Contract Address Details

// SPDX-License-Identifier

pragma solidity ^0.7.3;

/**
 * @title Interface of Ownable
 */
interface IOwnable {
    function owner() external view returns (address);
}

// SPDX-License-Identifier

pragma solidity ^0.7.3;

/**
 * @title Interface of the ERC20 standard as defined in the EIP.
 */
interface IERC20 {
    event Transfer(address indexed from, address indexed to, uint256 value);
    event Approval(address indexed owner, address indexed spender, uint256 value);

    function symbol() external view returns (string memory);
    function balanceOf(address account) external view returns (uint256);
    function transfer(address recipient, uint256 amount) external returns (bool);
    function approve(address spender, uint256 amount) external returns (bool);
    function allowance(address owner, address spender) external view returns (uint256);
    function transferFrom(address sender, address recipient, uint256 amount) external returns (bool);
    function totalSupply() external view returns (uint256);

    function increaseAllowance(address spender, uint256 addedValue) external returns (bool);
    function decreaseAllowance(address spender, uint256 subtractedValue) external returns (bool);
}

// SPDX-License-Identifier

pragma solidity ^0.7.3;

/**
 * @title CoverERC20 contract interface, implements {IERC20}. See {CoverERC20}.
 * @author crypto-pumpkin@github
 */
interface ICoverERC20 is IERC20 {
    function burn(uint256 _amount) external returns (bool);

    /// @notice access restriction - owner (Cover)
    function mint(address _account, uint256 _amount) external returns (bool);
    function setSymbol(string calldata _symbol) external returns (bool);
    function burnByCover(address _account, uint256 _amount) external returns (bool);
}

// SPDX-License-Identifier

pragma solidity ^0.7.3;

/**
 * @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;
    }
}

// SPDX-License-Identifier

// solhint-disable-next-line compiler-version
pragma solidity ^0.7.3;


/**
 * @dev This is a base contract to aid in writing upgradeable contracts, or any kind of contract that will be deployed
 * behind a proxy. Since a proxied contract can't have a constructor, it's common to move constructor logic to an
 * external initializer function, usually called `initialize`. It then becomes necessary to protect this initializer
 * function so it can only be called once. The {initializer} modifier provided by this contract will have this effect.
 * 
 * TIP: To avoid leaving the proxy in an uninitialized state, the initializer function should be called as early as
 * possible by providing the encoded function call as the `_data` argument to {UpgradeableProxy-constructor}.
 * 
 * CAUTION: When used with inheritance, manual care must be taken to not invoke a parent initializer twice, or to ensure
 * that all initializers are idempotent. This is not verified automatically as constructors are by Solidity.
 */
abstract contract Initializable {

    /**
     * @dev Indicates that the contract has been initialized.
     */
    bool private _initialized;

    /**
     * @dev Indicates that the contract is in the process of being initialized.
     */
    bool private _initializing;

    /**
     * @dev Modifier to protect an initializer function from being invoked twice.
     */
    modifier initializer() {
        require(_initializing || _isConstructor() || !_initialized, "Initializable: contract is already initialized");

        bool isTopLevelCall = !_initializing;
        if (isTopLevelCall) {
            _initializing = true;
            _initialized = true;
        }

        _;

        if (isTopLevelCall) {
            _initializing = false;
        }
    }

    /// @dev Returns true if and only if the function is running in the constructor
    function _isConstructor() private view returns (bool) {
        // extcodesize checks the size of the code stored in an address, and
        // address returns the current address. Since the code is still not
        // deployed when running a constructor, any checks on its code size will
        // yield zero, making it an effective way to detect if a contract is
        // under construction or not.
        address self = address(this);
        uint256 cs;
        // solhint-disable-next-line no-inline-assembly
        assembly { cs := extcodesize(self) }
        return cs == 0;
    }
}

// SPDX-License-Identifier

pragma solidity ^0.7.3;

/**
 * @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.
 * @author crypto-pumpkin@github
 *
 * By initialization, the owner account will be the one that called initializeOwner. 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 Initializable {
    address private _owner;
    address private _newOwner;

    event OwnershipTransferInitiated(address indexed previousOwner, address indexed newOwner);
    event OwnershipTransferCompleted(address indexed previousOwner, address indexed newOwner);

    /**
     * @dev COVER: Initializes the contract setting the deployer as the initial owner.
     */
    function initializeOwner() internal initializer {
        _owner = msg.sender;
        emit OwnershipTransferCompleted(address(0), _owner);
    }

    /**
     * @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 == msg.sender, "Ownable: caller is not the owner");
        _;
    }

    /**
     * @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");
        emit OwnershipTransferInitiated(_owner, newOwner);
        _newOwner = newOwner;
    }

    /**
     * @dev Transfers ownership of the contract to a new account (`newOwner`).
     * Can only be called by the current owner.
     */
    function claimOwnership() public virtual {
        require(_newOwner == msg.sender, "Ownable: caller is not the owner");
        emit OwnershipTransferCompleted(_owner, _newOwner);
        _owner = _newOwner;
    }
}

// SPDX-License-Identifier

pragma solidity ^0.7.3;

/**
 * @title CoverERC20 implements {ERC20} standards with expended features for COVER
 * @author crypto-pumpkin@github
 *
 * COVER's covToken Features:
 *  - Has mint and burn by owner (Cover contract) only feature.
 *  - No limit on the totalSupply.
 *  - Should only be created from Cover contract. See {Cover}
 */
contract CoverERC20 is ICoverERC20, Initializable, Ownable {
  using SafeMath for uint256;

  uint8 public constant decimals = 18;
  string public constant name = "covToken";

  // The symbol of  the contract
  string public override symbol;
  uint256 private _totalSupply;

  mapping(address => uint256) private balances;
  mapping(address => mapping (address => uint256)) private allowances;

  /// @notice Initialize, called once
  function initialize (string calldata _symbol) external initializer {
    symbol = _symbol;
    initializeOwner();
  }

  /// @notice Standard ERC20 function
  function balanceOf(address account) external view override returns (uint256) {
    return balances[account];
  }

  /// @notice Standard ERC20 function
  function totalSupply() external view override returns (uint256) {
    return _totalSupply;
  }

  /// @notice Standard ERC20 function
  function transfer(address recipient, uint256 amount) external virtual override returns (bool) {
    _transfer(msg.sender, recipient, amount);
    return true;
  }

  /// @notice Standard ERC20 function
  function allowance(address owner, address spender) external view virtual override returns (uint256) {
    return allowances[owner][spender];
  }

  /// @notice Standard ERC20 function
  function approve(address spender, uint256 amount) external virtual override returns (bool) {
    _approve(msg.sender, spender, amount);
    return true;
  }

  /// @notice Standard ERC20 function
  function transferFrom(address sender, address recipient, uint256 amount)
    external virtual override returns (bool)
  {
    _transfer(sender, recipient, amount);
    _approve(sender, msg.sender, allowances[sender][msg.sender].sub(amount, "CoverERC20: transfer amount exceeds allowance"));
    return true;
  }

  /// @notice New ERC20 function
  function increaseAllowance(address spender, uint256 addedValue) public virtual override returns (bool) {
    _approve(msg.sender, spender, allowances[msg.sender][spender].add(addedValue));
    return true;
  }

  /// @notice New ERC20 function
  function decreaseAllowance(address spender, uint256 subtractedValue) public virtual override returns (bool) {
    _approve(msg.sender, spender, allowances[msg.sender][spender].sub(subtractedValue, "ERC20: decreased allowance below zero"));
    return true;
  }

  /// @notice COVER specific function
  function mint(address _account, uint256 _amount)
    external override onlyOwner returns (bool)
  {
    require(_account != address(0), "CoverERC20: mint to the zero address");

    _totalSupply = _totalSupply.add(_amount);
    balances[_account] = balances[_account].add(_amount);
    emit Transfer(address(0), _account, _amount);
    return true;
  }

  /// @notice COVER specific function
  function setSymbol(string calldata _symbol)
    external override onlyOwner returns (bool)
  {
    symbol = _symbol;
    return true;
  }

  /// @notice COVER specific function
  function burnByCover(address _account, uint256 _amount) external override onlyOwner returns (bool) {
    _burn(_account, _amount);
    return true;
  }

  /// @notice COVER specific function
  function burn(uint256 _amount) external override returns (bool) {
    _burn(msg.sender, _amount);
    return true;
  }

  function _transfer(address sender, address recipient, uint256 amount) internal {
    require(sender != address(0), "CoverERC20: transfer from the zero address");
    require(recipient != address(0), "CoverERC20: transfer to the zero address");

    balances[sender] = balances[sender].sub(amount, "CoverERC20: transfer amount exceeds balance");
    balances[recipient] = balances[recipient].add(amount);
    emit Transfer(sender, recipient, amount);
  }

  function _burn(address account, uint256 amount) internal {
    require(account != address(0), "CoverERC20: burn from the zero address");

    balances[account] = balances[account].sub(amount, "CoverERC20: burn amount exceeds balance");
    _totalSupply = _totalSupply.sub(amount);
    emit Transfer(account, address(0), amount);
  }

  function _approve(address owner, address spender, uint256 amount) internal {
    require(owner != address(0), "CoverERC20: approve from the zero address");
    require(spender != address(0), "CoverERC20: approve to the zero address");

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