// File: contracts/PathRewards.sol



//SPDX-License-Identifier: MIT

import "@openzeppelin/contracts/token/ERC20/IERC20.sol";
import "@openzeppelin/contracts/access/Ownable.sol";

pragma solidity 0.8.4;

contract PathRewards is Ownable{
    IERC20 public token;

    //total reward tokens will be 150,000,000 given out
    uint public rewardRate = 0;
    uint public rewardsDuration = 365 days;
    uint public startRewardsTime;
    uint public lastUpdateTime;
    uint public lastRewardTimestamp;
    uint public rewardPerTokenStored;

    // last time
    uint private stakedSupply = 0;
    uint private claimedRewards = 0;

    mapping(address => uint) public userRewardPerTokenPaid;
    mapping(address => uint) public rewards;
    mapping(address => uint) private _balances;

    event Staked(address indexed user, uint amountStaked);
    event Withdrawn(address indexed user, uint amountWithdrawn);
    event RewardsClaimed(address indexed user, uint rewardsClaimed);
    event RewardAmountSet(uint rewardRate, uint duration);

    constructor(address  _tokenAddress, uint _startRewards) {
        token = IERC20(_tokenAddress);
        startRewardsTime = _startRewards;
    }

    modifier updateReward(address account) {
        rewardPerTokenStored = rewardPerToken();
        lastUpdateTime = rewardTimestamp();
        if (account != address(0)){
            rewards[account] = earned(account);
            userRewardPerTokenPaid[account] = rewardPerTokenStored;
        }
        _;
    }

    //function to check if staking rewards have ended
    function rewardTimestamp() internal view returns (uint) {
        if (block.timestamp < lastRewardTimestamp) {
            return block.timestamp;
        }
        else {
            return lastRewardTimestamp;
        }
    }

    //function to check if staking rewards have started
    function startTimestamp() internal view returns (uint) {
        if (startRewardsTime > lastUpdateTime) {
            return startRewardsTime;
        }
        else {
            return lastUpdateTime;
        }
    }

    function balanceOf(address account) external view returns (uint) {
        return _balances[account];
    }


    function totalStaked() public view returns (uint) {
        return stakedSupply;
    }

    function totalClaimed() public view returns (uint) {
        return claimedRewards;
    }

    function rewardPerToken() public view returns (uint) {
        if (stakedSupply == 0 || block.timestamp < startRewardsTime) {
            return 0;
        }
        return rewardPerTokenStored + (
            (rewardRate * (rewardTimestamp()- startTimestamp()) * 1e18 / stakedSupply)
        );
    }

    function earned(address account) public view returns (uint) {
        return (
            _balances[account] * (rewardPerToken() - userRewardPerTokenPaid[account]) / 1e18
        ) + rewards[account];
    }

    function stake(uint _amount) external updateReward(msg.sender) {
        require(_amount > 0, "Must stake > 0 tokens");
        stakedSupply += _amount;
        _balances[msg.sender] += _amount;
        require(token.transferFrom(msg.sender, address(this), _amount), "Token transfer failed");
        emit Staked(msg.sender, _amount);
    }

    function withdraw(uint _amount) public updateReward(msg.sender) {
        require(_amount > 0, "Must withdraw > 0 tokens");
        stakedSupply -= _amount;
        _balances[msg.sender] -= _amount;
        require(token.transfer(msg.sender, _amount), "Token transfer failed");
        emit Withdrawn(msg.sender, _amount);
    }

    function getReward() public updateReward(msg.sender) {
        uint reward = rewards[msg.sender];
        if (reward > 0) {
            rewards[msg.sender] = 0;
            claimedRewards += reward;
            require(token.transfer(msg.sender, reward), "Token transfer failed");
            emit RewardsClaimed(msg.sender, reward);
        }
    }

    function exit() external {
        withdraw(_balances[msg.sender]);
        getReward();
    }

    //owner only functions

    function setRewardAmount(uint reward, uint _rewardsDuration) onlyOwner external updateReward(address(0)) {
        rewardsDuration = _rewardsDuration;
        rewardRate = reward / rewardsDuration;
        uint balance = token.balanceOf(address(this)) - stakedSupply;

        require(rewardRate <= balance / rewardsDuration, "Contract does not have enough tokens for current reward rate");

        lastUpdateTime = block.timestamp;
        if (block.timestamp < startRewardsTime) {
            lastRewardTimestamp = startRewardsTime + rewardsDuration;
        }
        else {
            lastRewardTimestamp = block.timestamp + rewardsDuration;
        }
        emit RewardAmountSet(rewardRate, _rewardsDuration);
    }
}

// File: @openzeppelin/contracts/token/ERC20/IERC20.sol



// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

/**
 * @dev Interface of the ERC20 standard as defined in the EIP.
 */
interface IERC20 {
    /**
     * @dev Returns the amount of tokens in existence.
     */
    function totalSupply() external view returns (uint256);

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

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

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

    /**
     * @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);
}

// File: @openzeppelin/contracts/access/Ownable.sol



// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

import "../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.
 *
 * By default, the owner account will be the one that deploys the contract. 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;

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

    /**
     * @dev Initializes the contract setting the deployer as the initial owner.
     */
    constructor() {
        _setOwner(_msgSender());
    }

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

    /**
     * @dev Throws if called by any account other than the owner.
     */
    modifier onlyOwner() {
        require(owner() == _msgSender(), "Ownable: caller is not the owner");
        _;
    }

    /**
     * @dev Leaves the contract without owner. It will not be possible to call
     * `onlyOwner` functions anymore. Can only be called by the current owner.
     *
     * NOTE: Renouncing ownership will leave the contract without an owner,
     * thereby removing any functionality that is only available to the owner.
     */
    function renounceOwnership() public virtual onlyOwner {
        _setOwner(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 {
        require(newOwner != address(0), "Ownable: new owner is the zero address");
        _setOwner(newOwner);
    }

    function _setOwner(address newOwner) private {
        address oldOwner = _owner;
        _owner = newOwner;
        emit OwnershipTransferred(oldOwner, newOwner);
    }
}

// File: @openzeppelin/contracts/utils/Context.sol



// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

/**
 * @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;
    }
}