Create Custom Contracts

// SDPX-License-Identifier: MIT
pragma solidity 0.8.9;

import { IMessageProxyForSchain } from "./IMessageProxyForSchain.sol";

contract SendNumber {

  /// @notice lastNumber is the last value recieved via IMA. This is for testing purposes
  uint256 public lastNumber;

  /// @notice the dstChainHash is the keccak256 hash of the SKALE Chain name i.e keccak256(abi.encodePacked("elated-tan-skat"))
  bytes32 public dstChainHash;

  /// @notice the dstContractAddr is the address of the receiving contract on the other chain
  address public dstContractAddr;

  /// @notice messageProxy is a predeployed contract on all SKALE Chains
  IMessageProxyForSchain public messageProxy = IMessageProxyForSchain(0xd2AAa00100000000000000000000000000000000);

  event NumberReceived(uint256 indexed number, address indexed sender);

  constructor(
    bytes32 _dstChainHash,
    address _dstContractAddr
  ) {
    dstChainHash = _dstChainHash;
    dstContractAddr = _dstContractAddr;
  }

  function sendNumberToChain(uint256 number) external {
    /// this is how you post a message to IMA
    messageProxy.postOutgoingMessage(
      dstChainHash,
      dstContractAddr,
      abi.encode(number)
    );
  }

  /// @notice this is how you recieve a message from IMA
  function postMessage(
    bytes32 schainHash,
    address sender,
    bytes calldata data
  ) external {
    if (schainHash != dstChainHash) revert("Invalid Chain Hash");
    (uint256 number) = abi.decode(data, (uint256));
    lastNumber = number;
    emit NumberReceived(number, sender);
  }
}