pragma solidity ^0.4.24;

contract Ownable {

    address private _owner;
    
    event OwnershipRenounced(address indexed previousOwner);
    event OwnershipTransferred(
        address indexed previousOwner,
        address indexed newOwner
    );

    /**
    * @dev The Ownable constructor sets the original `owner` of the contract to the sender
    * account.
    */
    constructor() public {
        _owner = msg.sender;
    }

    /**
    * @return the address of the owner.
    */
    function owner() public view returns(address) {
        return _owner;
    }

    /**
    * @dev Throws if called by any account other than the owner.
    */
    modifier onlyOwner() {
        require(isOwner());
        _;
    }

    /**
    * @return true if `msg.sender` is the owner of the contract.
    */
    function isOwner() public view returns(bool) {
        return msg.sender == _owner;
    }

    /**
    * @dev Allows the current owner to relinquish control of the contract.
    * @notice Renouncing to ownership will leave the contract without an owner.
    * It will not be possible to call the functions with the `onlyOwner`
    * modifier anymore.
    */
    function renounceOwnership() public onlyOwner {
        emit OwnershipRenounced(_owner);
        _owner = address(0);
    }

    /**
    * @dev Allows the current owner to transfer control of the contract to a newOwner.
    * @param newOwner The address to transfer ownership to.
    */
    function transferOwnership(address newOwner) public onlyOwner {
        _transferOwnership(newOwner);
    }

    /**
    * @dev Transfers control of the contract to a newOwner.
    * @param newOwner The address to transfer ownership to.
    */
    function _transferOwnership(address newOwner) internal {
        require(newOwner != address(0));
        emit OwnershipTransferred(_owner, newOwner);
        _owner = newOwner;
    }
}

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;
    }
}

interface IERC20 {

    function totalSupply() external view returns (uint256);

    function balanceOf(address who) external view returns (uint256);

    function allowance(address owner, address spender)
        external view returns (uint256);

    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);

    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) private _balances;

    mapping (address => mapping (address => uint256)) private _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) {
        require(value <= _balances[msg.sender]);
        require(to != address(0));

        _balances[msg.sender] = _balances[msg.sender].sub(value);
        _balances[to] = _balances[to].add(value);
        emit 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
    * @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)
    {
        require(value <= _balances[from]);
        require(value <= _allowed[from][msg.sender]);
        require(to != address(0));

        _balances[from] = _balances[from].sub(value);
        _balances[to] = _balances[to].add(value);
        _allowed[from][msg.sender] = _allowed[from][msg.sender].sub(value);
        emit Transfer(from, to, value);
        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
    * @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
    * @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 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 amount The amount that will be created.
    */
    function _mint(address account, uint256 amount) internal {
        require(account != 0);
        _totalSupply = _totalSupply.add(amount);
        _balances[account] = _balances[account].add(amount);
        emit Transfer(address(0), account, amount);
    }

    /**
    * @dev Internal function that burns an amount of the token of a given
    * account.
    * @param account The account whose tokens will be burnt.
    * @param amount The amount that will be burnt.
    */
    function _burn(address account, uint256 amount) internal {
        require(account != 0);
        require(amount <= _balances[account]);

        _totalSupply = _totalSupply.sub(amount);
        _balances[account] = _balances[account].sub(amount);
        emit Transfer(account, address(0), amount);
    }

    /**
    * @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.
    * @param account The account whose tokens will be burnt.
    * @param amount The amount that will be burnt.
    */
    function _burnFrom(address account, uint256 amount) internal {
        require(amount <= _allowed[account][msg.sender]);

        // Should https://github.com/OpenZeppelin/zeppelin-solidity/issues/707 be accepted,
        // this function needs to emit an event with the updated approval.
        _allowed[account][msg.sender] = _allowed[account][msg.sender].sub(
        amount);
        _burn(account, amount);
    }
}

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);
    }

    /**
    * @dev Overrides ERC20._burn in order for burn and burnFrom to emit
    * an additional Burn event.
    */
    function _burn(address who, uint256 value) internal {
        super._burn(who, value);
    }
}

contract IFUM is Ownable, ERC20Burnable {

    string public name;
    
    string public symbol;
    
    uint8 public decimals;

    address private _crowdsale;

    bool private _freezed;

    mapping (address => bool) private _locked;
    
    constructor() public {
        symbol = "IFUM";
        name = "INFLEUM Token";
        decimals = 8;
        _crowdsale = address(0);
        _freezed = true;
    }

    function setCrowdsale(address crowdsale) public {
        require(crowdsale != address(0), "Invalid address");
        require(_crowdsale == address(0), "It is allowed only one time.");
        _crowdsale = crowdsale;
        _mint(crowdsale, 3000000000 * 10 ** uint(decimals));
    }

    function isFreezed() public view returns (bool) {
        return _freezed;
    }

    function unfreeze() public {
        require(msg.sender == _crowdsale, "Only crowdsale contract can unfreeze this token.");
        _freezed = false;
    }

    function isLocked(address account) public view returns (bool) {
        return _locked[account];
    }

    modifier test(address account) {
        require(!isLocked(account), "It is a locked account.");
        require(!_freezed || _crowdsale == account, "A token is frozen or not crowdsale contract executes this function.");
        _;
    }

    function lockAccount(address account) public onlyOwner {
        require(!isLocked(account), "It is already a locked account.");
        _locked[account] = true;
        emit LockAccount(account);
    }

    function unlockAccount(address account) public onlyOwner {
        require(isLocked(account), "It is already a unlocked account.");
        _locked[account] = false;
        emit UnlockAccount(account);
    }

    function transfer(address to, uint256 value) public test(msg.sender) returns (bool) {
        return super.transfer(to, value);
    }

    function approve(address spender, uint256 value) public test(msg.sender) returns (bool) {
        return super.approve(spender, value);
    }

    function transferFrom(address from, address to, uint256 value) public test(from) returns (bool) {
        return super.transferFrom(from, to, value);
    }

    function increaseAllowance(address spender, uint256 addedValue) public test(msg.sender) returns (bool) {
        return super.increaseAllowance(spender, addedValue);
    }

    function decreaseAllowance(address spender, uint256 subtractedValue) public test(msg.sender) returns (bool) {
        return super.decreaseAllowance(spender, subtractedValue);
    }

    function burn(uint256 value) public test(msg.sender) {
        return super.burn(value);
    }

    function burnFrom(address from, uint256 value) public test(from) {
        return super.burnFrom(from, value);
    }

    event LockAccount(address indexed account);

    event UnlockAccount(address indexed account);
}