# AuRa block rewards

Nethermind's plugin system abstracts consensus engine in modular components.

Each consensus must implement [`IRewardCalculator`](https://github.com/NethermindEth/nethermind/blob/90640a8f62e96a84af5234b17deae9898c702dd4/src/Nethermind/Nethermind.Consensus/Rewards/IRewardCalculator.cs#L21)

public interface IRewardCalculator {
    BlockReward[] CalculateRewards(Block block);
}

Where [`BlockReward`](https://github.com/NethermindEth/nethermind/blob/90640a8f62e96a84af5234b17deae9898c702dd4/src/Nethermind/Nethermind.Consensus/Rewards/BlockReward.cs#L22)

BlockReward {
    public Address Address
    public UInt256 Value
    public BlockRewardType RewardType
}

public enum BlockRewardType {
    Block = 0,
    Uncle = 1,
    EmptyStep = 2,
    External = 3
}

Specific implementation for AuRa consensus [`AuRaRewardCalculator.CalculateRewards`](https://github.com/NethermindEth/nethermind/blob/90640a8f62e96a84af5234b17deae9898c702dd4/src/Nethermind/Nethermind.Consensus.AuRa/Rewards/AuRaRewardCalculator.cs#L72) simplified code below.

- Calls onchain BlockReward contract and gets final rewards amounts
- Whatever those values are, apply to the block rewards

var (addresses, rewards) = contract.Reward(block.Header, beneficiaries, kinds);

for (int index = 0; index < addresses.Length; index++) {
    new BlockReward(addresses[index], rewards[index], BlockRewardType.External);
}

Jumping to [`BlockRewardAuRaBase.reward`](https://github.com/poanetwork/posdao-contracts/blob/0315e8ee854cb02d03f4c18965584a74f30796f7/contracts/base/BlockRewardAuRaBase.sol#L234) contract function, the header docs are a useful intro.

/// @dev Called by the validator's node when producing and closing a block,
/// see https://openethereum.github.io/Block-Reward-Contract.html.
/// This function performs all of the automatic operations needed for controlling numbers revealing by validators,
/// accumulating block producing statistics, starting a new staking epoch, snapshotting staking amounts
/// for the upcoming staking epoch, rewards distributing at the end of a staking epoch, and minting
/// native coins needed for the `erc-to-native` bridge.
/// The function has unlimited gas (according to OpenEthereum and/or Nethermind client code).
function reward(address[] calldata benefactors, uint16[] calldata kind)
    external
    onlySystem
    returns(address[] memory receiversNative, uint256[] memory rewardsNative)
{