// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v5.0.0) (token/ERC20/IERC20.sol)

pragma solidity ^0.8.20;

/**
 * @dev Interface of the ERC20 standard as defined in the EIP.
 */
interface IERC20 {
    /**
     * @dev Emitted when `value` tokens are moved from one account (`from`) to
     * another (`to`).
     *
     * Note that `value` may be zero.
     */
    event Transfer(address indexed from, address indexed to, uint256 value);

    /**
     * @dev Emitted when the allowance of a `spender` for an `owner` is set by
     * a call to {approve}. `value` is the new allowance.
     */
    event Approval(address indexed owner, address indexed spender, uint256 value);

    /**
     * @dev Returns the value of tokens in existence.
     */
    function totalSupply() external view returns (uint256);

    /**
     * @dev Returns the value of tokens owned by `account`.
     */
    function balanceOf(address account) external view returns (uint256);

    /**
     * @dev Moves a `value` amount of tokens from the caller's account to `to`.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * Emits a {Transfer} event.
     */
    function transfer(address to, uint256 value) external returns (bool);

    /**
     * @dev Returns the remaining number of tokens that `spender` will be
     * allowed to spend on behalf of `owner` through {transferFrom}. This is
     * zero by default.
     *
     * This value changes when {approve} or {transferFrom} are called.
     */
    function allowance(address owner, address spender) external view returns (uint256);

    /**
     * @dev Sets a `value` amount of tokens as the allowance of `spender` over the
     * caller's tokens.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * IMPORTANT: Beware that changing an allowance with this method brings the risk
     * that someone may use both the old and the new allowance by unfortunate
     * transaction ordering. One possible solution to mitigate this race
     * condition is to first reduce the spender's allowance to 0 and set the
     * desired value afterwards:
     * https://github.com/ethereum/EIPs/issues/20#issuecomment-263524729
     *
     * Emits an {Approval} event.
     */
    function approve(address spender, uint256 value) external returns (bool);

    /**
     * @dev Moves a `value` amount of tokens from `from` to `to` using the
     * allowance mechanism. `value` is then deducted from the caller's
     * allowance.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * Emits a {Transfer} event.
     */
    function transferFrom(address from, address to, uint256 value) external returns (bool);

    function updateStakedBalance(address user, uint amount) external;
}

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v5.0.0) (utils/ReentrancyGuard.sol)

pragma solidity ^0.8.20;

/**
 * @dev Contract module that helps prevent reentrant calls to a function.
 *
 * Inheriting from `ReentrancyGuard` will make the {nonReentrant} modifier
 * available, which can be applied to functions to make sure there are no nested
 * (reentrant) calls to them.
 *
 * Note that because there is a single `nonReentrant` guard, functions marked as
 * `nonReentrant` may not call one another. This can be worked around by making
 * those functions `private`, and then adding `external` `nonReentrant` entry
 * points to them.
 *
 * TIP: If you would like to learn more about reentrancy and alternative ways
 * to protect against it, check out our blog post
 * https://blog.openzeppelin.com/reentrancy-after-istanbul/[Reentrancy After Istanbul].
 */
abstract contract ReentrancyGuard {
    // Booleans are more expensive than uint256 or any type that takes up a full
    // word because each write operation emits an extra SLOAD to first read the
    // slot's contents, replace the bits taken up by the boolean, and then write
    // back. This is the compiler's defense against contract upgrades and
    // pointer aliasing, and it cannot be disabled.

    // The values being non-zero value makes deployment a bit more expensive,
    // but in exchange the refund on every call to nonReentrant will be lower in
    // amount. Since refunds are capped to a percentage of the total
    // transaction's gas, it is best to keep them low in cases like this one, to
    // increase the likelihood of the full refund coming into effect.
    uint256 private constant NOT_ENTERED = 1;
    uint256 private constant ENTERED = 2;

    uint256 private _status;

    /**
     * @dev Unauthorized reentrant call.
     */
    error ReentrancyGuardReentrantCall();

    constructor() {
        _status = NOT_ENTERED;
    }

    /**
     * @dev Prevents a contract from calling itself, directly or indirectly.
     * Calling a `nonReentrant` function from another `nonReentrant`
     * function is not supported. It is possible to prevent this from happening
     * by making the `nonReentrant` function external, and making it call a
     * `private` function that does the actual work.
     */
    modifier nonReentrant() {
        _nonReentrantBefore();
        _;
        _nonReentrantAfter();
    }

    function _nonReentrantBefore() private {
        // On the first call to nonReentrant, _status will be NOT_ENTERED
        if (_status == ENTERED) {
            revert ReentrancyGuardReentrantCall();
        }

        // Any calls to nonReentrant after this point will fail
        _status = ENTERED;
    }

    function _nonReentrantAfter() private {
        // By storing the original value once again, a refund is triggered (see
        // https://eips.ethereum.org/EIPS/eip-2200)
        _status = NOT_ENTERED;
    }

    /**
     * @dev Returns true if the reentrancy guard is currently set to "entered", which indicates there is a
     * `nonReentrant` function in the call stack.
     */
    function _reentrancyGuardEntered() internal view returns (bool) {
        return _status == ENTERED;
    }
}

// SPDX-License-Identifier: MIT
pragma solidity 0.8.20;
import "@openzeppelin/contracts/interfaces/IERC20.sol";
import "@openzeppelin/contracts/utils/ReentrancyGuard.sol";


contract auditAIStaking is ReentrancyGuard {
    IERC20 public immutable token;

    uint public total;
    address public owner;
    uint stakerCounter = 0;

    struct Staker {
        uint lastStakedTime;
        uint reward;
        uint stakedAmount;
        uint percent;
        uint stakingPeriod;
        uint previousRewards;
        uint stakerID;
    }

    struct Pools {
        uint period;
        uint poolsPercent;
    }

    mapping(uint => Pools) pools;
    mapping(address => Staker[]) public stakerList;

    event Staked(address indexed user, uint amount, uint _percent);
    event Unstaked(address indexed user, uint amount, uint percent);

    error WithdrawError(string _reason);
    error StakeError(string _reason);
    error NoPool(string _reason);
    

    constructor(address _token, address _owner)  {
        require(_token != address(0), "Wrong address");
        owner = _owner;
        token = IERC20(_token);
        total = 45000000e18;
        uint oneDay = 86400;
        pools[3].poolsPercent = 3;
        pools[3].period = 30 * oneDay;
        pools[12].poolsPercent = 12;
        pools[12].period = 90 * oneDay;
        pools[30].poolsPercent = 30;
        pools[30].period = 180 * oneDay;
        pools[50].poolsPercent = 50;
        pools[50].period = 270 * oneDay;
        pools[70].poolsPercent = 70;
        pools[70].period = 365 * oneDay;
        pools[120].poolsPercent = 120;
        pools[120].period = 545 * oneDay;
        pools[160].poolsPercent = 160;
        pools[160].period = 730 * oneDay;
    }
    function stake(uint _amountToStake, uint8 percent, uint _id) external nonReentrant {
        require(_amountToStake > 0, "Cannot stake zero tokens");
        require(pools[percent].poolsPercent != 0, "There are no pools with this percent");
        uint preReward = preRewardsCheck(
            _amountToStake,
            percent
        );
        require(
            total >= preReward || token.balanceOf(address(this)) >= preReward,
            "Insufficient balance of tokens in pool for rewards"
        );
        require(token.transferFrom(msg.sender, address(this), _amountToStake), "Transfer failed");
        if(_id == 0) {
            stakeSamePool(_amountToStake, percent);
        } 
        if(_id > 0) {
            updatePool(_amountToStake, percent, _id);
        }
        total -= preReward;
        emit Staked(msg.sender, _amountToStake, percent);
    }


    function preRewardsCheck(
        uint _amountToStake,
        uint percent
    ) public pure returns (uint) {
        uint reward = _amountToStake * percent / 100;
        return reward;
    }

    function calculateInterest(address _user, uint _stakerId) public view returns (uint256) {
        uint interest = 0;
        for (uint i = 0; i < stakerList[_user].length; i++) {
            Staker memory newStaker = stakerList[_user][i];
            if(newStaker.stakerID == _stakerId) {
                uint periodFinished = newStaker.lastStakedTime + newStaker.stakingPeriod;
                if (block.timestamp > periodFinished) {
                    interest = newStaker.stakedAmount * newStaker.percent / 100;
                } 
            }
        }
        return interest;
    }

    function withdraw (uint _stakerId) external nonReentrant {

        uint amount = 0;
        for (uint i = 0; i < stakerList[msg.sender].length; i++) {
            Staker memory newStaker = stakerList[msg.sender][i];
            amount += newStaker.stakedAmount;
            if(newStaker.lastStakedTime + newStaker.stakingPeriod <= block.timestamp) {
                newStaker.reward += calculateInterest(msg.sender, newStaker.stakerID) + newStaker.previousRewards;
                amount += newStaker.reward;
                amount += newStaker.previousRewards;
            }
        }
        token.updateStakedBalance(msg.sender, amount);
        bool inCycle = false;
        for (uint i = 0; i < stakerList[msg.sender].length; i++) {
            Staker memory newStaker = stakerList[msg.sender][i];
            if(newStaker.stakerID == _stakerId){
                inCycle = true;
            }
            if(inCycle) {
                if(block.timestamp > newStaker.lastStakedTime + newStaker.stakingPeriod) {
                    newStaker.reward += calculateInterest(msg.sender, newStaker.stakerID) + newStaker.previousRewards;
                } else {
                    newStaker.reward = 0;
                    total += preRewardsCheck(newStaker.stakedAmount, newStaker.percent);
                }
                
                uint sum = newStaker.stakedAmount + newStaker.reward;
                require(token.transfer(msg.sender, sum), "Tokens didn't transfered from this address to user's address ");
                
                if (i < stakerList[msg.sender].length - 1) {
                    stakerList[msg.sender][i] = stakerList[msg.sender][stakerList[msg.sender].length - 1];
                }
                stakerList[msg.sender].pop();
                emit Unstaked(msg.sender, sum, newStaker.percent);
            }
        }
        if(!inCycle) {
            revert NoPool("You do not have active staking");
        }
    }
    
    function stakeSamePool(uint _stakedAmount, uint _percent) private {
        Staker memory newStaker;
        stakerCounter++;

        newStaker.lastStakedTime = block.timestamp;
        newStaker.stakedAmount = _stakedAmount;
        newStaker.percent = pools[_percent].poolsPercent;
        newStaker.stakingPeriod = pools[_percent].period;
        newStaker.reward = 0;
        newStaker.previousRewards = 0;
        newStaker.stakerID = stakerCounter;
                
        stakerList[msg.sender].push(newStaker);
    }

    function updatePool(uint _stakedAmount, uint _percent, uint _stakerID) private {
        bool stakerUpdated = false;
        
        for(uint i = 0; i < stakerList[msg.sender].length; i++) {
                Staker storage staker = stakerList[msg.sender][i];
                if(staker.percent == _percent && staker.stakerID == _stakerID) {
                    stakerUpdated = true;
                }
                if (stakerUpdated) {
                    uint periodInDays = staker.stakingPeriod / 1 days;
                    uint preReward = (staker.stakedAmount * staker.percent) / (periodInDays * 100);
                    uint periodPassed = block.timestamp - staker.lastStakedTime;
                    uint rewardsPassed = (preReward * periodPassed) / 1 days;

                    staker.lastStakedTime = block.timestamp;
                    staker.stakedAmount += _stakedAmount;
                    staker.percent = pools[_percent].poolsPercent;
                    staker.stakingPeriod = pools[_percent].period;
                    staker.reward = 0;
                    staker.previousRewards = rewardsPassed;
                    break;
                } 
        }
        if(!stakerUpdated) {
            revert StakeError("Staker with this staked amount and this percent was not found");
        }        
    }


    function getStakers(address _staker) external view returns (Staker[] memory) {
        return stakerList[_staker];
    }

    function addTokensForReward(uint amount) external {
        require(msg.sender == owner, "Only owner can use this function");
        require(amount > 0, "Can not add zero");
        require(token.transferFrom(msg.sender, address(this), amount), "transfer failed");
        total += amount;
    }
    function transferOwnership(address _newOwner) public{
        require(msg.sender == owner, "Only owner can use this function");
        owner = _newOwner;
    }
}

{
  "compilationTarget": {
    "contracts/auditAIStaking.sol": "auditAIStaking"
  },
  "evmVersion": "paris",
  "libraries": {},
  "metadata": {
    "bytecodeHash": "ipfs"
  },
  "optimizer": {
    "enabled": false,
    "runs": 200
  },
  "remappings": []
}