wip: advertiser sig add

remappings.txt

@@ -1,5 +1,5 @@
 ds-test/=lib/forge-std/lib/ds-test/src/
 forge-std/=lib/forge-std/src/
 interfaces/=lib/interfaces/
-openzeppelin-contracts/=lib/openzeppelin-contracts/
+@openzeppelin/=lib/openzeppelin-contracts/
 solmate/=lib/solmate/src/

src/crosschainAdvertiser/l1/Forwarder.sol

@@ -32,7 +32,9 @@ contract AdForwarder {
         // The domain the campain contract is deployed
         uint32 destinationDomain,
         // The relayerFee that needs to be paid to the connext relayer
-        uint256 relayerFee
+        uint256 relayerFee,
+        // Signature of the advertiser
+        bytes32 signature
     ) external payable {
         (bool success, bytes memory result) = target.call{value: msg.value - relayerFee}(_calldata);
         require(success, "tx failed");
@@ -52,7 +54,7 @@ contract AdForwarder {
             msg.sender, // _delegate: address that can revert or forceLocal on destination
             0, // _amount: 0 because no funds are being transferred
             0, // _slippage: can be anything between 0-10000 because no funds are being transferred
-            abi.encode(adHash, advertiser) // _callData: the encoded calldata to send
+            abi.encode(adHash, advertiser, signature) // _callData: the encoded calldata to send
         );
 
         // getting selector from calldata

src/crosschainAdvertiser/l2/L2Campaign.sol

@@ -1,6 +1,7 @@
 pragma solidity ^0.8.15;
 
 import {getAdHash} from "../AdHash.sol";
+import { ECDSA } from "@openzeppelin/contracts/utils/cryptography/ECDSA.sol";
 
 contract L2Campaign {
     // The amount an advertiser will receive for a successful ad
@@ -18,9 +19,14 @@ contract L2Campaign {
     // Deadline after which the owner can withdraw the funds
     uint256 public immutable deadline;
 
+    mapping (address advertiser => bytes32 agreement) public agreements;
+
     mapping(bytes32 => address) claims;
+
     uint public claimableRewards;
 
+    using ECDSA for bytes32;
+
     constructor(
         uint256 _commission,
         address _target,
@@ -71,14 +77,37 @@ contract L2Campaign {
         uint32 _origin,
         bytes memory _callData
     ) external onlySource(_originSender, _origin) returns (bytes memory) {
-        (bytes32 adHash, address advertiser) = abi.decode(
+        (bytes32 adHash, address advertiser, bytes32 signature) = abi.decode(
             _callData,
-            (bytes32, address)
+            (bytes32, address, bytes32)
+        );
+        // TODO: Will relayer keep retrying if this fails?
+        // What if tx will never succeed?
+        require(
+            agreements[advertiser] == signature,
+            "Advertiser did not apply for this campaign"
         );
         claims[adHash] = advertiser;
         claimableRewards += commission;
     }
 
+    function applyTo(bytes memory signature) external payable {
+        require(
+            msg.value >= commission,
+            "Payment cannot be less than commission"
+        );
+        // TODO: return extra funds
+        require(
+            agreements[msg.sender] == 0x0,
+            "Advertiser already applied for this campaign"
+        );
+        require(
+            keccak256(abi.encodePacked(target, msg.sender)).toEthSignedMessageHash().recover(signature) == msg.sender,
+            "Signature is not valid"
+        );
+        agreements[msg.sender] = abi.encodePacked(signature);
+    }
+
     function withdraw() external onlyOwner onlyAfter(deadline) {
         require(
             address(this).balance > claimableRewards,