// SPDX-License-Identifier: GPL-2.0-or-later

pragma solidity >=0.8.0;

import '../libraries/Types.sol';
import './IMajorCandidates.sol';
import './IStake.sol';

/// @dev Slasher interface
/// @author Alexandas
interface ISlasher {

	/// @dev emit when governance address updated
	/// @param governance governance address
	event GovernanceUpdated(address governance);

	/// @dev emit when `Stake` contract updated
	/// @param stake `Stake` contract 
	event StakeUpdated(IStake stake);

	/// @dev emit when `MajorCandidates` contract updated
	/// @param majorCandidates `MajorCandidates` contract 
	event MajorCandidatesUpdated(IMajorCandidates majorCandidates);

	/// @dev emit when default slash amount updated
	/// @param amount slash amount
	event DefaultSlashAmountUpdated(uint256 amount);

	/// @dev emit when public notice period updated
	/// @param period public notice period
	event PublicNoticePeriodUpdated(uint256 period);

	/// @dev emit when max coefficient updated
	/// @param maxCoef max coefficient
	event MaxCoefUpdated(uint256 maxCoef);

	/// @dev emit when drafter slash reward coefficient updated
	/// @param drafterCoef drafter slash reward coefficient
	event DrafterCoefUpdated(uint64 drafterCoef);

	/// @dev emit when validator slash reward coefficient updated
	/// @param validatorCoef validator slash reward coefficient
	event ValidatorCoefUpdated(uint256 validatorCoef);

	/// @dev emit when executor slash reward coefficient updated
	/// @param executorCoef executor slash reward coefficient
	event ExecutorCoefUpdated(uint256 executorCoef);

	/// @dev emit when slash drafted
	/// @param nonce slash number
	/// @param candidate candidate address
	/// @param slashBlock slashed block in posc
	/// @param manifest node manifest
	/// @param accuracy posc accuracy
	event DraftSlash(uint256 nonce, address candidate, uint64 slashBlock, string manifest, uint64 accuracy);

	/// @dev emit when slash drafted
	/// @param nonce slash number
	event RejectSlash(uint256 nonce);

	/// @dev emit when slash drafted
	/// @param nonce slash number
	event ExecuteSlash(uint256 nonce, address executor);

	/// @dev return `Stake` contract address
	function stake() external view returns(IStake);

	/// @dev return `MajorCandidates` contract address
	function majorCandidates() external view returns(IMajorCandidates);

	/// @dev return default slash amount
	function defaultSlashAmount() external view returns(uint256);

	/// @dev return public notice period
	function publicNoticePeriod() external view returns(uint256);

	/// @dev return current slash nonce
	function nonce() external view returns(uint256);

	/// @dev return max coefficient
	function MAXCOEF() external view returns(uint64);

	/// @dev return drafter slash reward coefficient
	function drafterCoef() external view returns(uint64);

	/// @dev return validator slash reward coefficient
	function validatorCoef() external view returns(uint64);

	/// @dev return executor slash reward coefficient
	function executorCoef() external view returns(uint64);

	/// @dev return slash information at a specific nonce
	/// @param _nonce nonce number
	/// @return slash information
	function getSlashAt(uint256 _nonce) external view returns(Types.SlashInfo memory);

	/// @dev return nonce given a candidate if the candidate is in slashing
	/// @param candidate candidate address
	/// @return nonce number
	function nonceOf(address candidate) external view returns(uint256);

	/// @dev set drafter slash reward coefficient
	/// @param _drafterCoef drafter slash reward coefficient
	function setDrafterCoef(uint64 _drafterCoef) external;

	/// @dev set validator slash reward coefficient
	/// @param _validatorCoef validator slash reward coefficient
	function setValidatorCoef(uint64 _validatorCoef) external;

	/// @dev set executor slash reward coefficient
	/// @param _executorCoef executor slash reward coefficient
	function setExecutorCoef(uint64 _executorCoef) external;

	/// @dev draft a slash
	/// @param slashBlock slashed block in posc
	/// @param manifest node manifest
	/// @param accuracy posc accuracy
	/// @param signatures major candidates signatures
	function draft(uint64 slashBlock, string memory manifest, uint64 accuracy, bytes[] memory signatures) external;

	/// @dev reject a slash
	/// @param manifest node manifest
	function reject(string memory manifest) external;

	/// @dev execute a slash
	/// @param manifest node manifest
	function execute(string memory manifest) external;

	/// @dev return whether candidate is in slashing
	/// @param candidate candidate address
	/// @return whether candidate is in slashing
	function slashExists(address candidate) external view returns(bool);

	/// @dev check whether signatures is valid
	/// @param hash message hash
	/// @param signatures signatures for major candidates
	/// @param signers major candidate signers
	function checkNSignatures(bytes32 hash, bytes[] memory signatures) external view returns(address[] memory signers);

}