pragma solidity ^0.4.13;

/**
 * @title SafeMath
 * @dev Math operations with safety checks that throw on error
 */
library SafeMath {
  function mul(uint256 a, uint256 b) internal constant returns (uint256) {
    uint256 c = a * b;
    assert(a == 0 || c / a == b);
    return c;
  }

  function div(uint256 a, uint256 b) internal constant returns (uint256) {
    // assert(b > 0); // Solidity automatically throws when dividing by 0
    uint256 c = a / b;
    // assert(a == b * c + a % b); // There is no case in which this doesn't hold
    return c;
  }

  function sub(uint256 a, uint256 b) internal constant returns (uint256) {
    assert(b <= a);
    return a - b;
  }

  function add(uint256 a, uint256 b) internal constant returns (uint256) {
    uint256 c = a + b;
    assert(c >= a);
    return c;
  }
}


/**
 * @title ERC20Basic
 * @dev Simpler version of ERC20 interface
 * @dev see https://github.com/ethereum/EIPs/issues/179
 */
contract ERC20Basic {
  uint256 public totalSupply;
  function balanceOf(address who) constant returns (uint256);
  function transfer(address to, uint256 value) returns (bool);
  event Transfer(address indexed from, address indexed to, uint256 value);
}


/**
 * @title Basic token
 * @dev Basic version of StandardToken, with no allowances. 
 */
contract BasicToken is ERC20Basic {
  using SafeMath for uint256;

  mapping(address => uint256) balances;

  /**
  * @dev transfer token for a specified address
  * @param _to The address to transfer to.
  * @param _value The amount to be transferred.
  */
  function transfer(address _to, uint256 _value) returns (bool) {
    balances[msg.sender] = balances[msg.sender].sub(_value);
    balances[_to] = balances[_to].add(_value);
    Transfer(msg.sender, _to, _value);
    return true;
  }

  /**
  * @dev Gets the balance of the specified address.
  * @param _owner The address to query the the balance of. 
  * @return An uint256 representing the amount owned by the passed address.
  */
  function balanceOf(address _owner) constant returns (uint256 balance) {
    return balances[_owner];
  }

}



/**
 * @title ERC20 interface
 * @dev see https://github.com/ethereum/EIPs/issues/20
 */
contract ERC20 is ERC20Basic {
  function allowance(address owner, address spender) constant returns (uint256);
  function transferFrom(address from, address to, uint256 value) returns (bool);
  function approve(address spender, uint256 value) returns (bool);
  event Approval(address indexed owner, address indexed spender, uint256 value);
}



/**
 * @title Standard ERC20 token
 *
 * @dev Implementation of the basic standard token.
 * @dev https://github.com/ethereum/EIPs/issues/20
 * @dev Based on code by FirstBlood: https://github.com/Firstbloodio/token/blob/master/smart_contract/FirstBloodToken.sol
 */
contract StandardToken is ERC20, BasicToken {

  mapping (address => mapping (address => uint256)) allowed;


  /**
   * @dev Transfer tokens from one address to another
   * @param _from address The address which you want to send tokens from
   * @param _to address The address which you want to transfer to
   * @param _value uint256 the amout of tokens to be transfered
   */
  function transferFrom(address _from, address _to, uint256 _value) returns (bool) {
    var _allowance = allowed[_from][msg.sender];

    // Check is not needed because sub(_allowance, _value) will already throw if this condition is not met
    // require (_value <= _allowance);

    balances[_to] = balances[_to].add(_value);
    balances[_from] = balances[_from].sub(_value);
    allowed[_from][msg.sender] = _allowance.sub(_value);
    Transfer(_from, _to, _value);
    return true;
  }

  /**
   * @dev Aprove the passed address to spend the specified amount of tokens on behalf of msg.sender.
   * @param _spender The address which will spend the funds.
   * @param _value The amount of tokens to be spent.
   */
  function approve(address _spender, uint256 _value) returns (bool) {

    // 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
    require((_value == 0) || (allowed[msg.sender][_spender] == 0));

    allowed[msg.sender][_spender] = _value;
    Approval(msg.sender, _spender, _value);
    return true;
  }

  /**
   * @dev Function to check the amount of tokens that an owner allowed to a spender.
   * @param _owner address The address which owns the funds.
   * @param _spender address The address which will spend the funds.
   * @return A uint256 specifing the amount of tokens still avaible for the spender.
   */
  function allowance(address _owner, address _spender) constant returns (uint256 remaining) {
    return allowed[_owner][_spender];
  }

}


/**
 * @title Ownable
 * @dev The Ownable contract has an owner address, and provides basic authorization control
 * functions, this simplifies the implementation of "user permissions".
 */
contract Ownable {
  address public owner;


  /**
   * @dev The Ownable constructor sets the original `owner` of the contract to the sender
   * account.
   */
  function Ownable() {
    owner = msg.sender;
  }


  /**
   * @dev Throws if called by any account other than the owner.
   */
  modifier onlyOwner() {
    require(msg.sender == owner);
    _;
  }


  /**
   * @dev Allows the current owner to transfer control of the contract to a newOwner.
   * @param newOwner The address to transfer ownership to.
   */
  function transferOwnership(address newOwner) onlyOwner {
    if (newOwner != address(0)) {
      owner = newOwner;
    }
  }

}

/**
 * @title Pausable
 * @dev Base contract which allows children to implement an emergency stop mechanism.
 */
contract Pausable is Ownable {
  event Pause();
  event Unpause();

  bool public paused = false;


  /**
   * @dev modifier to allow actions only when the contract IS paused
   */
  modifier whenNotPaused() {
    require(!paused);
    _;
  }

  /**
   * @dev modifier to allow actions only when the contract IS NOT paused
   */
  modifier whenPaused {
    require(paused);
    _;
  }

  /**
   * @dev called by the owner to pause, triggers stopped state
   */
  function pause() onlyOwner whenNotPaused returns (bool) {
    paused = true;
    Pause();
    return true;
  }

  /**
   * @dev called by the owner to unpause, returns to normal state
   */
  function unpause() onlyOwner whenPaused returns (bool) {
    paused = false;
    Unpause();
    return true;
  }
}


/**
 * @title Mintable token
 * @dev Simple ERC20 Token example, with mintable token creation
 * @dev Issue: * https://github.com/OpenZeppelin/zeppelin-solidity/issues/120
 * Based on code by TokenMarketNet: https://github.com/TokenMarketNet/ico/blob/master/contracts/MintableToken.sol
 */

contract MintableToken is StandardToken, Ownable {
  event Mint(address indexed to, uint256 amount);
  event MintFinished();

  bool public mintingFinished = false;


  modifier canMint() {
    require(!mintingFinished);
    _;
  }

  /**
   * @dev Function to mint tokens
   * @param _to The address that will recieve the minted tokens.
   * @param _amount The amount of tokens to mint.
   * @return A boolean that indicates if the operation was successful.
   */
  function mint(address _to, uint256 _amount) onlyOwner canMint returns (bool) {
    totalSupply = totalSupply.add(_amount);
    balances[_to] = balances[_to].add(_amount);
    Mint(_to, _amount);
    return true;
  }

  /**
   * @dev Function to stop minting new tokens.
   * @return True if the operation was successful.
   */
  function finishMinting() onlyOwner returns (bool) {
    mintingFinished = true;
    MintFinished();
    return true;
  }
}

/**
 * @title EmpireToken token
 * @dev Simple ERC20 Token example, with mintable token creation
 * @dev Issue: * https://github.com/OpenZeppelin/zeppelin-solidity/issues/120
 * Based on code by TokenMarketNet: https://github.com/TokenMarketNet/ico/blob/master/contracts/MintableToken.sol
 */

contract EmpireToken is StandardToken, Ownable {

  string public name = 'Empire Token';
  uint8 public decimals = 18;
  string public symbol = 'EMP';
  string public version = '0.1';

  event Mint(address indexed to, uint256 amount);
  event MintFinished();

  bool public mintingFinished = false;


  modifier canMint() {
    require(!mintingFinished);
    _;
  }

  /**
   * @dev Function to mint tokens
   * @param _to The address that will recieve the minted tokens.
   * @param _amount The amount of tokens to mint.
   * @return A boolean that indicates if the operation was successful.
   */
  function mint(address _to, uint256 _amount) onlyOwner canMint returns (bool) {
    totalSupply = totalSupply.add(_amount);
    balances[_to] = balances[_to].add(_amount);
    Mint(_to, _amount);
    return true;
  }

  /**
   * @dev Function to stop minting new tokens.
   * @return True if the operation was successful.
   */
  function finishMinting() onlyOwner returns (bool) {
    mintingFinished = true;
    MintFinished();
    return true;
  }
}


/**
 * @title Crowdsale 
 * @dev Crowdsale is a base contract for managing a token crowdsale.
 * Crowdsales have a start and end block, where investors can make
 * token purchases and the crowdsale will assign them tokens based
 * on a token per ETH rate. Funds collected are forwarded to a wallet 
 * as they arrive.
 */
contract EmpireCrowdsale is Ownable, Pausable {
  using SafeMath for uint256;

  // The token being sold
  EmpireToken public token;

  // start and end dates where investments are allowed (both inclusive)
  uint256 public start;
  uint256 public end;

  // address where funds are collected
  address public wallet;

  // amount of raised money in wei
  uint256 public weiRaised;

  // amount of ether as presale and soft cap
  uint256 public presaleCap;
  uint256 public softCap;
  uint256 public gracePeriodCap;
    
  uint256 public gracePeriodStart;



  /**
   * event for token purchase logging
   * @param purchaser who paid for the tokens
   * @param beneficiary who got the tokens
   * @param value weis paid for purchase
   * @param amount amount of tokens purchased
   */ 
  event TokenPurchase(address indexed purchaser, address indexed beneficiary, uint256 value, uint256 amount);

  function EmpireCrowdsale(uint256 _start, uint256 _end, address _wallet, uint256 _presaleCap, uint256 _softCap, uint256 _graceCap) payable {
    require(_start >= now);
    require(_end >= _start);
    require(_wallet != 0x0);
    require(_presaleCap > 0);
    require(_softCap > 0);
    require(_graceCap > 0);

    start = _start;
    end = _end;
    wallet = _wallet;
    token = new EmpireToken();
    presaleCap = _presaleCap;   // in Ether
    softCap = _softCap;         // in Ether
    gracePeriodCap = _graceCap; // in Ether
  }

  // function to get the price of the token
  // returns how many token units a buyer gets per wei
  function getRate() constant returns (uint) {
    bool duringPresale = (now < start) && (weiRaised < presaleCap * 1 ether);
    bool gracePeriodSet = gracePeriodStart != 0;
    bool duringGracePeriod = gracePeriodSet && now <= gracePeriodStart + 24 hours;
    uint rate = 1000;
    
    if (duringPresale) rate = 1300;               // presale, 30% bonus
    else if (now <= start +  3 days) rate = 1250; // day 1 to 3, 25% bonus
    else if (now <= start + 10 days) rate = 1150; // day 4 to 10, 15% bonus
    else if (now <= start + 20 days) rate = 1050; // day 11 to 20, 5% bonus
    
    if (duringGracePeriod) return rate.sub(rate.div(10)); // 10% penalization
    
    return rate;
  }

  // fallback function can be used to buy tokens
  function () payable {
    buyTokens(msg.sender);
  }

  // low level token purchase function
  function buyTokens(address beneficiary) whenNotPaused() payable {
    require(beneficiary != 0x0);
    require(msg.value != 0);
    require(now <= end);

    // check if soft cap was reached, and for redefinition
    if ((weiRaised >= softCap * 1 ether) && gracePeriodStart == 0) 
      gracePeriodStart = block.timestamp;

    uint256 weiAmount = msg.value;

    // calculate token amount to be created
    uint256 tokens = weiAmount.mul(getRate());
    
    // update state
    weiRaised = weiRaised.add(weiAmount);

    token.mint(beneficiary, tokens);
    TokenPurchase(msg.sender, beneficiary, weiAmount, tokens);

    forwardFunds();
  }

  // send ether to the fund collection wallet
  // override to create custom fund forwarding mechanisms
  function forwardFunds() internal {
    wallet.transfer(msg.value);
  }
  
  /**
   * @dev Function to stop minting new tokens.
   * @return True if the operation was successful.
   */
  function finishMinting() onlyOwner returns (bool) {
    return token.finishMinting();
  }


}