AdPerformance.sol

AdPerformance.sol

pragma solidity ^0.4.21;

import "github.com/oraclize/ethereum-api/oraclizeAPI.sol";

contract AdPerformance is usingOraclize {
    address owner;
    address beneficiary;
    uint gweiToPayPerView;
    string youtubeId;
    bool withdrawn;
    
    event Deposit(address from, uint amount);
    event Withdraw(address to, uint amount);
    event Query(string query);
    event Callback(string result, uint viewCount, uint amount, uint balance);
    
    function AdPerformance(address _beneficiary, uint _gweiToPayPerView, string _youtubeId) public payable {
        owner = msg.sender;
        beneficiary = _beneficiary;
        gweiToPayPerView = _gweiToPayPerView;
        youtubeId = _youtubeId;
        withdrawn = false;
        
        emit Deposit(msg.sender, msg.value);
    }
    
    function withdraw() public {
        require(msg.sender == beneficiary);
        require(!withdrawn);
        
        string memory query = strConcat('json(https://www.googleapis.com/youtube/v3/videos?id=',
                youtubeId,
                '&key=AIzaSyAhV6cw7pjvrrBoSkIDxff4gvovbF_9rXk%20&part=statistics).items.0.statistics.viewCount');
        emit Query(query);
        oraclize_query('URL', query);
    }  
    
    function __callback(bytes32, string result) public {
        require(msg.sender == oraclize_cbAddress());
        require(!withdrawn);
        
        uint viewCount = stringToUint(result);
        uint amount = viewCount * gweiToPayPerView * 1000000000;
        uint balance = address(this).balance;
        
        emit Callback(result, viewCount, amount, balance);
        if (balance < amount) {
            amount = balance;
        }
        
        beneficiary.transfer(amount);
        withdrawn = true;
        
        emit Withdraw(beneficiary, amount);
    }
    
    function isWithdrawn() public view returns (bool) {
        return withdrawn;
    }
    
    function refund() public {
        require(msg.sender == owner);
        require(withdrawn);
        
        uint balance = address(this).balance;
        if (balance > 0) {
            owner.transfer(balance);
        }
    }
    
    function stringToUint(string s) internal pure returns (uint result) {
        bytes memory b = bytes(s);
        uint i;
        result = 0;
        for (i = 0; i < b.length; i++) {
            uint c = uint(b[i]);
            if (c >= 48 && c <= 57) {
                result = result * 10 + (c - 48);
            }
        }
    }
    
    function strConcat(string _a, string _b, string _c, string _d, string _e) internal returns (string){
        bytes memory _ba = bytes(_a);
        bytes memory _bb = bytes(_b);
        bytes memory _bc = bytes(_c);
        bytes memory _bd = bytes(_d);
        bytes memory _be = bytes(_e);
        string memory abcde = new string(_ba.length + _bb.length + _bc.length + _bd.length + _be.length);
        bytes memory babcde = bytes(abcde);
        uint k = 0;
        for (uint i = 0; i < _ba.length; i++) babcde[k++] = _ba[i];
        for (i = 0; i < _bb.length; i++) babcde[k++] = _bb[i];
        for (i = 0; i < _bc.length; i++) babcde[k++] = _bc[i];
        for (i = 0; i < _bd.length; i++) babcde[k++] = _bd[i];
        for (i = 0; i < _be.length; i++) babcde[k++] = _be[i];
        return string(babcde);
    }
    
    function strConcat(string _a, string _b, string _c, string _d) internal returns (string) {
        return strConcat(_a, _b, _c, _d, "");
    }

    function strConcat(string _a, string _b, string _c) internal returns (string) {
        return strConcat(_a, _b, _c, "", "");
    }

    function strConcat(string _a, string _b) internal returns (string) {
        return strConcat(_a, _b, "", "", "");
    }
}