# How to add Lock Function on solidity?

I have code for the ERC20 token which has freeze, unfreeze, lockUser & unlockUser functions. I want:

When I lock someone he will be automatically unlocked after x days or, Scheduled release of locked tokens. For example, 2% each day released. I want any of these included in my current contract or create a new one for me. Below Is My Code:

``````pragma solidity ^0.5.16;

// ----------------------------------------------------------------------------
// 'DexPortfolio' Token contract
//
// Symbol      : ****
// Name        : *****
// Total supply: *****
// Decimals    : 18
//
// ----------------------------------------------------------------------------

library SafeMath {

function add(uint256 a, uint256 b) internal pure returns (uint256) {
}

function add(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
uint256 c = a + b;
require(c >= a, errorMessage);

return c;
}

function sub(uint256 a, uint256 b) internal pure returns (uint256) {
return sub(a, b, "SafeMath: subtraction overflow");
}

function sub(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
require(b <= a, errorMessage);
uint256 c = a - b;

return c;
}

function mul(uint256 a, uint256 b) internal pure returns (uint256) {

if (a == 0) {
return 0;
}

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

return c;
}

function div(uint256 a, uint256 b) internal pure returns (uint256) {
return div(a, b, "SafeMath: division by zero");
}

function div(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
// Solidity only automatically asserts when dividing by 0
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;
}

function mod(uint256 a, uint256 b) internal pure returns (uint256) {
return mod(a, b, "SafeMath: modulo by zero");
}

function mod(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
require(b != 0, errorMessage);
return a % b;
}
}

contract Context {
// Empty internal constructor, to prevent people from mistakenly deploying
// an instance of this contract, which should be used via inheritance.
constructor () internal { }

function _msgSender() internal view returns (address payable) {
return msg.sender;
}

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

contract Ownable is Context {

constructor () internal {
_owner = msgSender;
}

function owner() public view returns (address) {
return _owner;
}

modifier onlyOwner() {
require(_owner == _msgSender(), "Ownable: caller is not the owner");
_;
}

function renounceOwnership() public onlyOwner {
}

function transferOwnership(address newOwner) public onlyOwner {
_transferOwnership(newOwner);
}

emit OwnershipTransferred(_owner, newOwner);
_owner = newOwner;
}
}

interface BEP20Interface {

function totalSupply() external view returns (uint256);

function decimals() external view returns (uint8);

function symbol() external view returns (string memory);

function name() external view returns (string memory);

function getOwner() external view returns (address);

/**
* @dev Returns the amount of tokens owned by `account`.
*/
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);

}

contract Tokenlock is Ownable {
/// @notice Indicates if token is locked
uint8 isLocked = 0;

event Freezed();
event UnFreezed();

modifier validLock {
require(isLocked == 0, "Token is locked");
_;
}

function freeze() public onlyOwner {
isLocked = 1;

emit Freezed();
}

function unfreeze() public onlyOwner {
isLocked = 0;

emit UnFreezed();
}
}

// ----------------------------------------------------------------------------
// Contract function to receive approval and execute function in one call
// ----------------------------------------------------------------------------
contract ApproveAndCallFallBack {
}

// ----------------------------------------------------------------------------
// Limit users in blacklist
// ----------------------------------------------------------------------------
contract UserLock is Ownable {

modifier permissionCheck {
require(!blacklist[msg.sender], "Blocked user");
_;
}

function lockUser(address who) public onlyOwner {
blacklist[who] = true;

emit LockUser(who);
}

function unlockUser(address who) public onlyOwner {
blacklist[who] = false;

emit UnlockUser(who);
}
}

contract DEXP is BEP20Interface, Tokenlock, UserLock {
using SafeMath for uint256;

/// @notice Official record of token balances for each account
mapping (address => uint256) private _balances;

/// @notice Allowance amounts on behalf of others

uint256 private _totalSupply;

uint8 private _decimals;

string private _symbol;

string private _name;

_name = "*******";
_symbol = "******";
_decimals = 18;
_totalSupply = 1000000e18;
_balances[account] = _totalSupply;

}

function getOwner() external view returns (address) {
return owner();
}

function decimals() external view returns (uint8) {
return _decimals;
}

function symbol() external view returns (string memory) {
return _symbol;
}

function name() external view returns (string memory) {
return _name;
}

function totalSupply() external view returns (uint256) {
return _totalSupply;
}

function balanceOf(address account) external view returns (uint256) {
return _balances[account];
}

function transfer(address recipient, uint256 amount) external validLock permissionCheck returns (bool) {
emit Transfer(_msgSender(), recipient, amount);
return true;
}

return _allowances[owner][spender];
}

function approve(address spender, uint256 amount) external validLock permissionCheck returns (bool) {
_approve(_msgSender(), spender, amount);
return true;
}

function approveAndCall(address spender, uint256 amount, bytes memory data) public validLock permissionCheck returns (bool) {
_approve(_msgSender(), spender, amount);
return true;
}

function transferFrom(address sender, address recipient, uint256 amount) external validLock permissionCheck returns (bool) {
emit Transfer(sender, recipient, amount);
uint256 spenderAllowance = _allowances[sender][spender];
if (spenderAllowance != uint256(-1)) {
_approve(sender, spender, spenderAllowance.sub(amount, "The transfer amount exceeds allowance"));
}
return true;
}

return true;
}

function decreaseAllowance(address spender, uint256 subtractedValue) public validLock permissionCheck returns (bool) {
_approve(_msgSender(), spender, _allowances[_msgSender()][spender].sub(subtractedValue, "The decreased allowance below zero"));
return true;
}

function burn(uint256 amount) public validLock permissionCheck returns (bool) {
_burn(_msgSender(), amount);
return true;
}

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

function _burn(address account, uint256 amount) internal {