pragma solidity ^0.4.11;



contract ERC20Token {
    /* This is a slight change to the ERC20 base standard.
    function totalSupply() constant returns (uint256 supply);
    is replaced with:
    uint256 public totalSupply;
    This automatically creates a getter function for the totalSupply.
    This is moved to the base contract since public getter functions are not
    currently recognised as an implementation of the matching abstract
    function by the compiler.
    */
    /// total amount of tokens
    uint256 public totalSupply;

    /// @param _owner The address from which the balance will be retrieved
    /// @return The balance
    function balanceOf(address _owner) constant returns (uint256 balance);

    /// @notice send `_value` token to `_to` from `msg.sender`
    /// @param _to The address of the recipient
    /// @param _value The amount of token to be transferred
    /// @return Whether the transfer was successful or not
    function transfer(address _to, uint256 _value) returns (bool success);

    /// @notice send `_value` token to `_to` from `_from` on the condition it is approved by `_from`
    /// @param _from The address of the sender
    /// @param _to The address of the recipient
    /// @param _value The amount of token to be transferred
    /// @return Whether the transfer was successful or not
    function transferFrom(address _from, address _to, uint256 _value) returns (bool success);

    /// @notice `msg.sender` approves `_spender` to spend `_value` tokens
    /// @param _spender The address of the account able to transfer the tokens
    /// @param _value The amount of tokens to be approved for transfer
    /// @return Whether the approval was successful or not
    function approve(address _spender, uint256 _value) returns (bool success);

    /// @param _owner The address of the account owning tokens
    /// @param _spender The address of the account able to transfer the tokens
    /// @return Amount of remaining tokens allowed to spent
    function allowance(address _owner, address _spender) constant returns (uint256 remaining);

    event Transfer(address indexed _from, address indexed _to, uint256 _value);
    event Approval(address indexed _owner, address indexed _spender, uint256 _value);
}

contract Owned {
    /// @dev `owner` is the only address that can call a function with this
    /// modifier
    modifier onlyOwner() {
        require(msg.sender == owner) ;
        _;
    }

    address public owner;

    /// @notice The Constructor assigns the message sender to be `owner`
    function Owned() {
        owner = msg.sender;
    }

    address public newOwner;

    /// @notice `owner` can step down and assign some other address to this role
    /// @param _newOwner The address of the new owner. 0x0 can be used to create
    ///  an unowned neutral vault, however that cannot be undone
    function changeOwner(address _newOwner) onlyOwner {
        newOwner = _newOwner;
    }

    function acceptOwnership() {
        if (msg.sender == newOwner) {
            owner = newOwner;
        }
    }
}

contract SafeMath {
    
    /*
    standard uint256 functions
     */

    function add(uint256 x, uint256 y) constant internal returns (uint256 z) {
        assert((z = x + y) >= x);
    }

    function sub(uint256 x, uint256 y) constant internal returns (uint256 z) {
        assert((z = x - y) <= x);
    }

    function mul(uint256 x, uint256 y) constant internal returns (uint256 z) {
        assert((z = x * y) >= x);
    }

    function div(uint256 x, uint256 y) constant internal returns (uint256 z) {
        z = x / y;
    }

    function min(uint256 x, uint256 y) constant internal returns (uint256 z) {
        return x <= y ? x : y;
    }
    function max(uint256 x, uint256 y) constant internal returns (uint256 z) {
        return x >= y ? x : y;
    }

    /*
    uint128 functions (h is for half)
     */


    function hadd(uint128 x, uint128 y) constant internal returns (uint128 z) {
        assert((z = x + y) >= x);
    }

    function hsub(uint128 x, uint128 y) constant internal returns (uint128 z) {
        assert((z = x - y) <= x);
    }

    function hmul(uint128 x, uint128 y) constant internal returns (uint128 z) {
        assert((z = x * y) >= x);
    }

    function hdiv(uint128 x, uint128 y) constant internal returns (uint128 z) {
        z = x / y;
    }

    function hmin(uint128 x, uint128 y) constant internal returns (uint128 z) {
        return x <= y ? x : y;
    }
    function hmax(uint128 x, uint128 y) constant internal returns (uint128 z) {
        return x >= y ? x : y;
    }


    /*
    int256 functions
     */

    function imin(int256 x, int256 y) constant internal returns (int256 z) {
        return x <= y ? x : y;
    }
    function imax(int256 x, int256 y) constant internal returns (int256 z) {
        return x >= y ? x : y;
    }

    /*
    WAD math
     */

    uint128 constant WAD = 10 ** 18;

    function wadd(uint128 x, uint128 y) constant internal returns (uint128) {
        return hadd(x, y);
    }

    function wsub(uint128 x, uint128 y) constant internal returns (uint128) {
        return hsub(x, y);
    }

    function wmul(uint128 x, uint128 y) constant internal returns (uint128 z) {
        z = cast((uint256(x) * y + WAD / 2) / WAD);
    }

    function wdiv(uint128 x, uint128 y) constant internal returns (uint128 z) {
        z = cast((uint256(x) * WAD + y / 2) / y);
    }

    function wmin(uint128 x, uint128 y) constant internal returns (uint128) {
        return hmin(x, y);
    }
    function wmax(uint128 x, uint128 y) constant internal returns (uint128) {
        return hmax(x, y);
    }

    /*
    RAY math
     */

    uint128 constant RAY = 10 ** 27;

    function radd(uint128 x, uint128 y) constant internal returns (uint128) {
        return hadd(x, y);
    }

    function rsub(uint128 x, uint128 y) constant internal returns (uint128) {
        return hsub(x, y);
    }

    function rmul(uint128 x, uint128 y) constant internal returns (uint128 z) {
        z = cast((uint256(x) * y + RAY / 2) / RAY);
    }

    function rdiv(uint128 x, uint128 y) constant internal returns (uint128 z) {
        z = cast((uint256(x) * RAY + y / 2) / y);
    }

    function rpow(uint128 x, uint64 n) constant internal returns (uint128 z) {
        // This famous algorithm is called "exponentiation by squaring"
        // and calculates x^n with x as fixed-point and n as regular unsigned.
        //
        // It's O(log n), instead of O(n) for naive repeated multiplication.
        //
        // These facts are why it works:
        //
        //  If n is even, then x^n = (x^2)^(n/2).
        //  If n is odd,  then x^n = x * x^(n-1),
        //   and applying the equation for even x gives
        //    x^n = x * (x^2)^((n-1) / 2).
        //
        //  Also, EVM division is flooring and
        //    floor[(n-1) / 2] = floor[n / 2].

        z = n % 2 != 0 ? x : RAY;

        for (n /= 2; n != 0; n /= 2) {
            x = rmul(x, x);

            if (n % 2 != 0) {
                z = rmul(z, x);
            }
        }
    }

    function rmin(uint128 x, uint128 y) constant internal returns (uint128) {
        return hmin(x, y);
    }
    function rmax(uint128 x, uint128 y) constant internal returns (uint128) {
        return hmax(x, y);
    }

    function cast(uint256 x) constant internal returns (uint128 z) {
        assert((z = uint128(x)) == x);
    }

}

contract StandardToken is ERC20Token {
    function transfer(address _to, uint256 _value) returns (bool success) {
        if (balances[msg.sender] >= _value && _value > 0) {
            balances[msg.sender] -= _value;
            balances[_to] += _value;
            Transfer(msg.sender, _to, _value);
            return true;
        } else {
            return false;
        }
    }

    function transferFrom(address _from, address _to, uint256 _value) returns (bool success) {
        if (balances[_from] >= _value && allowed[_from][msg.sender] >= _value && _value > 0) {
            balances[_to] += _value;
            balances[_from] -= _value;
            allowed[_from][msg.sender] -= _value;
            Transfer(_from, _to, _value);
            return true;
        } else {
            return false;
        }
    }

    function balanceOf(address _owner) constant returns (uint256 balance) {
        return balances[_owner];
    }

    function approve(address _spender, uint256 _value) returns (bool success) {
        // To change the approve amount you first have to reduce the addresses`
        //  allowance to zero by calling `approve(_spender,0)` if it is not
        //  already 0 to mitigate the race condition described here:
        //  https://github.com/ethereum/EIPs/issues/20#issuecomment-263524729
        if ((_value!=0) && (allowed[msg.sender][_spender] !=0)) throw;

        allowed[msg.sender][_spender] = _value;
        Approval(msg.sender, _spender, _value);
        return true;
    }

    function allowance(address _owner, address _spender) constant returns (uint256 remaining) {
        return allowed[_owner][_spender];
    }

    mapping (address => uint256) public balances;
    mapping (address => mapping (address => uint256)) allowed;
}

contract MHToken is StandardToken, Owned {
    // metadata
    string public constant name = "Medicine Health Token";
    string public constant symbol = "MHT";
    string public version = "1.0";
    uint256 public constant decimals = 4;
    bool public disabled;
    mapping(address => bool) public isMHTHolder;
    address[] public MHTHolders;
    // constructor
    function MHToken(uint256 _amount) {
        totalSupply = _amount; 
        balances[msg.sender] = _amount;
    }

    function getMHTTotalSupply() external constant returns(uint256) {
        return totalSupply;
    }
    function getMHTHoldersNumber() external constant returns(uint256) {
        return MHTHolders.length;
    }

    function setDisabled(bool flag) external onlyOwner {
        disabled = flag;
    }

    function transfer(address _to, uint256 _value) returns (bool success) {
        require(!disabled);
        if(isMHTHolder[_to] == false){
            isMHTHolder[_to] = true;
            MHTHolders.push(_to);
        }
        return super.transfer(_to, _value);
    }

    function transferFrom(address _from, address _to, uint256 _value) returns (bool success) {
        require(!disabled);
        if(isMHTHolder[_to] == false){
            isMHTHolder[_to] = true;
            MHTHolders.push(_to);
        }
        return super.transferFrom(_from, _to, _value);
    }
}