// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v5.0.1) (utils/Context.sol)

pragma solidity ^0.8.20;

/**
 * @dev Provides information about the current execution context, including the
 * sender of the transaction and its data. While these are generally available
 * via msg.sender and msg.data, they should not be accessed in such a direct
 * manner, since when dealing with meta-transactions the account sending and
 * paying for execution may not be the actual sender (as far as an application
 * is concerned).
 *
 * This contract is only required for intermediate, library-like contracts.
 */
abstract contract Context {
    function _msgSender() internal view virtual returns (address) {
        return msg.sender;
    }

    function _msgData() internal view virtual returns (bytes calldata) {
        return msg.data;
    }

    function _contextSuffixLength() internal view virtual returns (uint256) {
        return 0;
    }
}

// SPDX-License-Identifier: UNLICENSED
pragma solidity ^0.8.24;

import '@openzeppelin/contracts/utils/ReentrancyGuard.sol';
import '@openzeppelin/contracts/access/Ownable.sol';
import '@openzeppelin/contracts/utils/Pausable.sol';

interface IERC20 {
  function transfer(address recipient, uint256 amount) external returns (bool);

  function transferFrom(
    address sender,
    address recipient,
    uint256 amount
  ) external returns (bool);

  function balanceOf(address account) external view returns (uint256);

  function approve(address spender, uint256 value) external returns (bool);
}

contract NodeStaking is ReentrancyGuard, Ownable, Pausable {
  IERC20 public stakingToken;

  struct Stake {
    uint256 amount;
    uint256 startTime;
    uint256 rewardPaid;
  }

  mapping(address => Stake[]) public stakes;
  mapping(address => uint256) public totalUserRewards;

  address[] public stakers;
  mapping(address => bool) public isStaker;

  uint256 public totalRewards = 0;

  uint256 public totalStaked;

  uint256 public earlyUnstakePenality = 30;

  uint256 public maxTotalStaked = 10_000_000 * (10 ** 18); // Example: 10 million tokens
  uint256 public maxPerWallet = 1_000 * (10 ** 18); // Example: 1,000 tokens per wallet

  uint256 public constant stakingPeriod = 30 days;
  address public constant deadWallet =
    0x000000000000000000000000000000000000dEaD;

  event Staked(address indexed user, uint256 amount, uint256 index);
  event Unstaked(address indexed user, uint256 amount, uint256 index);
  event RewardPaid(address indexed user, uint256 reward);
  event Migrated(
    address indexed newStakingContract,
    uint256 tokenAmount,
    uint256 ethAmount
  );

  /* Initializes the constructure with the staking token set and owner */
  constructor(address _stakingToken) Ownable(_msgSender()) {
    stakingToken = IERC20(_stakingToken);
  }

  /* Sets the staking token */
  function setStakingToken(address _stakingToken) external onlyOwner {
    require(_stakingToken != address(0), 'Invalid address');

    stakingToken = IERC20(_stakingToken);
  }

  /* Sets the maximum total staked amount */
  function setMaxTotalStaked(uint256 _maxTotalStaked) external onlyOwner {
    maxTotalStaked = _maxTotalStaked;
  }

  /* Sets the maximum staked amount per wallet */
  function setMaxPerWallet(uint256 _maxPerWallet) external onlyOwner {
    maxPerWallet = _maxPerWallet;
  }

  /* Sets the pause state of the contract */
  function setPaused(bool _paused) external onlyOwner {
    require(_paused != paused(), 'Already in the requested state');

    if (_paused) {
      _pause();
    } else {
      _unpause();
    }
  }

  /* Migrates the staking contract to a new contract */
  function migrate(address _newStakingContract) external onlyOwner {
    require(_newStakingContract != address(0), 'Invalid address');

    uint256 contractTokenBalance = stakingToken.balanceOf(address(this));
    require(
      stakingToken.transfer(_newStakingContract, contractTokenBalance),
      'Failed to transfer tokens to owner'
    );

    uint256 contractETHBalance = address(this).balance;
    (bool sent, ) = _newStakingContract.call{value: contractETHBalance}('');

    require(sent, 'Failed to transfer ETH');

    emit Migrated(
      _newStakingContract,
      contractTokenBalance,
      contractETHBalance
    );
  }

  function stake(uint256 _amount) external nonReentrant whenNotPaused {
    require(_amount > 0, 'Amount must be greater than 0');
    require(totalStaked + _amount <= maxTotalStaked, 'Staking limit exceeded');

    uint256 walletStaked = getWalletStaked(msg.sender);
    require(walletStaked + _amount <= maxPerWallet, 'Staking limit exceeded');

    if(!isStaker[msg.sender]) {
      stakers.push(msg.sender);
      isStaker[msg.sender] = true;
    }

    bool success = stakingToken.transferFrom(msg.sender, address(this), _amount);
    require(success, 'Failed to transfer tokens');
    stakes[msg.sender].push(Stake(_amount, block.timestamp, 0));
    totalStaked += _amount;

    emit Staked(msg.sender, _amount, stakes[msg.sender].length - 1);
  }

  function unstake(uint256 _index, uint256 _amount) external nonReentrant {
    require(_index < stakes[msg.sender].length, 'Invalid stake index');

    Stake storage userStake = stakes[msg.sender][_index];

    require(
      block.timestamp >= userStake.startTime + stakingPeriod,
      'Stake is still locked'
    );

    require(userStake.amount >= _amount, 'Insufficient staked amount');

    uint256 reward = _claimRewards(msg.sender, _index);

    if(reward > 0) {
      (bool sent, ) = payable(msg.sender).call{value: reward}('');
      require(sent, 'Failed to send Ether');

      emit RewardPaid(msg.sender, reward);
    }

    userStake.amount -= _amount;
    totalStaked -= _amount;

    if (userStake.amount == 0) {
      removeStake(msg.sender, _index);
    }

    bool success = stakingToken.transfer(msg.sender, _amount);
    require(success, 'Failed to transfer tokens');
    emit Unstaked(msg.sender, _amount, _index);
  }

  function earlyUnstake(uint256 _index, uint256 _amount) external nonReentrant {
    require(_index < stakes[msg.sender].length, 'Invalid stake index');

    Stake storage userStake = stakes[msg.sender][_index];
    require(userStake.amount >= _amount, 'Insufficient staked amount');

    uint256 timeElapsed = block.timestamp - userStake.startTime;
    require(
      timeElapsed < stakingPeriod,
      'Stake is not in early unstake period'
    );

    uint256 reward = _claimRewards(msg.sender, _index);

    if(reward > 0) {
      (bool sent, ) = payable(msg.sender).call{value: reward}('');
      require(sent, 'Failed to send Ether');

      emit RewardPaid(msg.sender, reward);
    }

    // Calculate the penalty fee, which linearly decreases from 50% to 0% over the lock-up period
    uint256 penaltyPercentage = earlyUnstakePenality -
      ((timeElapsed * earlyUnstakePenality) / stakingPeriod);
    uint256 penaltyAmount = (_amount * penaltyPercentage) / 100;

    // Apply the penalty
    uint256 returnAmount = _amount - penaltyAmount;

    // Update the stake and total staked amount
    userStake.amount -= _amount;
    totalStaked -= _amount;

    // Burn the penalty amount
    bool successBurn = stakingToken.transfer(deadWallet, penaltyAmount);
    require(successBurn, 'Failed to burn tokens');

    // Return the remaining tokens to the user
    bool sucessUnstake = stakingToken.transfer(msg.sender, returnAmount);
    require(sucessUnstake, 'Failed to transfer tokens');

    // Remove the stake if it's fully unstaked
    if (userStake.amount == 0) {
      removeStake(msg.sender, _index);
    }

    emit Unstaked(msg.sender, returnAmount, _index);
  }

  function _claimRewards(
    address user,
    uint256 index
  ) private returns (uint256) {
    require(index < stakes[user].length, 'Invalid stake index');

    Stake storage userStake = stakes[user][index];
    uint256 reward = calculateReward(user, index);

    if (reward > 0) {
      userStake.rewardPaid += reward;
      totalUserRewards[user] += reward;
      totalRewards += reward;
    }

    return reward;
  }

  function claimRewards() external nonReentrant {
    uint256 stakeCount = stakes[msg.sender].length;
    require(stakeCount > 0, 'No stakes available');

    uint256 totalReward = 0;
    for (uint256 i = 0; i < stakeCount; i++) {
      totalReward += _claimRewards(msg.sender, i); // Aggregate rewards
    }

    if(totalReward <= 0) {
      return;
    }

    (bool sent, ) = payable(msg.sender).call{value: totalReward}('');
    require(sent, 'Failed to send Ether');

    emit RewardPaid(msg.sender, totalReward);
  }

  function getWalletStaked(address _user) public view returns (uint256) {
    uint256 walletStaked = 0;

    for (uint256 i = 0; i < stakes[_user].length; i++) {
      walletStaked += stakes[_user][i].amount;
    }

    return walletStaked;
  }

  function getWalletReward(address _user) public view returns (uint256) {
    uint256 walletReward = 0;

    for (uint256 i = 0; i < stakes[_user].length; i++) {
      walletReward += stakes[_user][i].rewardPaid;
    }

    return walletReward;
  }

  function getWalletStakes(address _user) public view returns (Stake[] memory) {
    return stakes[_user];
  }

  function getWalletClaimableRewards(
    address _user
  ) public view returns (uint256 totalClaimable) {
    totalClaimable = 0;
    for (uint256 i = 0; i < stakes[_user].length; i++) {
      uint256 reward = calculateReward(_user, i);
      totalClaimable += reward;
    }
  }

  function calculateAllPendingRewards() public view returns (uint256 totalClaimable) {
    totalClaimable = 0;
    for (uint256 i = 0; i < stakers.length; i++) {
      address staker = stakers[i];
      totalClaimable += getWalletClaimableRewards(staker);
    }
  }

  function calculateReward(
    address _user,
    uint256 _index
  ) public view returns (uint256) {
    Stake storage userStake = stakes[_user][_index];
    uint256 stakeDuration = block.timestamp - userStake.startTime;
    if (stakeDuration > stakingPeriod) {
      stakeDuration = stakingPeriod; // Cap the stake duration to the lock-up period for reward calculation
    }
    // Scale the numerator before dividing
    uint256 scaledReward = (address(this).balance *
      userStake.amount *
      stakeDuration) / stakingPeriod;
    uint256 reward = scaledReward / totalStaked;

    if(userStake.rewardPaid > reward) {
      return 0;
    }

    return reward - userStake.rewardPaid; // Assuming rewardPaid is correctly managed elsewhere
  }

  function getUserStakingDetails(
    address _user
  )
    public
    view
    returns (
      uint256 _totalStaked,
      uint256 totalRewardsInEth,
      uint256[] memory timeElapsedPerStake
    )
  {
    _totalStaked = 0;
    totalRewardsInEth = 0;
    timeElapsedPerStake = new uint256[](stakes[_user].length);

    for (uint256 i = 0; i < stakes[_user].length; i++) {
      _totalStaked += stakes[_user][i].amount;
      totalRewardsInEth += calculateReward(_user, i); // This should return ETH rewards
      timeElapsedPerStake[i] = block.timestamp - stakes[_user][i].startTime;
    }
  }

  function removeStake(address _user, uint256 _index) private {
    require(_index < stakes[_user].length, 'Invalid stake index');

    stakes[_user][_index] = stakes[_user][stakes[_user].length - 1];
    stakes[_user].pop();
  }

  receive() external payable {}
}

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

pragma solidity ^0.8.20;

import {Context} from "../utils/Context.sol";

/**
 * @dev Contract module which provides a basic access control mechanism, where
 * there is an account (an owner) that can be granted exclusive access to
 * specific functions.
 *
 * The initial owner is set to the address provided by the deployer. This can
 * later be changed with {transferOwnership}.
 *
 * This module is used through inheritance. It will make available the modifier
 * `onlyOwner`, which can be applied to your functions to restrict their use to
 * the owner.
 */
abstract contract Ownable is Context {
    address private _owner;

    /**
     * @dev The caller account is not authorized to perform an operation.
     */
    error OwnableUnauthorizedAccount(address account);

    /**
     * @dev The owner is not a valid owner account. (eg. `address(0)`)
     */
    error OwnableInvalidOwner(address owner);

    event OwnershipTransferred(address indexed previousOwner, address indexed newOwner);

    /**
     * @dev Initializes the contract setting the address provided by the deployer as the initial owner.
     */
    constructor(address initialOwner) {
        if (initialOwner == address(0)) {
            revert OwnableInvalidOwner(address(0));
        }
        _transferOwnership(initialOwner);
    }

    /**
     * @dev Throws if called by any account other than the owner.
     */
    modifier onlyOwner() {
        _checkOwner();
        _;
    }

    /**
     * @dev Returns the address of the current owner.
     */
    function owner() public view virtual returns (address) {
        return _owner;
    }

    /**
     * @dev Throws if the sender is not the owner.
     */
    function _checkOwner() internal view virtual {
        if (owner() != _msgSender()) {
            revert OwnableUnauthorizedAccount(_msgSender());
        }
    }

    /**
     * @dev Leaves the contract without owner. It will not be possible to call
     * `onlyOwner` functions. Can only be called by the current owner.
     *
     * NOTE: Renouncing ownership will leave the contract without an owner,
     * thereby disabling any functionality that is only available to the owner.
     */
    function renounceOwnership() public virtual onlyOwner {
        _transferOwnership(address(0));
    }

    /**
     * @dev Transfers ownership of the contract to a new account (`newOwner`).
     * Can only be called by the current owner.
     */
    function transferOwnership(address newOwner) public virtual onlyOwner {
        if (newOwner == address(0)) {
            revert OwnableInvalidOwner(address(0));
        }
        _transferOwnership(newOwner);
    }

    /**
     * @dev Transfers ownership of the contract to a new account (`newOwner`).
     * Internal function without access restriction.
     */
    function _transferOwnership(address newOwner) internal virtual {
        address oldOwner = _owner;
        _owner = newOwner;
        emit OwnershipTransferred(oldOwner, newOwner);
    }
}

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

pragma solidity ^0.8.20;

import {Context} from "../utils/Context.sol";

/**
 * @dev Contract module which allows children to implement an emergency stop
 * mechanism that can be triggered by an authorized account.
 *
 * This module is used through inheritance. It will make available the
 * modifiers `whenNotPaused` and `whenPaused`, which can be applied to
 * the functions of your contract. Note that they will not be pausable by
 * simply including this module, only once the modifiers are put in place.
 */
abstract contract Pausable is Context {
    bool private _paused;

    /**
     * @dev Emitted when the pause is triggered by `account`.
     */
    event Paused(address account);

    /**
     * @dev Emitted when the pause is lifted by `account`.
     */
    event Unpaused(address account);

    /**
     * @dev The operation failed because the contract is paused.
     */
    error EnforcedPause();

    /**
     * @dev The operation failed because the contract is not paused.
     */
    error ExpectedPause();

    /**
     * @dev Initializes the contract in unpaused state.
     */
    constructor() {
        _paused = false;
    }

    /**
     * @dev Modifier to make a function callable only when the contract is not paused.
     *
     * Requirements:
     *
     * - The contract must not be paused.
     */
    modifier whenNotPaused() {
        _requireNotPaused();
        _;
    }

    /**
     * @dev Modifier to make a function callable only when the contract is paused.
     *
     * Requirements:
     *
     * - The contract must be paused.
     */
    modifier whenPaused() {
        _requirePaused();
        _;
    }

    /**
     * @dev Returns true if the contract is paused, and false otherwise.
     */
    function paused() public view virtual returns (bool) {
        return _paused;
    }

    /**
     * @dev Throws if the contract is paused.
     */
    function _requireNotPaused() internal view virtual {
        if (paused()) {
            revert EnforcedPause();
        }
    }

    /**
     * @dev Throws if the contract is not paused.
     */
    function _requirePaused() internal view virtual {
        if (!paused()) {
            revert ExpectedPause();
        }
    }

    /**
     * @dev Triggers stopped state.
     *
     * Requirements:
     *
     * - The contract must not be paused.
     */
    function _pause() internal virtual whenNotPaused {
        _paused = true;
        emit Paused(_msgSender());
    }

    /**
     * @dev Returns to normal state.
     *
     * Requirements:
     *
     * - The contract must be paused.
     */
    function _unpause() internal virtual whenPaused {
        _paused = false;
        emit Unpaused(_msgSender());
    }
}

// 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;
    }
}

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