Added chainlink resolver

contracts/protocols/chainlink.sol

@@ -0,0 +1,110 @@
+pragma solidity ^0.6.0;
+
+interface ChainLinkInterface {
+    function latestAnswer() external view returns (int256);
+}
+
+interface ConnectorsInterface {
+  function chief(address) external view returns (bool);
+}
+
+interface IndexInterface {
+  function master() external view returns (address);
+}
+
+
+contract Basic {
+    address public constant connectors = 0xD6A602C01a023B98Ecfb29Df02FBA380d3B21E0c;
+    address public constant instaIndex = 0x2971AdFa57b20E5a416aE5a708A8655A9c74f723;
+    address public constant ethAddr = 0xEeeeeEeeeEeEeeEeEeEeeEEEeeeeEeeeeeeeEEeE;
+    uint public version = 1;
+
+    modifier isChief {
+        require(
+        ConnectorsInterface(connectors).chief(msg.sender) ||
+        IndexInterface(instaIndex).master() == msg.sender, "not-Chief");
+        _;
+    }
+
+    event LogAddChainLinkMapping(
+        address tokenAddr,
+        address chainlinkFeed
+    );
+
+    event LogRemoveChainLinkMapping(
+        address tokenAddr,
+        address chainlinkFeed
+    );
+
+    event LogChangeGasPriceFeed(
+        address chainlinkFeed
+    );
+
+    mapping (address => address) public chainLinkMapping;
+    address public gasFastChainLink;
+
+    function _addChainLinkMapping(
+        address tokenAddr,
+        address chainlinkFeed
+    ) internal {
+        require(tokenAddr != address(0), "tokenAddr-not-vaild");
+        require(chainlinkFeed != address(0), "chainlinkFeed-not-vaild");
+        require(chainLinkMapping[tokenAddr] == address(0), "chainlinkFeed-already-added");
+
+        chainLinkMapping[tokenAddr] == chainlinkFeed;
+        emit LogAddChainLinkMapping(tokenAddr, chainlinkFeed);
+    }
+
+    function _removeChainLinkMapping(address tokenAddr) internal {
+        require(tokenAddr != address(0), "tokenAddr-not-vaild");
+        require(chainLinkMapping[tokenAddr] != address(0), "chainlinkFeed-not-added-yet");
+
+        emit LogRemoveChainLinkMapping(tokenAddr, chainLinkMapping[tokenAddr]);
+        delete chainLinkMapping[tokenAddr];
+    }
+
+    function addChainLinkMapping(
+        address[] memory tokensAddr,
+        address[] memory chainlinkFeeds
+    ) public isChief {
+        require(tokensAddr.length == chainlinkFeeds.length, "Lenght-not-same");
+        for (uint i = 0; i < tokensAddr.length; i++) {
+            _addChainLinkMapping(tokensAddr[i], chainlinkFeeds[i]);
+        }
+    }
+
+    function removeChainLinkMapping(address tokenAddr) public isChief {
+        for (uint i = 0; i < tokensAddr.length; i++) {
+            _removeChainLinkMapping(tokensAddr[i]);
+        }
+    }
+
+    function changeGasMapping(address chainlinkFeed) public isChief {
+        require(chainlinkFeed != address(0), "chainlinkFeed-not-vaild");
+        require(chainlinkFeed != gasFastChainLink, "chainlinkFeed-is-same");
+        gasFastChainLink = chainlinkFeed;
+        emit LogChangeGasPriceFeed(gasFastChainLink);
+    }
+}
+
+contract Resolver is Basic {
+    function getPrice(address[] memory tokens) public view returns (uint ethPriceInUsd, uint[] memory tokensPriceInETH) {
+        tokensPriceInETH = new uint[](tokens.length);
+        ethPriceInUsd = uint(ChainLinkInterface(chainLinkMapping[ethAddr]).latestAnswer());
+        for (uint i = 0; i < tokens.length; i++) {
+            tokensPriceInETH[i] = uint(ChainLinkInterface(chainLinkMapping[tokens[i]]).latestAnswer());
+        }
+    }
+
+    function getGasPrice() public view returns (uint gasPrice) {
+        gasPrice = uint(ChainLinkInterface(gasFastChainLink).latestAnswer());
+    }
+}
+
+contract InstaChainLinkResolver is Resolver {
+    constructor (address[] memory tokensAddr, address[] memory chainlinkFeeds) public {
+        addChainLinkMapping(tokensAddr, chainlinkFeeds);
+    }
+
+    string public constant name = "ChainLink-Resolver-v1";
+}