/// @title MiniMeToken Contract
/// @author Jordi Baylina
/// @dev This token contract's goal is to make it easy for anyone to clone this
///  token using the token distribution at a given block, this will allow DAO's
///  and DApps to upgrade their features in a decentralized manner without
///  affecting the original token
/// @dev It is ERC20 compliant, but still needs to under go further testing.


interface ITokenController {
/// @notice Called when `_owner` sends ether to the MiniMe Token contract
/// @param _owner The address that sent the ether to create tokens
/// @return True if the ether is accepted, false if it throws
function proxyPayment(address _owner) public payable returns(bool);

/// @notice Notifies the controller about a token transfer allowing the
///  controller to react if desired
/// @param _from The origin of the transfer
/// @param _to The destination of the transfer
/// @param _amount The amount of the transfer
/// @return False if the controller does not authorize the transfer
function onTransfer(address _from, address _to, uint _amount) public constant returns(bool);

/// @notice Notifies the controller about an approval allowing the
///  controller to react if desired
/// @param _owner The address that calls `approve()`
/// @param _spender The spender in the `approve()` call
/// @param _amount The amount in the `approve()` call
/// @return False if the controller does not authorize the approval
function onApprove(address _owner, address _spender, uint _amount) public constant returns(bool);
}


contract Controlled {
/// @notice The address of the controller is the only address that can call
///  a function with this modifier
modifier onlyController {
    require(msg.sender == controller);
    _;
}

address public controller;

function Controlled()  public { controller = msg.sender;}

/// @notice Changes the controller of the contract
/// @param _newController The new controller of the contract
function changeController(address _newController) onlyController  public {
    controller = _newController;
}
}

contract ApproveAndCallFallBack {
function receiveApproval(
    address from,
    uint256 _amount,
    address _token,
    bytes _data
) public;
}

/// @dev The actual token contract, the default controller is the msg.sender
///  that deploys the contract, so usually this token will be deployed by a
///  token controller contract, which Giveth will call a "Campaign"
contract MiniMeToken is Controlled {

string public name;                //The Token's name: e.g. DigixDAO Tokens
uint8 public decimals;             //Number of decimals of the smallest unit
string public symbol;              //An identifier: e.g. REP
string public version = "MMT_0.1"; //An arbitrary versioning scheme


/// @dev `Checkpoint` is the structure that attaches a block number to a
///  given value, the block number attached is the one that last changed the
///  value
struct Checkpoint {

    // `fromBlock` is the block number that the value was generated from
    uint128 fromBlock;

    // `value` is the amount of tokens at a specific block number
    uint128 value;
}

// `parentToken` is the Token address that was cloned to produce this token;
//  it will be 0x0 for a token that was not cloned
MiniMeToken public parentToken;

// `parentSnapShotBlock` is the block number from the Parent Token that was
//  used to determine the initial distribution of the Clone Token
uint public parentSnapShotBlock;

// `creationBlock` is the block number that the Clone Token was created
uint public creationBlock;

// `balances` is the map that tracks the balance of each address, in this
//  contract when the balance changes the block number that the change
//  occurred is also included in the map
mapping (address => Checkpoint[]) balances;

// `allowed` tracks any extra transfer rights as in all ERC20 tokens
mapping (address => mapping (address => uint256)) allowed;

// Tracks the history of the `totalSupply` of the token
Checkpoint[] totalSupplyHistory;

// Flag that determines if the token is transferable or not.
bool public transfersEnabled;

// The factory used to create new clone tokens
MiniMeTokenFactory public tokenFactory;

////////////////
// Constructor
////////////////

/// @notice Constructor to create a MiniMeToken
/// @param _tokenFactory The address of the MiniMeTokenFactory contract that
///  will create the Clone token contracts, the token factory needs to be
///  deployed first
/// @param _parentToken Address of the parent token, set to 0x0 if it is a
///  new token
/// @param _parentSnapShotBlock Block of the parent token that will
///  determine the initial distribution of the clone token, set to 0 if it
///  is a new token
/// @param _tokenName Name of the new token
/// @param _decimalUnits Number of decimals of the new token
/// @param _tokenSymbol Token Symbol for the new token
/// @param _transfersEnabled If true, tokens will be able to be transferred
function MiniMeToken(
    address _tokenFactory,
    address _parentToken,
    uint _parentSnapShotBlock,
    string _tokenName,
    uint8 _decimalUnits,
    string _tokenSymbol,
    bool _transfersEnabled
)  public
{
    tokenFactory = MiniMeTokenFactory(_tokenFactory);
    name = _tokenName;                                 // Set the name
    decimals = _decimalUnits;                          // Set the decimals
    symbol = _tokenSymbol;                             // Set the symbol
    parentToken = MiniMeToken(_parentToken);
    parentSnapShotBlock = _parentSnapShotBlock;
    transfersEnabled = _transfersEnabled;
    creationBlock = block.number;
}


///////////////////
// ERC20 Methods
///////////////////

/// @notice Send `_amount` tokens to `_to` from `msg.sender`
/// @param _to The address of the recipient
/// @param _amount The amount of tokens to be transferred
/// @return Whether the transfer was successful or not
function transfer(address _to, uint256 _amount) public returns (bool success) {
    require(transfersEnabled);
    return doTransfer(msg.sender, _to, _amount);
}

/// @notice Send `_amount` tokens to `_to` from `_from` on the condition it
///  is approved by `_from`
/// @param _from The address holding the tokens being transferred
/// @param _to The address of the recipient
/// @param _amount The amount of tokens to be transferred
/// @return True if the transfer was successful
function transferFrom(address _from, address _to, uint256 _amount) public returns (bool success) {

    // The controller of this contract can move tokens around at will,
    //  this is important to recognize! Confirm that you trust the
    //  controller of this contract, which in most situations should be
    //  another open source smart contract or 0x0
    if (msg.sender != controller) {
        require(transfersEnabled);

        // The standard ERC 20 transferFrom functionality
        if (allowed[_from][msg.sender] < _amount)
            return false;
        allowed[_from][msg.sender] -= _amount;
    }
    return doTransfer(_from, _to, _amount);
}

/// @dev This is the actual transfer function in the token contract, it can
///  only be called by other functions in this contract.
/// @param _from The address holding the tokens being transferred
/// @param _to The address of the recipient
/// @param _amount The amount of tokens to be transferred
/// @return True if the transfer was successful
function doTransfer(address _from, address _to, uint _amount) internal returns(bool) {
    if (_amount == 0) {
        return true;
    }
    require(parentSnapShotBlock < block.number);
    // Do not allow transfer to 0x0 or the token contract itself
    require((_to != 0) && (_to != address(this)));
    // If the amount being transfered is more than the balance of the
    //  account the transfer returns false
    var previousBalanceFrom = balanceOfAt(_from, block.number);
    if (previousBalanceFrom < _amount) {
        return false;
    }
    // Alerts the token controller of the transfer
    if (isContract(controller)) {
        // Adding the ` == true` makes the linter shut up so...
        require(ITokenController(controller).onTransfer(_from, _to, _amount) == true);
    }
    // First update the balance array with the new value for the address
    //  sending the tokens
    updateValueAtNow(balances[_from], previousBalanceFrom - _amount);
    // Then update the balance array with the new value for the address
    //  receiving the tokens
    var previousBalanceTo = balanceOfAt(_to, block.number);
    require(previousBalanceTo + _amount >= previousBalanceTo); // Check for overflow
    updateValueAtNow(balances[_to], previousBalanceTo + _amount);
    // An event to make the transfer easy to find on the blockchain
    Transfer(_from, _to, _amount);
    return true;
}

/// @param _owner The address that's balance is being requested
/// @return The balance of `_owner` at the current block
function balanceOf(address _owner) public constant returns (uint256 balance) {
    return balanceOfAt(_owner, block.number);
}

/// @notice `msg.sender` approves `_spender` to spend `_amount` tokens on
///  its behalf. This is a modified version of the ERC20 approve function
///  to be a little bit safer
/// @param _spender The address of the account able to transfer the tokens
/// @param _amount The amount of tokens to be approved for transfer
/// @return True if the approval was successful
function approve(address _spender, uint256 _amount) public returns (bool success) {
    require(transfersEnabled);

    // 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((_amount == 0) || (allowed[msg.sender][_spender] == 0));

    // Alerts the token controller of the approve function call
    if (isContract(controller)) {
        // Adding the ` == true` makes the linter shut up so...
        require(ITokenController(controller).onApprove(msg.sender, _spender, _amount) == true);
    }

    allowed[msg.sender][_spender] = _amount;
    Approval(msg.sender, _spender, _amount);
    return true;
}

/// @dev This function makes it easy to read the `allowed[]` map
/// @param _owner The address of the account that owns the token
/// @param _spender The address of the account able to transfer the tokens
/// @return Amount of remaining tokens of _owner that _spender is allowed
///  to spend
function allowance(address _owner, address _spender) public constant returns (uint256 remaining) {
    return allowed[_owner][_spender];
}

/// @notice `msg.sender` approves `_spender` to send `_amount` tokens on
///  its behalf, and then a function is triggered in the contract that is
///  being approved, `_spender`. This allows users to use their tokens to
///  interact with contracts in one function call instead of two
/// @param _spender The address of the contract able to transfer the tokens
/// @param _amount The amount of tokens to be approved for transfer
/// @return True if the function call was successful
function approveAndCall(address _spender, uint256 _amount, bytes _extraData) public returns (bool success) {
    require(approve(_spender, _amount));

    ApproveAndCallFallBack(_spender).receiveApproval(
        msg.sender,
        _amount,
        this,
        _extraData
    );

    return true;
}

/// @dev This function makes it easy to get the total number of tokens
/// @return The total number of tokens
function totalSupply() public constant returns (uint) {
    return totalSupplyAt(block.number);
}


////////////////
// Query balance and totalSupply in History
////////////////

/// @dev Queries the balance of `_owner` at a specific `_blockNumber`
/// @param _owner The address from which the balance will be retrieved
/// @param _blockNumber The block number when the balance is queried
/// @return The balance at `_blockNumber`
function balanceOfAt(address _owner, uint _blockNumber) public constant returns (uint) {

    // These next few lines are used when the balance of the token is
    //  requested before a check point was ever created for this token, it
    //  requires that the `parentToken.balanceOfAt` be queried at the
    //  genesis block for that token as this contains initial balance of
    //  this token
    if ((balances[_owner].length == 0) || (balances[_owner][0].fromBlock > _blockNumber)) {
        if (address(parentToken) != 0) {
            return parentToken.balanceOfAt(_owner, min(_blockNumber, parentSnapShotBlock));
        } else {
            // Has no parent
            return 0;
        }

    // This will return the expected balance during normal situations
    } else {
        return getValueAt(balances[_owner], _blockNumber);
    }
}

/// @notice Total amount of tokens at a specific `_blockNumber`.
/// @param _blockNumber The block number when the totalSupply is queried
/// @return The total amount of tokens at `_blockNumber`
function totalSupplyAt(uint _blockNumber) public constant returns(uint) {

    // These next few lines are used when the totalSupply of the token is
    //  requested before a check point was ever created for this token, it
    //  requires that the `parentToken.totalSupplyAt` be queried at the
    //  genesis block for this token as that contains totalSupply of this
    //  token at this block number.
    if ((totalSupplyHistory.length == 0) || (totalSupplyHistory[0].fromBlock > _blockNumber)) {
        if (address(parentToken) != 0) {
            return parentToken.totalSupplyAt(min(_blockNumber, parentSnapShotBlock));
        } else {
            return 0;
        }

    // This will return the expected totalSupply during normal situations
    } else {
        return getValueAt(totalSupplyHistory, _blockNumber);
    }
}

////////////////
// Clone Token Method
////////////////

/// @notice Creates a new clone token with the initial distribution being
///  this token at `_snapshotBlock`
/// @param _cloneTokenName Name of the clone token
/// @param _cloneDecimalUnits Number of decimals of the smallest unit
/// @param _cloneTokenSymbol Symbol of the clone token
/// @param _snapshotBlock Block when the distribution of the parent token is
///  copied to set the initial distribution of the new clone token;
///  if the block is zero than the actual block, the current block is used
/// @param _transfersEnabled True if transfers are allowed in the clone
/// @return The address of the new MiniMeToken Contract
function createCloneToken(
    string _cloneTokenName,
    uint8 _cloneDecimalUnits,
    string _cloneTokenSymbol,
    uint _snapshotBlock,
    bool _transfersEnabled
) public returns(address)
{
    uint256 snapshot = _snapshotBlock == 0 ? block.number - 1 : _snapshotBlock;

    MiniMeToken cloneToken = tokenFactory.createCloneToken(
        this,
        snapshot,
        _cloneTokenName,
        _cloneDecimalUnits,
        _cloneTokenSymbol,
        _transfersEnabled
    );

    cloneToken.changeController(msg.sender);

    // An event to make the token easy to find on the blockchain
    NewCloneToken(address(cloneToken), snapshot);
    return address(cloneToken);
}

////////////////
// Generate and destroy tokens
////////////////

/// @notice Generates `_amount` tokens that are assigned to `_owner`
/// @param _owner The address that will be assigned the new tokens
/// @param _amount The quantity of tokens generated
/// @return True if the tokens are generated correctly
function generateTokens(address _owner, uint _amount) onlyController public returns (bool) {
    uint curTotalSupply = totalSupply();
    require(curTotalSupply + _amount >= curTotalSupply); // Check for overflow
    uint previousBalanceTo = balanceOf(_owner);
    require(previousBalanceTo + _amount >= previousBalanceTo); // Check for overflow
    updateValueAtNow(totalSupplyHistory, curTotalSupply + _amount);
    updateValueAtNow(balances[_owner], previousBalanceTo + _amount);
    Transfer(0, _owner, _amount);
    return true;
}


/// @notice Burns `_amount` tokens from `_owner`
/// @param _owner The address that will lose the tokens
/// @param _amount The quantity of tokens to burn
/// @return True if the tokens are burned correctly
function destroyTokens(address _owner, uint _amount) onlyController public returns (bool) {
    uint curTotalSupply = totalSupply();
    require(curTotalSupply >= _amount);
    uint previousBalanceFrom = balanceOf(_owner);
    require(previousBalanceFrom >= _amount);
    updateValueAtNow(totalSupplyHistory, curTotalSupply - _amount);
    updateValueAtNow(balances[_owner], previousBalanceFrom - _amount);
    Transfer(_owner, 0, _amount);
    return true;
}

////////////////
// Enable tokens transfers
////////////////


/// @notice Enables token holders to transfer their tokens freely if true
/// @param _transfersEnabled True if transfers are allowed in the clone
function enableTransfers(bool _transfersEnabled) onlyController public {
    transfersEnabled = _transfersEnabled;
}

////////////////
// Internal helper functions to query and set a value in a snapshot array
////////////////

/// @dev `getValueAt` retrieves the number of tokens at a given block number
/// @param checkpoints The history of values being queried
/// @param _block The block number to retrieve the value at
/// @return The number of tokens being queried
function getValueAt(Checkpoint[] storage checkpoints, uint _block) constant internal returns (uint) {
    if (checkpoints.length == 0)
        return 0;

    // Shortcut for the actual value
    if (_block >= checkpoints[checkpoints.length-1].fromBlock)
        return checkpoints[checkpoints.length-1].value;
    if (_block < checkpoints[0].fromBlock)
        return 0;

    // Binary search of the value in the array
    uint min = 0;
    uint max = checkpoints.length-1;
    while (max > min) {
        uint mid = (max + min + 1) / 2;
        if (checkpoints[mid].fromBlock<=_block) {
            min = mid;
        } else {
            max = mid-1;
        }
    }
    return checkpoints[min].value;
}

/// @dev `updateValueAtNow` used to update the `balances` map and the
///  `totalSupplyHistory`
/// @param checkpoints The history of data being updated
/// @param _value The new number of tokens
function updateValueAtNow(Checkpoint[] storage checkpoints, uint _value) internal {
    if ((checkpoints.length == 0) || (checkpoints[checkpoints.length - 1].fromBlock < block.number)) {
        Checkpoint storage newCheckPoint = checkpoints[checkpoints.length++];
        newCheckPoint.fromBlock = uint128(block.number);
        newCheckPoint.value = uint128(_value);
    } else {
        Checkpoint storage oldCheckPoint = checkpoints[checkpoints.length - 1];
        oldCheckPoint.value = uint128(_value);
    }
}

/// @dev Internal function to determine if an address is a contract
/// @param _addr The address being queried
/// @return True if `_addr` is a contract
function isContract(address _addr) constant internal returns(bool) {
    uint size;
    if (_addr == 0)
        return false;

    assembly {
        size := extcodesize(_addr)
    }

    return size>0;
}

/// @dev Helper function to return a min betwen the two uints
function min(uint a, uint b) internal returns (uint) {
    return a < b ? a : b;
}

/// @notice The fallback function: If the contract's controller has not been
///  set to 0, then the `proxyPayment` method is called which relays the
///  ether and creates tokens as described in the token controller contract
function ()  payable  public {
    require(isContract(controller));
    // Adding the ` == true` makes the linter shut up so...
    require(ITokenController(controller).proxyPayment.value(msg.value)(msg.sender) == true);
}

//////////
// Safety Methods
//////////

/// @notice This method can be used by the controller to extract mistakenly
///  sent tokens to this contract.
/// @param _token The address of the token contract that you want to recover
///  set to 0 in case you want to extract ether.
function claimTokens(address _token) onlyController  public {
    if (_token == 0x0) {
        controller.transfer(this.balance);
        return;
    }

    MiniMeToken token = MiniMeToken(_token);
    uint balance = token.balanceOf(this);
    token.transfer(controller, balance);
    ClaimedTokens(_token, controller, balance);
}

////////////////
// Events
////////////////
event ClaimedTokens(address indexed _token, address indexed _controller, uint _amount);
event Transfer(address indexed _from, address indexed _to, uint256 _amount);
event NewCloneToken(address indexed _cloneToken, uint _snapshotBlock);
event Approval(
    address indexed _owner,
    address indexed _spender,
    uint256 _amount
    );

}


////////////////
// MiniMeTokenFactory
////////////////

/// @dev This contract is used to generate clone contracts from a contract.
///  In solidity this is the way to create a contract from a contract of the
///  same class
contract MiniMeTokenFactory {

/// @notice Update the DApp by creating a new token with new functionalities
///  the msg.sender becomes the controller of this clone token
/// @param _parentToken Address of the token being cloned
/// @param _snapshotBlock Block of the parent token that will
///  determine the initial distribution of the clone token
/// @param _tokenName Name of the new token
/// @param _decimalUnits Number of decimals of the new token
/// @param _tokenSymbol Token Symbol for the new token
/// @param _transfersEnabled If true, tokens will be able to be transferred
/// @return The address of the new token contract
function createCloneToken(
    address _parentToken,
    uint _snapshotBlock,
    string _tokenName,
    uint8 _decimalUnits,
    string _tokenSymbol,
    bool _transfersEnabled
) public returns (MiniMeToken)
{
    MiniMeToken newToken = new MiniMeToken(
        this,
        _parentToken,
        _snapshotBlock,
        _tokenName,
        _decimalUnits,
        _tokenSymbol,
        _transfersEnabled
    );

    newToken.changeController(msg.sender);
    return newToken;
}
}