feat: Otterspace badges voting strategy

.gitmodules

@@ -25,3 +25,9 @@
 	path = lib/openzeppelin-contracts-upgradeable
 	url = https://github.com/openzeppelin/openzeppelin-contracts-upgradeable
 	branch = v4.8.0
+[submodule "lib/otterspace-contracts"]
+	path = lib/otterspace-contracts
+	url = https://github.com/otterspace-xyz/otterspace-contracts
+[submodule "lib/ERC4973"]
+	path = lib/ERC4973
+	url = https://github.com/otterspace-xyz/ERC4973

remappings.txt

@@ -5,3 +5,5 @@ forge-gas-snapshot/=lib/forge-gas-snapshot/src
 @prb/test/=lib/prb-test/src/
 @zodiac/=lib/zodiac/contracts/
 @gnosis.pm/safe-contracts=lib/safe-contracts
+@otterspace/contracts/=lib/otterspace-contracts/src
+ERC4973/=lib/ERC4973/src/

src/voting-strategies/OtterspaceBadgesVotingStrategy.sol

@@ -0,0 +1,61 @@
+// SPDX-License-Identifier: MIT
+
+pragma solidity ^0.8.18;
+
+// import { Badges } from "@otterspace/contracts/Badges.sol";
+import { IVotingStrategy } from "../interfaces/IVotingStrategy.sol";
+
+interface IBadges {
+    function ownerOf(uint256 tokenId) external view returns (address);
+}
+
+/// @title Otterspace Badge Voting Strategy
+/// @notice Allows Otterspace Badges to be used for voting power.
+contract OtterspaceBadgesVotingStrategy is IVotingStrategy {
+    error InvalidBadge();
+
+    /// @notice The address of the Otterspace Badges Contract.
+    address public badgesRegistry;
+
+    /// @dev Data stored as parameters for each Badge.
+    struct Badge {
+        // spec of the badge.
+        string specUri;
+        // The voting power granted to badges of this spec.
+        uint96 vp;
+    }
+
+    constructor(address BadgesRegistry) {
+        badgesRegistry = BadgesRegistry;
+    }
+
+    /// @notice Returns the voting power of an address.
+    /// @param voter The address to get the voting power of.
+    /// @param params Parameter array containing the encoded whitelist of addresses and their voting power.
+    ///               The array should be an ABI encoded array of Member structs.
+    /// @param userParams Parameter array containing an array of indices of
+    /// @return votingPower The voting power of the address if it exists in the whitelist, otherwise reverts.
+    function getVotingPower(
+        uint32 /* blockNumber */,
+        address voter,
+        bytes calldata params,
+        bytes calldata userParams
+    ) external view override returns (uint256 votingPower) {
+        Badge[] memory badges = abi.decode(params, (Badge[]));
+        uint8[] memory userBadgeIndices = abi.decode(userParams, (uint8[]));
+
+        uint256 vp;
+        for (uint8 i = 0; i < userBadgeIndices.length; i++) {
+            uint256 tokenId = uint256(getBadgeIdHash(voter, badges[userBadgeIndices[i]].specUri));
+            if (IBadges(badgesRegistry).ownerOf(tokenId) != voter) revert InvalidBadge();
+            vp += badges[userBadgeIndices[i]].vp;
+        }
+
+        return vp;
+    }
+
+    /// @dev Generates the unique ID of a badge for a given address and spec.
+    function getBadgeIdHash(address _to, string memory _uri) internal pure returns (bytes32) {
+        return keccak256(abi.encode(_to, _uri));
+    }
+}