feat: finish up challenges

packages/hardhat/contracts/00_Whitelist/WhitelistOracle.sol

@@ -60,7 +60,11 @@ contract WhitelistOracle {
      * @dev Creates a new SimpleOracle instance and adds it to the oracles array.
      * @param _owner The address that will own the newly created oracle and can update its price
      */
-    function addOracle(address _owner) public onlyOwner {}
+    function addOracle(address _owner) public onlyOwner {
+      SimpleOracle newOracle = new SimpleOracle(_owner);
+      oracles.push(newOracle);
+      emit OracleAdded(address(newOracle), _owner);
+    }
 
     /**
      * @notice Removes an oracle from the whitelist by its array index (only contract owner)
@@ -68,7 +72,18 @@ contract WhitelistOracle {
      *      Reverts with IndexOutOfBounds, if the provided index is >= oracles.length.
      * @param index The index of the oracle to remove from the oracles array
      */
-    function removeOracle(uint256 index) public onlyOwner {}
+    function removeOracle(uint256 index) public onlyOwner {
+      uint256 oraclesSize = oracles.length;
+      if (index >= oraclesSize) revert IndexOutOfBounds();
+
+      address deletedOracle = address(oracles[index]);
+      if (index != oraclesSize - 1) {
+        oracles[index] = oracles[oraclesSize - 1];
+      }
+      
+      oracles.pop();
+      emit OracleRemoved(deletedOracle);
+    }
 
     /**
      * @notice Returns the aggregated price from all active oracles using median calculation
@@ -76,7 +91,28 @@ contract WhitelistOracle {
      *      of remaining valid prices. Uses StatisticsUtils for sorting and median calculation.
      * @return The median price from all active oracles
      */
-    function getPrice() public view returns (uint256) {}
+    function getPrice() public view returns (uint256) {
+      if (oracles.length == 0) revert NoOraclesAvailable();
+      uint256[] memory prices = new uint256[](oracles.length);
+      uint256 priceIndex = 0;
+      uint256 currentTime = block.timestamp;
+
+      for (uint256 i = 0; i < oracles.length; i++) {
+        (uint256 price, uint256 timestamp) = oracles[i].getPrice();
+	if (currentTime - timestamp < STALE_DATA_WINDOW) {
+	  prices[priceIndex] = price;
+	  priceIndex++;
+	}
+      }
+
+      uint256[] memory fixedPrices = new uint256[](priceIndex);
+      for (uint256 i = 0; i < priceIndex; i++) {
+        fixedPrices[i] = prices[i];
+      }
+
+      fixedPrices.sort();
+      return fixedPrices.getMedian();
+    }
 
     /**
      * @notice Returns the addresses of all oracles that have updated their price within the last STALE_DATA_WINDOW
@@ -85,5 +121,24 @@ contract WhitelistOracle {
      *      for gas optimization.
      * @return An array of addresses representing the currently active oracle contracts
      */
-    function getActiveOracleNodes() public view returns (address[] memory) {}
+    function getActiveOracleNodes() public view returns (address[] memory) {
+      address[] memory activeOracles = new address[](oracles.length);
+      uint256 oracleIndex = 0;
+      uint256 currentTime = block.timestamp;
+
+      for (uint256 i = 0; i < oracles.length; i++) {
+        (, uint256 timestamp) = oracles[i].getPrice();
+	if (currentTime - timestamp < STALE_DATA_WINDOW) {
+	  activeOracles[oracleIndex] = address(oracles[i]);
+	  oracleIndex++;
+	}
+      }
+
+      address[] memory fixedActiveOracles = new address[](oracleIndex);
+      for (uint256 i = 0; i < oracleIndex; i++) {
+        fixedActiveOracles[i] = activeOracles[i];
+      }
+
+      return fixedActiveOracles;
+    }
 }