feat: store membership details

contracts/IPriceCalculator.sol

@@ -5,4 +5,4 @@ interface IPriceCalculator {
    /// Returns the token and price to pay in `token` for some `_rateLimit`
    /// @param _rateLimit the rate limit the user wants to acquire
    function calculate(uint _rateLimit) external view returns (address, uint);
-}
+}

contracts/Membership.sol

@@ -12,85 +12,208 @@ error TokenMismatch();
 
 error InvalidRateLimit();
 error ExceedMaxRateLimitPerEpoch();
+error NotInGracePeriod(uint256 membershipMapIdx);
+error NotHolder(uint256 membershipMapIdx);
 
 contract Membership {
     using SafeERC20 for IERC20;
 
-    IPriceCalculator public priceCalculator;
+    // TODO START - add owned setters to all these variables
 
-    uint public maxTotalRateLimitPerEpoch;
+    IPriceCalculator public priceCalculator;
+    uint256 public maxTotalRateLimitPerEpoch;
     uint16 public maxRateLimitPerMembership;
     uint16 public minRateLimitPerMembership;
 
-    enum MembershipStatus { Undefined, Active, GracePeriod, Expired, ErasedAwaitsWithdrawal, Erased }
+    uint256 public expirationTerm;
+    uint256 public gracePeriod;
+
+    // TODO END
+
+    enum MembershipStatus {
+        NonExistent,
+        Active,
+        GracePeriod,
+        Expired,
+        ErasedAwaitsWithdrawal,
+        Erased
+    }
 
     uint public totalRateLimitPerEpoch;
 
+    mapping(uint256 => MembershipDetails) public memberships;
+    uint256 public oldestMembership = 1;
+    uint256 public newestMembership = 1;
+
+    struct MembershipDetails {
+        address holder;
+        // TODO: should we store the commitment?
+        uint256 expirationDate;
+        address token;
+        uint256 amount;
+    }
+
+    event ExpiredMembership(uint256 membershipMapIndex, address holder); // TODO: should it contain the commitment?
+    event MembershipExtended(
+        uint256 membershipMapIndex,
+        uint256 newExpirationDate
+    ); // TODO: should it contain the commitment?
+
     function __Membership_init(
         address _priceCalculator,
         uint _maxTotalRateLimitPerEpoch,
         uint16 _maxRateLimitPerMembership,
-        uint16 _minRateLimitPerMembership
+        uint16 _minRateLimitPerMembership,
+        uint _expirationTerm,
+        uint _gracePeriod
     ) internal {
         priceCalculator = IPriceCalculator(_priceCalculator);
         maxTotalRateLimitPerEpoch = _maxTotalRateLimitPerEpoch;
         maxRateLimitPerMembership = _maxRateLimitPerMembership;
         minRateLimitPerMembership = _minRateLimitPerMembership;
+        expirationTerm = _expirationTerm;
+        gracePeriod = _gracePeriod;
     }
 
-    function transferMembershipFees(address _from, uint _rateLimit) internal {
-        (address token, uint price) = priceCalculator.calculate(_rateLimit);
-        if (token == address(0)) {
-            if (msg.value != price) revert IncorrectAmount();
+    function registerMembership(
+        address _sender,
+        uint256[] memory commitments,
+        uint _rateLimit
+    ) internal {
+        // TODO: for each commitment?
+        (address token, uint amount) = priceCalculator.calculate(_rateLimit);
+        acquireRateLimit(_sender, commitments, _rateLimit, token, amount);
+        transferMembershipFees(
+            _sender,
+            token,
+            amount * _rateLimit * commitments.length
+        );
+    }
+
+    function transferMembershipFees(
+        address _from,
+        address _token,
+        uint _amount
+    ) internal {
+        if (_token == address(0)) {
+            if (msg.value != _amount) revert IncorrectAmount();
         } else {
             if (msg.value != 0) revert OnlyTokensAccepted();
-            IERC20(token).safeTransferFrom(_from, address(this), price);
+            IERC20(_token).safeTransferFrom(_from, address(this), _amount);
         }
     }
 
-    function acquireRateLimit(uint256[] memory commitments, uint _rateLimit) internal {
+    function acquireRateLimit(
+        address _sender,
+        uint256[] memory _commitments,
+        uint256 _rateLimit,
+        address _token,
+        uint256 _amount
+    ) internal {
+        // TODO: for each commitment?
         if (
             _rateLimit < minRateLimitPerMembership ||
             _rateLimit > maxRateLimitPerMembership
         ) revert InvalidRateLimit();
 
         uint newTotalRateLimitPerEpoch = totalRateLimitPerEpoch + _rateLimit;
-        if (newTotalRateLimitPerEpoch > maxTotalRateLimitPerEpoch) revert ExceedMaxRateLimitPerEpoch();
 
-        // TODO: store _rateLimit
-        // TODO:
-        // Epoch length 	epoch 	10 	minutes
-        // Membership expiration term 	T 	180 	days
-        // Membership grace period 	G 	30 	days
+        if (newTotalRateLimitPerEpoch > maxTotalRateLimitPerEpoch) {
+            // Determine if there are any available spot in the membership map
+            // by looking at the oldest membership. If it's expired, we can use it
+            MembershipDetails storage oldestMembershipDetails = memberships[
+                oldestMembership
+            ];
+
+            if (isExpired(oldestMembershipDetails.expirationDate)) {
+                emit ExpiredMembership(
+                    oldestMembership,
+                    memberships[oldestMembership].holder
+                );
+                deleteOldestMembership();
+                // TODO: move balance from expired to the current holder
+            } else {
+                revert ExceedMaxRateLimitPerEpoch();
+            }
+        }
+
+        newestMembership += 1;
+        memberships[newestMembership] = MembershipDetails({
+            holder: _sender,
+            expirationDate: block.timestamp + expirationTerm,
+            token: _token,
+            amount: _amount
+        });
     }
 
-    mapping (uint256 => TODO) memberships;
-    
-    uint256 private oldest = 1;
-    uint256 private newest = 1;
+    function extendMembership(
+        address _sender,
+        uint256[] memory membershipMapIdx
+    ) public {
+        for (uint256 i = 0; i < membershipMapIdx.length; i++) {
+            uint256 currentMembershipMapIdx = membershipMapIdx[i];
 
-    // TODO - use a struct to store the membership details: commitment, date, status
-    // TODO - keep track of balances, use msg.sender?
+            MembershipDetails storage mdetails = memberships[
+                currentMembershipMapIdx
+            ];
 
-    function pushMembership(TODO data) internal {
-        newest += 1;
-        memberships[newest] = data;
+            if (!_isGracePeriod(mdetails.expirationDate))
+                revert NotInGracePeriod(currentMembershipMapIdx);
+
+            if (_sender != mdetails.holder)
+                revert NotHolder(currentMembershipMapIdx);
+
+            uint256 newExpirationDate = block.timestamp + expirationTerm;
+
+            // TODO: remove current membership
+            // TODO: add membership at the end (since it will be the newest)
+
+            emit MembershipExtended(currentMembershipMapIdx, newExpirationDate);
+        }
     }
 
-    function oldestMembership() public TODO  {
-        return memberships[oldest];
+    function _isExpired(uint256 expirationDate) internal view returns (bool) {
+        return expirationDate + gracePeriod > block.timestamp;
     }
 
-    function popOldestMembership() public returns (uint256) {
-        TODO data;
-        require(newest > oldest);
-        data = memberships[oldest];
-        delete memberships[oldest];
-        oldest += 1;
-        return data;
+    function isExpired(uint256 membershipMapIdx) public view returns (bool) {
+        return _isExpired(memberships[membershipMapIdx].expirationDate);
     }
 
-    function length() public view returns (uint256) {
-        return newest - oldest;
+    function _isGracePeriod(
+        uint256 expirationDate
+    ) internal view returns (bool) {
+        return
+            block.timestamp >= expirationDate &&
+            block.timestamp <= expirationDate + gracePeriod;
+    }
+
+    function isGracePeriod(
+        uint256 membershipMapIdx
+    ) public view returns (bool) {
+        uint256 expirationDate = memberships[membershipMapIdx].expirationDate;
+        return _isGracePeriod(expirationDate);
+    }
+
+    function withdraw() public {}
+
+    // TODO - keep track of balances, use msg.sender
+
+    function getOldestMembership()
+        public
+        view
+        returns (MembershipDetails memory)
+    {
+        return memberships[oldestMembership];
+    }
+
+    function deleteOldestMembership() internal {
+        require(newestMembership > oldestMembership);
+        delete memberships[oldestMembership];
+        oldestMembership += 1;
+    }
+
+    function getMembershipLength() public view returns (uint256) {
+        return newestMembership - oldestMembership;
     }
 }

contracts/WakuRlnRegistry.sol

@@ -83,8 +83,7 @@ contract WakuRlnRegistry is OwnableUpgradeable, UUPSUpgradeable, Membership {
     function register(uint16 storageIndex, uint256[] calldata commitments) external onlyValidStorageIndex(storageIndex) {
         // TODO: modify function to receive the ratelimit to buy
         uint _rateLimit = 4;
-        acquireRateLimit(commitments, _rateLimit);
-        transferMembershipFees(_msgSender(), _rateLimit * commitments.length);
+        registerMembership(_msgSender(), commitments, _rateLimit);
         WakuRln(storages[storageIndex]).register(commitments);
     }
 
@@ -95,8 +94,7 @@ contract WakuRlnRegistry is OwnableUpgradeable, UUPSUpgradeable, Membership {
 
         // TODO: modify function to receive the number of messages
         uint _rateLimit = 4;
-        acquireRateLimit(commitments, _rateLimit);
-        transferMembershipFees(_msgSender(), _rateLimit);
+        registerMembership(_msgSender(), commitments, _rateLimit);
 
         WakuRln(storages[storageIndex]).register(commitments);
     }