// SPDX-License-Identifier: UNLICENSED
// solhint-disable-next-line
pragma solidity 0.8.4;
import {NullAddrIsNotAnERC20Token, NullAddrIsNotAValidSpender, NoTransferToNullAddress, InvalidAmount, NativeValueWithERC, NativeAssetTransferFailed} from "../errors/GenericErrors.sol";
import "@openzeppelin/contracts/token/ERC20/utils/SafeERC20.sol";
import "@openzeppelin/contracts/token/ERC20/IERC20.sol";

/// @title LibAsset
/// @author Connext <support@connext.network>
/// @notice This library contains helpers for dealing with onchain transfers
///         of assets, including accounting for the native asset `assetId`
///         conventions and any noncompliant ERC20 transfers
library LibAsset {
    uint256 private constant MAX_INT = type(uint256).max;

    address internal constant NULL_ADDRESS =
        0x0000000000000000000000000000000000000000; //address(0)

    /// @dev All native assets use the empty address for their asset id
    ///      by convention

    address internal constant NATIVE_ASSETID = NULL_ADDRESS; //address(0)

    /// @notice Gets the balance of the inheriting contract for the given asset
    /// @param assetId The asset identifier to get the balance of
    /// @return Balance held by contracts using this library
    function getOwnBalance(address assetId) internal view returns (uint256) {
        return
            assetId == NATIVE_ASSETID
                ? address(this).balance
                : IERC20(assetId).balanceOf(address(this));
    }

    /// @notice Transfers ether from the inheriting contract to a given
    ///         recipient
    /// @param recipient Address to send ether to
    /// @param amount Amount to send to given recipient
    function transferNativeAsset(address payable recipient, uint256 amount)
        private
    {
        if (recipient == NULL_ADDRESS) revert NoTransferToNullAddress();
        // solhint-disable-next-line avoid-low-level-calls
        (bool success, ) = recipient.call{value: amount}("");
        if (!success) revert NativeAssetTransferFailed();
    }

    /// @notice Gives MAX approval for another address to spend tokens
    /// @param assetId Token address to transfer
    /// @param spender Address to give spend approval to
    /// @param amount Amount to approve for spending
    function maxApproveERC20(
        IERC20 assetId,
        address spender,
        uint256 amount
    ) internal {
        if (address(assetId) == NATIVE_ASSETID) return;
        if (spender == NULL_ADDRESS) revert NullAddrIsNotAValidSpender();
        uint256 allowance = assetId.allowance(address(this), spender);
        if (allowance < amount)
            SafeERC20.safeApprove(IERC20(assetId), spender, MAX_INT);
    }

    /// @notice Transfers tokens from the inheriting contract to a given
    ///         recipient
    /// @param assetId Token address to transfer
    /// @param recipient Address to send token to
    /// @param amount Amount to send to given recipient
    function transferERC20(
        address assetId,
        address recipient,
        uint256 amount
    ) private {
        if (isNativeAsset(assetId)) revert NullAddrIsNotAnERC20Token();
        SafeERC20.safeTransfer(IERC20(assetId), recipient, amount);
    }

    /// @notice Transfers tokens from a sender to a given recipient
    /// @param assetId Token address to transfer
    /// @param from Address of sender/owner
    /// @param to Address of recipient/spender
    /// @param amount Amount to transfer from owner to spender
    function transferFromERC20(
        address assetId,
        address from,
        address to,
        uint256 amount
    ) internal {
        if (assetId == NATIVE_ASSETID) revert NullAddrIsNotAnERC20Token();
        if (to == NULL_ADDRESS) revert NoTransferToNullAddress();
        SafeERC20.safeTransferFrom(IERC20(assetId), from, to, amount);
    }

    /// @notice Deposits an asset into the contract and performs checks to avoid NativeValueWithERC
    /// @param tokenId Token to deposit
    /// @param amount Amount to deposit
    /// @param isNative Wether the token is native or ERC20
    function depositAsset(
        address tokenId,
        uint256 amount,
        bool isNative
    ) internal {
        if (amount == 0) revert InvalidAmount();
        if (isNative) {
            if (msg.value != amount) revert InvalidAmount();
        } else {
            if (msg.value != 0) revert NativeValueWithERC();
            uint256 _fromTokenBalance = LibAsset.getOwnBalance(tokenId);
            LibAsset.transferFromERC20(
                tokenId,
                msg.sender,
                address(this),
                amount
            );
            if (LibAsset.getOwnBalance(tokenId) - _fromTokenBalance != amount)
                revert InvalidAmount();
        }
    }

    /// @notice Overload for depositAsset(address tokenId, uint256 amount, bool isNative)
    /// @param tokenId Token to deposit
    /// @param amount Amount to deposit
    function depositAsset(address tokenId, uint256 amount) internal {
        return depositAsset(tokenId, amount, tokenId == NATIVE_ASSETID);
    }

    /// @notice Determines whether the given assetId is the native asset
    /// @param assetId The asset identifier to evaluate
    /// @return Boolean indicating if the asset is the native asset
    function isNativeAsset(address assetId) internal pure returns (bool) {
        return assetId == NATIVE_ASSETID;
    }

    /// @notice Wrapper function to transfer a given asset (native or erc20) to
    ///         some recipient. Should handle all non-compliant return value
    ///         tokens as well by using the SafeERC20 contract by open zeppelin.
    /// @param assetId Asset id for transfer (address(0) for native asset,
    ///                token address for erc20s)
    /// @param recipient Address to send asset to
    /// @param amount Amount to send to given recipient
    function transferAsset(
        address assetId,
        address payable recipient,
        uint256 amount
    ) internal {
        (assetId == NATIVE_ASSETID)
            ? transferNativeAsset(recipient, amount)
            : transferERC20(assetId, recipient, amount);
    }

    /// @dev Checks whether the given address is a contract and contains code
    function isContract(address _contractAddr) internal view returns (bool) {
        uint256 size;
        // solhint-disable-next-line no-inline-assembly
        assembly {
            size := extcodesize(_contractAddr)
        }
        return size > 0;
    }
}