posm: add staking through subscribers (#229)

* compiling

* compiling, gas snaps added

* add unit tests for PositionConfigLibrary

* subscriber tests

* pr comments

* use gas limit calcualtor

* test return data

* use solidity

* comments

* natspec & more tests

* payable

* pr comments

* pr comments

* inheritdoc

.forge-snapshots/PositionManager_burn_empty.snap

@@ -1 +1 @@
-47059
+47186

.forge-snapshots/PositionManager_burn_empty_native.snap

@@ -1 +1 @@
-46876
+47004

.forge-snapshots/PositionManager_burn_nonEmpty.snap

@@ -1 +1 @@
-129852
+130136

.forge-snapshots/PositionManager_burn_nonEmpty_native.snap

@@ -1 +1 @@
-122773
+123058

.forge-snapshots/PositionManager_collect.snap

@@ -1 +1 @@
-149984
+150257

.forge-snapshots/PositionManager_collect_native.snap

@@ -1 +1 @@
-141136
+141409

.forge-snapshots/PositionManager_collect_sameRange.snap

@@ -1 +1 @@
-149984
+150257

.forge-snapshots/PositionManager_decreaseLiquidity.snap

@@ -1 +1 @@
-115527
+115800

.forge-snapshots/PositionManager_decreaseLiquidity_native.snap

@@ -1 +1 @@
-108384
+108602

.forge-snapshots/PositionManager_decrease_burnEmpty.snap

@@ -1 +1 @@
-133885
+134196

.forge-snapshots/PositionManager_decrease_burnEmpty_native.snap

@@ -1 +1 @@
-126624
+126935

.forge-snapshots/PositionManager_decrease_sameRange_allLiquidity.snap

@@ -1 +1 @@
-128243
+128516

.forge-snapshots/PositionManager_increaseLiquidity_erc20_withClose.snap

@@ -1 +1 @@
-152100
+152363

.forge-snapshots/PositionManager_increaseLiquidity_erc20_withSettlePair.snap

@@ -1 +1 @@
-151341
+151604

.forge-snapshots/PositionManager_increaseLiquidity_native.snap

@@ -1 +1 @@
-133900
+134163

.forge-snapshots/PositionManager_increase_autocompoundExactUnclaimedFees.snap

@@ -1 +1 @@
-130065
+130328

.forge-snapshots/PositionManager_increase_autocompoundExcessFeesCredit.snap

@@ -1 +1 @@
-170759
+171022

.forge-snapshots/PositionManager_increase_autocompound_clearExcess.snap

@@ -1 +1 @@
-140581
+140866

.forge-snapshots/PositionManager_mint_native.snap

@@ -1 +1 @@
-336663
+336841

.forge-snapshots/PositionManager_mint_nativeWithSweep_withClose.snap

@@ -1 +1 @@
-345169
+345347

.forge-snapshots/PositionManager_mint_nativeWithSweep_withSettlePair.snap

@@ -1 +1 @@
-344710
+344888

.forge-snapshots/PositionManager_mint_onSameTickLower.snap

@@ -1 +1 @@
-314645
+314823

.forge-snapshots/PositionManager_mint_onSameTickUpper.snap

@@ -1 +1 @@
-315287
+315465

.forge-snapshots/PositionManager_mint_sameRange.snap

@@ -1 +1 @@
-240869
+241047

.forge-snapshots/PositionManager_mint_settleWithBalance_sweep.snap

@@ -1 +1 @@
-370969
+371147

.forge-snapshots/PositionManager_mint_warmedPool_differentRange.snap

@@ -1 +1 @@
-320663
+320841

.forge-snapshots/PositionManager_mint_withClose.snap

@@ -1 +1 @@
-371963
+372141

.forge-snapshots/PositionManager_mint_withSettlePair.snap

@@ -1 +1 @@
-371342
+371520

.forge-snapshots/PositionManager_multicall_initialize_mint.snap

@@ -1 +1 @@
-416316
+416538

foundry.toml

@@ -11,4 +11,7 @@ fuzz_runs = 10_000
 [profile.ci]
 fuzz_runs = 100_000
 
+[profile.gas]
+gas_limit=30_000_000
+
 # See more config options https://github.com/foundry-rs/foundry/tree/master/config

src/PositionManager.sol

@@ -24,7 +24,9 @@ import {DeltaResolver} from "./base/DeltaResolver.sol";
 import {PositionConfig, PositionConfigLibrary} from "./libraries/PositionConfig.sol";
 import {BaseActionsRouter} from "./base/BaseActionsRouter.sol";
 import {Actions} from "./libraries/Actions.sol";
+import {Notifier} from "./base/Notifier.sol";
 import {CalldataDecoder} from "./libraries/CalldataDecoder.sol";
+import {INotifier} from "./interfaces/INotifier.sol";
 import {Permit2Forwarder} from "./base/Permit2Forwarder.sol";
 import {SlippageCheckLibrary} from "./libraries/SlippageCheck.sol";
 
@@ -36,12 +38,13 @@ contract PositionManager is
     DeltaResolver,
     ReentrancyLock,
     BaseActionsRouter,
+    Notifier,
     Permit2Forwarder
 {
     using SafeTransferLib for *;
     using CurrencyLibrary for Currency;
     using PoolIdLibrary for PoolKey;
-    using PositionConfigLibrary for PositionConfig;
+    using PositionConfigLibrary for *;
     using StateLibrary for IPoolManager;
     using TransientStateLibrary for IPoolManager;
     using SafeCast for uint256;
@@ -51,20 +54,39 @@ contract PositionManager is
     /// @dev The ID of the next token that will be minted. Skips 0
     uint256 public nextTokenId = 1;
 
-    /// @inheritdoc IPositionManager
-    mapping(uint256 tokenId => bytes32 configId) public positionConfigs;
+    mapping(uint256 tokenId => bytes32 config) private positionConfigs;
 
     constructor(IPoolManager _poolManager, IAllowanceTransfer _permit2)
         BaseActionsRouter(_poolManager)
         Permit2Forwarder(_permit2)
         ERC721Permit("Uniswap V4 Positions NFT", "UNI-V4-POSM", "1")
     {}
 
+    /// @notice Reverts if the deadline has passed
+    /// @param deadline The timestamp at which the call is no longer valid, passed in by the caller
     modifier checkDeadline(uint256 deadline) {
         if (block.timestamp > deadline) revert DeadlinePassed();
         _;
     }
 
+    /// @notice Reverts if the caller is not the owner or approved for the ERC721 token
+    /// @param caller The address of the caller
+    /// @param tokenId the unique identifier of the ERC721 token
+    /// @dev either msg.sender or _msgSender() is passed in as the caller
+    /// _msgSender() should ONLY be used if this is being called from within the unlockCallback
+    modifier onlyIfApproved(address caller, uint256 tokenId) {
+        if (!_isApprovedOrOwner(caller, tokenId)) revert NotApproved(caller);
+        _;
+    }
+
+    /// @notice Reverts if the hash of the config does not equal the saved hash
+    /// @param tokenId the unique identifier of the ERC721 token
+    /// @param config the PositionConfig to check against
+    modifier onlyValidConfig(uint256 tokenId, PositionConfig calldata config) {
+        if (positionConfigs.getConfigId(tokenId) != config.toId()) revert IncorrectPositionConfigForTokenId(tokenId);
+        _;
+    }
+
     /// @param unlockData is an encoding of actions, params, and currencies
     /// @param deadline is the timestamp at which the unlockData will no longer be valid
     function modifyLiquidities(bytes calldata unlockData, uint256 deadline)
@@ -76,6 +98,29 @@ contract PositionManager is
         _executeActions(unlockData);
     }
 
+    /// @inheritdoc INotifier
+    function subscribe(uint256 tokenId, PositionConfig calldata config, address subscriber)
+        external
+        payable
+        onlyIfApproved(msg.sender, tokenId)
+        onlyValidConfig(tokenId, config)
+    {
+        // call to _subscribe will revert if the user already has a sub
+        positionConfigs.setSubscribe(tokenId);
+        _subscribe(tokenId, config, subscriber);
+    }
+
+    /// @inheritdoc INotifier
+    function unsubscribe(uint256 tokenId, PositionConfig calldata config)
+        external
+        payable
+        onlyIfApproved(msg.sender, tokenId)
+        onlyValidConfig(tokenId, config)
+    {
+        positionConfigs.setUnsubscribe(tokenId);
+        _unsubscribe(tokenId, config);
+    }
+
     function _handleAction(uint256 action, bytes calldata params) internal virtual override {
         if (action == Actions.INCREASE_LIQUIDITY) {
             (
@@ -149,8 +194,7 @@ contract PositionManager is
         uint128 amount0Max,
         uint128 amount1Max,
         bytes calldata hookData
-    ) internal {
-        if (positionConfigs[tokenId] != config.toId()) revert IncorrectPositionConfigForTokenId(tokenId);
+    ) internal onlyValidConfig(tokenId, config) {
         // Note: The tokenId is used as the salt for this position, so every minted position has unique storage in the pool manager.
         BalanceDelta liquidityDelta = _modifyLiquidity(config, liquidity.toInt256(), bytes32(tokenId), hookData);
         liquidityDelta.validateMaxInNegative(amount0Max, amount1Max);
@@ -164,10 +208,7 @@ contract PositionManager is
         uint128 amount0Min,
         uint128 amount1Min,
         bytes calldata hookData
-    ) internal {
-        if (!_isApprovedOrOwner(_msgSender(), tokenId)) revert NotApproved(_msgSender());
-        if (positionConfigs[tokenId] != config.toId()) revert IncorrectPositionConfigForTokenId(tokenId);
-
+    ) internal onlyIfApproved(_msgSender(), tokenId) onlyValidConfig(tokenId, config) {
         // Note: the tokenId is used as the salt.
         BalanceDelta liquidityDelta = _modifyLiquidity(config, -(liquidity.toInt256()), bytes32(tokenId), hookData);
         liquidityDelta.validateMinOut(amount0Min, amount1Min);
@@ -192,7 +233,7 @@ contract PositionManager is
         // _beforeModify is not called here because the tokenId is newly minted
         BalanceDelta liquidityDelta = _modifyLiquidity(config, liquidity.toInt256(), bytes32(tokenId), hookData);
         liquidityDelta.validateMaxIn(amount0Max, amount1Max);
-        positionConfigs[tokenId] = config.toId();
+        positionConfigs.setConfigId(tokenId, config);
     }
 
     function _close(Currency currency) internal {
@@ -231,9 +272,7 @@ contract PositionManager is
         uint128 amount0Min,
         uint128 amount1Min,
         bytes calldata hookData
-    ) internal {
-        if (!_isApprovedOrOwner(_msgSender(), tokenId)) revert NotApproved(_msgSender());
-        if (positionConfigs[tokenId] != config.toId()) revert IncorrectPositionConfigForTokenId(tokenId);
+    ) internal onlyIfApproved(_msgSender(), tokenId) onlyValidConfig(tokenId, config) {
         uint256 liquidity = uint256(_getPositionLiquidity(config, tokenId));
 
         BalanceDelta liquidityDelta;
@@ -264,6 +303,10 @@ contract PositionManager is
             }),
             hookData
         );
+
+        if (positionConfigs.hasSubscriber(uint256(salt))) {
+            _notifyModifyLiquidity(uint256(salt), config, liquidityChange);
+        }
     }
 
     function _getPositionLiquidity(PositionConfig calldata config, uint256 tokenId)
@@ -291,4 +334,20 @@ contract PositionManager is
             permit2.transferFrom(payer, address(poolManager), uint160(amount), Currency.unwrap(currency));
         }
     }
+
+    /// @dev overrides solmate transferFrom in case a notification to subscribers is needed
+    function transferFrom(address from, address to, uint256 id) public override {
+        super.transferFrom(from, to, id);
+        if (positionConfigs.hasSubscriber(id)) _notifyTransfer(id, from, to);
+    }
+
+    /// @inheritdoc IPositionManager
+    function getPositionConfigId(uint256 tokenId) external view returns (bytes32) {
+        return positionConfigs.getConfigId(tokenId);
+    }
+
+    /// @inheritdoc INotifier
+    function hasSubscriber(uint256 tokenId) external view returns (bool) {
+        return positionConfigs.hasSubscriber(tokenId);
+    }
 }

src/base/Notifier.sol

@@ -0,0 +1,57 @@
+// SPDX-License-Identifier: GPL-3.0-or-later
+pragma solidity ^0.8.24;
+
+import {ISubscriber} from "../interfaces/ISubscriber.sol";
+import {PositionConfig} from "../libraries/PositionConfig.sol";
+import {GasLimitCalculator} from "../libraries/GasLimitCalculator.sol";
+
+import "../interfaces/INotifier.sol";
+
+/// @notice Notifier is used to opt in to sending updates to external contracts about position modifications or transfers
+abstract contract Notifier is INotifier {
+    using GasLimitCalculator for uint256;
+
+    error AlreadySubscribed(address subscriber);
+
+    event Subscribed(uint256 tokenId, address subscriber);
+    event Unsubscribed(uint256 tokenId, address subscriber);
+
+    ISubscriber private constant NO_SUBSCRIBER = ISubscriber(address(0));
+
+    // a percentage of the block.gaslimit denoted in BPS, used as the gas limit for subscriber calls
+    // 100 bps is 1%
+    // at 30M gas, the limit is 300K
+    uint256 private constant BLOCK_LIMIT_BPS = 100;
+
+    mapping(uint256 tokenId => ISubscriber subscriber) public subscriber;
+
+    function _subscribe(uint256 tokenId, PositionConfig memory config, address newSubscriber) internal {
+        ISubscriber _subscriber = subscriber[tokenId];
+
+        if (_subscriber != NO_SUBSCRIBER) revert AlreadySubscribed(address(_subscriber));
+        subscriber[tokenId] = ISubscriber(newSubscriber);
+
+        ISubscriber(newSubscriber).notifySubscribe(tokenId, config);
+        emit Subscribed(tokenId, address(newSubscriber));
+    }
+
+    /// @dev Must always allow a user to unsubscribe. In the case of a malicious subscriber, a user can always unsubscribe safely, ensuring liquidity is always modifiable.
+    function _unsubscribe(uint256 tokenId, PositionConfig memory config) internal {
+        ISubscriber _subscriber = subscriber[tokenId];
+
+        uint256 subscriberGasLimit = BLOCK_LIMIT_BPS.toGasLimit();
+
+        try _subscriber.notifyUnsubscribe{gas: subscriberGasLimit}(tokenId, config) {} catch {}
+
+        delete subscriber[tokenId];
+        emit Unsubscribed(tokenId, address(_subscriber));
+    }
+
+    function _notifyModifyLiquidity(uint256 tokenId, PositionConfig memory config, int256 liquidityChange) internal {
+        subscriber[tokenId].notifyModifyLiquidity(tokenId, config, liquidityChange);
+    }
+
+    function _notifyTransfer(uint256 tokenId, address previousOwner, address newOwner) internal {
+        subscriber[tokenId].notifyTransfer(tokenId, previousOwner, newOwner);
+    }
+}

src/interfaces/IERC721Permit.sol

@@ -21,6 +21,7 @@ interface IERC721Permit {
     /// @param v Must produce valid secp256k1 signature from the holder along with `r` and `s`
     /// @param r Must produce valid secp256k1 signature from the holder along with `v` and `s`
     /// @param s Must produce valid secp256k1 signature from the holder along with `r` and `v`
+    /// @dev payable so it can be multicalled with NATIVE related actions
     function permit(address spender, uint256 tokenId, uint256 deadline, uint256 nonce, uint8 v, bytes32 r, bytes32 s)
         external
         payable;