/*
 * ERC20 interface
 * see https://github.com/ethereum/EIPs/issues/20
 */
contract ERC20 {
  uint public totalSupply;
  function balanceOf(address who) constant returns (uint);
  function allowance(address owner, address spender) constant returns (uint);

  function transfer(address to, uint value) returns (bool ok);
  function transferFrom(address from, address to, uint value) returns (bool ok);
  function approve(address spender, uint value) returns (bool ok);
  event Transfer(address indexed from, address indexed to, uint value);
  event Approval(address indexed owner, address indexed spender, uint value);
}



/**
 * Math operations with safety checks
 */
contract SafeMath {
  function safeMul(uint a, uint b) internal returns (uint) {
    uint c = a * b;
    assert(a == 0 || c / a == b);
    return c;
  }

  function safeDiv(uint a, uint b) internal returns (uint) {
    assert(b > 0);
    uint c = a / b;
    assert(a == b * c + a % b);
    return c;
  }

  function safeSub(uint a, uint b) internal returns (uint) {
    assert(b <= a);
    return a - b;
  }

  function safeAdd(uint a, uint b) internal returns (uint) {
    uint c = a + b;
    assert(c>=a && c>=b);
    return c;
  }

  function max64(uint64 a, uint64 b) internal constant returns (uint64) {
    return a >= b ? a : b;
  }

  function min64(uint64 a, uint64 b) internal constant returns (uint64) {
    return a < b ? a : b;
  }

  function max256(uint256 a, uint256 b) internal constant returns (uint256) {
    return a >= b ? a : b;
  }

  function min256(uint256 a, uint256 b) internal constant returns (uint256) {
    return a < b ? a : b;
  }

  function assert(bool assertion) internal {
    if (!assertion) {
      throw;
    }
  }
}



/**
 * Standard ERC20 token
 *
 * https://github.com/ethereum/EIPs/issues/20
 * Based on code by FirstBlood:
 * https://github.com/Firstbloodio/token/blob/master/smart_contract/FirstBloodToken.sol
 */
contract StandardToken is ERC20, SafeMath {

  mapping(address => uint) balances;
  mapping (address => mapping (address => uint)) allowed;

  function transfer(address _to, uint _value) returns (bool success) {
    balances[msg.sender] = safeSub(balances[msg.sender], _value);
    balances[_to] = safeAdd(balances[_to], _value);
    Transfer(msg.sender, _to, _value);
    return true;
  }

  function transferFrom(address _from, address _to, uint _value) returns (bool success) {
    var _allowance = allowed[_from][msg.sender];

    // Check is not needed because safeSub(_allowance, _value) will already throw if this condition is not met
    // if (_value > _allowance) throw;

    balances[_to] = safeAdd(balances[_to], _value);
    balances[_from] = safeSub(balances[_from], _value);
    allowed[_from][msg.sender] = safeSub(_allowance, _value);
    Transfer(_from, _to, _value);
    return true;
  }

  function balanceOf(address _owner) constant returns (uint balance) {
    return balances[_owner];
  }

  function approve(address _spender, uint _value) returns (bool success) {
    allowed[msg.sender][_spender] = _value;
    Approval(msg.sender, _spender, _value);
    return true;
  }

  function allowance(address _owner, address _spender) constant returns (uint remaining) {
    return allowed[_owner][_spender];
  }

}





/**
 * Upgrade agent interface inspired by Lunyr.
 *
 * Upgrade agent transfers tokens to a new contract.
 * Upgrade agent itself can be the token contract, or just a middle man contract doing the heavy lifting.
 */
contract UpgradeAgent {

  uint public originalSupply;

  /** Interface marker */
  function isUpgradeAgent() public constant returns (bool) {
    return true;
  }

  function upgradeFrom(address _from, uint256 _value) public;

}


/**
 * Safe unsigned safe math.
 *
 * https://blog.aragon.one/library-driven-development-in-solidity-2bebcaf88736#.750gwtwli
 *
 * Originally from https://raw.githubusercontent.com/AragonOne/zeppelin-solidity/master/contracts/SafeMathLib.sol
 *
 * Maintained here until merged to mainline zeppelin-solidity.
 *
 */
library SafeMathLib {

  function times(uint a, uint b) returns (uint) {
    uint c = a * b;
    assert(a == 0 || c / a == b);
    return c;
  }

  function minus(uint a, uint b) returns (uint) {
    assert(b <= a);
    return a - b;
  }

  function plus(uint a, uint b) returns (uint) {
    uint c = a + b;
    assert(c>=a && c>=b);
    return c;
  }

  function assert(bool assertion) private {
    if (!assertion) throw;
  }
}


/**
 * A token upgrade mechanism where users can opt-in amount of tokens to the next smart contract revision.
 *
 * First envisioned by Golem and Lunyr projects.
 */
contract UpgradeableToken is StandardToken {

  using SafeMathLib for uint;

  /** Contract / person who can set the upgrade path. This can be the same as team multisig wallet, as what it is with its default value. */
  address public upgradeMaster;

  /** The next contract where the tokens will be migrated. */
  UpgradeAgent public upgradeAgent;

  /** How many tokens we have upgraded by now. */
  uint256 public totalUpgraded;

  /**
   * Upgrade states.
   *
   * - NotAllowed: The child contract has not reached a condition where the upgrade can bgun
   * - WaitingForAgent: Token allows upgrade, but we don't have a new agent yet
   * - ReadyToUpgrade: The agent is set, but not a single token has been upgraded yet
   * - Upgrading: Upgrade agent is set and the balance holders can upgrade their tokens
   *
   */
  enum UpgradeState {Unknown, NotAllowed, WaitingForAgent, ReadyToUpgrade, Upgrading}

  event Upgrade(address indexed _from, address indexed _to, uint256 _value);
  event UpgradeAgentSet(address agent);

  /**
   * Do not allow construction without upgrade master set.
   */
  function UpgradeAgentEnabledToken(address _upgradeMaster) {
    upgradeMaster = _upgradeMaster;
  }

  /**
   * Allow the token holder to upgrade some of their tokens to a new contract.
   */
  function upgrade(uint256 value) public {

      UpgradeState state = getUpgradeState();
      if(!(state == UpgradeState.ReadyToUpgrade || state == UpgradeState.Upgrading)) {
        // Called in a bad state
        throw;
      }

      // Validate input value.
      if (value == 0) throw;

      balances[msg.sender] = balances[msg.sender].minus(value);

      // Take tokens out from circulation
      totalSupply = totalSupply.minus(value);
      totalUpgraded = totalUpgraded.plus(value);

      // Upgrade agent reissues the tokens
      upgradeAgent.upgradeFrom(msg.sender, value);
      Upgrade(msg.sender, upgradeAgent, value);
  }

  /**
   * Set an upgrade agent that handles
   */
  function setUpgradeAgent(address agent) external {

      if(!canUpgrade()) {
        // The token is not yet in a state that we could think upgrading
        throw;
      }

      if (agent == 0x0) throw;
      // Only a master can designate the next agent
      if (msg.sender != upgradeMaster) throw;
      // Upgrade has already begun for an agent
      if (getUpgradeState() == UpgradeState.Upgrading) throw;

      upgradeAgent = UpgradeAgent(agent);

      // Bad interface
      if(!upgradeAgent.isUpgradeAgent()) throw;

      // Make sure that token supplies match in source and target
      if (upgradeAgent.originalSupply() != totalSupply) throw;

      UpgradeAgentSet(upgradeAgent);
  }

  /**
   * Get the state of the token upgrade.
   */
  function getUpgradeState() public constant returns(UpgradeState) {
    if(!canUpgrade()) return UpgradeState.NotAllowed;
    else if(address(upgradeAgent) == 0x00) return UpgradeState.WaitingForAgent;
    else if(totalUpgraded == 0) return UpgradeState.ReadyToUpgrade;
    else return UpgradeState.Upgrading;
  }

  /**
   * Change the upgrade master.
   *
   * This allows us to set a new owner for the upgrade mechanism.
   */
  function setUpgradeMaster(address master) external {
      if (master == 0x0) throw;
      if (msg.sender != upgradeMaster) throw;
      upgradeMaster = master;
  }

  /**
   * Child contract can enable to provide the condition when the upgrade can begun.
   */
  function canUpgrade() public constant returns(bool) {
     return true;
  }

}




/*
 * Ownable
 *
 * Base contract with an owner.
 * Provides onlyOwner modifier, which prevents function from running if it is called by anyone other than the owner.
 */
contract Ownable {
  address public owner;

  function Ownable() {
    owner = msg.sender;
  }

  modifier onlyOwner() {
    if (msg.sender != owner) {
      throw;
    }
    _;
  }

  function transferOwnership(address newOwner) onlyOwner {
    if (newOwner != address(0)) {
      owner = newOwner;
    }
  }

}




/*

TransferableToken defines the generic interface and the implementation
to limit token transferability for different events.

It is intended to be used as a base class for other token contracts.

Over-writting transferableTokens(address holder, uint64 time) is the way to provide
the specific logic for limitting token transferability for a holder over time.

TransferableToken has been designed to allow for different limitting factors,
this can be achieved by recursively calling super.transferableTokens() until the
base class is hit. For example:

function transferableTokens(address holder, uint64 time) constant public returns (uint256) {
  return min256(unlockedTokens, super.transferableTokens(holder, time));
}

A working example is VestedToken.sol:
https://github.com/OpenZeppelin/zeppelin-solidity/blob/master/contracts/token/VestedToken.sol

*/

contract TransferableToken is ERC20 {
  // Checks whether it can transfer or otherwise throws.
  modifier canTransfer(address _sender, uint _value) {
   if (_value > transferableTokens(_sender, uint64(now))) throw;
   _;
  }

  // Checks modifier and allows transfer if tokens are not locked.
  function transfer(address _to, uint _value) canTransfer(msg.sender, _value) returns (bool success) {
   return super.transfer(_to, _value);
  }

  // Checks modifier and allows transfer if tokens are not locked.
  function transferFrom(address _from, address _to, uint _value) canTransfer(_from, _value) returns (bool success) {
   return super.transferFrom(_from, _to, _value);
  }

  // Default transferable tokens function returns all tokens for a holder (no limit).
  function transferableTokens(address holder, uint64 time) constant public returns (uint256) {
    return balanceOf(holder);
  }
}




/**
 * Define interface for releasing the token transfer after a successful crowdsale.
 */
contract ReleasableToken is ERC20, Ownable {

  /* The finalizer contract that allows unlift the transfer limits on this token */
  address public releaseAgent;

  /** A crowdsale contract can release us to the wild if ICO success. If false we are are in transfer lock up period.*/
  bool public released = false;

  /** Map of agents that are allowed to transfer tokens regardless of the lock down period. These are crowdsale contracts and possible the team multisig itself. */
  mapping (address => bool) public transferAgents;

  /**
   * Limit token transfer until the crowdsale is over.
   *
   */
  modifier canTransfer(address _sender) {

    if(!released) {
        if(!transferAgents[_sender]) {
            throw;
        }
    }

    _;
  }

  /**
   * Set the contract that can call release and make the token transferable.
   */
  function setReleaseAgent(address addr) onlyOwner inReleaseState(false) public {

    // Already set
    if(releaseAgent != 0) {
      throw;
    }

    // We don't do interface check here as we might want to a normal wallet address to act as a release agent
    releaseAgent = addr;
  }

  /**
   * Owner can allow a particular address (a crowdsale contract) to transfer tokens despite the lock up period.
   */
  function setTransferAgent(address addr, bool state) onlyOwner inReleaseState(false) public {
    transferAgents[addr] = state;
  }

  /**
   * One way function to release the tokens to the wild.
   *
   * Can be called only from the release agent that is the final ICO contract. It is only called if the crowdsale has been success (first milestone reached).
   */
  function releaseTokenTransfer() public onlyReleaseAgent {
    released = true;
  }

  /** The function can be called only before or after the tokens have been releasesd */
  modifier inReleaseState(bool releaseState) {
    if(releaseState != released) {
        throw;
    }
    _;
  }

  /** The function can be called only by a whitelisted release agent. */
  modifier onlyReleaseAgent() {
    if(msg.sender != releaseAgent) {
        throw;
    }
    _;
  }

  function transfer(address _to, uint _value) canTransfer(msg.sender) returns (bool success) {
    // Call StandardToken.transfer()
   return super.transfer(_to, _value);
  }

  function transferFrom(address _from, address _to, uint _value) canTransfer(_from) returns (bool success) {
    // Call StandardToken.transferForm()
    return super.transferFrom(_from, _to, _value);
  }

}







/**
 * A token that can increase its supply by another contract.
 *
 * This allows uncapped crowdsale by dynamically increasing the supply when money pours in.
 * Only mint agents, contracts whitelisted by owner, can mint new tokens.
 *
 */
contract MintableToken is StandardToken, Ownable {

  using SafeMathLib for uint;

  bool public mintingFinished = false;

  /** List of agents that are allowed to create new tokens */
  mapping (address => bool) public mintAgents;

  /**
   * Create new tokens and allocate them to an address..
   *
   * Only callably by a crowdsale contract (mint agent).
   */
  function mint(address receiver, uint amount) onlyMintAgent canMint public {
    totalSupply = totalSupply.plus(amount);
    balances[receiver] = balances[receiver].plus(amount);
    Transfer(0, receiver, amount);
  }

  /**
   * Owner can allow a crowdsale contract to mint new tokens.
   */
  function setMintAgent(address addr, bool state) onlyOwner canMint public {
    mintAgents[addr] = state;
  }

  modifier onlyMintAgent() {
    // Only crowdsale contracts are allowed to mint new tokens
    if(!mintAgents[msg.sender]) {
        throw;
    }
    _;
  }

  /** Make sure we are not done yet. */
  modifier canMint() {
    if(mintingFinished) throw;
    _;
  }
}




/**
 * A crowdsaled token.
 *
 * An ERC-20 token designed specifically for crowdsales with investor protection and further development path.
 *
 * - The token transfer() is disabled until the crowdsale is over
 * - The token contract gives an opt-in upgrade path to a new contract
 * - The same token can be part of several crowdsales through approve() mechanism
 * - The token can be capped (supply set in the constructor) or uncapped (crowdsale contract can mint new tokens)
 *
 */
contract CrowdsaleToken is ReleasableToken, MintableToken, UpgradeableToken {

  string public name;

  string public symbol;

  /** We don't want to support decimal places as it's not very well handled by different wallets */
  uint public decimals = 0;

  /**
   * Construct the token.
   *
   * This token must be created through a team multisig wallet, so that it is owned by that wallet.
   */
  function CrowdsaleToken(string _name, string _symbol, uint _initialSupply) {

    // Create from team multisig
    owner = msg.sender;

    // Initially set the upgrade master same as owner
    upgradeMaster = owner;

    name = _name;
    symbol = _symbol;

    totalSupply = _initialSupply;

    // Create initially all balance on the team multisig
    balances[msg.sender] = totalSupply;
  }

  /**
   * When token is released to be transferable, enforce no new tokens can be created.
   */
  function releaseTokenTransfer() public onlyReleaseAgent {
    mintingFinished = true;
    super.releaseTokenTransfer();
  }

  /**
   * Allow upgrade agent functionality kick in only if the crowdsale was success.
   */
  function canUpgrade() public constant returns(bool) {
    return released;
  }

}