pragma solidity ^0.5.0;

/**
 * @title SafeMath
 * @dev Math operations with safety checks that revert on error
 */
library SafeMath {

    /**
    * @dev Multiplies two numbers, reverts on 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-solidity/pull/522
        if (a == 0) {
            return 0;
        }
        
        uint256 c = a * b;
        require(c / a == b);
        
        return c;
    }

    /**
    * @dev Integer division of two numbers truncating the quotient, reverts on division by zero.
    */
    function div(uint256 a, uint256 b) internal pure returns (uint256) {
    require(b > 0); // Solidity only automatically asserts when dividing by 0
    uint256 c = a / b;
    // assert(a == b * c + a % b); // There is no case in which this doesn't hold
    
    return c;
    }
    
    /**
    * @dev Subtracts two numbers, reverts on overflow (i.e. if subtrahend is greater than minuend).
    */
    function sub(uint256 a, uint256 b) internal pure returns (uint256) {
        require(b <= a);
        uint256 c = a - b;
    
        return c;
    }
    
    /**
    * @dev Adds two numbers, reverts on overflow.
    */
    function add(uint256 a, uint256 b) internal pure returns (uint256) {
        uint256 c = a + b;
        require(c >= a);
    
        return c;
    }
    
    /**
    * @dev Divides two numbers and returns the remainder (unsigned integer modulo),
    * reverts when dividing by zero.
    */
    function mod(uint256 a, uint256 b) internal pure returns (uint256) {
        require(b != 0);
        return a % b;
    }
}

library Roles {
    struct Role {
        mapping (address => bool) bearer;
    }

    function add(Role storage role, address account) internal {
        require(account != address(0));
        require(!has(role, account));
        role.bearer[account] = true;
    }
    function remove(Role storage role, address account) internal {
        require(account != address(0));
        require(has(role, account));
        role.bearer[account] = false;
    }
    function has(Role storage role, address account) internal view returns (bool) {
        require(account != address(0));
        return role.bearer[account];
    }
}

contract Ownable {
    address public owner;

    event OwnershipTransferred(address indexed previousOwner, address indexed newOwner);

    constructor() public {
        owner = msg.sender;
    }

    modifier onlyOwner() {
        require(msg.sender == owner);
        _;
    }

    function isOwner(address account) public view returns (bool) {
        if( account == owner ){
            return true;
        }
        else {
            return false;
        }
    }
    function transferOwnership(address newOwner) public onlyOwner {
        require(newOwner != address(0));
        emit OwnershipTransferred(owner, newOwner);
        owner = newOwner;
    }
}

contract AdminRole is Ownable{
    using Roles for Roles.Role;

    event AdminAdded(address indexed account);
    event AdminRemoved(address indexed account);

    Roles.Role private _admin_list;

    constructor () internal {
        _addAdmin(msg.sender);
    }

    modifier onlyAdmin() {
        require(isAdmin(msg.sender)|| isOwner(msg.sender));
        _;
    }

    function isAdmin(address account) public view returns (bool) {
        return _admin_list.has(account);
    }
    function addAdmin(address account) public onlyAdmin {
        _addAdmin(account);
    }
    function removeAdmin(address account) public onlyOwner {
        _removeAdmin(account);
    }
    function renounceAdmin() public {
        _removeAdmin(msg.sender);
    }
    function _addAdmin(address account) internal {
        _admin_list.add(account);
        emit AdminAdded(account);
    }
    function _removeAdmin(address account) internal {
        _admin_list.remove(account);
        emit AdminRemoved(account);
    }
}


contract Pausable is AdminRole {
    event Paused(address account);
    event Unpaused(address account);

    bool private _paused;

    constructor () internal {
        _paused = false;
    }

    /**
     * @return true if the contract is paused, false otherwise.
     */
    function paused() public view returns (bool) {
        return _paused;
    }

    /**
     * @dev Modifier to make a function callable only when the contract is not paused.
     */
    modifier whenNotPaused() {
        require(!_paused);
        _;
    }

    /**
     * @dev Modifier to make a function callable only when the contract is paused.
     */
    modifier whenPaused() {
        require(_paused);
        _;
    }

    /**
     * @dev called by the owner to pause, triggers stopped state
     */
    function pause() public onlyAdmin whenNotPaused {
        _paused = true;
        emit Paused(msg.sender);
    }

    /**
     * @dev called by the owner to unpause, returns to normal state
     */
    function unpause() public onlyAdmin whenPaused {
        _paused = false;
        emit Unpaused(msg.sender);
    }
}

interface IERC20 {
    function transfer(address to, uint256 value) external returns (bool);
    function approve(address spender, uint256 value) external returns (bool);
    function transferFrom(address from, address to, uint256 value) external returns (bool);
    function totalSupply() external view returns (uint256);
    function balanceOf(address who) external view returns (uint256);
    function allowance(address owner, address spender) external view returns (uint256);

    event Transfer(address indexed from, address indexed to, uint256 value);
    event Approval(address indexed owner, address indexed spender, uint256 value);
}

contract ERC20 is IERC20 {
    using SafeMath for uint256;

    mapping (address => uint256) internal _balances;
    mapping (address => mapping (address => uint256)) internal _allowed;

    uint256 private _totalSupply;

    /**
    * @dev Total number of tokens in existence
    */
    function totalSupply() public view returns (uint256) {
        return _totalSupply;
    }

    /**
    * @dev Gets the balance of the specified address.
    * @param owner The address to query the balance of.
    * @return An uint256 representing the amount owned by the passed address.
    */
    function balanceOf(address owner) public view returns (uint256) {
        return _balances[owner];
    }

    /**
     * @dev Function to check the amount of tokens that an owner allowed to a spender.
     * @param owner address The address which owns the funds.
     * @param spender address The address which will spend the funds.
     * @return A uint256 specifying the amount of tokens still available for the spender.
     */
    function allowance(address owner, address spender) public view returns (uint256) {
        return _allowed[owner][spender];
    }

    /**
    * @dev Transfer token for a specified address
    * @param to The address to transfer to.
    * @param value The amount to be transferred.
    */
    function transfer(address to, uint256 value) public returns (bool) {
        _transfer(msg.sender, to, value);
        return true;
    }

    /**
     * @dev Approve the passed address to spend the specified amount of tokens on behalf of msg.sender.
     * 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
     * @param spender The address which will spend the funds.
     * @param value The amount of tokens to be spent.
     */
    function approve(address spender, uint256 value) public returns (bool) {
        require(spender != address(0));

        _allowed[msg.sender][spender] = value;
        emit Approval(msg.sender, spender, value);
        return true;
    }

    /**
     * @dev Transfer tokens from one address to another.
     * Note that while this function emits an Approval event, this is not required as per the specification,
     * and other compliant implementations may not emit the event.
     * @param from address The address which you want to send tokens from
     * @param to address The address which you want to transfer to
     * @param value uint256 the amount of tokens to be transferred
     */
    function transferFrom(address from, address to, uint256 value) public returns (bool) {
        _allowed[from][msg.sender] = _allowed[from][msg.sender].sub(value);
        _transfer(from, to, value);
        emit Approval(from, msg.sender, _allowed[from][msg.sender]);
        return true;
    }

    /**
     * @dev Increase the amount of tokens that an owner allowed to a spender.
     * approve should be called when allowed_[_spender] == 0. To increment
     * allowed value is better to use this function to avoid 2 calls (and wait until
     * the first transaction is mined)
     * From MonolithDAO Token.sol
     * Emits an Approval event.
     * @param spender The address which will spend the funds.
     * @param addedValue The amount of tokens to increase the allowance by.
     */
    function increaseAllowance(address spender, uint256 addedValue) public returns (bool) {
        require(spender != address(0));

        _allowed[msg.sender][spender] = _allowed[msg.sender][spender].add(addedValue);
        emit Approval(msg.sender, spender, _allowed[msg.sender][spender]);
        return true;
    }

    /**
     * @dev Decrease the amount of tokens that an owner allowed to a spender.
     * approve should be called when allowed_[_spender] == 0. To decrement
     * allowed value is better to use this function to avoid 2 calls (and wait until
     * the first transaction is mined)
     * From MonolithDAO Token.sol
     * Emits an Approval event.
     * @param spender The address which will spend the funds.
     * @param subtractedValue The amount of tokens to decrease the allowance by.
     */
    function decreaseAllowance(address spender, uint256 subtractedValue) public returns (bool) {
        require(spender != address(0));

        _allowed[msg.sender][spender] = _allowed[msg.sender][spender].sub(subtractedValue);
        emit Approval(msg.sender, spender, _allowed[msg.sender][spender]);
        return true;
    }

    /**
    * @dev Transfer token for a specified addresses
    * @param from The address to transfer from.
    * @param to The address to transfer to.
    * @param value The amount to be transferred.
    */
    function _transfer(address from, address to, uint256 value) internal {
        require(to != address(0));

        _balances[from] = _balances[from].sub(value);
        _balances[to] = _balances[to].add(value);
        emit Transfer(from, to, value);
    }

    /**
     * @dev Internal function that mints an amount of the token and assigns it to
     * an account. This encapsulates the modification of balances such that the
     * proper events are emitted.
     * @param account The account that will receive the created tokens.
     * @param value The amount that will be created.
     */
    function _mint(address account, uint256 value) internal {
        require(account != address(0));

        _totalSupply = _totalSupply.add(value);
        _balances[account] = _balances[account].add(value);
        emit Transfer(address(0), account, value);
    }

    /**
     * @dev Internal function that burns an amount of the token of a given
     * account.
     * @param account The account whose tokens will be burnt.
     * @param value The amount that will be burnt.
     */
    function _burn(address account, uint256 value) internal {
        require(account != address(0));

        _totalSupply = _totalSupply.sub(value);
        _balances[account] = _balances[account].sub(value);
        emit Transfer(account, address(0), value);
    }

    /**
     * @dev Internal function that burns an amount of the token of a given
     * account, deducting from the sender's allowance for said account. Uses the
     * internal burn function.
     * Emits an Approval event (reflecting the reduced allowance).
     * @param account The account whose tokens will be burnt.
     * @param value The amount that will be burnt.
     */
    function _burnFrom(address account, uint256 value) internal {
        _allowed[account][msg.sender] = _allowed[account][msg.sender].sub(value);
        _burn(account, value);
        emit Approval(account, msg.sender, _allowed[account][msg.sender]);
    }
}

contract ERC20Burnable is ERC20 {
    /**
     * @dev Burns a specific amount of tokens.
     * @param value The amount of token to be burned.
     */
    function burn(uint256 value) public {
        _burn(msg.sender, value);
    }

    /**
     * @dev Burns a specific amount of tokens from the target address and decrements allowance
     * @param from address The address which you want to send tokens from
     * @param value uint256 The amount of token to be burned
     */
    function burnFrom(address from, uint256 value) public {
        _burnFrom(from, value);
    }
}

contract ERC20Pausable is ERC20, Pausable {
    function transfer(address to, uint256 value) public whenNotPaused returns (bool) {
        return super.transfer(to, value);
    }

    function transferFrom(address from, address to, uint256 value) public whenNotPaused returns (bool) {
        return super.transferFrom(from, to, value);
    }

    function approve(address spender, uint256 value) public whenNotPaused returns (bool) {
        return super.approve(spender, value);
    }

    function increaseAllowance(address spender, uint addedValue) public whenNotPaused returns (bool success) {
        return super.increaseAllowance(spender, addedValue);
    }

    function decreaseAllowance(address spender, uint subtractedValue) public whenNotPaused returns (bool success) {
        return super.decreaseAllowance(spender, subtractedValue);
    }
}

contract ERC20Detailed is IERC20 {
    string private _name;
    string private _symbol;
    uint8 private _decimals;

    constructor (string memory name, string memory symbol, uint8 decimals) public {
        _name = name;
        _symbol = symbol;
        _decimals = decimals;
    }

    /**
     * @return the name of the token.
     */
    function name() public view returns (string memory) {
        return _name;
    }

    /**
     * @return the symbol of the token.
     */
    function symbol() public view returns (string memory) {
        return _symbol;
    }

    /**
     * @return the number of decimals of the token.
     */
    function decimals() public view returns (uint8) {
        return _decimals;
    }
}

contract STAT is ERC20Detailed, ERC20Pausable, ERC20Burnable {
    
    struct LockInfo {
        uint256 _releaseTime;
        uint256 _amount;
    }
    
    address public implementation;

    mapping (address => LockInfo[]) public timelockList;
	mapping (address => bool) public frozenAccount;
    
    event Freeze(address indexed holder);
    event Unfreeze(address indexed holder);
    event Lock(address indexed holder, uint256 value, uint256 releaseTime);
    event Unlock(address indexed holder, uint256 value);

    modifier notFrozen(address _holder) {
        require(!frozenAccount[_holder]);
        _;
    }
    
    constructor() ERC20Detailed("STAT", "STAT", 18) public  {
        
        _mint(msg.sender, 100000000 * (10 ** 18));
    }
    
    function balanceOf(address owner) public view returns (uint256) {
        
        uint256 totalBalance = super.balanceOf(owner);
        if( timelockList[owner].length >0 ){
            for(uint i=0; i<timelockList[owner].length;i++){
                totalBalance = totalBalance.add(timelockList[owner][i]._amount);
            }
        }
        
        return totalBalance;
    }
    
    function transfer(address to, uint256 value) public notFrozen(msg.sender) returns (bool) {
        if (timelockList[msg.sender].length > 0 ) {
            _autoUnlock(msg.sender);            
        }
        return super.transfer(to, value);
    }

    function transferFrom(address from, address to, uint256 value) public notFrozen(from) returns (bool) {
        if (timelockList[from].length > 0) {
            _autoUnlock(from);            
        }
        return super.transferFrom(from, to, value);
    }
    
    function freezeAccount(address holder) public onlyAdmin returns (bool) {
        require(!frozenAccount[holder]);
        frozenAccount[holder] = true;
        emit Freeze(holder);
        return true;
    }

    function unfreezeAccount(address holder) public onlyAdmin returns (bool) {
        require(frozenAccount[holder]);
        frozenAccount[holder] = false;
        emit Unfreeze(holder);
        return true;
    }
    
    function lock(address holder, uint256 value, uint256 releaseTime) public onlyAdmin returns (bool) {
        require(_balances[holder] >= value,"There is not enough balance of holder.");
        _lock(holder,value,releaseTime);
        
        return true;
    }
    
    function transferWithLock(address holder, uint256 value, uint256 releaseTime) public onlyAdmin returns (bool) {
        _transfer(msg.sender, holder, value);
        _lock(holder,value,releaseTime);
        return true;
    }
    
    function unlock(address holder, uint256 idx) public onlyAdmin returns (bool) {
        require( timelockList[holder].length > idx, "There is not lock info.");
        _unlock(holder,idx);
        return true;
    }
    
    /**
     * @dev Upgrades the implementation address
     * @param _newImplementation address of the new implementation
     */
    function upgradeTo(address _newImplementation) public onlyOwner {
        require(implementation != _newImplementation);
        _setImplementation(_newImplementation);
    }
    
    function _lock(address holder, uint256 value, uint256 releaseTime) internal returns(bool) {
        _balances[holder] = _balances[holder].sub(value);
        timelockList[holder].push( LockInfo(releaseTime, value) );
        
        emit Lock(holder, value, releaseTime);
        return true;
    }
    
    function _unlock(address holder, uint256 idx) internal returns(bool) {
        LockInfo storage lockinfo = timelockList[holder][idx];
        uint256 releaseAmount = lockinfo._amount;

        delete timelockList[holder][idx];
        timelockList[holder][idx] = timelockList[holder][timelockList[holder].length.sub(1)];
        timelockList[holder].length -=1;
        
        emit Unlock(holder, releaseAmount);
        _balances[holder] = _balances[holder].add(releaseAmount);
        
        return true;
    }
    
    function _autoUnlock(address holder) internal returns(bool) {
        for(uint256 idx =0; idx < timelockList[holder].length ; idx++ ) {
            if (timelockList[holder][idx]._releaseTime <= now) {
                // If lockupinfo was deleted, loop restart at same position.
                if( _unlock(holder, idx) ) {
                    idx -=1;
                }
            }
        }
        return true;
    }
    
    /**
     * @dev Sets the address of the current implementation
     * @param _newImp address of the new implementation
     */
    function _setImplementation(address _newImp) internal {
        implementation = _newImp;
    }
    
    /**
     * @dev Fallback function allowing to perform a delegatecall 
     * to the given implementation. This function will return 
     * whatever the implementation call returns
     */
    function () payable external {
        address impl = implementation;
        require(impl != address(0));
        assembly {
            /*
                0x40 is the "free memory slot", meaning a pointer to next slot of empty memory. mload(0x40)
                loads the data in the free memory slot, so `ptr` is a pointer to the next slot of empty
                memory. It's needed because we're going to write the return data of delegatecall to the
                free memory slot.
            */
            let ptr := mload(0x40)
            /*
                `calldatacopy` is copy calldatasize bytes from calldata
                First argument is the destination to which data is copied(ptr)
                Second argument specifies the start position of the copied data.
                    Since calldata is sort of its own unique location in memory,
                    0 doesn't refer to 0 in memory or 0 in storage - it just refers to the zeroth byte of calldata.
                    That's always going to be the zeroth byte of the function selector.
                Third argument, calldatasize, specifies how much data will be copied.
                    calldata is naturally calldatasize bytes long (same thing as msg.data.length)
            */
            calldatacopy(ptr, 0, calldatasize)
            /*
                delegatecall params explained:
                gas: the amount of gas to provide for the call. `gas` is an Opcode that gives
                    us the amount of gas still available to execution
                _impl: address of the contract to delegate to
                ptr: to pass copied data
                calldatasize: loads the size of `bytes memory data`, same as msg.data.length
                0, 0: These are for the `out` and `outsize` params. Because the output could be dynamic,
                        these are set to 0, 0 so the output data will not be written to memory. The output
                        data will be read using `returndatasize` and `returdatacopy` instead.
                result: This will be 0 if the call fails and 1 if it succeeds
            */
            let result := delegatecall(gas, impl, ptr, calldatasize, 0, 0)
            let size := returndatasize
            /*
                `returndatacopy` is an Opcode that copies the last return data to a slot. `ptr` is the
                    slot it will copy to, 0 means copy from the beginning of the return data, and size is
                    the amount of data to copy.
                `returndatasize` is an Opcode that gives us the size of the last return data. In this case, that is the size of the data returned from delegatecall
            */
            returndatacopy(ptr, 0, size)
            
            /*
                if `result` is 0, revert.
                if `result` is 1, return `size` amount of data from `ptr`. This is the data that was
                copied to `ptr` from the delegatecall return data
            */
            switch result
            case 0 { revert(ptr, size) }
            default { return(ptr, size) }
        }
    }
}