BasicTokenSender.sol

// SPDX-License-Identifier: MIT
pragma solidity 0.8.19;

import {LinkTokenInterface} from "@chainlink/contracts/src/v0.8/interfaces/LinkTokenInterface.sol";
import {IERC20} from "@chainlink/contracts-ccip/src/v0.8/vendor/openzeppelin-solidity/v4.8.0/token/ERC20/IERC20.sol";
import {IRouterClient} from "@chainlink/contracts-ccip/src/v0.8/ccip/interfaces/IRouterClient.sol";
import {Client} from "@chainlink/contracts-ccip/src/v0.8/ccip/libraries/Client.sol";
import {Withdraw} from "./utils/Withdraw.sol";

/**
 * THIS IS AN EXAMPLE CONTRACT THAT USES HARDCODED VALUES FOR CLARITY.
 * THIS IS AN EXAMPLE CONTRACT THAT USES UN-AUDITED CODE.
 * DO NOT USE THIS CODE IN PRODUCTION.
 */
contract BasicTokenSender is Withdraw {
    enum PayFeesIn {
        Native,
        LINK
    }

    address immutable i_router;
    address immutable i_link;
    uint16 immutable i_maxTokensLength;

    event MessageSent(bytes32 messageId);

    constructor(address router, address link) {
        i_router = router;
        i_link = link;
        i_maxTokensLength = 5;
        LinkTokenInterface(i_link).approve(i_router, type(uint256).max);
    }

    receive() external payable {}

    function getSupportedTokens(
        uint64 chainSelector
    ) external view returns (address[] memory tokens) {
        tokens = IRouterClient(i_router).getSupportedTokens(chainSelector);
    }

    function send(
        uint64 destinationChainSelector,
        address receiver,
        Client.EVMTokenAmount[] memory tokensToSendDetails,
        PayFeesIn payFeesIn
    ) external {
        uint256 length = tokensToSendDetails.length;
        require(
            length <= i_maxTokensLength,
            "Maximum 5 different tokens can be sent per CCIP Message"
        );

        for (uint256 i = 0; i < length; ) {
            IERC20(tokensToSendDetails[i].token).transferFrom(
                msg.sender,
                address(this),
                tokensToSendDetails[i].amount
            );
            IERC20(tokensToSendDetails[i].token).approve(
                i_router,
                tokensToSendDetails[i].amount
            );

            unchecked {
                ++i;
            }
        }

        Client.EVM2AnyMessage memory message = Client.EVM2AnyMessage({
            receiver: abi.encode(receiver),
            data: "",
            tokenAmounts: tokensToSendDetails,
            extraArgs: "",
            feeToken: payFeesIn == PayFeesIn.LINK ? i_link : address(0)
        });

        uint256 fee = IRouterClient(i_router).getFee(
            destinationChainSelector,
            message
        );

        bytes32 messageId;

        if (payFeesIn == PayFeesIn.LINK) {
            // LinkTokenInterface(i_link).approve(i_router, fee);
            messageId = IRouterClient(i_router).ccipSend(
                destinationChainSelector,
                message
            );
        } else {
            messageId = IRouterClient(i_router).ccipSend{value: fee}(
                destinationChainSelector,
                message
            );
        }

        emit MessageSent(messageId);
    }
}