// SPDX-License-Identifier: LGPL-3.0-or-later

// Vendored from GPv2 contracts v1.1.2, see:
// <https://raw.githubusercontent.com/gnosis/gp-v2-contracts/7fb88982021e9a274d631ffb598694e6d9b30089/src/contracts/libraries/GPv2SafeERC20.sol>
// The following changes were made:
// - Bumped up Solidity version and checked that the assembly is still valid.
// - Use own vendored IERC20 instead of custom implementation.
// - Removed "GPv2" from contract name.
// - Modified revert messages, including length.

pragma solidity ^0.8.10;

import "../interfaces/IERC20.sol";

/// @title Gnosis Protocol v2 Safe ERC20 Transfer Library
/// @author Gnosis Developers
/// @dev Gas-efficient version of Openzeppelin's SafeERC20 contract.
library SafeERC20 {
    /// @dev Wrapper around a call to the ERC20 function `transfer` that reverts
    /// also when the token returns `false`.
    function safeTransfer(
        IERC20 token,
        address to,
        uint256 value
    ) internal {
        bytes4 selector_ = token.transfer.selector;

        // solhint-disable-next-line no-inline-assembly
        assembly {
            let freeMemoryPointer := mload(0x40)
            mstore(freeMemoryPointer, selector_)
            mstore(
                add(freeMemoryPointer, 4),
                and(to, 0xffffffffffffffffffffffffffffffffffffffff)
            )
            mstore(add(freeMemoryPointer, 36), value)

            if iszero(call(gas(), token, 0, freeMemoryPointer, 68, 0, 0)) {
                returndatacopy(0, 0, returndatasize())
                revert(0, returndatasize())
            }
        }

        require(getLastTransferResult(token), "SafeERC20: failed transfer");
    }

    /// @dev Wrapper around a call to the ERC20 function `transferFrom` that
    /// reverts also when the token returns `false`.
    function safeTransferFrom(
        IERC20 token,
        address from,
        address to,
        uint256 value
    ) internal {
        bytes4 selector_ = token.transferFrom.selector;

        // solhint-disable-next-line no-inline-assembly
        assembly {
            let freeMemoryPointer := mload(0x40)
            mstore(freeMemoryPointer, selector_)
            mstore(
                add(freeMemoryPointer, 4),
                and(from, 0xffffffffffffffffffffffffffffffffffffffff)
            )
            mstore(
                add(freeMemoryPointer, 36),
                and(to, 0xffffffffffffffffffffffffffffffffffffffff)
            )
            mstore(add(freeMemoryPointer, 68), value)

            if iszero(call(gas(), token, 0, freeMemoryPointer, 100, 0, 0)) {
                returndatacopy(0, 0, returndatasize())
                revert(0, returndatasize())
            }
        }

        require(getLastTransferResult(token), "SafeERC20: failed transferFrom");
    }

    /// @dev Verifies that the last return was a successful `transfer*` call.
    /// This is done by checking that the return data is either empty, or
    /// is a valid ABI encoded boolean.
    function getLastTransferResult(IERC20 token)
        private
        view
        returns (bool success)
    {
        // NOTE: Inspecting previous return data requires assembly. Note that
        // we write the return data to memory 0 in the case where the return
        // data size is 32, this is OK since the first 64 bytes of memory are
        // reserved by Solidy as a scratch space that can be used within
        // assembly blocks.
        // <https://docs.soliditylang.org/en/v0.8.10/internals/layout_in_memory.html>
        // solhint-disable-next-line no-inline-assembly
        assembly {
            /// @dev Revert with an ABI encoded Solidity error with a message
            /// that fits into 32-bytes.
            ///
            /// An ABI encoded Solidity error has the following memory layout:
            ///
            /// ------------+----------------------------------
            ///  byte range | value
            /// ------------+----------------------------------
            ///  0x00..0x04 |        selector("Error(string)")
            ///  0x04..0x24 |      string offset (always 0x20)
            ///  0x24..0x44 |                    string length
            ///  0x44..0x64 | string value, padded to 32-bytes
            function revertWithMessage(length, message) {
                mstore(0x00, "\x08\xc3\x79\xa0")
                mstore(0x04, 0x20)
                mstore(0x24, length)
                mstore(0x44, message)
                revert(0x00, 0x64)
            }

            switch returndatasize()
            // Non-standard ERC20 transfer without return.
            case 0 {
                // NOTE: When the return data size is 0, verify that there
                // is code at the address. This is done in order to maintain
                // compatibility with Solidity calling conventions.
                // <https://docs.soliditylang.org/en/v0.8.10/control-structures.html#external-function-calls>
                if iszero(extcodesize(token)) {
                    revertWithMessage(25, "SafeERC20: not a contract")
                }

                success := 1
            }
            // Standard ERC20 transfer returning boolean success value.
            case 32 {
                returndatacopy(0, 0, returndatasize())

                // NOTE: For ABI encoding v1, any non-zero value is accepted
                // as `true` for a boolean. In order to stay compatible with
                // OpenZeppelin's `SafeERC20` library which is known to work
                // with the existing ERC20 implementation we care about,
                // make sure we return success for any non-zero return value
                // from the `transfer*` call.
                success := iszero(iszero(mload(0)))
            }
            default {
                revertWithMessage(30, "SafeERC20: bad transfer result")
            }
        }
    }
}