# Liquidation Smart Contract Interface

## Contract interface to implement

Note for all calls from Karura/Acala runtime, the `sender` will be `0x31382d495fed5a6820d9c07e8b6efe8d2166e9dd`, which liquidation contracts should check for security reason.

- `liquidate(address collateral, address repay_dest, uint256 amount, uint256 - min_repayment)`
- `onCollateralTransfer(address collateral, uint256 amount)`
- `onRepaymentRefund(address collateral, uint256 repayment)`

Note that gas fee will be charged from contract address, which should be guaranteed to have sufficient balance.

## Liquidation process on Karura/Acala

1. Call `liquidate` to try to liquidate.
2. If can liquidate with `min_repayment` requirements, liquidation contracts need to transfer sufficient repayment to `repay_dest`.
3. If sufficient repayment recieved, collateral will be transferred to liquidation contract addr, and then `on_collateral_transfer` will be called. If not, repayment will be refunded and `onRepaymentRefund` will be called.