HelloWorld.solpp

pragma soliditypp ^0.4.3;

contract Social {
    
    mapping(address=>mapping(address=>uint)) public balances;
    mapping(address=>uint) public reserve;
    mapping(address=>uint8) public hasMinted; 

    tokenId token = tokenId("tti_5649544520544f4b454e6e40");

    uint public factor = 3000000000000000;

    event buyEvent(address indexed addr, address indexed vftid, uint256 value, tokenId tid);
    event sellEvent(address indexed addr, address indexed vftid, uint256 value, tokenId tid);
    event mintEvent(address indexed addr);

    constructor() public {}

    onMessage mint() {
        require(hasMinted[msg.sender] == 0, "Address has already mint VFT");
        hasMinted[msg.sender] = 1;
        reserve[msg.sender] = 1000;
        emit mintEvent(msg.sender);
    }

    onMessage buyVFT(address vftid) payable {
        require(reserve[vftid] > 0, "Not enough VFT");
        uint price = calculatePrice(vftid, 1);
        require(msg.amount >= price, "Price is not equal to sended amount");

        reserve[vftid]--;
        balances[vftid][msg.sender]++;
        emit buyEvent(msg.sender, vftid, price, token);
    }

    onMessage sellVFT(address vftid) {
        require(balances[vftid][msg.sender] > 0, "Not enough VFT");
        uint price = calculatePrice(vftid, 0);

        reserve[vftid]++;
        balances[vftid][msg.sender]--;
        msg.sender.transfer(token, price);
        emit sellEvent(msg.sender, vftid, price, token);
    }

    getter getReserve(address vftid) returns(uint) {
        return reserve[vftid];
    }

    getter getBuyPrice(address vftid) returns(uint) {
        return calculatePrice(vftid, 1);
    }

    getter getSellPrice(address vftid) returns(uint) {
        return calculatePrice(vftid, 0);
    }

    getter getBalance(address vftid, address holder) returns(uint) {
        return balances[vftid][holder];
    }

    function calculatePrice(address vftid, int forBuy) public view returns(uint) {
        uint postCirculating = 1000 - reserve[vftid];

        if(forBuy == 1) {
            if(reserve[vftid] <= 0) return 0;
            postCirculating++;
        } else {
            if(reserve[vftid] >= 1000) return 0;
            postCirculating--;
        }

        return 3000000000000000 * (postCirculating * postCirculating);
    }
}