Erc20Token

// SPDX-License-Identifier: MIT



pragma solidity 0.8.30;

abstract contract Context {
    function _msgSender() internal view virtual returns (address) {
        return msg.sender;
    }
}

interface IERC20 {
    function totalSupply() external view returns (uint256);
    function balanceOf(address account) external view returns (uint256);
    function transfer(address recipient, uint256 amount) external returns (bool);
    function allowance(address owner, address spender) external view returns (uint256);
    function approve(address spender, uint256 amount) external returns (bool);
    function transferFrom(address sender, address recipient, uint256 amount) external returns (bool);
    event Transfer(address indexed from, address indexed to, uint256 value);
    event Approval(address indexed owner, address indexed spender, uint256 value);
}

library SafeMath {
    function add(uint256 a, uint256 b) internal pure returns (uint256) {
        uint256 c = a + b;
        require(c >= a, "SafeMath: addition overflow");
        return c;
    }

    function sub(uint256 a, uint256 b) internal pure returns (uint256) {
        return sub(a, b, "SafeMath: subtraction overflow");
    }

    function sub(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
        require(b <= a, errorMessage);
        uint256 c = a - b;
        return c;
    }

    function mul(uint256 a, uint256 b) internal pure returns (uint256) {
        if (a == 0) {
            return 0;
        }
        uint256 c = a * b;
        require(c / a == b, "SafeMath: multiplication overflow");
        return c;
    }

    function div(uint256 a, uint256 b) internal pure returns (uint256) {
        return div(a, b, "SafeMath: division by zero");
    }

    function div(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
        require(b > 0, errorMessage);
        uint256 c = a / b;
        return c;
    }

}

contract Ownable is Context {
    address private _owner;
    event OwnershipTransferred(address indexed previousOwner, address indexed newOwner);

    constructor (address firstOwner) {
        _owner = firstOwner;
        emit OwnershipTransferred(address(0), firstOwner);
    }

    function owner() public view returns (address) {
        return _owner;
    }

    modifier onlyOwner() {
        require(_owner == _msgSender(), "Ownable: caller is not the owner");
        _;
    }

    function renounceOwnership() public virtual onlyOwner {
        emit OwnershipTransferred(_owner, address(0));
        _owner = address(0);
    }

}

interface IERC5267 {
    function eip712Domain()
        external
        view
        returns (
            bytes1 fields,
            string memory name,
            string memory version,
            uint256 chainId,
            address verifyingContract,
            bytes32 salt,
            uint256[] memory extensions
        );
}

library StorageSlot {
    struct StringSlot {
        string value;
    }

    function getStringSlot(string storage store) internal pure returns (StringSlot storage r) {
        assembly ("memory-safe") {
            r.slot := store.slot
        }
    }
}

type ShortString is bytes32;
library ShortStrings {
    // Used as an identifier for strings longer than 31 bytes.
    bytes32 private constant FALLBACK_SENTINEL = 0x00000000000000000000000000000000000000000000000000000000000000FF;

    error StringTooLong(string str);
    error InvalidShortString();

    function toShortString(string memory str) internal pure returns (ShortString) {
        bytes memory bstr = bytes(str);
        if (bstr.length > 0x1f) {
            revert StringTooLong(str);
        }
        return ShortString.wrap(bytes32(uint256(bytes32(bstr)) | bstr.length));
    }

    function toString(ShortString sstr) internal pure returns (string memory) {
        uint256 len = byteLength(sstr);
        string memory str = new string(0x20);
        assembly ("memory-safe") {
            mstore(str, len)
            mstore(add(str, 0x20), sstr)
        }
        return str;
    }

    function byteLength(ShortString sstr) internal pure returns (uint256) {
        uint256 result = uint256(ShortString.unwrap(sstr)) & 0xFF;
        if (result > 0x1f) {
            revert InvalidShortString();
        }
        return result;
    }

    function toShortStringWithFallback(string memory value, string storage store) internal returns (ShortString) {
        if (bytes(value).length < 0x20) {
            return toShortString(value);
        } else {
            StorageSlot.getStringSlot(store).value = value;
            return ShortString.wrap(FALLBACK_SENTINEL);
        }
    }

    function toStringWithFallback(ShortString value, string storage store) internal pure returns (string memory) {
        if (ShortString.unwrap(value) != FALLBACK_SENTINEL) {
            return toString(value);
        } else {
            return store;
        }
    }
}

library MessageHashUtils {
    function toTypedDataHash(bytes32 domainSeparator, bytes32 structHash) internal pure returns (bytes32 digest) {
        assembly ("memory-safe") {
            let ptr := mload(0x40)
            mstore(ptr, hex"19_01")
            mstore(add(ptr, 0x02), domainSeparator)
            mstore(add(ptr, 0x22), structHash)
            digest := keccak256(ptr, 0x42)
        }
    }
}

interface IERC20Permit {
    function permit(
        address owner,
        address spender,
        uint256 value,
        uint256 deadline,
        uint8 v,
        bytes32 r,
        bytes32 s
    ) external;
    function nonces(address owner) external view returns (uint256);
    function DOMAIN_SEPARATOR() external view returns (bytes32);
}

abstract contract EIP712 is IERC5267 {
    using ShortStrings for *;

    bytes32 private constant TYPE_HASH =
        keccak256("EIP712Domain(string name,string version,uint256 chainId,address verifyingContract)");

    bytes32 private immutable _cachedDomainSeparator;
    uint256 private immutable _cachedChainId;
    address private immutable _cachedThis;

    bytes32 private immutable _hashedName;
    bytes32 private immutable _hashedVersion;

    ShortString private immutable _name;
    ShortString private immutable _version;

    string private _nameFallback;

    string private _versionFallback;


    constructor(string memory name, string memory version) {
        _name = name.toShortStringWithFallback(_nameFallback);
        _version = version.toShortStringWithFallback(_versionFallback);
        _hashedName = keccak256(bytes(name));
        _hashedVersion = keccak256(bytes(version));

        _cachedChainId = block.chainid;
        _cachedDomainSeparator = _buildDomainSeparator();
        _cachedThis = address(this);
    }

    function _domainSeparatorV4() internal view returns (bytes32) {
        if (address(this) == _cachedThis && block.chainid == _cachedChainId) {
            return _cachedDomainSeparator;
        } else {
            return _buildDomainSeparator();
        }
    }

    function _buildDomainSeparator() private view returns (bytes32) {
        return keccak256(abi.encode(TYPE_HASH, _hashedName, _hashedVersion, block.chainid, address(this)));
    }

    function _hashTypedDataV4(bytes32 structHash) internal view virtual returns (bytes32) {
        return MessageHashUtils.toTypedDataHash(_domainSeparatorV4(), structHash);
    }

    function eip712Domain()
        public
        view
        virtual
        returns (
            bytes1 fields,
            string memory name,
            string memory version,
            uint256 chainId,
            address verifyingContract,
            bytes32 salt,
            uint256[] memory extensions
        )
    {
        return (
            hex"0f", // 01111
            _EIP712Name(),
            _EIP712Version(),
            block.chainid,
            address(this),
            bytes32(0),
            new uint256[](0)
        );
    }

    function _EIP712Name() internal view returns (string memory) {
        return _name.toStringWithFallback(_nameFallback);
    }

    function _EIP712Version() internal view returns (string memory) {
        return _version.toStringWithFallback(_versionFallback);
    }
}

abstract contract Nonces{
    mapping(address account => uint256) private _nonces;

    function nonces(address owner) public view virtual returns (uint256) {
        return _nonces[owner];
    }

    function _useNonce(address owner) internal virtual returns (uint256) {
        unchecked {
            return _nonces[owner]++;
        }
    }
}



contract Erc20Token is Context, IERC20, Ownable, Nonces, EIP712, IERC20Permit
{
    using SafeMath for uint256;

    error ECDSAInvalidSignature();
    error ECDSAInvalidSignatureS(bytes32 s);

    bytes32 private constant PERMIT_TYPEHASH =
        keccak256("Permit(address owner,address spender,uint256 value,uint256 nonce,uint256 deadline)");

    error ERC2612ExpiredSignature(uint256 deadline);
    error ERC2612InvalidSigner(address signer, address owner);

    mapping (address => uint256) private _balances;
    mapping (address => mapping (address => uint256)) private _allowances;
    mapping (address => bool) private maxTxExemptAddresses;

    uint256 private _numOfTransfersMade = 0;
    uint256 private _numOfTxToLiftLimit = 30;

    uint8 private constant _decimals = 18;
    uint256 private _tTotal;
    string private _name;
    string private _symbol;
    uint256 public _maxTxAmount;
    bool public tradingOpen;

    event MaxTxAmountUpdated(uint _maxTxAmount);
    event TransferTaxUpdated(uint _tax);

    string private _metadataURL;
    string private _imageURL;

    error MaxTxAmountExceeded(uint256 limit, uint256 attemptedTransferAmount, address from, address to);

    constructor (
        string memory name_,
        string memory symbol_,
        uint256 initialSupply_,
        address owner_,
        string memory metadataUrl_,
        string memory imageUrl_
    ) Ownable(owner_) EIP712(name_, "1") {
        _name = name_;
        _symbol = symbol_;
        _metadataURL = metadataUrl_;
        _imageURL = imageUrl_;
        _tTotal = initialSupply_ * 10**_decimals;

        _maxTxAmount = _tTotal / 100;
        emit MaxTxAmountUpdated(_maxTxAmount);

        _balances[owner()] = initialSupply_ * (10**_decimals);
        emit Transfer(address(0), owner(), initialSupply_ * (10**_decimals));
    }

    function name() public view returns (string memory) {
        return _name;
    }

    function symbol() public view returns (string memory) {
        return _symbol;
    }

    function imageURL() public view virtual returns (string memory) {
        return _imageURL;
    }

    function imageURI() public view virtual returns (string memory) {
        return _imageURL;
    }

    function tokenURI() public view returns (string memory) {
        return _metadataURL;
    }

    function contractURI() public view returns (string memory) {
        return _metadataURL;
    }

    function metadataURI() public view returns (string memory) {
        return _metadataURL;
    }

    

    function decimals() public pure returns (uint8) {
        return _decimals;
    }

    function totalSupply() public view override returns (uint256) {
        return _tTotal;
    }

    function balanceOf(address account) public view override returns (uint256) {
        return _balances[account];
    }

    function transfer(address recipient, uint256 amount) public override returns (bool) {
        _transfer(_msgSender(), recipient, amount);
        return true;
    }

    function allowance(address owner, address spender) public view override returns (uint256) {
        return _allowances[owner][spender];
    }

    function approve(address spender, uint256 amount) public override returns (bool) {
        _approve(_msgSender(), spender, amount);
        return true;
    }

    function transferFrom(address sender, address recipient, uint256 amount) public override returns (bool) {
        _transfer(sender, recipient, amount);
        _approve(sender, _msgSender(), _allowances[sender][_msgSender()].sub(amount, "ERC20: transfer amount exceeds allowance"));
        return true;
    }

    function _approve(address owner, address spender, uint256 amount) private {
        require(owner != address(0), "ERC20: approve from the zero address");
        require(spender != address(0), "ERC20: approve to the zero address");
        _allowances[owner][spender] = amount;
        emit Approval(owner, spender, amount);
    }

    function _transfer(address from, address to, uint256 amount) private {
        require(from != address(0), "ERC20: transfer from the zero address");
        require(to != address(0), "ERC20: transfer to the zero address");
        require(amount > 0, "Transfer amount must be greater than zero");

        _balances[from]=_balances[from].sub(amount);
        _balances[to]=_balances[to].add(amount);
        emit Transfer(from, to, amount);
    }

    function _isMaxTxExempt(address addr) private view returns (bool) {
        if(addr == owner()) return true;
        if(maxTxExemptAddresses[addr]) return true;
        return false;
    }

    function removeLimits() external onlyOwner {
        _maxTxAmount = _tTotal;
        emit MaxTxAmountUpdated(_maxTxAmount);
    }

    function permit(
        address owner,
        address spender,
        uint256 value,
        uint256 deadline,
        uint8 v,
        bytes32 r,
        bytes32 s
    ) public virtual {
        if (block.timestamp > deadline) {
            revert ERC2612ExpiredSignature(deadline);
        }

        bytes32 structHash = keccak256(abi.encode(PERMIT_TYPEHASH, owner, spender, value, _useNonce(owner), deadline));

        bytes32 hash = _hashTypedDataV4(structHash);

        //ECDSA recover
        if (uint256(s) > 0x7FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF5D576E7357A4501DDFE92F46681B20A0) {
            revert ECDSAInvalidSignatureS(s);
        }
        address signer = ecrecover(hash, v, r, s);
        if (signer == address(0)) {
            revert ECDSAInvalidSignature();
        }
        
        if (signer != owner) {
            revert ERC2612InvalidSigner(signer, owner);
        }

        _approve(owner, spender, value);
    }

    function nonces(address owner) public view virtual override(IERC20Permit, Nonces) returns (uint256) {
        return super.nonces(owner);
    }

    function DOMAIN_SEPARATOR() external view returns (bytes32) {
        return _domainSeparatorV4();
    }
}