipient, uint256 amount, uint256 fee)

only

modifier only(address authorizedCaller)

onlyAfterGovernanceDelay

modifier onlyAfterGovernanceDelay(uint256 changeInitiatedTimestamp)

constructor

constructor(contract IERC20 _tbtcV1, contract TBTC _tbtcV2, uint256 _unmintFee) public

mint

function mint(uint256 amount) external

Mints TBTC v2 to the caller from TBTC v1 with 1:1 ratio. The caller needs to have at least amount of TBTC v1 balance approved for transfer to the VendingMachine before calling this function.

Parameters

Name	Type	Description
amount	uint256	The amount of TBTC v2 to mint from TBTC v1

receiveApproval

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

Mints TBTC v2 to from address from TBTC v1 with 1:1 ratio. from address needs to have at least amount of TBTC v1 balance approved for transfer to the VendingMachine before calling this function.

This function is a shortcut for approve + mint. 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 minting TBTC v2 tokens
amount	uint256	The amount of TBTC v2 to mint from TBTC v1
token	address	TBTC v1 token address
	bytes

unmint

function unmint(uint256 amount) external

Unmints TBTC v2 from the caller into TBTC v1. Depending on unmintFee value, may require paying an additional unmint fee in TBTC v2 in addition to the amount being unminted. To see what is the value of the fee, please call unmintFeeFor(amount) function. The caller needs to have at least amount + unmintFeeFor(amount) of TBTC v2 balance approved for transfer to the VendingMachine before calling this function.

Parameters

Name	Type	Description
amount	uint256	The amount of TBTC v2 to unmint to TBTC v1

withdrawFees

function withdrawFees(address recipient, uint256 amount) external

Allows the Governance to withdraw unmint fees accumulated by VendingMachine.

Parameters

Name	Type	Description
recipient	address	The address receiving the fees
amount	uint256	The amount of fees in TBTC v2 to withdraw

initiateUnmintFeeUpdate

function initiateUnmintFeeUpdate(uint256 _newUnmintFee) external

Initiates unmint fee update process. The update process needs to be finalized with a call to finalizeUnmintFeeUpdate function after the GOVERNANCE_DELAY passes. Only unmint fee update initiator role can initiate the update.

Parameters

Name	Type	Description
_newUnmintFee	uint256	The new unmint fee

finalizeUnmintFeeUpdate

function finalizeUnmintFeeUpdate() external

Allows the contract owner to finalize unmint fee update process. The update process needs to be first initiated with a call to initiateUnmintFeeUpdate and the GOVERNANCE_DELAY needs to pass.

initiateVendingMachineUpgrade

function initiateVendingMachineUpgrade(address _newVendingMachine) external

Initiates vending machine upgrade process. The upgrade process needs to be finalized with a call to finalizeVendingMachineUpgrade function after the GOVERNANCE_DELAY passes. Only vending machine upgrade initiator role can initiate the upgrade.

Parameters

Name	Type	Description
_newVendingMachine	address	The new vending machine address

finalizeVendingMachineUpgrade

function finalizeVendingMachineUpgrade() external

Allows the contract owner to finalize vending machine upgrade process. The upgrade process needs to be first initiated with a call to initiateVendingMachineUpgrade and the GOVERNANCE_DELAY needs to pass. Once the upgrade is finalized, the new vending machine will become an owner of TBTC v2 token and all TBTC v1 held by this contract will be transferred to the new vending machine.

transferUnmintFeeUpdateInitiatorRole

function transferUnmintFeeUpdateInitiatorRole(address newInitiator) external

Transfers unmint fee update initiator role to another address. Can be called only by the current unmint fee update initiator.

Parameters

Name	Type	Description
newInitiator	address	The new unmint fee update initiator

transferVendingMachineUpgradeInitiatorRole

function transferVendingMachineUpgradeInitiatorRole(address newInitiator) external

Transfers vending machine upgrade initiator role to another address. Can be called only by the current vending machine upgrade initiator.

Parameters

Name	Type	Description
newInitiator	address	The new vending machine upgrade initiator

getRemainingUnmintFeeUpdateTime

function getRemainingUnmintFeeUpdateTime() external view returns (uint256)

Get the remaining time that needs to pass until unmint fee update can be finalized by the Governance. If the update has not been initiated, the function reverts.

getRemainingVendingMachineUpgradeTime

function getRemainingVendingMachineUpgradeTime() external view returns (uint256)

Get the remaining time that needs to pass until vending machine upgrade can be finalized by the Governance. If the upgrade has not been initiated, the function reverts.

unmintFeeFor

function unmintFeeFor(uint256 amount) public view returns (uint256)

Calculates the fee that needs to be paid to the VendingMachine to unmint the given amount of TBTC v2 back into TBTC v1.

_mint

function _mint(address tokenOwner, uint256 amount) internal