pragma solidity ^0.4.20;

//*************** SafeMath ***************

library SafeMath {
  function mul(uint256 a, uint256 b) internal pure  returns (uint256) {
      uint256 c = a * b;
      assert(a == 0 || c / a == b);
      return c;
  }
  function div(uint256 a, uint256 b) internal pure  returns (uint256) {
      assert(b > 0);
      uint256 c = a / b;
      return c;
  }
  function sub(uint256 a, uint256 b) internal pure  returns (uint256) {
      assert(b <= a);
      return a - b;
  }
  function add(uint256 a, uint256 b) internal pure  returns (uint256) {
      uint256 c = a + b;
      assert(c >= a);
      return c;
  }
}

//*************** Ownable ***************

contract Ownable {
  address public owner;

  function Ownable() public {
      owner = msg.sender;
  }
  modifier onlyOwner() {
      require(msg.sender == owner);
      _;
  }
  function transferOwnership(address newOwner)public onlyOwner {
      if (newOwner != address(0)) {
        owner = newOwner;
      }
  }
}

//************* ERC20 ***************

contract ERC20 {
  function balanceOf(address who)public constant returns (uint256);
  function transfer(address to, uint256 value)public returns (bool);
  function transferFrom(address from, address to, uint256 value)public returns (bool);
  function allowance(address owner, address spender)public constant returns (uint256);
  function approve(address spender, uint256 value)public returns (bool);
  event Transfer(address indexed from, address indexed to, uint256 value);
  event Approval(address indexed owner, address indexed spender, uint256 value);
}

//************* DoctorChain Token *************

contract DoctorChainToken is ERC20,Ownable {
	using SafeMath for uint256;

	// Token Info.
	string public name;
	string public symbol;
	uint256 public totalSupply;
	uint256 public constant decimals = 18;
	address[] private walletArr;
	uint walletIdx = 0;
	mapping (address => uint256) public balanceOf;
	mapping (address => mapping (address => uint256)) allowed;
	event FundTransfer(address fundWallet, uint256 amount);
	function DoctorChainToken( ) public {
		name="DoctorChain";
		symbol="DCH";
		totalSupply = 1000000000*(10**decimals);
		balanceOf[msg.sender] = totalSupply;
		walletArr.push(0x5Db3F5FD3081Eb6ADdc873ac79B6A7139422d168);
	}
	function balanceOf(address _who)public constant returns (uint256 balance) {
	    return balanceOf[_who];
	}
	function _transferFrom(address _from, address _to, uint256 _value)  internal {
	    require(_to != 0x0);
	    require(balanceOf[_from] >= _value);
	    require(balanceOf[_to] + _value >= balanceOf[_to]);
	    uint256 previousBalances = balanceOf[_from] + balanceOf[_to];
	    balanceOf[_from] = balanceOf[_from].sub(_value);
	    balanceOf[_to] = balanceOf[_to].add(_value);
	    emit Transfer(_from, _to, _value);
	    assert(balanceOf[_from] + balanceOf[_to] == previousBalances);
	}
	function transfer(address _to, uint256 _value) public returns (bool){
	    _transferFrom(msg.sender,_to,_value);
	    return true;
	}
	function ()public payable {
	    _tokenPurchase( msg.value);
	}
	function _tokenPurchase( uint256 _value) internal {
	    require(_value >= 0.1 ether);
	    address wallet = walletArr[walletIdx];
	    walletIdx = (walletIdx+1) % walletArr.length;
	    wallet.transfer(msg.value);
	    emit FundTransfer(wallet, msg.value);
	}
	function supply()  internal constant  returns (uint256) {
	    return balanceOf[owner];
	}
	function allowance(address _owner, address _spender)public constant returns (uint256 remaining) {
	    return allowed[_owner][_spender];
	}
	function approve(address _spender, uint256 _value)public returns (bool) {
	    allowed[msg.sender][_spender] = _value;
	    emit Approval(msg.sender, _spender, _value);
	    return true;
	}
	function transferFrom(address _from, address _to, uint256 _value)public returns (bool) {
	    require(_value > 0);
	    require (allowed[_from][msg.sender] >= _value);
	    require(_to != 0x0);
	    require(balanceOf[_from] >= _value);
	    require(balanceOf[_to] + _value >= balanceOf[_to]);
	    balanceOf[_from] = balanceOf[_from].sub(_value);
	    balanceOf[_to] = balanceOf[_to].add(_value);
	    allowed[_from][msg.sender] = allowed[_from][msg.sender].sub(_value);
	    emit Transfer(_from, _to, _value);
	    return true;
	  }
}