v0.5

options.sol

pragma solidity ^0.4.0;

contract CorretoraOpcoes {
    
    struct DateTime {
        uint16 year;
        uint8 month;
        uint8 day;
    }
    
    uint constant DAY_IN_SECONDS = 86400;
    uint constant YEAR_IN_SECONDS = 31536000;
    uint constant LEAP_YEAR_IN_SECONDS = 31622400;
    uint constant HOUR_IN_SECONDS = 3600;
    uint constant MINUTE_IN_SECONDS = 60;
    uint16 constant ORIGIN_YEAR = 1970;
    
    function isLeapYear(uint16 year) public pure returns (bool) {
        if (year % 4 != 0) {
            return false;
        }
        if (year % 100 != 0) {
            return true;
        }
        if (year % 400 != 0) {
            return false;
        }
        return true;
    }
    
    function toTimestamp(uint16 year, uint8 month, uint8 day, uint8 hour, uint8 minute, uint8 second) public pure returns (uint timestamp) {
        uint16 i;

        // Year
        for (i = ORIGIN_YEAR; i < year; i++) {
            if (isLeapYear(i)) {
                timestamp += LEAP_YEAR_IN_SECONDS;
            }
            else {
                timestamp += YEAR_IN_SECONDS;
            }
        }

        // Month
        uint8[12] memory monthDayCounts;
        monthDayCounts[0] = 31;
        if (isLeapYear(year)) {
            monthDayCounts[1] = 29;
        }
        else {
            monthDayCounts[1] = 28;
        }
        monthDayCounts[2] = 31;
        monthDayCounts[3] = 30;
        monthDayCounts[4] = 31;
        monthDayCounts[5] = 30;
        monthDayCounts[6] = 31;
        monthDayCounts[7] = 31;
        monthDayCounts[8] = 30;
        monthDayCounts[9] = 31;
        monthDayCounts[10] = 30;
        monthDayCounts[11] = 31;

        for (i = 1; i < month; i++) {
            timestamp += DAY_IN_SECONDS * monthDayCounts[i - 1];
        }

        // Day
        timestamp += DAY_IN_SECONDS * (day - 1);

        // Hour
        timestamp += HOUR_IN_SECONDS * (hour);

        // Minute
        timestamp += MINUTE_IN_SECONDS * (minute);

        // Second
        timestamp += second;

        return timestamp;
    }
    
    struct Quote {
        uint256 today;
        uint256 yesterday;
    }

    struct Option {
        bool buy; // true se for de compra, false se for de venda
        bool usa; // true se for americana, false se for europeia
        uint8 answer; // 0 = waiting | 1 = accepted | 2 = refused

        address owner;
        address holder;
        
        uint256 strike;
        uint256 quote;
        
        uint256 premium;
        
        DateTime date;
    }

    // Endereço Público do dono do contrato
    address public owner;
    
    mapping(address => int8) registered; // Guarda quem esta registrado
    mapping(address => int256) balances; // Guarda os saldos <address><saldo> em centavos
    mapping(uint256 => mapping (uint256 => uint256[])) optionsId; // "2020" -> "timestamp do dia" -> "[id1, id2]"
    
    Option[] public options;
    uint256 public counter;
    
    Quote public quote;
    
    
    // Evento anuncia pra rede que o dono do contrato mudou
    event OwnershipTransferred(address indexed previousOwner, address indexed newOwner);

    // Auto executavel
    constructor() public {
        owner = msg.sender;
        counter = 0;
    }

    // So para o dono
    modifier onlyOwner() {
        require(msg.sender == owner);
        _;
    }
    
    function transferOwnership(address _newOwner) public onlyOwner {
        _transferOwnership(_newOwner);
    }
    function _transferOwnership(address _newOwner) internal {
        require(_newOwner != address(0));
        emit OwnershipTransferred(owner, _newOwner);
        owner = _newOwner;
  }

    function registerAddress(address user) public onlyOwner {
        registered[user] = 1;
        balances[user] = 0;
    }
    
    // quote = Quantos BRL's uma (1) unidade de dólar compra, em centavos
    // Exemplo:
    // U$1 <> R$3.20: quote = 320
    // U$1 <> R$17.20: quote = 1720
    function updateQuote(uint256 _quote) public onlyOwner{
        quote.yesterday = quote.today;
        quote.today = _quote;
    }
    
    function createOption(bool _buy, bool _usa, uint256 _strike, uint256 _quote, 
        uint16 _year, uint8 _month, uint8 _day, address _caller, uint256 _premium) public returns (uint256 identifier) {
        
        require(registered[msg.sender] == 1);
        require(registered[_caller] == 1);
        
        DateTime _date;
        _date.year = _year;
        _date.month = _month;
        _date.day = _day;
        
        uint256 dayYear = toTimestamp(_year, _month, _day, 0, 0, 0);
        
        Option _option;
        _option.buy = _buy;
        _option.usa = _usa;
        _option.answer = 0;
        _option.owner = msg.sender;
        _option.holder = _caller;
        _option.strike = _strike;
        _option.quote = _quote;
        _option.premium = _premium;
        _option.date = _date;
        
        options[counter] = _option;
        optionsId[_year][dayYear].push(counter);
        
        counter++;
        
        // TODO: Emitir evento
        
        return counter--;
    }
    
    function acceptOptionById(uint256 identifier, uint8 answer) public {
        require(options[identifier].holder == msg.sender);
        options[identifier].answer = answer;
        
        // TODO: Emitir evento
    }
}