smart-contracts/coin flip smart contracts done 🎉

smart-contracts/contracts/CoinFlip.sol

@@ -11,12 +11,13 @@ contract CoinFlip is VRFV2WrapperConsumerBase {
     // what the result is
     event CoinFlipResult(unit256 requestId, bool didWin);
     // check each user status
-    struct coinFlipStatus {
+    struct CoinFlipStatus {
         uint256 fees;
-        uint256 randomWords;
+        uint256 randomWord;
         address player;
         bool didWin;
-        CoinFlipSelection choice
+        bool fulfilled;
+        CoinFlipSelection choice;
     }
     // coin flip selection 
     enum CoinFlipSelection {
@@ -27,18 +28,89 @@ contract CoinFlip is VRFV2WrapperConsumerBase {
     mapping(uint256 => CoinFlipStatus) public statuses;
 
 
-    // link contract address and wrappper address
+    // link contract address and wrappper address on polygon
     address constant linkAddress = 0x326C977E6efc84E512bB9C30f76E30c160eD06FB;
-    address constant vrfwrapper = 0x99aFAf084eBA697E584501b8Ed2c0B37Dd136693;
+    address constant vrfWrapperAddress = 0x99aFAf084eBA697E584501b8Ed2c0B37Dd136693;
 
-    //entry fee [update on function or sth later on]
-    uint128 constant entryFees = 0.01 ether
+    //entry fee [update on function on the frontend later on]
+    uint128 constant entryFees = 0.01 ether;
+
+   // gas limit to spare in LINK
+    uint32 constant callbackGasLimit = 1_000_000;
 
+   // number of words to get from the LINK wrapper
+    uint32 constant numWords = 1;
+
+   // number of confirmations or blocks should it wait before sending the confirmation
+    uint16 constant requestConfirmations = 3;
+
+  // VRF instance
+  constructor() payable VRFV2WrapperConsumerBase(linkAddress, vrfWrapperAddress) {
+
+  }
     // flip function
    function flip(CoinFlipSelection choice) 
         external 
         payable 
         returns (uint256) {
+     // if  user already pays the entry fee or staking fee
+       require(msg.value == entryFees, "Entry Fees not sent");
 
+     // then request randomness
+     uint256 requestId = requestRandomness(
+         callbackGasLimit,
+         requestConfirmations,
+         numWords
+     );
+
+     // update coinflipstatus with the requestId
+     statuses[requestId] = CoinFlipStatus({
+         fees : VRF_V2_WRAPPER.calculateRequestPrice(callbackGasLimit),
+         randomWord : 0;
+         player : msg.sender;
+         didWin : false;
+         fulfilled : false;
+         choice : choice;
+     });
+
+    // since it is a request emit coinflip request
+    emit CoinFlipRequest(requestId);
+    return requestId;
   }
+
+   // we send the request ID to chainlink to get the random words
+  function fulfillRandomWords(uint256 requestid, uint256[] memory randomWords)
+       internal
+       override
+   {
+    // check fees 
+    require(statuses[requestId].fees > 0, "Request not found");
+    //update status
+    statuses.[requestId].fulfilled = true;
+    statuses.[requestId].randomWord = randomWords[0];
+
+    // set coinFlipselection with the random words chainlink generate for us
+    CoinFlipSelection result = CoinFlipSelection.HEADS;
+
+    // if even
+    if(randomWords[0] % 2 == 0) {
+      result = CoinFlipSelection.TAILS
+    }
+    // pay *2 of staked amount if user win
+    if (statuses[requestId].choice == result) {
+        statuses[request].didWin = true;
+        payable(statuses[requestId].player).transfer(entryFees * 2);
+    }
+    emit CoinFlipResult(requestId, statuses[requestId].didWin);
+
+   }
+
+// get each user status
+   function getStatus(uint256 requestId)
+    public
+    view
+    returns (CoinFlipStatus memory)
+    {
+        return statuses[requestId]
+    }
 }