Added validation of moved funds sweep proposal

solidity/contracts/bridge/WalletProposalValidator.sol

@@ -22,6 +22,7 @@ import "./BitcoinTx.sol";
 import "./Bridge.sol";
 import "./Deposit.sol";
 import "./Redemption.sol";
+import "./MovingFunds.sol";
 import "./Wallets.sol";
 
 /// @title Wallet proposal validator.
@@ -104,6 +105,20 @@ contract WalletProposalValidator {
         uint256 movingFundsTxFee;
     }
 
+    /// @notice Helper structure representing a moved funds sweep proposal.
+    struct MovedFundsSweepProposal {
+        // 20-byte public key hash of the wallet.
+        bytes20 walletPubKeyHash;
+        // 32-byte hash of the moving funds transaction that caused the sweep
+        // request to be created.
+        bytes32 movingFundsTxHash;
+        // Index of the moving funds transaction output that is subject of the
+        // sweep request.
+        uint32 movingFundsTxOutputIndex;
+        // Proposed BTC fee for the entire transaction.
+        uint256 movedFundsSweepTxFee;
+    }
+
     /// @notice Helper structure representing a heartbeat proposal.
     struct HeartbeatProposal {
         // 20-byte public key hash of the target wallet.
@@ -662,6 +677,61 @@ contract WalletProposalValidator {
         return true;
     }
 
+    function validateMovedFundsSweepProposal(
+        MovedFundsSweepProposal calldata proposal
+    ) external view returns (bool) {
+        Wallets.Wallet memory wallet = bridge.wallets(
+            proposal.walletPubKeyHash
+        );
+
+        // Make sure the wallet is in Live or MovingFunds state.
+        require(
+            wallet.state == Wallets.WalletState.Live ||
+                wallet.state == Wallets.WalletState.MovingFunds,
+            "Source wallet is not in Live or MovingFunds state"
+        );
+
+        // Make sure the moved funds sweep request is valid.
+        uint256 sweepRequestKeyUint = uint256(
+            keccak256(
+                abi.encodePacked(
+                    proposal.movingFundsTxHash,
+                    proposal.movingFundsTxOutputIndex
+                )
+            )
+        );
+
+        MovingFunds.MovedFundsSweepRequest memory sweepRequest = bridge
+            .movedFundsSweepRequests(sweepRequestKeyUint);
+
+        require(
+            sweepRequest.state ==
+                MovingFunds.MovedFundsSweepRequestState.Pending,
+            "Sweep request is not in Pending state"
+        );
+
+        require(
+            sweepRequest.walletPubKeyHash == proposal.walletPubKeyHash,
+            "Sweep request does not belong to the wallet"
+        );
+
+        // Make sure the proposed fee is valid.
+        (, , , , , , , uint64 movedFundsSweepTxMaxTotalFee, , , ) = bridge
+            .movingFundsParameters();
+
+        require(
+            proposal.movedFundsSweepTxFee > 0,
+            "Proposed transaction fee cannot be zero"
+        );
+
+        require(
+            proposal.movedFundsSweepTxFee <= movedFundsSweepTxMaxTotalFee,
+            "Proposed transaction fee is too high"
+        );
+
+        return true;
+    }
+
     /// @notice View function encapsulating the main rules of a valid heartbeat
     ///         proposal. This function is meant to facilitate the off-chain
     ///         validation of the incoming proposals. Thanks to it, most