SystemDebtEngine

https://github.com/Into-the-Fathom/fathom-stablecoin-smart-contracts/blob/master/contracts/main/stablecoin-core/SystemDebtEngine.sol

The SystemDebtEngine contract is responsible for managing the system's surplus and bad debt. It acts as the central financial manager within a FXD system, specifically designed to handle scenarios where debts become unmanageable or when excess funds are accumulated beyond what is required for the system's stability.

Storage Variables

• bookKeeper: Reference to the IBookKeeper contract, which handles the ledger of all financial operations within the system.

• surplusBuffer: The minimum amount of surplus (in RAD, 10^45) that should always be maintained in the system to cover unexpected liabilities.

• live: A flag indicating whether the system is active (1) or has been shut down (0).

Functions

• withdrawCollateralSurplus(bytes32 _collateralPoolId, address _to, uint256 _amount): Allows the owner to withdraw surplus collateral from a specific collateral pool.

• withdrawStablecoinSurplus(address _to, uint256 _value): Allows the owner to withdraw surplus stablecoins from the system, provided there is no outstanding bad debt and the withdrawal does not drop the balance below the surplus buffer.

• setSurplusBuffer(uint256 _data): Sets the minimum surplus buffer required in the system.

• settleSystemBadDebt(uint256 _value): Allows anyone to settle bad debt using the surplus funds available in the system.

• cage(): Can be called by the owner or a designated emergency role to shut down the system in case of a significant issue. It settles as much bad debt as possible with available funds during the shutdown.

• pause(): Pauses all critical functionalities of the contract, preventing state-changing operations.

• unpause(): Resumes all operations after a pause.

Events

• LogSetSurplusBuffer(address indexed _caller, uint256 _data): Emitted when the surplus buffer is updated.

• LogCage(): Emitted when the system is shut down.