provable/ethereum-api

// SPDX-License-Identifier: MIT
pragma solidity ^0.6.12;
import "github.com/provable-things/ethereum-api/provableAPI_0.6.sol";

// example of calling an API
contract Example is usingProvable {

    struct ApiResult {
        string clientSeed;
        string serverSeed;
        string hash;
    }

    string public lastResult;
    mapping (bytes32 => bool) private validIds;
    event LogMessage(string description);

    constructor() public {}

    function __callback(bytes32 requestId, string memory result) override public {
        require(validIds[requestId], "query id is invalid!!!");
        require(msg.sender == provable_cbAddress(), "invalid sender detected!!!");
        lastResult = result;
    }

    function getRamdon(string memory clientSeed) public {
        require(bytes(clientSeed).length > 0, "client seed is required!!!");

        if (provable_getPrice("URL") > address(this).balance) {
            emit LogMessage("Contract out of gas!");
        } else {
            bytes32 requestId = provable_query("URL", string(abi.encodePacked("json(https://oracles.azurewebsites.net/Random/GetRandomHash/", clientSeed, ").path.to[\"clientSeed\", \"serverSeed\", \"hash\"]")));
            validIds[requestId] = true;
        }
    }

}