Cryo Explorer Ethereum Mainnet

pragma solidity ^0.8.4;

// SPDX-License-Identifier: MIT

import "./IERC20.sol";
import "./IERC20Metadata.sol";
import "./Context.sol";
import "./SafeMath.sol";
import "./Address.sol";

/**
 * @dev Implementation of the {IERC20} interface.
 *
 * This implementation is agnostic to the way tokens are created. This means
 * that a supply mechanism has to be added in a derived contract using {_mint}.
 * For a generic mechanism see {ERC20PresetMinterPauser}.
 *
 * TIP: For a detailed writeup see our guide
 * https://forum.zeppelin.solutions/t/how-to-implement-erc20-supply-mechanisms/226[How
 * to implement supply mechanisms].
 *
 * We have followed general OpenZeppelin guidelines: functions revert instead
 * of returning `false` on failure. This behavior is nonetheless conventional
 * and does not conflict with the expectations of ERC20 applications.
 *
 * Additionally, an {Approval} event is emitted on calls to {transferFrom}.
 * This allows applications to reconstruct the allowance for all accounts just
 * by listening to said events. Other implementations of the EIP may not emit
 * these events, as it isn't required by the specification.
 *
 * Finally, the non-standard {decreaseAllowance} and {increaseAllowance}
 * functions have been added to mitigate the well-known issues around setting
 * allowances. See {IERC20-approve}.
 */
contract ERC20 is Context, IERC20, IERC20Metadata {
    using SafeMath for uint256;
    using Address for address;

    mapping(address => uint256) internal _balances;

    mapping(address => mapping(address => uint256)) private _allowances;

    uint256 internal _totalSupply;

    string private _name;
    string private _symbol;

    /**
     * @dev Sets the values for {name} and {symbol}.
     *
     * The default value of {decimals} is 18. To select a different value for
     * {decimals} you should overload it.
     *
     * All two of these values are immutable: they can only be set once during
     * construction.
     */
    constructor(string memory name_, string memory symbol_) {
        _name = name_;
        _symbol = symbol_;
    }

    /**
     * @dev Returns the name of the token.
     */
    function name() public view virtual override returns (string memory) {
        return _name;
    }

    /**
     * @dev Returns the symbol of the token, usually a shorter version of the
     * name.
     */
    function symbol() public view virtual override returns (string memory) {
        return _symbol;
    }

    /**
     * @dev Returns the number of decimals used to get its user representation.
     * For example, if `decimals` equals `2`, a balance of `505` tokens should
     * be displayed to a user as `5,05` (`505 / 10 ** 2`).
     *
     * Tokens usually opt for a value of 18, imitating the relationship between
     * Ether and Wei. This is the value {ERC20} uses, unless this function is
     * overridden;
     *
     * NOTE: This information is only used for _display_ purposes: it in
     * no way affects any of the arithmetic of the contract, including
     * {IERC20-balanceOf} and {IERC20-transfer}.
     */
    function decimals() public view virtual override returns (uint8) {
        return 18;
    }

    /**
     * @dev See {IERC20-totalSupply}.
     */
    function totalSupply() public view virtual override returns (uint256) {
        return _totalSupply;
    }

    /**
     * @dev See {IERC20-balanceOf}.
     */
    function balanceOf(address account) public view virtual override returns (uint256) {
        return _balances[account];
    }

    /**
     * @dev See {IERC20-transfer}.
     *
     * Requirements:
     *
     * - `recipient` cannot be the zero address.
     * - the caller must have a balance of at least `amount`.
     */
    function transfer(address recipient, uint256 amount) public virtual override returns (bool) {
        _transfer(_msgSender(), recipient, amount);
        return true;
    }

    /**
     * @dev See {IERC20-allowance}.
     */
    function allowance(address owner, address spender) public view virtual override returns (uint256) {
        return _allowances[owner][spender];
    }

    /**
     * @dev See {IERC20-approve}.
     *
     * Requirements:
     *
     * - `spender` cannot be the zero address.
     */
    function approve(address spender, uint256 amount) public virtual override returns (bool) {
        _approve(_msgSender(), spender, amount);
        return true;
    }

    /**
     * @dev See {IERC20-transferFrom}.
     *
     * Emits an {Approval} event indicating the updated allowance. This is not
     * required by the EIP. See the note at the beginning of {ERC20}.
     *
     * Requirements:
     *
     * - `sender` and `recipient` cannot be the zero address.
     * - `sender` must have a balance of at least `amount`.
     * - the caller must have allowance for ``sender``'s tokens of at least
     * `amount`.
     */
    function transferFrom(
        address sender,
        address recipient,
        uint256 amount
    ) public virtual override returns (bool) {
        _transfer(sender, recipient, amount);
        _approve(sender, _msgSender(), _allowances[sender][_msgSender()].sub(amount, "ERC20: transfer amount exceeds allowance"));
        return true;
    }

    /**
     * @dev Atomically increases the allowance granted to `spender` by the caller.
     *
     * This is an alternative to {approve} that can be used as a mitigation for
     * problems described in {IERC20-approve}.
     *
     * Emits an {Approval} event indicating the updated allowance.
     *
     * Requirements:
     *
     * - `spender` cannot be the zero address.
     */
    function increaseAllowance(address spender, uint256 addedValue) public virtual returns (bool) {
        _approve(_msgSender(), spender, _allowances[_msgSender()][spender].add(addedValue));
        return true;
    }

    /**
     * @dev Atomically decreases the allowance granted to `spender` by the caller.
     *
     * This is an alternative to {approve} that can be used as a mitigation for
     * problems described in {IERC20-approve}.
     *
     * Emits an {Approval} event indicating the updated allowance.
     *
     * Requirements:
     *
     * - `spender` cannot be the zero address.
     * - `spender` must have allowance for the caller of at least
     * `subtractedValue`.
     */
    function decreaseAllowance(address spender, uint256 subtractedValue) public virtual returns (bool) {
        _approve(_msgSender(), spender, _allowances[_msgSender()][spender].sub(subtractedValue, "ERC20: decreased allowance below zero"));
        return true;
    }

    /**
     * @dev Moves tokens `amount` from `sender` to `recipient`.
     *
     * This is internal function is equivalent to {transfer}, and can be used to
     * e.g. implement automatic token fees, slashing mechanisms, etc.
     *
     * Emits a {Transfer} event.
     *
     * Requirements:
     *
     * - `sender` cannot be the zero address.
     * - `recipient` cannot be the zero address.
     * - `sender` must have a balance of at least `amount`.
     */
    function _transfer(
        address sender,
        address recipient,
        uint256 amount
    ) internal virtual {
        require(sender != address(0), "ERC20: transfer from the zero address");
        require(recipient != address(0), "ERC20: transfer to the zero address");

        _beforeTokenTransfer(sender, recipient, amount);

        _balances[sender] = _balances[sender].sub(amount, "ERC20: transfer amount exceeds balance");
        _balances[recipient] = _balances[recipient].add(amount);
        emit Transfer(sender, recipient, amount);
    }

    /** @dev Creates `amount` tokens and assigns them to `account`, increasing
     * the total supply.
     *
     * Emits a {Transfer} event with `from` set to the zero address.
     *
     * Requirements:
     *
     * - `account` cannot be the zero address.
     */
    function _mint(address account, uint256 amount) internal virtual {
        require(account != address(0), "ERC20: mint to the zero address");

        _beforeTokenTransfer(address(0), account, amount);

        _totalSupply = _totalSupply.add(amount);
        _balances[account] = _balances[account].add(amount);
        emit Transfer(address(0), account, amount);
    }

    /**
     * @dev Destroys `amount` tokens from `account`, reducing the
     * total supply.
     *
     * Emits a {Transfer} event with `to` set to the zero address.
     *
     * Requirements:
     *
     * - `account` cannot be the zero address.
     * - `account` must have at least `amount` tokens.
     */
    function _burn(address account, uint256 amount) internal virtual {
        require(account != address(0), "ERC20: burn from the zero address");

        _beforeTokenTransfer(account, address(0), amount);

        _balances[account] = _balances[account].sub(amount, "ERC20: burn amount exceeds balance");
        _totalSupply = _totalSupply.sub(amount);
        emit Transfer(account, address(0), amount);
    }

    /**
     * @dev Sets `amount` as the allowance of `spender` over the `owner` s tokens.
     *
     * This internal function is equivalent to `approve`, and can be used to
     * e.g. set automatic allowances for certain subsystems, etc.
     *
     * Emits an {Approval} event.
     *
     * Requirements:
     *
     * - `owner` cannot be the zero address.
     * - `spender` cannot be the zero address.
     */
    function _approve(
        address owner,
        address spender,
        uint256 amount
    ) internal virtual {
        require(owner != address(0), "ERC20: approve from the zero address");
        require(spender != address(0), "ERC20: approve to the zero address");

        _allowances[owner][spender] = amount;
        emit Approval(owner, spender, amount);
    }

    /**
     * @dev Hook that is called before any transfer of tokens. This includes
     * minting and burning.
     *
     * Calling conditions:
     *
     * - when `from` and `to` are both non-zero, `amount` of ``from``'s tokens
     * will be to transferred to `to`.
     * - when `from` is zero, `amount` tokens will be minted for `to`.
     * - when `to` is zero, `amount` of ``from``'s tokens will be burned.
     * - `from` and `to` are never both zero.
     *
     * To learn more about hooks, head to xref:ROOT:extending-contracts.adoc#using-hooks[Using Hooks].
     */
    function _beforeTokenTransfer(
        address from,
        address to,
        uint256 amount
    ) internal virtual {}
}

pragma solidity ^0.8.4;

// SPDX-License-Identifier: MIT

/**
 * @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);
}

pragma solidity ^0.8.4;

// SPDX-License-Identifier: MIT

/**
 * @dev Collection of functions related to the address type
 */
library Address {
    /**
     * @dev Returns true if `account` is a contract.
     *
     * [IMPORTANT]
     * ====
     * It is unsafe to assume that an address for which this function returns
     * false is an externally-owned account (EOA) and not a contract.
     *
     * Among others, `isContract` will return false for the following
     * types of addresses:
     *
     *  - an externally-owned account
     *  - a contract in construction
     *  - an address where a contract will be created
     *  - an address where a contract lived, but was destroyed
     * ====
     */
    function isContract(address account) internal view returns (bool) {
        // According to EIP-1052, 0x0 is the value returned for not-yet created accounts
        // and 0xc5d2460186f7233c927e7db2dcc703c0e500b653ca82273b7bfad8045d85a470 is returned
        // for accounts without code, i.e. `keccak256('')`
        bytes32 codehash;
        bytes32 accountHash = 0xc5d2460186f7233c927e7db2dcc703c0e500b653ca82273b7bfad8045d85a470;
        // solhint-disable-next-line no-inline-assembly
        assembly {
            codehash := extcodehash(account)
        }
        return (codehash != accountHash && codehash != 0x0);
    }

    /**
     * @dev Replacement for Solidity's `transfer`: sends `amount` wei to
     * `recipient`, forwarding all available gas and reverting on errors.
     *
     * https://eips.ethereum.org/EIPS/eip-1884[EIP1884] increases the gas cost
     * of certain opcodes, possibly making contracts go over the 2300 gas limit
     * imposed by `transfer`, making them unable to receive funds via
     * `transfer`. {sendValue} removes this limitation.
     *
     * https://diligence.consensys.net/posts/2019/09/stop-using-soliditys-transfer-now/[Learn more].
     *
     * IMPORTANT: because control is transferred to `recipient`, care must be
     * taken to not create reentrancy vulnerabilities. Consider using
     * {ReentrancyGuard} or the
     * https://solidity.readthedocs.io/en/v0.5.11/security-considerations.html#use-the-checks-effects-interactions-pattern[checks-effects-interactions pattern].
     */
    function sendValue(address payable recipient, uint256 amount) internal {
        require(
            address(this).balance >= amount,
            "Address: insufficient balance"
        );

        // solhint-disable-next-line avoid-low-level-calls, avoid-call-value
        (bool success, ) = recipient.call{value: amount}("");
        require(
            success,
            "Address: unable to send value, recipient may have reverted"
        );
    }

    /**
     * @dev Performs a Solidity function call using a low level `call`. A
     * plain`call` is an unsafe replacement for a function call: use this
     * function instead.
     *
     * If `target` reverts with a revert reason, it is bubbled up by this
     * function (like regular Solidity function calls).
     *
     * Returns the raw returned data. To convert to the expected return value,
     * use https://solidity.readthedocs.io/en/latest/units-and-global-variables.html?highlight=abi.decode#abi-encoding-and-decoding-functions[`abi.decode`].
     *
     * Requirements:
     *
     * - `target` must be a contract.
     * - calling `target` with `data` must not revert.
     *
     * _Available since v3.1._
     */
    function functionCall(address target, bytes memory data)
        internal
        returns (bytes memory)
    {
        return functionCall(target, data, "Address: low-level call failed");
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`], but with
     * `errorMessage` as a fallback revert reason when `target` reverts.
     *
     * _Available since v3.1._
     */
    function functionCall(
        address target,
        bytes memory data,
        string memory errorMessage
    ) internal returns (bytes memory) {
        return _functionCallWithValue(target, data, 0, errorMessage);
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
     * but also transferring `value` wei to `target`.
     *
     * Requirements:
     *
     * - the calling contract must have an ETH balance of at least `value`.
     * - the called Solidity function must be `payable`.
     *
     * _Available since v3.1._
     */
    function functionCallWithValue(
        address target,
        bytes memory data,
        uint256 value
    ) internal returns (bytes memory) {
        return
            functionCallWithValue(
                target,
                data,
                value,
                "Address: low-level call with value failed"
            );
    }

    /**
     * @dev Same as {xref-Address-functionCallWithValue-address-bytes-uint256-}[`functionCallWithValue`], but
     * with `errorMessage` as a fallback revert reason when `target` reverts.
     *
     * _Available since v3.1._
     */
    function functionCallWithValue(
        address target,
        bytes memory data,
        uint256 value,
        string memory errorMessage
    ) internal returns (bytes memory) {
        require(
            address(this).balance >= value,
            "Address: insufficient balance for call"
        );
        return _functionCallWithValue(target, data, value, errorMessage);
    }

    function _functionCallWithValue(
        address target,
        bytes memory data,
        uint256 weiValue,
        string memory errorMessage
    ) private returns (bytes memory) {
        require(isContract(target), "Address: call to non-contract");

        // solhint-disable-next-line avoid-low-level-calls
        (bool success, bytes memory returndata) = target.call{value: weiValue}(
            data
        );
        if (success) {
            return returndata;
        } else {
            // Look for revert reason and bubble it up if present
            if (returndata.length > 0) {
                // The easiest way to bubble the revert reason is using memory via assembly

                // solhint-disable-next-line no-inline-assembly
                assembly {
                    let returndata_size := mload(returndata)
                    revert(add(32, returndata), returndata_size)
                }
            } else {
                revert(errorMessage);
            }
        }
    }
}

pragma solidity ^0.8.4;

// SPDX-License-Identifier: MIT

abstract contract Context {
    function _msgSender() internal view virtual returns (address) {
        return msg.sender;
    }

    function _msgData() internal view virtual returns (bytes memory) {
        this; // silence state mutability warning without generating bytecode - see https://github.com/ethereum/solidity/issues/2691
        return msg.data;
    }
}

pragma solidity 0.8.4;

// SPDX-License-Identifier: MIT

import "./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.
 */
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() {
        address msgSender = _msgSender();
        _owner = msgSender;
        emit OwnershipTransferred(address(0), msgSender);
    }

    /**
     * @dev Returns the address of the current owner.
     */
    function owner() public view 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() external virtual onlyOwner {
        emit OwnershipTransferred(_owner, address(0));
        _owner = 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) external virtual onlyOwner {
        require(
            newOwner != address(0),
            "Ownable: new owner is the zero address"
        );
        emit OwnershipTransferred(_owner, newOwner);
        _owner = newOwner;
    }
}

pragma solidity ^0.8.4;

// SPDX-License-Identifier: MIT

/**
 * @dev Wrappers over Solidity's arithmetic operations with added overflow
 * checks.
 *
 * Arithmetic operations in Solidity wrap on overflow. This can easily result
 * in bugs, because programmers usually assume that an overflow raises an
 * error, which is the standard behavior in high level programming languages.
 * `SafeMath` restores this intuition by reverting the transaction when an
 * operation overflows.
 *
 * Using this library instead of the unchecked operations eliminates an entire
 * class of bugs, so it's recommended to use it always.
 */

library SafeMath {
    /**
     * @dev Returns the addition of two unsigned integers, reverting on
     * overflow.
     *
     * Counterpart to Solidity's `+` operator.
     *
     * Requirements:
     *
     * - Addition cannot overflow.
     */
    function add(uint256 a, uint256 b) internal pure returns (uint256) {
        uint256 c = a + b;
        require(c >= a, "SafeMath: addition overflow");

        return c;
    }

    /**
     * @dev Returns the subtraction of two unsigned integers, reverting on
     * overflow (when the result is negative).
     *
     * Counterpart to Solidity's `-` operator.
     *
     * Requirements:
     *
     * - Subtraction cannot overflow.
     */
    function sub(uint256 a, uint256 b) internal pure returns (uint256) {
        return sub(a, b, "SafeMath: subtraction overflow");
    }

    /**
     * @dev Returns the subtraction of two unsigned integers, reverting with custom message on
     * overflow (when the result is negative).
     *
     * Counterpart to Solidity's `-` operator.
     *
     * Requirements:
     *
     * - Subtraction cannot overflow.
     */
    function sub(
        uint256 a,
        uint256 b,
        string memory errorMessage
    ) internal pure returns (uint256) {
        require(b <= a, errorMessage);
        uint256 c = a - b;

        return c;
    }

    /**
     * @dev Returns the multiplication of two unsigned integers, reverting on
     * overflow.
     *
     * Counterpart to Solidity's `*` operator.
     *
     * Requirements:
     *
     * - Multiplication cannot overflow.
     */
    function mul(uint256 a, uint256 b) internal pure returns (uint256) {
        // Gas optimization: this is cheaper than requiring 'a' not being zero, but the
        // benefit is lost if 'b' is also tested.
        // See: https://github.com/OpenZeppelin/openzeppelin-contracts/pull/522
        if (a == 0) {
            return 0;
        }

        uint256 c = a * b;
        require(c / a == b, "SafeMath: multiplication overflow");

        return c;
    }

    /**
     * @dev Returns the integer division of two unsigned integers. Reverts on
     * division by zero. The result is rounded towards zero.
     *
     * Counterpart to Solidity's `/` operator. Note: this function uses a
     * `revert` opcode (which leaves remaining gas untouched) while Solidity
     * uses an invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     *
     * - The divisor cannot be zero.
     */
    function div(uint256 a, uint256 b) internal pure returns (uint256) {
        return div(a, b, "SafeMath: division by zero");
    }

    /**
     * @dev Returns the integer division of two unsigned integers. Reverts with custom message on
     * division by zero. The result is rounded towards zero.
     *
     * Counterpart to Solidity's `/` operator. Note: this function uses a
     * `revert` opcode (which leaves remaining gas untouched) while Solidity
     * uses an invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     *
     * - The divisor cannot be zero.
     */
    function div(
        uint256 a,
        uint256 b,
        string memory errorMessage
    ) internal pure returns (uint256) {
        require(b > 0, errorMessage);
        uint256 c = a / b;
        // assert(a == b * c + a % b); // There is no case in which this doesn't hold

        return c;
    }

    /**
     * @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),
     * Reverts when dividing by zero.
     *
     * Counterpart to Solidity's `%` operator. This function uses a `revert`
     * opcode (which leaves remaining gas untouched) while Solidity uses an
     * invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     *
     * - The divisor cannot be zero.
     */
    function mod(uint256 a, uint256 b) internal pure returns (uint256) {
        return mod(a, b, "SafeMath: modulo by zero");
    }

    /**
     * @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),
     * Reverts with custom message when dividing by zero.
     *
     * Counterpart to Solidity's `%` operator. This function uses a `revert`
     * opcode (which leaves remaining gas untouched) while Solidity uses an
     * invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     *
     * - The divisor cannot be zero.
     */
    function mod(
        uint256 a,
        uint256 b,
        string memory errorMessage
    ) internal pure returns (uint256) {
        require(b != 0, errorMessage);
        return a % b;
    }
}

pragma solidity ^0.8.4;

// SPDX-License-Identifier: Apache-2.0

import "./SafeMath.sol";
import "./Address.sol";
import "./RewardsToken.sol";
import "./IUniswapV2Factory.sol";
import "./IUniswapV2Router.sol";
import "./IRewardsTracker.sol";

contract ChallengeCoin is RewardsToken {
    using SafeMath for uint256;
    using Address for address;
    
    // Supply, limits and fees
    uint256 private constant REWARDS_TRACKER_IDENTIFIER = 9;
    uint256 private constant TOTAL_SUPPLY = 500000000000 * (10**9);

    uint256 public maxTxAmount = TOTAL_SUPPLY.mul(2).div(1000); // 2%

    uint256 private platformFee = 600; //  6%
    uint256 private _previousPlatformFee = platformFee;

    uint256 public devFee = 400; // 4%
    uint256 public sellDevFee = 700; // 7%
    uint256 private _previousDevFee = devFee;
    
    uint256 public rewardsFee = 200; // 2%
    uint256 public sellRewardsFee = 200; // 2%
    uint256 private _previousRewardsFee = rewardsFee;

    uint256 public launchSellFee = 925; // 9.25%
    uint256 private _previousLaunchSellFee = launchSellFee;

    address payable private _platformWalletAddress =
        payable(0x3E99a588eE8cD107dbD8F8Ae125c1F50D2b81140);
    address payable private _devWalletAddress =
        payable(0x05d9864854C60E8d2e46eF46D5968D12aCd30D63);

    uint256 public blacklistDeadline = 0;
    uint256 public launchSellFeeDeadline = 0;

    IRewardsTracker private _rewardsTracker;

    // Fallback to generic transfer. On by default
    bool public useGenericTransfer = true;

    // Prepared for launch
    bool private preparedForLaunch = false;

    // Blacklist
    mapping(address => bool) public isBlacklisted;
    
    // Exclusions
    mapping(address => bool) private _isExcludedFromFee;
    mapping(address => bool) private _isExcludedFromMaxTx;
    
    // Token -> ETH swap support
    IUniswapV2Router public uniswapV2Router;
    address public uniswapV2Pair;

    bool currentlySwapping;
    bool public swapAndRedirectEthFeesEnabled = true;

    uint256 private minTokensBeforeSwap = 1250000000 * 10**9;

    // Events and modifiers
    event MinTokensBeforeSwapUpdated(uint256 minTokensBeforeSwap);
    event SwapAndRedirectEthFeesUpdated(bool enabled);
    event OnSwapAndRedirectEthFees(
        uint256 tokensSwapped,
        uint256 ethToDevWallet
    );
    event MaxTxAmountUpdated(uint256 maxTxAmount);
    event GenericTransferChanged(bool useGenericTransfer);
    event ExcludeFromFees(address wallet);
    event IncludeInFees(address wallet);
    event DevWalletUpdated(address newDevWallet);
    event RewardsTrackerUpdated(address newRewardsTracker);
    event RouterUpdated(address newRouterAddress);
    event FeesChanged(
        uint256 newDevFee,
        uint256 newSellDevFee,
        uint256 newRewardsFee,
        uint256 newSellRewardsFee
    );
    event LaunchFeeUpdated(uint256 newLaunchSellFee);

    modifier lockTheSwap() {
        currentlySwapping = true;
        _;
        currentlySwapping = false;
    }

    constructor() ERC20("Challenge Coin", "HERO") {
        IUniswapV2Router _uniswapV2Router = IUniswapV2Router(
            0x7a250d5630B4cF539739dF2C5dAcb4c659F2488D
        );
        // Create a uniswap pair for this new token
        uniswapV2Pair = IUniswapV2Factory(_uniswapV2Router.factory())
            .createPair(address(this), _uniswapV2Router.WETH());

        // set the rest of the contract variables
        uniswapV2Router = _uniswapV2Router;
        
        // mint supply
        _mint(owner(), TOTAL_SUPPLY);

        // exclude owner and this contract from fee
        _isExcludedFromFee[owner()] = true;
        _isExcludedFromFee[address(this)] = true;
        
        // internal exclude from max tx
        _isExcludedFromMaxTx[owner()] = true;
        _isExcludedFromMaxTx[address(this)] = true;
        
        // exclude from rewards
        excludeFromRewards(address(this));
        excludeFromRewards(address(0xdead));
        excludeFromRewards(uniswapV2Pair);
    }
    
    function decimals() public view virtual override returns (uint8) {
        return 9;
    }

    function _transfer(
        address from,
        address to,
        uint256 amount
    ) internal virtual override {
        // launch preparation
        require(preparedForLaunch || _msgSender() == owner(), "Contract has not been prepared for launch and user is not owner");

        // blacklist
        require(
            !isBlacklisted[from] && !isBlacklisted[to],
            "Blacklisted address"
        );

        // fallback implementation
        if (useGenericTransfer) {
            super._transfer(from, to, amount);
            return;
        }

        if (
            !_isExcludedFromMaxTx[from] &&
            !_isExcludedFromMaxTx[to] // by default false
        ) {
            require(
                amount <= maxTxAmount,
                "Transfer amount exceeds the maxTxAmount"
            );
        }

        // sell fees
        uint256 baseRewardsFee = rewardsFee;
        uint256 baseDevFee = devFee;
        if (to == uniswapV2Pair) {
            devFee = sellDevFee;
            rewardsFee = sellRewardsFee;

            if (launchSellFeeDeadline >= block.timestamp) {
                devFee = devFee.add(launchSellFee);
            }
        }

        // start swap to ETH
        uint256 contractTokenBalance = balanceOf(address(this));
        bool overMinTokenBalance = contractTokenBalance >= minTokensBeforeSwap;
        if (
            overMinTokenBalance &&
            !currentlySwapping &&
            from != uniswapV2Pair &&
            swapAndRedirectEthFeesEnabled
        ) {
            // add dev fee
            swapAndRedirectEthFees(contractTokenBalance);
        }

        if (_isExcludedFromFee[from] || _isExcludedFromFee[to]) {
            removeAllFee();
        }

        (uint256 tTransferAmount, uint256 tFee) = _getValues(amount);
        _balances[from] = _balances[from].sub(amount);
        _balances[to] = _balances[to].add(tTransferAmount);

        _takeFee(tFee);

        if (_isExcludedFromFee[from] || _isExcludedFromFee[to]) {
            restoreAllFee();
        }

        // restore fees
        devFee = baseDevFee;
        rewardsFee = baseRewardsFee;

        emit Transfer(from, to, tTransferAmount);
    }

    //to recieve ETH from uniswapV2Router when swaping
    receive() external payable {}

    function _getValues(uint256 tAmount)
        private
        view
        returns (uint256, uint256)
    {
        uint256 tFee = calculateFee(tAmount);
        uint256 tTransferAmount = tAmount.sub(tFee);
        return (tTransferAmount, tFee);
    }

    function _takeFee(uint256 fee) private {
        _balances[address(this)] = _balances[address(this)].add(fee);
    }

    function calculateFee(uint256 _amount)
        private
        view
        returns (uint256)
    {
        uint256 totalFee = devFee.add(rewardsFee).add(platformFee);
        return _amount.mul(totalFee).div(10000);
    }

    function removeAllFee() private {
        if (devFee == 0 && rewardsFee == 0 && platformFee == 0) return;

        _previousPlatformFee = platformFee;
        _previousDevFee = devFee;
        _previousRewardsFee = rewardsFee;

        platformFee = 0;
        devFee = 0;
        rewardsFee = 0;
    }

    function restoreAllFee() private {
        platformFee = _previousPlatformFee;
        devFee = _previousDevFee;
        rewardsFee = _previousRewardsFee;
    }

    function swapAndRedirectEthFees(uint256 contractTokenBalance)
        private
        lockTheSwap
    {
        uint256 totalRedirectFee = devFee.add(rewardsFee).add(platformFee);
        if (totalRedirectFee == 0) return;
        
        // capture the contract's current ETH balance.
        // this is so that we can capture exactly the amount of ETH that the
        // swap creates, and not make the fee events include any ETH that
        // has been manually sent to the contract
        uint256 initialBalance = address(this).balance;

        // swap tokens for ETH
        swapTokensForEth(contractTokenBalance);

        uint256 newBalance = address(this).balance.sub(initialBalance);

        if (newBalance > 0) {
            // send to platform wallet
            uint256 platformBalance = newBalance.mul(platformFee).div(totalRedirectFee);
            sendEthToWallet(_platformWalletAddress, platformBalance);

            //
            // send to rewards wallet
            //
            uint256 rewardsBalance = newBalance.mul(rewardsFee).div(totalRedirectFee);
            if (rewardsBalance > 0 && address(_rewardsTracker) != address(0)) {
                try _rewardsTracker.addAllocation{value: rewardsBalance}(REWARDS_TRACKER_IDENTIFIER) {} catch {}
            }
            
            //
            // send to dev wallet
            //
            uint256 devBalance = newBalance.mul(devFee).div(totalRedirectFee);
            sendEthToWallet(_devWalletAddress, devBalance);

            emit OnSwapAndRedirectEthFees(contractTokenBalance, newBalance);
        }
    }

    function sendEthToWallet(address wallet, uint256 amount) private {
        if (amount > 0) {
            payable(wallet).transfer(amount);
        }
    }

    function swapTokensForEth(uint256 tokenAmount) private {
        // generate the uniswap pair path of token -> weth
        address[] memory path = new address[](2);
        path[0] = address(this);
        path[1] = uniswapV2Router.WETH();

        _approve(address(this), address(uniswapV2Router), tokenAmount);

        // make the swap
        uniswapV2Router.swapExactTokensForETHSupportingFeeOnTransferTokens(
            tokenAmount,
            0, // accept any amount of ETH
            path,
            address(this),
            block.timestamp
        );
    }

    function prepareForLaunch() external onlyOwner {
        require(!preparedForLaunch, "Already prepared for launch");

        // ready for launch
        preparedForLaunch = true;

        // a maximum of 1 hour is given to blacklist snipers/flashbots
        blacklistDeadline = block.timestamp + 1 hours;

        // sell penalty for the first 24 hours
        launchSellFeeDeadline = block.timestamp + 7 days;
    }

    function setUseGenericTransfer(bool genericTransfer) external onlyOwner {
        useGenericTransfer = genericTransfer;
        emit GenericTransferChanged(genericTransfer);
    }

    function blacklistAddress(address account, bool value) public onlyOwner {
        if (value) {
            require(block.timestamp < blacklistDeadline, "The ability to blacklist accounts has been disabled.");
        }
        isBlacklisted[account] = value;
    }

    
    // for 0.5% input 5, for 1% input 10
    function setMaxTxPercent(uint256 newMaxTx) external onlyOwner {
        require(newMaxTx >= 5, "Max TX should be above 0.5%");
        maxTxAmount = TOTAL_SUPPLY.mul(newMaxTx).div(1000);
        emit MaxTxAmountUpdated(maxTxAmount);
    }
    
    function isExcludedFromFee(address account) external view returns (bool) {
        return _isExcludedFromFee[account];
    }

    function excludeFromFee(address account) external onlyOwner {
        _isExcludedFromFee[account] = true;
        emit ExcludeFromFees(account);
    }

    function includeInFee(address account) external onlyOwner {
        _isExcludedFromFee[account] = false;
        emit IncludeInFees(account);
    }

    function setFees(
        uint256 newDevFee,
        uint256 newSellDevFee,
        uint256 newRewardsFee,
        uint256 newSellRewardsFee
    ) external onlyOwner {
        require(
            newDevFee <= 1000 &&
            newSellDevFee <= 1000 &&
            newRewardsFee <= 1000 &&
            newSellRewardsFee <= 1000,
            "Fees exceed maximum allowed value"
        );
        devFee = newDevFee;
        sellDevFee = newSellDevFee;
        rewardsFee = newRewardsFee;
        sellRewardsFee = newSellRewardsFee;
        emit FeesChanged(newDevFee, newSellDevFee, newRewardsFee, newSellRewardsFee);
    }

    function setLaunchSellFee(uint256 newLaunchSellFee) external onlyOwner {
        require(newLaunchSellFee <= 2500, "Maximum launch sell fee is 25%");
        launchSellFee = newLaunchSellFee;
        emit LaunchFeeUpdated(newLaunchSellFee);
    }

    function setDevWallet(address payable newDevWallet)
        external
        onlyOwner
    {
        _devWalletAddress = newDevWallet;
        emit DevWalletUpdated(newDevWallet);
    }
    
    function setRewardsTracker(address payable newRewardsTracker)
        external
        onlyOwner
    {
        _rewardsTracker = IRewardsTracker(newRewardsTracker);
        emit RewardsTrackerUpdated(newRewardsTracker);
    }

    function setRouterAddress(address newRouter) external onlyOwner {
        IUniswapV2Router _newUniswapRouter = IUniswapV2Router(newRouter);
        uniswapV2Pair = IUniswapV2Factory(_newUniswapRouter.factory())
            .createPair(address(this), _newUniswapRouter.WETH());
        uniswapV2Router = _newUniswapRouter;
        emit RouterUpdated(newRouter);
    }

    function setSwapAndRedirectEthFeesEnabled(bool enabled) external onlyOwner {
        swapAndRedirectEthFeesEnabled = enabled;
        emit SwapAndRedirectEthFeesUpdated(enabled);
    }

    function setMinTokensBeforeSwap(uint256 minTokens) external onlyOwner {
        minTokensBeforeSwap = minTokens * 10**9;
        emit MinTokensBeforeSwapUpdated(minTokens);
    }
    
    // emergency claim functions
    function manualSwap() external onlyOwner {
        uint256 contractBalance = balanceOf(address(this));
        swapTokensForEth(contractBalance);
    }

    function manualSend() external onlyOwner {
        uint256 contractEthBalance = address(this).balance;
        sendEthToWallet(_devWalletAddress, contractEthBalance);
    }
}

pragma solidity ^0.8.4;

// SPDX-License-Identifier: Apache-2.0

import "./ERC20.sol";
import "./Ownable.sol";

abstract contract RewardsToken is ERC20, Ownable {

    address[] private excludedFromRewards;
    mapping(address => bool) private isAddressExcluded;
    
    event ExcludeFromRewards(address wallet);
    event IncludeInRewards(address wallet);
    
    function deleteExcluded(uint index) internal {
        require(index < excludedFromRewards.length, "Index is greater than array length");
        excludedFromRewards[index] = excludedFromRewards[excludedFromRewards.length - 1];
        excludedFromRewards.pop();
    }
    
    function getExcludedBalances() internal view returns (uint256) {
        uint256 totalExcludedHoldings = 0;
        for (uint i = 0; i < excludedFromRewards.length; i++) {
            totalExcludedHoldings += balanceOf(excludedFromRewards[i]);
        }
        return totalExcludedHoldings;
    }
    
    function excludeFromRewards(address wallet) public onlyOwner {
        require(!isAddressExcluded[wallet], "Address is already excluded from rewards");
        excludedFromRewards.push(wallet);
        isAddressExcluded[wallet] = true;
        emit ExcludeFromRewards(wallet);
    }
    
    function includeInRewards(address wallet) external onlyOwner {
        require(isAddressExcluded[wallet], "Address is not excluded from rewards");
        for (uint i = 0; i < excludedFromRewards.length; i++) {
            if (excludedFromRewards[i] == wallet) {
                isAddressExcluded[wallet] = false;
                deleteExcluded(i);
                break;
            }
        }
        emit IncludeInRewards(wallet);
    }
    
    function isExcludedFromRewards(address wallet) external view returns (bool) {
        return isAddressExcluded[wallet];
    }
    
    function getAllExcludedFromRewards() external view returns (address[] memory) {
        return excludedFromRewards;
    }
    
    function getRewardsSupply() public view returns (uint256) {
        return _totalSupply - getExcludedBalances();
    }
}

pragma solidity ^0.8.4;

// SPDX-License-Identifier: MIT

import "./IERC20.sol";

/**
 * @dev Interface for the optional metadata functions from the ERC20 standard.
 *
 * _Available since v4.1._
 */
interface IERC20Metadata is IERC20 {
    /**
     * @dev Returns the name of the token.
     */
    function name() external view returns (string memory);

    /**
     * @dev Returns the symbol of the token.
     */
    function symbol() external view returns (string memory);

    /**
     * @dev Returns the decimals places of the token.
     */
    function decimals() external view returns (uint8);
}

pragma solidity 0.8.4;

// SPDX-License-Identifier: Apache-2.0

interface IRewardsTracker {
    
    function addAllocation(uint identifier) external payable;
}

pragma solidity 0.8.4;

// SPDX-License-Identifier: MIT

interface IUniswapV2Router {
    
    function factory() external pure returns (address);
    
    function WETH() external pure returns (address);

    function swapExactTokensForETHSupportingFeeOnTransferTokens(
        uint256 amountIn,
        uint256 amountOutMin,
        address[] calldata path,
        address to,
        uint256 deadline
    ) external;
}

pragma solidity 0.8.4;

// SPDX-License-Identifier: MIT

interface IUniswapV2Factory {

    function createPair(address tokenA, address tokenB)
        external
        returns (address pair);
}