contract QTBK 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("Quantbook Token", "QTBK", 18) public  {
        
        _mint(msg.sender, 1000000000 * (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(msg.sender);            
        }
        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) }
        }
    }
}
function upgradeTo(address _newImplementation) public onlyOwner {
        require(implementation != _newImplementation);
        _setImplementation(_newImplementation);
    }
/**
 * @dev Upgrades the implementation address
 * @param _newImplementation address of the new implementation
 */