brlt.sol

pragma solidity ^0.4.18;
 
// ----------------------------------------------------------------------------------------------
// BRL TOKEN EXCHANGE CONTRACT
// Enjoy. (c) tegila 2017. The MIT Licence.
// ----------------------------------------------------------------------------------------------
 
// ERC Token Standard #20 Interface
// https://github.com/ethereum/EIPs/issues/20
contract ERC20Interface {
    // Get the total token supply
    function totalSupply() constant returns (uint256 totalSupply);
 
    // Get the account balance of another account with address _owner
    function balanceOf(address _owner) constant returns (uint256 balance);
 
    // Send _value amount of tokens to address _to
    function transfer(address _to, uint256 _value) returns (bool success);
 
    // Send _value amount of tokens from address _from to address _to
    function transferFrom(address _from, address _to, uint256 _value) returns (bool success);
 
    // Allow _spender to withdraw from your account, multiple times, up to the _value amount.
    // If this function is called again it overwrites the current allowance with _value.
    // this function is required for some DEX functionality
    function approve(address _spender, uint256 _value) returns (bool success);
 
    // Returns the amount which _spender is still allowed to withdraw from _owner
    function allowance(address _owner, address _spender) constant returns (uint256 remaining);
 
    // Triggered when tokens are transferred.
    event Transfer(address indexed _from, address indexed _to, uint256 _value);
 
    // Triggered whenever approve(address _spender, uint256 _value) is called.
    event Approval(address indexed _owner, address indexed _spender, uint256 _value);
    
}

contract BRLTConsensus {
    // Owner of this contract
    address public owner;
 
    // Balances for each account
    mapping(address => uint256) balances;
    uint256 _totalSupply = 0;
    
    // Determina o intervalo entre os ROUNDS (em blocos)
    uint32 public constant INTERVAL_BETWEEN_ROUNDS = 2000;
    uint32 public constant ROUND_DURATION = 200;
    // Essa taxa será cobrada sempre que alguem usar a funcao transfer
    // está fixa mas meu objetivo final é transformar ela em uma curva logaritma
    uint8 public constant FEES = 2; // #TODO (2% + GAS)
}

contract StandardToken is ERC20Interface, BRLTConsensus {
    string public constant symbol = "BRLT";
    string public constant name = "Brazilian token tied to REAL";
    uint8 public constant decimals = 2;

    // Owner of account approves the transfer of an amount to another account
    mapping(address => mapping (address => uint256)) allowed;
 
    // Functions with this modifier can only be executed by the owner
    modifier onlyOwner() {
        if (msg.sender != owner) {
            throw;
        }
        _;
    }
 
    // Constructor
    function StandardToken() {

    }

    function totalSupply() constant returns (uint256 totalSupply) {
        totalSupply = _totalSupply;
    }
 
    // What is the balance of a particular account?
    function balanceOf(address _owner) constant returns (uint256 balance) {
        return balances[_owner];
    }
 
    // Transfer the balance from owner's account to another account
    function transfer(address _to, uint256 _amount) returns (bool success) {
        if (balances[msg.sender] >= _amount 
            && _amount > 0
            && balances[_to] + _amount > balances[_to]) {
            balances[msg.sender] -= _amount;
            balances[_to] += _amount;
            Transfer(msg.sender, _to, _amount);
            return true;
        } else {
            return false;
        }
    }
 
    // Send _value amount of tokens from address _from to address _to
    // The transferFrom method is used for a withdraw workflow, allowing contracts to send
    // tokens on your behalf, for example to "deposit" to a contract address and/or to charge
    // fees in sub-currencies; the command should fail unless the _from account has
    // deliberately authorized the sender of the message via some mechanism; we propose
    // these standardized APIs for approval:
    function transferFrom(
        address _from,
        address _to,
        uint256 _amount
    ) returns (bool success) {
        if (balances[_from] >= _amount
            && allowed[_from][msg.sender] >= _amount
            && _amount > 0
            && balances[_to] + _amount > balances[_to]) {
            balances[_from] -= _amount;
            allowed[_from][msg.sender] -= _amount;
            balances[_to] += _amount;
            Transfer(_from, _to, _amount);
            return true;
        } else {
            return false;
        }
    }
 
    // Allow _spender to withdraw from your account, multiple times, up to the _value amount.
    // If this function is called again it overwrites the current allowance with _value.
    function approve(address _spender, uint256 _amount) returns (bool success) {
        allowed[msg.sender][_spender] = _amount;
        Approval(msg.sender, _spender, _amount);
        return true;
    }
 
    function allowance(address _owner, address _spender) constant returns (uint256 remaining) {
        return allowed[_owner][_spender];
    }
}

contract BRLT is StandardToken {
    uint public collected_fees = 0;
    // media *ponderada* da taxa de conversao das ofertas
    // x = amount_eth
    // y = amount_brlt
    struct Average {
        // coefficient = soma(x*y) 
        uint coefficient;
        // denominator = soma(y)
        uint denominator;
        uint weighted_average;
    }
    Average public average;
    
    struct Offer {
        address owner;
        // brlt_eth = amount_brlt / amount_eth
        uint eth_brlt;
        uint amount_eth;
    }
    
    Offer[] public offers;
    
    // livro caixa
    mapping(address => Offer[]) public bookkipping;

    event Bid(address indexed _from, uint amount_eth, uint eth_brlt);
    
    function bid(uint _exchange_rate) payable returns (bool success) {
        // #TODO: CONFERIR SE ROUND JA COMECOU
        Offer _offer;
        
        _offer.owner = msg.sender;
        _offer.amount_eth = uint(msg.value);
        _offer.eth_brlt = _exchange_rate;
        
        offers.push(_offer);
      
        average.coefficient += _offer.amount_eth*_offer.eth_brlt;
        average.denominator += _offer.amount_eth;
        
        // #REMOVE: ENVIA DE VOLTA AO REMETENTE
        _offer.owner.send(msg.value);
        
        return true;
    }
    
    function digest() returns (bool success) {
        // #TODO: CONFERIR SE ROUND JA TERMINOU
        // soma (brlt - media)
        uint coefficient;
        average.weighted_average = average.coefficient / average.denominator;
        for (uint i = 0; i < offers.length; i++) {
            coefficient = (offers[i].eth_brlt - average.weighted_average)**2;
        }
        uint sd = sqrt((coefficient/(offers.length-1)));
        
        for (i = 0; i < offers.length; i++) {
            Offer _offer = offers[i];
            // if winner
            if(_offer.eth_brlt > (average.weighted_average - sd)) {
                balances[_offer.owner] += (_offer.amount_eth * average.weighted_average)/(10**16);
                _offer.eth_brlt = average.weighted_average;
                bookkipping[_offer.owner].push(_offer);
                _totalSupply += _offer.amount_eth;
            }
        }

        return true;
    }

    function redeem(uint offer_number) {
        // #TODO: get back my ethereum
        address _owner = msg.sender;
        uint amount = bookkipping[_owner][offer_number].amount_eth;
        bookkipping[_owner][offer_number].amount_eth = 0;
        msg.sender.send(amount);        
    }
 
    function sqrt(uint x) returns (uint y) {
        uint z = (x + 1) / 2;
        y = x;
        while (z < y) {
            y = z;
            z = (x / z + z) / 2;
        }
    }
}