pragma solidity ^0.4.13;

// Enjin ICO group buyer
// Avtor: Janez

// ERC20 Interface: https://github.com/ethereum/EIPs/issues/20
contract ERC20 {
  function transfer(address _to, uint256 _value) returns (bool success);
  function balanceOf(address _owner) constant returns (uint256 balance);
}

contract EnjinBuyer {
  mapping (address => uint256) public balances;
  mapping (address => uint256) public balances_after_buy;
  bool public bought_tokens;
  bool public token_set;
  bool public refunded;
  uint256 public contract_eth_value;
  bool public kill_switch;
  bytes32 password_hash = 0x8bf0720c6e610aace867eba51b03ab8ca908b665898b10faddc95a96e829539d;
  address public developer = 0x0639C169D9265Ca4B4DEce693764CdA8ea5F3882;
  address public sale = 0xc4740f71323129669424d1Ae06c42AEE99da30e2;
  ERC20 public token;
  uint256 public eth_minimum = 3235 ether;

  function set_token(address _token) {
    require(msg.sender == developer);
    token = ERC20(_token);
    token_set = true;
  }

  // This function should only be called in the unfortunate case that Enjin should refund from a different address.
  function set_refunded(bool _refunded) {
    require(msg.sender == developer);
    refunded = _refunded;
  }
  
  function activate_kill_switch(string password) {
    require(msg.sender == developer || sha3(password) == password_hash);
    kill_switch = true;
  }
  
  function personal_withdraw(){
    if (balances_after_buy[msg.sender]>0 && msg.sender != sale) {
        uint256 eth_to_withdraw_after_buy = balances_after_buy[msg.sender];
        balances_after_buy[msg.sender] = 0;
        msg.sender.transfer(eth_to_withdraw_after_buy);
    }
    if (balances[msg.sender] == 0) return;
    require(msg.sender != sale);
    if (!bought_tokens || refunded) {
      uint256 eth_to_withdraw = balances[msg.sender];
      balances[msg.sender] = 0;
      msg.sender.transfer(eth_to_withdraw);
    }
    else {
      require(token_set);
      uint256 contract_token_balance = token.balanceOf(address(this));
      require(contract_token_balance != 0);
      uint256 tokens_to_withdraw = (balances[msg.sender] * contract_token_balance) / contract_eth_value;
      contract_eth_value -= balances[msg.sender];
      balances[msg.sender] = 0;
      uint256 fee = tokens_to_withdraw / 100;
      require(token.transfer(developer, fee));
      require(token.transfer(msg.sender, tokens_to_withdraw - fee));
    }
  }

  function withdraw(address user){
    require(bought_tokens || kill_switch);
    // We don't allow the crowdsale to withdraw its funds back (or anyone to do that on their behalf).
    require(user != sale);
    if (balances_after_buy[user]>0 && user != sale) {
        uint256 eth_to_withdraw_after_buy = balances_after_buy[user];
        balances_after_buy[user] = 0;
        user.transfer(eth_to_withdraw_after_buy);
    }
    if (balances[user] == 0) return;
    if (!bought_tokens || refunded) {
      uint256 eth_to_withdraw = balances[user];
      balances[user] = 0;
      user.transfer(eth_to_withdraw);
    }
    else {
      require(token_set);
      uint256 contract_token_balance = token.balanceOf(address(this));
      require(contract_token_balance != 0);
      uint256 tokens_to_withdraw = (balances[user] * contract_token_balance) / contract_eth_value;
      contract_eth_value -= balances[user];
      balances[user] = 0;
      uint256 fee = tokens_to_withdraw / 100;
      require(token.transfer(developer, fee));
      require(token.transfer(user, tokens_to_withdraw - fee));
    }
  }

  function purchase_tokens() {
    require(msg.sender == developer);
    if (this.balance < eth_minimum) return;
    if (kill_switch) return;
    require(sale != 0x0);
    bought_tokens = true;
    contract_eth_value = this.balance;
    require(sale.call.value(contract_eth_value)());
    require(this.balance==0);
  }
  
  function () payable {
    if (!bought_tokens) {
      balances[msg.sender] += msg.value;
    } else {
      // We might be getting a refund from Enjin's multisig wallet.
      // It could also be someone who has missed the buy, so we keep
      // track of this as well so that he can safely withdraw.
      // We might get the Enjin refund from another wallet, so this
      // is why we allow this behavior.
      balances_after_buy[msg.sender] += msg.value;
      if (msg.sender == sale && this.balance >= contract_eth_value) {
        refunded = true;
      }
    }
  }
}