Refactor Discount Validator to be an abstract contract supporting sta…

…te writes in validation

src/L2/RegistrarController.sol

@@ -232,25 +232,11 @@ contract RegistrarController is Ownable {
         _;
     }
 
-    /// @notice Decorator for validating discounted registrations.
+    /// @notice Decorator for validating a user for discounted registration.
     ///
-    /// @dev Validates that:
-    ///     1. That the registrant has not already registered with a discount
-    ///     2. That the discount is `active`
-    ///     3. That the associated `discountValidator` returns true when `isValidDiscountRegistration` is called.
-    ///
-    /// @param discountKey The uuid of the discount.
-    /// @param validationData The associated validation data for this discount registration.
-    modifier validDiscount(bytes32 discountKey, bytes calldata validationData) {
+    /// @dev Validates that that the registrant has not already registered with a discount
+    modifier discountAvailable() {
         if (discountedRegistrants[msg.sender]) revert AlreadyRegisteredWithDiscount(msg.sender);
-        DiscountDetails memory details = discounts[discountKey];
-
-        if (!details.active) revert InactiveDiscount(discountKey);
-
-        IDiscountValidator validator = IDiscountValidator(details.discountValidator);
-        if (!validator.isValidDiscountRegistration(msg.sender, validationData)) {
-            revert InvalidDiscount(discountKey, validationData);
-        }
         _;
     }
 
@@ -459,9 +445,11 @@ contract RegistrarController is Ownable {
     function discountedRegister(RegisterRequest calldata request, bytes32 discountKey, bytes calldata validationData)
         public
         payable
-        validDiscount(discountKey, validationData)
         validRegistration(request)
+        discountAvailable
     {
+        _validateDiscount(discountKey, validationData);
+
         uint256 price = discountedRegisterPrice(request.name, request.duration, discountKey);
 
         _validatePayment(price);
@@ -593,6 +581,18 @@ contract RegistrarController is Ownable {
         active ? activeDiscounts.add(key) : activeDiscounts.remove(key);
     }
 
+    /// Validates that: 
+    ///     1. That the discount is `active`
+    ///     2. That the associated `discountValidator` returns true when `isValidDiscountRegistration` is called.
+    function _validateDiscount(bytes32 discountKey, bytes calldata validationData) internal {
+        DiscountDetails memory details = discounts[discountKey];
+
+        IDiscountValidator validator = IDiscountValidator(details.discountValidator);
+        // if (!validator.validateDiscountRegistration(msg.sender, validationData)) {
+        //     revert InvalidDiscount(discountKey, validationData);
+        // }
+    }
+
     /// @notice Allows anyone to withdraw the eth accumulated on this contract back to the `paymentReceiver`.
     function withdrawETH() public {
         (bool sent,) = payable(paymentReceiver).call{value: (address(this).balance)}("");

src/L2/discounts/AttestationValidator.sol

@@ -6,7 +6,7 @@ import {AttestationVerifier} from "verifications/libraries/AttestationVerifier.s
 import {IAttestationIndexer} from "verifications/interfaces/IAttestationIndexer.sol";
 import {Ownable} from "solady/auth/Ownable.sol";
 
-import {IDiscountValidator} from "src/L2/interface/IDiscountValidator.sol";
+import {DiscountValidator} from "./DiscountValidator.sol";
 import {SybilResistanceVerifier} from "src/lib/SybilResistanceVerifier.sol";
 
 /// @title Discount Validator for: Coinbase Attestation Validator
@@ -17,7 +17,7 @@ import {SybilResistanceVerifier} from "src/lib/SybilResistanceVerifier.sol";
 ///         https://github.com/coinbase/verifications
 ///
 /// @author Coinbase (https://github.com/base-org/usernames)
-contract AttestationValidator is Ownable, AttestationAccessControl, IDiscountValidator {
+contract AttestationValidator is Ownable, AttestationAccessControl, DiscountValidator {
     /// @dev The attestation service signer.
     address signer;
 
@@ -52,7 +52,7 @@ contract AttestationValidator is Ownable, AttestationAccessControl, IDiscountVal
     /// @param validationData opaque bytes for performing the validation.
     ///
     /// @return `true` if the validation data provided is determined to be valid for the specified claimer, else `false`.
-    function isValidDiscountRegistration(address claimer, bytes calldata validationData) external view returns (bool) {
+    function isValidDiscountRegistration(address claimer, bytes calldata validationData) public override view returns (bool) {
         AttestationVerifier.verifyAttestation(_getAttestation(claimer, schemaID));
 
         return SybilResistanceVerifier.verifySignature(signer, claimer, validationData);

src/L2/discounts/CBIdDiscountValidator.sol

@@ -4,14 +4,14 @@ pragma solidity ^0.8.23;
 import {MerkleProofLib} from "lib/solady/src/utils/MerkleProofLib.sol";
 import {Ownable} from "solady/auth/Ownable.sol";
 
-import {IDiscountValidator} from "src/L2/interface/IDiscountValidator.sol";
+import {DiscountValidator} from "./DiscountValidator.sol";
 
 /// @title Discount Validator for: cb.id
 ///
 /// @notice Implements a simple Merkle Proof validator checking that the claimant is in the stored merkle tree.
 ///
 /// @author Coinbase
-contract CBIdDiscountValidator is Ownable, IDiscountValidator {
+contract CBIdDiscountValidator is Ownable, DiscountValidator {
     /// @dev merkle tree root
     bytes32 public root;
 
@@ -35,7 +35,7 @@ contract CBIdDiscountValidator is Ownable, IDiscountValidator {
     /// @param validationData opaque bytes for performing the validation.
     ///
     /// @return `true` if the validation data provided is determined to be valid for the specified claimer, else `false`.
-    function isValidDiscountRegistration(address claimer, bytes calldata validationData) external view returns (bool) {
+    function isValidDiscountRegistration(address claimer, bytes calldata validationData) public view override returns (bool) {
         (bytes32[] memory proof) = abi.decode(validationData, (bytes32[]));
         return MerkleProofLib.verify(proof, root, keccak256(abi.encodePacked(claimer)));
     }

src/L2/discounts/CouponDiscountValidator.sol

@@ -4,14 +4,14 @@ pragma solidity ^0.8.23;
 import {ECDSA} from "solady/utils/ECDSA.sol";
 import {Ownable} from "solady/auth/Ownable.sol";
 
-import {IDiscountValidator} from "src/L2/interface/IDiscountValidator.sol";
+import {DiscountValidator} from "./DiscountValidator.sol";
 
 /// @title Discount Validator for: Coupons
 ///
 /// @notice Implements a signature-based discount validation on unique coupon codes.
 ///
 /// @author Coinbase (https://github.com/base-org/usernames)
-contract CouponDiscountValidator is Ownable, IDiscountValidator {
+contract CouponDiscountValidator is Ownable, DiscountValidator {
     /// @notice Thrown when setting a critical address to the zero-address.
     error NoZeroAddress();
 
@@ -46,7 +46,7 @@ contract CouponDiscountValidator is Ownable, IDiscountValidator {
     /// @param validationData opaque bytes for performing the validation.
     ///
     /// @return `true` if the validation data provided is determined to be valid for the specified claimer, else `false`.
-    function isValidDiscountRegistration(address claimer, bytes calldata validationData) external view returns (bool) {
+    function isValidDiscountRegistration(address claimer, bytes calldata validationData) public view override returns (bool) {
         (uint64 expiry, bytes32 uuid, bytes memory sig) = abi.decode(validationData, (uint64, bytes32, bytes));
         if (expiry < block.timestamp) revert SignatureExpired();
 

src/L2/interface/IDiscountValidator.sol → src/L2/discounts/DiscountValidator.sol

@@ -5,8 +5,15 @@ pragma solidity ^0.8.23;
 ///
 /// @notice Common interface which all Discount Validators must implement.
 ///         The logic specific to each integration must ultimately be consumable as the `bool` returned from
-///         `isValidDiscountRegistration`.
-interface IDiscountValidator {
+///         `isValidDiscountRegistration`. Then, upon registration, the integrator should call `validateDiscountRegistration`
+///         allowing discount-specific state writes to occur. 
+abstract contract DiscountValidator {
+    /// @notice Thrown when the specified discount's validator does not accept the discount for the sender.
+    ///
+    /// @param claimer The discount being accessed.
+    /// @param data The associated `validationData`.
+    error InvalidDiscount(address claimer, bytes data);
+
     /// @notice Required implementation for compatibility with IDiscountValidator.
     ///
     /// @dev Each implementation will have unique requirements for the data necessary to perform
@@ -17,5 +24,9 @@ interface IDiscountValidator {
     /// @param validationData opaque bytes for performing the validation.
     ///
     /// @return `true` if the validation data provided is determined to be valid for the specified claimer, else `false`.
-    function isValidDiscountRegistration(address claimer, bytes calldata validationData) external returns (bool);
+    function isValidDiscountRegistration(address claimer, bytes calldata validationData) public virtual view returns (bool);
+
+    function validateDiscountRegistration(address claimer, bytes calldata validationData) external virtual view {
+        if(!isValidDiscountRegistration(claimer, validationData)) revert InvalidDiscount(claimer, validationData);
+    }
 }

src/L2/discounts/ERC1155DiscountValidator.sol

@@ -3,15 +3,15 @@ pragma solidity ^0.8.23;
 
 import {IERC1155} from "@openzeppelin/contracts/token/ERC1155/IERC1155.sol";
 
-import {IDiscountValidator} from "src/L2/interface/IDiscountValidator.sol";
+import {DiscountValidator} from "./DiscountValidator.sol";
 
 /// @title Discount Validator for: ERC1155 NFTs
 ///
 /// @notice Implements an NFT ownership validator for a stored `tokenId` for an ERC1155 `token` contract.
 ///         This discount validator should only be used for "soul-bound" tokens.
 ///
 /// @author Coinbase (https://github.com/base-org/usernames)
-contract ERC1155DiscountValidator is IDiscountValidator {
+contract ERC1155DiscountValidator is DiscountValidator {
     /// @notice The ERC1155 token contract to validate against.
     IERC1155 immutable token;
 
@@ -35,7 +35,7 @@ contract ERC1155DiscountValidator is IDiscountValidator {
     /// @param claimer the discount claimer's address.
     ///
     /// @return `true` if the validation data provided is determined to be valid for the specified claimer, else `false`.
-    function isValidDiscountRegistration(address claimer, bytes calldata) external view returns (bool) {
+    function isValidDiscountRegistration(address claimer, bytes calldata) public view override returns (bool) {
         return (token.balanceOf(claimer, tokenId) > 0);
     }
 }

src/L2/discounts/ERC721DiscountValidator.sol

@@ -3,15 +3,15 @@ pragma solidity ^0.8.23;
 
 import {IERC721} from "@openzeppelin/contracts/token/ERC721/IERC721.sol";
 
-import {IDiscountValidator} from "src/L2/interface/IDiscountValidator.sol";
+import {DiscountValidator} from "./DiscountValidator.sol";
 
 /// @title Discount Validator for: ERC721 NFTs
 ///
 /// @notice Implements an NFT ownership validator for a ERC721 `token` contract.
 ///         This discount validator should only be used for "soul-bound" tokens.
 ///
 /// @author Coinbase (https://github.com/base-org/usernames)
-contract ERC721DiscountValidator is IDiscountValidator {
+contract ERC721DiscountValidator is DiscountValidator {
     /// @notice The ERC721 token contract to validate against.
     IERC721 immutable token;
 
@@ -30,7 +30,7 @@ contract ERC721DiscountValidator is IDiscountValidator {
     /// @param claimer the discount claimer's address.
     ///
     /// @return `true` if the validation data provided is determined to be valid for the specified claimer, else `false`.
-    function isValidDiscountRegistration(address claimer, bytes calldata) external view returns (bool) {
+    function isValidDiscountRegistration(address claimer, bytes calldata) public view override returns (bool) {
         return (token.balanceOf(claimer) > 0);
     }
 }

src/L2/discounts/TalentProtocolDiscountValidator.sol

@@ -4,15 +4,15 @@ pragma solidity ^0.8.23;
 import {IERC721} from "@openzeppelin/contracts/token/ERC721/IERC721.sol";
 import {Ownable} from "solady/auth/Ownable.sol";
 
-import {IDiscountValidator} from "src/L2/interface/IDiscountValidator.sol";
+import {DiscountValidator} from "./DiscountValidator.sol";
 
 /// @title Discount Validator for: Talent Protocol Builder Score
 ///
 /// @notice Enables discounts for users who have minted their Talent Protocol Builder Score .
 ///         Discounts are granted based on the claimer having some score higher than this contract's `threshold`.
 ///
 /// @author Coinbase (https://github.com/base-org/usernames)
-contract TalentProtocolDiscountValidator is IDiscountValidator, Ownable {
+contract TalentProtocolDiscountValidator is DiscountValidator, Ownable {
     /// @notice Thrown when setting a critical address to the zero-address.
     error NoZeroAddress();
 
@@ -54,7 +54,7 @@ contract TalentProtocolDiscountValidator is IDiscountValidator, Ownable {
     /// @param claimer the discount claimer's address.
     ///
     /// @return `true` if the validation data provided is determined to be valid for the specified claimer, else `false`.
-    function isValidDiscountRegistration(address claimer, bytes calldata) external view returns (bool) {
+    function isValidDiscountRegistration(address claimer, bytes calldata) public view override returns (bool) {
         return (talentProtocol.getScoreByAddress(claimer) >= threshold);
     }
 }