pragma solidity ^0.4.19;

library SafeMath {
  function add(uint a, uint b) internal pure returns (uint c) {
    c = a + b;
    require(c >= a);
  }
  function sub(uint a, uint b) internal pure returns (uint c) {
    require(b <= a);
    c = a - b;
  }
  function mul(uint a, uint b) internal pure returns (uint c) {
    c = a * b;
    require(a == 0 || c / a == b);
  }
  function div(uint a, uint b) internal pure returns (uint c) {
    require(b > 0);
    c = a / b;
  }
}

contract ERC20Interface {
  function totalSupply()
    public
    constant
    returns(uint);
  function balanceOf(
    address tokenOwner)
    public
    constant
    returns(uint balance);
  function allowance(
    address tokenOwner,
    address spender)
    public
    constant
    returns(uint approve);
  function transfer(
    address to,
    uint tokens)
    public
    returns(bool success);
  function approve(
    address spender,
    uint tokens)
    public
    returns(bool success);
  function transferFrom(
    address from,
    address to,
    uint tokens)
    public
    returns(bool success);

  event Transfer(
    address indexed from,
    address indexed to,
    uint tokens);
  event Approval(
    address indexed tokenOwner,
    address indexed spender,
    uint tokens);
}

contract Owned {
  address public owner;
  address public newOwner;

  event OwnershipTransferred(address indexed _from, address indexed _to);

  function Owned() public {
    owner = msg.sender;
  }

  modifier onlyOwner() {
    require(msg.sender == owner);
    _;
  }

  function transferOwnership(address _newOwner) public onlyOwner {
    newOwner = _newOwner;
  }

  function acceptOwnership() public {
    require(msg.sender == newOwner);
    OwnershipTransferred(owner, newOwner);
    owner = newOwner;
    newOwner = address(0);
  }
}

contract ApproveAndCallFallBack {
  function receiveApproval(
    address from,
    uint256 tokens,
    address token,
    bytes data) public;
}

contract CryptopusToken is ERC20Interface, Owned {
  using SafeMath for uint;

  address public preSaleContract;

  string public symbol;
  string public name;
  uint8 public decimals;
  uint public _totalSupply;
  uint public saleLimit;
  uint public alreadySold;

  uint public firstWavePrice;
  uint public secondWavePrice;
  uint public thirdWavePrice;

  bool public saleOngoing;

  mapping(address => uint8) approved;
  mapping(address => uint) balances;
  mapping(address => mapping(address => uint)) allowed;

  function CryptopusToken() public {
    symbol = "CPP";
    name = "Cryptopus Token";
    decimals = 18;
    _totalSupply = 100000000 * 10**uint(decimals);
    saleLimit = 40000000 * 10**uint(decimals);
    alreadySold = 0;
    balances[owner] = _totalSupply;
    Transfer(address(0), owner, _totalSupply);
    firstWavePrice = 0.0008 ether;
    secondWavePrice = 0.0009 ether;
    thirdWavePrice = 0.001 ether;
    saleOngoing = false;
  }

  modifier onlyIfOngoing() {
    require(saleOngoing);
    _;
  }

  modifier onlyApproved(address _owner) {
    require(approved[_owner] != 0);
    _;
  }

  function setPrices(
    uint _newPriceFirst,
    uint _newPriceSecond,
    uint _newPriceThird)
    public
    onlyOwner
    returns(bool) {
    firstWavePrice = _newPriceFirst;
    secondWavePrice = _newPriceSecond;
    thirdWavePrice = _newPriceThird;
    return true;
  }

  function setPreSaleContract(
    address _owner)
    public
    onlyOwner
    returns(bool) {
    preSaleContract = _owner;
    return true;
  }

  function updateSaleStatus()
    public
    onlyOwner
    returns(bool) {
    saleOngoing = !saleOngoing;
    return true;
  }

  function pushToApproved(
    address _contributor,
    uint8 waveNumber)
    public
    onlyOwner
    returns(bool) {
    approved[_contributor] = waveNumber;
    return true;
  }

  function totalSupply()
    public
    constant
    returns(uint) {
    return _totalSupply - balances[address(0)];
  }

  function balanceOf(
    address tokenOwner)
    public
    constant
    returns(uint) {
    return balances[tokenOwner];
  }

  function transfer(
    address to,
    uint tokens)
    public
    returns(bool) {
    balances[msg.sender] = balances[msg.sender].sub(tokens);
    balances[to] = balances[to].add(tokens);
    Transfer(msg.sender, to, tokens);
    return true;
  }

  function approve(
    address spender,
    uint tokens)
    public
    returns(bool) {
    allowed[msg.sender][spender] = tokens;
    Approval(msg.sender, spender, tokens);
    return true;
  }

  function transferFrom(
    address from,
    address to,
    uint tokens)
    public
    returns(bool) {
    balances[from] = balances[from].sub(tokens);
    allowed[from][msg.sender] = allowed[from][msg.sender].sub(tokens);
    balances[to] = balances[to].add(tokens);
    Transfer(from, to, tokens);
    return true;
  }

  function allowance(
    address tokenOwner,
    address spender)
    public
    constant
    returns(uint) {
    return allowed[tokenOwner][spender];
  }

  function approveAndCall(
    address spender,
    uint tokens,
    bytes data)
    public
    returns(bool) {
    allowed[msg.sender][spender] = tokens;
    Approval(msg.sender, spender, tokens);
    ApproveAndCallFallBack(spender)
      .receiveApproval(
        msg.sender,
        tokens,
        this,
        data);
    return true;
  }

  function burnTokens(
    uint tokens)
    public
    returns(bool) {
    balances[msg.sender] = balances[msg.sender].sub(tokens);
    balances[address(0)] = balances[address(0)].add(tokens);
    Transfer(msg.sender, address(0), tokens);
    return true;
  }

  function withdraw()
    public
    onlyOwner
    returns(bool) {
    owner.transfer(address(this).balance);
    return true;
  }

  function exchangeTokens()
    public
    returns(bool) {
    uint tokens = uint(
      ERC20Interface(preSaleContract)
        .allowance(msg.sender, this));
    require(tokens > 0 &&
            ERC20Interface(preSaleContract)
              .balanceOf(msg.sender) == tokens);
    ERC20Interface(preSaleContract)
      .transferFrom(msg.sender, address(0), tokens);
    balances[owner] = balances[owner].sub(tokens);
    balances[msg.sender] = balances[msg.sender].add(tokens);
    Transfer(owner, msg.sender, tokens);
    return true;
  }

  function()
    public
    onlyIfOngoing
    onlyApproved(msg.sender)
    payable {
    uint tokenPrice;
    if(approved[msg.sender] == 1) {
      tokenPrice = firstWavePrice;
    } else if(approved[msg.sender] == 2) {
      tokenPrice = secondWavePrice;
    } else if(approved[msg.sender] == 3) {
      tokenPrice = thirdWavePrice;
    } else {
      revert();
    }
    require(msg.value >= tokenPrice);
    uint tokenAmount = (msg.value / tokenPrice) * 10 ** uint(decimals);
    require(saleOngoing && alreadySold.add(tokenAmount) <= saleLimit);
    balances[owner] = balances[owner].sub(tokenAmount);
    balances[msg.sender] = balances[msg.sender].add(tokenAmount);
    alreadySold = alreadySold.add(tokenAmount);
    Transfer(owner, msg.sender, tokenAmount);
  }
}