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

pragma solidity >=0.8.0;

import './IElection.sol';
import './IMajorCandidates.sol';
import './ISlasher.sol';
import './IPools.sol';
import './ICandidateRegistry.sol';

/// @dev Stake interface
/// @author Alexandas
interface IStake is IPools, ICandidateRegistry {

	/// @dev emit when `Election` contract changed
	/// @param election `Election` contract address
	event ElectionUpdated(IElection election);

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

	/// @dev emit when `Slasher` contract updated
	/// @param slasher `Slasher` contract 
	event SlasherUpdated(ISlasher slasher);

	/// @dev emit when minimum stake updated
	/// @param amount minimum stake
	event MinStakeUpdated(uint256 amount);

	/// @dev emit when stake frozen period updated
	/// @param period stake frozen period
	event StakeFrozenPeriodUpdated(uint256 period);

	/// @dev emit when claim frozen period updated
	/// @param period claim frozen period
	event ClaimFrozenPeriodUpdated(uint256 period);

	/// @dev emit when a candidate upgraded
	/// @param candidate candidate address
	/// @param fromGrade from grade
	/// @param toGrade to grade
	event Upgrade(address candidate, Types.Grade fromGrade, Types.Grade toGrade);

	/// @dev emit when a candidate downgraded
	/// @param candidate candidate address
	/// @param fromGrade from grade
	/// @param toGrade to grade
	event Downgrade(address candidate, Types.Grade fromGrade, Types.Grade toGrade);

	/// @dev emit when a candidate staked tokens
	/// @param from token consumer
	/// @param candidate candidate address
	/// @param amount token amount
	event Stake(address from, address candidate, uint256 amount);

	/// @dev emit when a candidate withdraw tokens
	/// @param candidate candidate address
	/// @param to token receiver
	/// @param amount token amount
	event Withdrawn(address candidate, address to, uint256 amount);

	/// @dev emit when a candidate claimed reward
	/// @param candidate candidate address
	/// @param to token receiver
	/// @param pending token amount
	event Claimed(address candidate, address to, uint256 pending);

	/// @dev emit when a candidate quit from the protocol
	/// @param grade candidate grade
	/// @param candidate candidate address
	event Quit(Types.Grade grade, address candidate);

	/// @dev emit when a candidate allocate reward for the voters
	/// @param candidate candidate address
	/// @param amount token amount
	event VoterAllocated(address candidate, uint256 amount);

	/// @dev emit when the reward for a candidate
	/// @param candidate candidate address
	/// @param amount token amount
	event CandidateAllocated(address candidate, uint256 amount);

	/// @dev emit when the vote reward coefficient updated
	/// @param coef vote reward coefficient
	event VoteRewardCoefUpdated(uint256 coef);

	/// @dev emit when drafted a slash
	/// @param candidate candidate address
	/// @param pendingSlash pending slash amount
	event DraftSlash(address candidate, uint256 pendingSlash);

	/// @dev emit when rejected a slash
	/// @param candidate candidate address
	/// @param pendingSlash pending slash amount
	event RejectSlash(address candidate, uint256 pendingSlash);

	/// @dev emit when executed a slash
	/// @param candidate candidate address
	/// @param pendingSlash pending slash amount
	/// @param beneficiaries slash reward beneficiaries
	/// @param amounts slash reward amounts
	/// @param burned burned amount
	event ExcuteSlash(address candidate, uint256 pendingSlash, address[] beneficiaries, uint256[] amounts, uint256 burned);

	/// @dev return `Election` contract
	function election() external view returns(IElection);

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

	/// @dev return `Slasher` contract
	function slasher() external returns(ISlasher);

	/// @dev candidate stake tokens
	/// @param amount token amount
	function stake(uint256 amount) external;

	/// @dev register a candidate and stake tokens
	/// @param amount token amount
	/// @param manifest node manifest
	function registerAndStake(uint256 amount, string memory manifest) external;

	/// @dev candidate quit from the protocol
	/// @param to token receiver
	function quit(address to) external;

	/// @dev candidate claim reward from the protocol
	/// @param to token receiver
	function claim(address to) external;

	/// @dev candidate withdraw the tokens and claim reward from the protocol
	/// @param amount token amount
	/// @param to token receiver
	// function withdrawAndClaim(uint256 amount, address to) external;

	/// @dev return pending reward for a specific candidate
	/// @param candidate candidate address
	/// @return pending reward for the candidate
	function pendingReward(address candidate) external view returns (uint256 pending);

	/// @dev set voter slash reward coefficient
	/// @param coef voter reward coefficient
	function setVoteRewardCoef(uint256 coef) external;

	/// @dev set allocate the reward to voters from the candidate
	/// @param candidate candidate address
	function voterAllocate(address candidate) external;

	/// @dev return voter reward coefficient for a specific candidate
	/// @param candidate candidate address
	/// @return coef voter reward coefficient
	function voteRewardCoef(address candidate) external view returns (uint256 coef);

	/// @dev return pending voters allocation for a specific candidate
	/// @param candidate candidate address
	/// @return pending pending voters allocation
	function pendingVoterAllocation(address candidate) external view returns (uint256 pending);

	/// @dev return pending candidate allocation
	/// @param candidate candidate address
	/// @return pending pending candidate allocation
	function pendingCandidateAllocation(address candidate) external view returns (uint256 pending);

	/// @dev upgrade a candidate
	/// @param candidate candidate address
	function upgrade(address candidate) external;

	/// @dev downgrade a candidate
	/// @param candidate candidate address
	function downgrade(address candidate) external;

	/// @dev draft a slash for a candidate
	/// @param candidate candidate address
	/// @param amount slash amount
	/// @return pendingSlash real slash amount
	function draftSlash(address candidate, uint256 amount) external returns(uint256 pendingSlash);

	/// @dev reject a slash for a candidate
	/// @param candidate candidate address
	/// @param pendingSlash real slash amount
	function rejectSlash(address candidate, uint256 pendingSlash) external;

	/// @dev executed a slash for a candiate
	/// @param candidate candidate address
	/// @param slash slash amount
	/// @param beneficiaries slash reward beneficiaries
	/// @param amounts slash reward amounts
	/// @param burned burned amount
	function executeSlash(
		address candidate, 
		uint256 slash,
		address[] memory beneficiaries, 
		uint256[] memory amounts,
		uint256 burned
	) external;
}