contract UniversalMobileToken is Ownable {
    
    using SafeMath for uint;

    /*
        Standard ERC20 token
    */
    
    event Transfer(address indexed from, address indexed to, uint tokens);
    event Approval(address indexed tokenOwner, address indexed spender, uint tokens);

    // Name of token
    string public name;
    // Short symbol for token
    string public symbol;

    // Nubmer of decimal places
    uint public decimals;

    // Token's total supply
    uint public totalSupply;

    // Is minting active
    bool public mintingIsFinished;

    // Is transfer possible
    bool public transferIsPossible;

    modifier onlyEmitter() {
        require(emitters[msg.sender] == true);
        _;
    }
    
    mapping (address => uint) public balances;
    mapping (address => bool) public emitters;
    mapping (address => mapping (address => uint)) internal allowed;
    
    constructor() Ownable() public {
        name = "Universal Mobile Token";
        symbol = "UMT";
        decimals = 18;   
        // Make the Owner also an emitter
        emitters[msg.sender] = true;
    }

    /**
    *   @dev Finish minting process
    */
    function finishMinting() public onlyOwner {
        mintingIsFinished = true;
        transferIsPossible = true;
    }

    /**
    *   @dev Send coins
    *   throws on any error rather then return a false flag to minimize
    *   user errors
    *   @param _to           target address
    *   @param _value       transfer amount
    *
    *   @return true if the transfer was successful
    */
    function transfer(address _to, uint _value) public returns (bool success) {
        // Make transfer only if transfer is possible
        require(transferIsPossible);
        require(_to != address(0) && _to != address(this));
        balances[msg.sender] = balances[msg.sender].sub(_value);
        balances[_to] = balances[_to].add(_value);
        emit Transfer(msg.sender, _to, _value);
        return true;
    }

    /**
    *   @dev Allows another account/contract to spend some tokens on its behalf
    *   throws on any error rather then return a false flag to minimize user errors
    *
    *   also, to minimize the risk of the approve/transferFrom attack vector
    *   approve has to be called twice in 2 separate transactions - once to
    *   change the allowance to 0 and secondly to change it to the new allowance
    *   value
    *
    *   @param _spender      approved address
    *   @param _value       allowance amount
    *
    *   @return true if the approval was successful
    */
    function approve(address _spender, uint _value) public returns (bool success) {
        require((_value == 0) || (allowed[msg.sender][_spender] == 0));
        allowed[msg.sender][_spender] = _value;
        emit Approval(msg.sender, _spender, _value);
        return true;
    }

    /**
    *   @dev An account/contract attempts to get the coins
    *   throws on any error rather then return a false flag to minimize user errors
    *
    *   @param _from         source address
    *   @param _to           target address
    *   @param _value        amount
    *
    *   @return true if the transfer was successful
    */
    function transferFrom(address _from, address _to, uint _value) public returns (bool success) {
        // Make transfer only if transfer is possible
        require(transferIsPossible);

        require(_to != address(0) && _to != address(this));

        balances[_from] = balances[_from].sub(_value);
        allowed[_from][msg.sender] = allowed[_from][msg.sender].sub(_value);
        balances[_to] = balances[_to].add(_value);
        emit Transfer(_from, _to, _value);
        return true;
    }

    /**
    *   @dev Add an emitter account
    *   
    *   @param _emitter     emitter's address
    */
    function addEmitter(address _emitter) public onlyOwner {
        emitters[_emitter] = true;
    }
    
    /**
    *   @dev Remove an emitter account
    *   
    *   @param _emitter     emitter's address
    */
    function removeEmitter(address _emitter) public onlyOwner {
        emitters[_emitter] = false;
    }
    
    /**
    *   @dev Mint token in batches
    *   
    *   @param _adresses     token holders' adresses
    *   @param _values       token holders' values
    */
    function batchMint(address[] _adresses, uint[] _values) public onlyEmitter {
        require(_adresses.length == _values.length);
        for (uint i = 0; i < _adresses.length; i++) {
            require(minted(_adresses[i], _values[i]));
        }
    }

    /**
    *   @dev Transfer token in batches
    *   
    *   @param _adresses     token holders' adresses
    *   @param _values       token holders' values
    */
    function batchTransfer(address[] _adresses, uint[] _values) public {
        require(_adresses.length == _values.length);
        for (uint i = 0; i < _adresses.length; i++) {
            require(transfer(_adresses[i], _values[i]));
        }
    }

    /**
    *   @dev Burn Tokens
    *   @param _from       token holder address which the tokens will be burnt
    *   @param _value      number of tokens to burn
    */
    function burn(address _from, uint _value) public onlyEmitter {
        // Burn tokens only if minting stage is not finished
        require(!mintingIsFinished);

        require(_value <= balances[_from]);
        balances[_from] = balances[_from].sub(_value);
        totalSupply = totalSupply.sub(_value);
    }

    /**
    *   @dev Function to check the amount of tokens that an owner allowed to a spender.
    *
    *   @param _tokenOwner        the address which owns the funds
    *   @param _spender      the address which will spend the funds
    *
    *   @return              the amount of tokens still avaible for the spender
    */
    function allowance(address _tokenOwner, address _spender) public constant returns (uint remaining) {
        return allowed[_tokenOwner][_spender];
    }

    /**
    *   @dev Function to check the amount of tokens that _tokenOwner has.
    *
    *   @param _tokenOwner        the address which owns the funds
    *
    *   @return              the amount of tokens _tokenOwner has
    */
    function balanceOf(address _tokenOwner) public constant returns (uint balance) {
        return balances[_tokenOwner];
    }

    function minted(address _to, uint _value) internal returns (bool) {
        // Mint tokens only if minting stage is not finished
        require(!mintingIsFinished);
        balances[_to] = balances[_to].add(_value);
        totalSupply = totalSupply.add(_value);
        emit Transfer(address(0), _to, _value);
        return true;
    }
}
function transfer(address _to, uint _value) public returns (bool success) {
    // Make transfer only if transfer is possible
    require(transferIsPossible);
    require(_to != address(0) && _to != address(this));
    balances[msg.sender] = balances[msg.sender].sub(_value);
    balances[_to] = balances[_to].add(_value);
    emit Transfer(msg.sender, _to, _value);
    return true;
}

/**
 *   @dev Send coins
 *   throws on any error rather then return a false flag to minimize
 *   user errors
 *   @param _to           target address
 *   @param _value       transfer amount
 *
 *   @return true if the transfer was successful
 */