add contract and tests

packages/contracts-periphery/contracts/universal/op-nft/OptimistAllowlist.sol

+// SPDX-License-Identifier: MIT
+pragma solidity 0.8.15;
+
+import { Semver } from "@eth-optimism/contracts-bedrock/contracts/universal/Semver.sol";
+import { AttestationStation } from "./AttestationStation.sol";
+
+/**
+ * @title  OptimistAllowlist
+ * @notice Source of truth for whether an address is able to mint an Optimist NFT.
+           isAllowedToMint function checks various signals to return boolean value for whether an
+           address is eligible or not.
+ */
+contract OptimistAllowlist is Semver {
+    /**
+     * @notice Attestation key used by the AllowlistAttestor to manually add addresses to the
+     *         allowlist.
+     */
+    bytes32 public constant OPTIMIST_CAN_MINT_ATTESTATION_KEY = bytes32("optimist.can-mint");
+
+    /**
+     * @notice Attestation key used by Coinbase to issue attestations for Quest participants.
+     */
+    bytes32 public constant COINBASE_QUEST_ELIGIBLE_ATTESTATION_KEY =
+        bytes32("coinbase.quest-eligible");
+
+    /**
+     * @notice Attestation key the OptimistInviter needs to issue to allow an address to mint.
+     */
+    bytes32 public constant OPTIMIST_CAN_MINT_FROM_INVITE_ATTESTATION_KEY =
+        bytes32("optimist.can-mint-from-invite");
+
+    /**
+     * @notice Address of the AttestationStation contract.
+     */
+    AttestationStation public immutable ATTESTATION_STATION;
+
+    /**
+     * @notice Attestor that issues 'optimist.can-mint' attestations.
+     */
+    address public immutable ALLOWLIST_ATTESTOR;
+
+    /**
+     * @notice Attestor that issues 'coinbase.quest-eligible' attestations.
+     */
+    address public immutable COINBASE_QUEST_ATTESTOR;
+
+    /**
+     * @notice Address of OptimistInviter contract that issues 'optimist.can-mint-from-invite'
+     *         attestations.
+     */
+    address public immutable OPTIMIST_INVITER;
+
+    /**
+     * @custom:semver 1.0.0
+     *
+     * @param _attestationStation    Address of the AttestationStation contract.
+     * @param _allowlistAttestor     Address of the allowlist attestor.
+     * @param _coinbaseQuestAttestor Address of the Coinbase Quest attestor.
+     * @param _optimistInviter       Address of the OptimistInviter contract.
+     */
+    constructor(
+        AttestationStation _attestationStation,
+        address _allowlistAttestor,
+        address _coinbaseQuestAttestor,
+        address _optimistInviter
+    ) Semver(1, 0, 0) {
+        ATTESTATION_STATION = _attestationStation;
+        ALLOWLIST_ATTESTOR = _allowlistAttestor;
+        COINBASE_QUEST_ATTESTOR = _coinbaseQuestAttestor;
+        OPTIMIST_INVITER = _optimistInviter;
+    }
+
+    /**
+     * @notice Checks whether an address has a valid 'optimist.can-mint' attestation from the
+     *         allowlist attestor.
+     *
+     * @param _claimer Address to check.
+     *
+     * @return Whether or not the address has a valid attestation.
+     */
+    function _hasAttestationFromAllowlistAttestor(address _claimer) internal view returns (bool) {
+        // Expected attestation value is bytes32("true"), but we consider any non-zero value
+        // to be truthy.
+        return
+            ATTESTATION_STATION
+                .attestations(ALLOWLIST_ATTESTOR, _claimer, OPTIMIST_CAN_MINT_ATTESTATION_KEY)
+                .length > 0;
+    }
+
+    /**
+     * @notice Checks whether an address has a valid attestation from the Coinbase attestor.
+     *
+     * @param _claimer Address to check.
+     *
+     * @return Whether or not the address has a valid attestation.
+     */
+    function _hasAttestationFromCoinbaseQuestAttestor(address _claimer)
+        internal
+        view
+        returns (bool)
+    {
+        // Expected attestation value is bytes32("true"), but we consider any non-zero value
+        // to be truthy.
+        return
+            ATTESTATION_STATION
+                .attestations(
+                    COINBASE_QUEST_ATTESTOR,
+                    _claimer,
+                    COINBASE_QUEST_ELIGIBLE_ATTESTATION_KEY
+                )
+                .length > 0;
+    }
+
+    /**
+     * @notice Checks whether an address has a valid attestation from the OptimistInviter contract.
+     *
+     * @param _claimer Address to check.
+     *
+     * @return Whether or not the address has a valid attestation.
+     */
+    function _hasAttestationFromOptimistInviter(address _claimer) internal view returns (bool) {
+        // Expected attestation value is the inviter's address, but we just check that it's set.
+        return
+            ATTESTATION_STATION
+                .attestations(
+                    OPTIMIST_INVITER,
+                    _claimer,
+                    OPTIMIST_CAN_MINT_FROM_INVITE_ATTESTATION_KEY
+                )
+                .length > 0;
+    }
+
+    /**
+     * @notice Checks whether a given address is allowed to mint the Optimist NFT yet. Since the
+     *         Optimist NFT will also be used as part of the Citizens House, mints are currently
+     *         restricted. Eventually anyone will be able to mint.
+     *
+     *         Currently, address is allowed to mint if it satisfies any of the following:
+     *         1) Has a valid 'optimist.can-mint' attestation from the allowlist attestor.
+     *         2) Has a valid 'coinbase.quest-eligible' attestation from Coinbase Quest attestor
+     *         3) Has a valid 'optimist.can-mint-from-invite' attestation from the OptimistInviter
+     *            contract.
+     *
+     * @return Whether or not the address is allowed to mint yet.
+     */
+    function isAllowedToMint(address _claimer) public view returns (bool) {
+        return
+            _hasAttestationFromAllowlistAttestor(_claimer) ||
+            _hasAttestationFromCoinbaseQuestAttestor(_claimer) ||
+            _hasAttestationFromOptimistInviter(_claimer);
+    }
+}