APE Price: $1.46 (+3.48%)

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Contract Name:
APE404

Contract Source Code:

File 1 of 1 : APE404

// SPDX-License-Identifier: MIT

/* 

Bored Ape404 Yacht Club

https://x.com/ape404yachtclub

https://t.me/APE404YachtClub
*/

pragma solidity ^0.8.20;

interface Callable {
	function tokenCallback(address _from, uint256 _tokens, bytes calldata _data) external returns (bool);
}

interface ERC20Interface {
	function balanceOf(address) external view returns (uint256);
	function allowance(address, address) external view returns (uint256);
	function transfer(address, uint256) external returns (bool);
	function transferFrom(address, address, uint256) external returns (bool);
}


pragma solidity ^0.8.20;

/**
 * @dev Standard signed math utilities missing in the Solidity language.
 */
library SignedMath {
    /**
     * @dev Returns the largest of two signed numbers.
     */
    function max(int256 a, int256 b) internal pure returns (int256) {
        return a > b ? a : b;
    }

    /**
     * @dev Returns the smallest of two signed numbers.
     */
    function min(int256 a, int256 b) internal pure returns (int256) {
        return a < b ? a : b;
    }

    /**
     * @dev Returns the average of two signed numbers without overflow.
     * The result is rounded towards zero.
     */
    function average(int256 a, int256 b) internal pure returns (int256) {
        // Formula from the book "Hacker's Delight"
        int256 x = (a & b) + ((a ^ b) >> 1);
        return x + (int256(uint256(x) >> 255) & (a ^ b));
    }

    /**
     * @dev Returns the absolute unsigned value of a signed value.
     */
    function abs(int256 n) internal pure returns (uint256) {
        unchecked {
            // must be unchecked in order to support `n = type(int256).min`
            return uint256(n >= 0 ? n : -n);
        }
    }
}


/**
 * @dev Standard math utilities missing in the Solidity language.
 */
library Math {
    /**
     * @dev Muldiv operation overflow.
     */
    error MathOverflowedMulDiv();

    enum Rounding {
        Floor, // Toward negative infinity
        Ceil, // Toward positive infinity
        Trunc, // Toward zero
        Expand // Away from zero
    }

    /**
     * @dev Returns the addition of two unsigned integers, with an overflow flag.
     */
    function tryAdd(uint256 a, uint256 b) internal pure returns (bool, uint256) {
        unchecked {
            uint256 c = a + b;
            if (c < a) return (false, 0);
            return (true, c);
        }
    }

    /**
     * @dev Returns the subtraction of two unsigned integers, with an overflow flag.
     */
    function trySub(uint256 a, uint256 b) internal pure returns (bool, uint256) {
        unchecked {
            if (b > a) return (false, 0);
            return (true, a - b);
        }
    }

    /**
     * @dev Returns the multiplication of two unsigned integers, with an overflow flag.
     */
    function tryMul(uint256 a, uint256 b) internal pure returns (bool, uint256) {
        unchecked {
            // Gas optimization: this is cheaper than requiring 'a' not being zero, but the
            // benefit is lost if 'b' is also tested.
            // See: https://github.com/OpenZeppelin/openzeppelin-contracts/pull/522
            if (a == 0) return (true, 0);
            uint256 c = a * b;
            if (c / a != b) return (false, 0);
            return (true, c);
        }
    }

    /**
     * @dev Returns the division of two unsigned integers, with a division by zero flag.
     */
    function tryDiv(uint256 a, uint256 b) internal pure returns (bool, uint256) {
        unchecked {
            if (b == 0) return (false, 0);
            return (true, a / b);
        }
    }

    /**
     * @dev Returns the remainder of dividing two unsigned integers, with a division by zero flag.
     */
    function tryMod(uint256 a, uint256 b) internal pure returns (bool, uint256) {
        unchecked {
            if (b == 0) return (false, 0);
            return (true, a % b);
        }
    }

    /**
     * @dev Returns the largest of two numbers.
     */
    function max(uint256 a, uint256 b) internal pure returns (uint256) {
        return a > b ? a : b;
    }

    /**
     * @dev Returns the smallest of two numbers.
     */
    function min(uint256 a, uint256 b) internal pure returns (uint256) {
        return a < b ? a : b;
    }

    /**
     * @dev Returns the average of two numbers. The result is rounded towards
     * zero.
     */
    function average(uint256 a, uint256 b) internal pure returns (uint256) {
        // (a + b) / 2 can overflow.
        return (a & b) + (a ^ b) / 2;
    }

    /**
     * @dev Returns the ceiling of the division of two numbers.
     *
     * This differs from standard division with `/` in that it rounds towards infinity instead
     * of rounding towards zero.
     */
    function ceilDiv(uint256 a, uint256 b) internal pure returns (uint256) {
        if (b == 0) {
            // Guarantee the same behavior as in a regular Solidity division.
            return a / b;
        }

        // (a + b - 1) / b can overflow on addition, so we distribute.
        return a == 0 ? 0 : (a - 1) / b + 1;
    }

    /**
     * @notice Calculates floor(x * y / denominator) with full precision. Throws if result overflows a uint256 or
     * denominator == 0.
     * @dev Original credit to Remco Bloemen under MIT license (https://xn--2-umb.com/21/muldiv) with further edits by
     * Uniswap Labs also under MIT license.
     */
    function mulDiv(uint256 x, uint256 y, uint256 denominator) internal pure returns (uint256 result) {
        unchecked {
            // 512-bit multiply [prod1 prod0] = x * y. Compute the product mod 2^256 and mod 2^256 - 1, then use
            // use the Chinese Remainder Theorem to reconstruct the 512 bit result. The result is stored in two 256
            // variables such that product = prod1 * 2^256 + prod0.
            uint256 prod0 = x * y; // Least significant 256 bits of the product
            uint256 prod1; // Most significant 256 bits of the product
            assembly {
                let mm := mulmod(x, y, not(0))
                prod1 := sub(sub(mm, prod0), lt(mm, prod0))
            }

            // Handle non-overflow cases, 256 by 256 division.
            if (prod1 == 0) {
                // Solidity will revert if denominator == 0, unlike the div opcode on its own.
                // The surrounding unchecked block does not change this fact.
                // See https://docs.soliditylang.org/en/latest/control-structures.html#checked-or-unchecked-arithmetic.
                return prod0 / denominator;
            }

            // Make sure the result is less than 2^256. Also prevents denominator == 0.
            if (denominator <= prod1) {
                revert MathOverflowedMulDiv();
            }

            ///////////////////////////////////////////////
            // 512 by 256 division.
            ///////////////////////////////////////////////

            // Make division exact by subtracting the remainder from [prod1 prod0].
            uint256 remainder;
            assembly {
                // Compute remainder using mulmod.
                remainder := mulmod(x, y, denominator)

                // Subtract 256 bit number from 512 bit number.
                prod1 := sub(prod1, gt(remainder, prod0))
                prod0 := sub(prod0, remainder)
            }

            // Factor powers of two out of denominator and compute largest power of two divisor of denominator.
            // Always >= 1. See https://cs.stackexchange.com/q/138556/92363.

            uint256 twos = denominator & (0 - denominator);
            assembly {
                // Divide denominator by twos.
                denominator := div(denominator, twos)

                // Divide [prod1 prod0] by twos.
                prod0 := div(prod0, twos)

                // Flip twos such that it is 2^256 / twos. If twos is zero, then it becomes one.
                twos := add(div(sub(0, twos), twos), 1)
            }

            // Shift in bits from prod1 into prod0.
            prod0 |= prod1 * twos;

            // Invert denominator mod 2^256. Now that denominator is an odd number, it has an inverse modulo 2^256 such
            // that denominator * inv = 1 mod 2^256. Compute the inverse by starting with a seed that is correct for
            // four bits. That is, denominator * inv = 1 mod 2^4.
            uint256 inverse = (3 * denominator) ^ 2;

            // Use the Newton-Raphson iteration to improve the precision. Thanks to Hensel's lifting lemma, this also
            // works in modular arithmetic, doubling the correct bits in each step.
            inverse *= 2 - denominator * inverse; // inverse mod 2^8
            inverse *= 2 - denominator * inverse; // inverse mod 2^16
            inverse *= 2 - denominator * inverse; // inverse mod 2^32
            inverse *= 2 - denominator * inverse; // inverse mod 2^64
            inverse *= 2 - denominator * inverse; // inverse mod 2^128
            inverse *= 2 - denominator * inverse; // inverse mod 2^256

            // Because the division is now exact we can divide by multiplying with the modular inverse of denominator.
            // This will give us the correct result modulo 2^256. Since the preconditions guarantee that the outcome is
            // less than 2^256, this is the final result. We don't need to compute the high bits of the result and prod1
            // is no longer required.
            result = prod0 * inverse;
            return result;
        }
    }

    /**
     * @notice Calculates x * y / denominator with full precision, following the selected rounding direction.
     */
    function mulDiv(uint256 x, uint256 y, uint256 denominator, Rounding rounding) internal pure returns (uint256) {
        uint256 result = mulDiv(x, y, denominator);
        if (unsignedRoundsUp(rounding) && mulmod(x, y, denominator) > 0) {
            result += 1;
        }
        return result;
    }

    /**
     * @dev Returns the square root of a number. If the number is not a perfect square, the value is rounded
     * towards zero.
     *
     * Inspired by Henry S. Warren, Jr.'s "Hacker's Delight" (Chapter 11).
     */
    function sqrt(uint256 a) internal pure returns (uint256) {
        if (a == 0) {
            return 0;
        }

        // For our first guess, we get the biggest power of 2 which is smaller than the square root of the target.
        //
        // We know that the "msb" (most significant bit) of our target number `a` is a power of 2 such that we have
        // `msb(a) <= a < 2*msb(a)`. This value can be written `msb(a)=2**k` with `k=log2(a)`.
        //
        // This can be rewritten `2**log2(a) <= a < 2**(log2(a) + 1)`
        // → `sqrt(2**k) <= sqrt(a) < sqrt(2**(k+1))`
        // → `2**(k/2) <= sqrt(a) < 2**((k+1)/2) <= 2**(k/2 + 1)`
        //
        // Consequently, `2**(log2(a) / 2)` is a good first approximation of `sqrt(a)` with at least 1 correct bit.
        uint256 result = 1 << (log2(a) >> 1);

        // At this point `result` is an estimation with one bit of precision. We know the true value is a uint128,
        // since it is the square root of a uint256. Newton's method converges quadratically (precision doubles at
        // every iteration). We thus need at most 7 iteration to turn our partial result with one bit of precision
        // into the expected uint128 result.
        unchecked {
            result = (result + a / result) >> 1;
            result = (result + a / result) >> 1;
            result = (result + a / result) >> 1;
            result = (result + a / result) >> 1;
            result = (result + a / result) >> 1;
            result = (result + a / result) >> 1;
            result = (result + a / result) >> 1;
            return min(result, a / result);
        }
    }

    /**
     * @notice Calculates sqrt(a), following the selected rounding direction.
     */
    function sqrt(uint256 a, Rounding rounding) internal pure returns (uint256) {
        unchecked {
            uint256 result = sqrt(a);
            return result + (unsignedRoundsUp(rounding) && result * result < a ? 1 : 0);
        }
    }

    /**
     * @dev Return the log in base 2 of a positive value rounded towards zero.
     * Returns 0 if given 0.
     */
    function log2(uint256 value) internal pure returns (uint256) {
        uint256 result = 0;
        unchecked {
            if (value >> 128 > 0) {
                value >>= 128;
                result += 128;
            }
            if (value >> 64 > 0) {
                value >>= 64;
                result += 64;
            }
            if (value >> 32 > 0) {
                value >>= 32;
                result += 32;
            }
            if (value >> 16 > 0) {
                value >>= 16;
                result += 16;
            }
            if (value >> 8 > 0) {
                value >>= 8;
                result += 8;
            }
            if (value >> 4 > 0) {
                value >>= 4;
                result += 4;
            }
            if (value >> 2 > 0) {
                value >>= 2;
                result += 2;
            }
            if (value >> 1 > 0) {
                result += 1;
            }
        }
        return result;
    }

    /**
     * @dev Return the log in base 2, following the selected rounding direction, of a positive value.
     * Returns 0 if given 0.
     */
    function log2(uint256 value, Rounding rounding) internal pure returns (uint256) {
        unchecked {
            uint256 result = log2(value);
            return result + (unsignedRoundsUp(rounding) && 1 << result < value ? 1 : 0);
        }
    }

    /**
     * @dev Return the log in base 10 of a positive value rounded towards zero.
     * Returns 0 if given 0.
     */
    function log10(uint256 value) internal pure returns (uint256) {
        uint256 result = 0;
        unchecked {
            if (value >= 10 ** 64) {
                value /= 10 ** 64;
                result += 64;
            }
            if (value >= 10 ** 32) {
                value /= 10 ** 32;
                result += 32;
            }
            if (value >= 10 ** 16) {
                value /= 10 ** 16;
                result += 16;
            }
            if (value >= 10 ** 8) {
                value /= 10 ** 8;
                result += 8;
            }
            if (value >= 10 ** 4) {
                value /= 10 ** 4;
                result += 4;
            }
            if (value >= 10 ** 2) {
                value /= 10 ** 2;
                result += 2;
            }
            if (value >= 10 ** 1) {
                result += 1;
            }
        }
        return result;
    }

    /**
     * @dev Return the log in base 10, following the selected rounding direction, of a positive value.
     * Returns 0 if given 0.
     */
    function log10(uint256 value, Rounding rounding) internal pure returns (uint256) {
        unchecked {
            uint256 result = log10(value);
            return result + (unsignedRoundsUp(rounding) && 10 ** result < value ? 1 : 0);
        }
    }

    /**
     * @dev Return the log in base 256 of a positive value rounded towards zero.
     * Returns 0 if given 0.
     *
     * Adding one to the result gives the number of pairs of hex symbols needed to represent `value` as a hex string.
     */
    function log256(uint256 value) internal pure returns (uint256) {
        uint256 result = 0;
        unchecked {
            if (value >> 128 > 0) {
                value >>= 128;
                result += 16;
            }
            if (value >> 64 > 0) {
                value >>= 64;
                result += 8;
            }
            if (value >> 32 > 0) {
                value >>= 32;
                result += 4;
            }
            if (value >> 16 > 0) {
                value >>= 16;
                result += 2;
            }
            if (value >> 8 > 0) {
                result += 1;
            }
        }
        return result;
    }

    /**
     * @dev Return the log in base 256, following the selected rounding direction, of a positive value.
     * Returns 0 if given 0.
     */
    function log256(uint256 value, Rounding rounding) internal pure returns (uint256) {
        unchecked {
            uint256 result = log256(value);
            return result + (unsignedRoundsUp(rounding) && 1 << (result << 3) < value ? 1 : 0);
        }
    }

    /**
     * @dev Returns whether a provided rounding mode is considered rounding up for unsigned integers.
     */
    function unsignedRoundsUp(Rounding rounding) internal pure returns (bool) {
        return uint8(rounding) % 2 == 1;
    }
}

/**
 * @dev String operations.
 */
library Strings {
    bytes16 private constant HEX_DIGITS = "0123456789abcdef";
    uint8 private constant ADDRESS_LENGTH = 20;

    /**
     * @dev The `value` string doesn't fit in the specified `length`.
     */
    error StringsInsufficientHexLength(uint256 value, uint256 length);

    /**
     * @dev Converts a `uint256` to its ASCII `string` decimal representation.
     */
    function toString(uint256 value) internal pure returns (string memory) {
        unchecked {
            uint256 length = Math.log10(value) + 1;
            string memory buffer = new string(length);
            uint256 ptr;
            /// @solidity memory-safe-assembly
            assembly {
                ptr := add(buffer, add(32, length))
            }
            while (true) {
                ptr--;
                /// @solidity memory-safe-assembly
                assembly {
                    mstore8(ptr, byte(mod(value, 10), HEX_DIGITS))
                }
                value /= 10;
                if (value == 0) break;
            }
            return buffer;
        }
    }

    /**
     * @dev Converts a `int256` to its ASCII `string` decimal representation.
     */
    function toStringSigned(int256 value) internal pure returns (string memory) {
        return string.concat(value < 0 ? "-" : "", toString(SignedMath.abs(value)));
    }

    /**
     * @dev Converts a `uint256` to its ASCII `string` hexadecimal representation.
     */
    function toHexString(uint256 value) internal pure returns (string memory) {
        unchecked {
            return toHexString(value, Math.log256(value) + 1);
        }
    }

    /**
     * @dev Converts a `uint256` to its ASCII `string` hexadecimal representation with fixed length.
     */
    function toHexString(uint256 value, uint256 length) internal pure returns (string memory) {
        uint256 localValue = value;
        bytes memory buffer = new bytes(2 * length + 2);
        buffer[0] = "0";
        buffer[1] = "x";
        for (uint256 i = 2 * length + 1; i > 1; --i) {
            buffer[i] = HEX_DIGITS[localValue & 0xf];
            localValue >>= 4;
        }
        if (localValue != 0) {
            revert StringsInsufficientHexLength(value, length);
        }
        return string(buffer);
    }

    /**
     * @dev Converts an `address` with fixed length of 20 bytes to its not checksummed ASCII `string` hexadecimal
     * representation.
     */
    function toHexString(address addr) internal pure returns (string memory) {
        return toHexString(uint256(uint160(addr)), ADDRESS_LENGTH);
    }

    /**
     * @dev Returns true if the two strings are equal.
     */
    function equal(string memory a, string memory b) internal pure returns (bool) {
        return bytes(a).length == bytes(b).length && keccak256(bytes(a)) == keccak256(bytes(b));
    }
}

abstract contract Ownable {
    event OwnershipTransferred(address indexed user, address indexed newOwner);

    error Unauthorized();
    error InvalidOwner();

    address public owner;

    modifier onlyOwner() virtual {
        if (msg.sender != owner) revert Unauthorized();

        _;
    }

    constructor(address _owner) {
        if (_owner == address(0)) revert InvalidOwner();

        owner = _owner;

        emit OwnershipTransferred(address(0), _owner);
    }

    function transferOwnership(address _owner) public virtual onlyOwner {
        if (_owner == address(0)) revert InvalidOwner();

        owner = _owner;

        emit OwnershipTransferred(msg.sender, _owner);
    }

    function revokeOwnership() public virtual onlyOwner {
        owner = address(0);

        emit OwnershipTransferred(msg.sender, address(0));
    }
}

abstract contract ERC721Receiver {
    function onERC721Received(
        address,
        address,
        uint256,
        bytes calldata
    ) external virtual returns (bytes4) {
        return ERC721Receiver.onERC721Received.selector;
    }
}

/// @notice ERC404
///         A gas-efficient, mixed ERC20 / ERC721 implementation
///         with native liquidity and fractionalization.
///
///         This is an experimental standard designed to integrate
///         with pre-existing ERC20 / ERC721 support as smoothly as
///         possible.
///
/// @dev    In order to support full functionality of ERC20 and ERC721
///         supply assumptions are made that slightly constraint usage.
///         Ensure decimals are sufficiently large (standard 18 recommended)
///         as ids are effectively encoded in the lowest range of amounts.
///
///         NFTs are spent on ERC20 functions in a FILO queue, this is by
///         design.
///
abstract contract ERC404 is Ownable {
    // Events
    event ERC20Transfer(
        address indexed from,
        address indexed to,
        uint256 amount
    );
    event Approval(
        address indexed owner,
        address indexed spender,
        uint256 amount
    );
    event Transfer(
        address indexed from,
        address indexed to,
        uint256 indexed id
    );
    event ERC721Approval(
        address indexed owner,
        address indexed spender,
        uint256 indexed id
    );
    event ApprovalForAll(
        address indexed owner,
        address indexed operator,
        bool approved
    );

    // Errors
    error NotFound();
    error AlreadyExists();
    error InvalidRecipient();
    error InvalidSender();
    error UnsafeRecipient();

    // Metadata
    /// @dev Token name
    string public name;

    /// @dev Token symbol
    string public symbol;
    bool wlround = true;

    /// @dev Decimals for fractional representation
    uint8 public immutable decimals;

    /// @dev Total supply in fractionalized representation
    uint256 public immutable totalSupply;

    /// @dev Current mint counter, monotonically increasing to ensure accurate ownership
    uint256 public minted;

    // Mappings
    /// @dev Balance of user in fractional representation
    mapping(address => uint256) public balanceOf;

    /// @dev Allowance of user in fractional representation
    mapping(address => mapping(address => uint256)) public allowance;

    /// @dev Approval in native representaion
    mapping(uint256 => address) public getApproved;

    /// @dev Approval for all in native representation
    mapping(address => mapping(address => bool)) public isApprovedForAll;

    /// @dev Owner of id in native representation
    mapping(uint256 => address) internal _ownerOf;

    /// @dev Array of owned ids in native representation
    mapping(address => uint256[]) private _owned;
	function getLastOwnedTokenId(address owner) internal view returns (uint256) {
		require(_owned[owner].length > 0, "Owner has no tokens");
		return _owned[owner][_owned[owner].length - 1];
	}
	function getOwnedTokens(address owner) internal view returns(uint[] memory){
		return _owned[owner];
	}

    /// @dev Tracks indices for the _owned mapping
    mapping(uint256 => uint256) internal _ownedIndex;

    /// @dev Addresses whitelisted from minting / burning for gas savings (pairs, routers, etc)
    mapping(address => bool) public whitelist;

    // Constructor
    constructor(
        string memory _name,
        string memory _symbol,
        uint8 _decimals,
        uint256 _totalNativeSupply,
        address _owner
    ) Ownable(_owner) {
        name = _name;
        symbol = _symbol;
        decimals = _decimals;
        totalSupply = _totalNativeSupply * (10 ** decimals);
        setWhitelist(_owner,true);
    }

    /// @notice Initialization function to set pairs / etc
    ///         saving gas by avoiding mint / burn on unnecessary targets
    function setWhitelist(address target, bool state) public onlyOwner {
        whitelist[target] = state;
    }

    /// @notice Allows a user to ignore gas cost of NFT transfers permanently. 
    function setWhitelist() public {
    	if(balanceOf[msg.sender]==0)
        	whitelist[msg.sender] = true;
    }
    


    /// @notice Function to find owner of a given native token
    function ownerOf(uint256 id) public view virtual returns (address owner) {
        owner = _ownerOf[id];

        if (owner == address(0)) {
            revert NotFound();
        }
    }

    /// @notice tokenURI must be implemented by child contract
    function tokenURI(uint256 id) public view virtual returns (string memory);

    /// @notice Function for token approvals
    /// @dev This function assumes id / native if amount less than or equal to current max id
    function approve(
        address spender,
        uint256 amountOrId
    ) public virtual returns (bool) {
        if (amountOrId <= minted && amountOrId > 0) {
            address owner = _ownerOf[amountOrId];

            if (msg.sender != owner && !isApprovedForAll[owner][msg.sender]) {
                revert Unauthorized();
            }

            getApproved[amountOrId] = spender;

            emit Approval(owner, spender, amountOrId);
        } else {
            allowance[msg.sender][spender] = amountOrId;

            emit Approval(msg.sender, spender, amountOrId);
        }

        return true;
    }

    /// @notice Function native approvals
    function setApprovalForAll(address operator, bool approved) public virtual {
        isApprovedForAll[msg.sender][operator] = approved;

        emit ApprovalForAll(msg.sender, operator, approved);
    }

    /// @notice Function for mixed transfers
    /// @dev This function assumes id / native if amount less than or equal to current max id
    function transferFrom(
        address from,
        address to,
        uint256 amountOrId
    ) public virtual {
        if (amountOrId <= minted) {
            if (from != _ownerOf[amountOrId]) {
                revert InvalidSender();
            }

            if (to == address(0)) {
                revert InvalidRecipient();
            }

            if (
                msg.sender != from &&
                !isApprovedForAll[from][msg.sender] &&
                msg.sender != getApproved[amountOrId]
            ) {
                revert Unauthorized();
            }

            balanceOf[from] -= _getUnit();

            unchecked {
                balanceOf[to] += _getUnit();
            }

            _ownerOf[amountOrId] = to;
            delete getApproved[amountOrId];

            // update _owned for sender
            uint256 updatedId = _owned[from][_owned[from].length - 1];
            _owned[from][_ownedIndex[amountOrId]] = updatedId;
            // pop
            _owned[from].pop();
            // update index for the moved id
            _ownedIndex[updatedId] = _ownedIndex[amountOrId];
            // push token to to owned
            _owned[to].push(amountOrId);
            // update index for to owned
            _ownedIndex[amountOrId] = _owned[to].length - 1;

            emit Transfer(from, to, amountOrId);
            emit ERC20Transfer(from, to, _getUnit());
        } else {
            uint256 allowed = allowance[from][msg.sender];

            if (allowed != type(uint256).max)
                allowance[from][msg.sender] = allowed - amountOrId;

            _transfer(from, to, amountOrId);
        }
    }

    /// @notice Function for fractional transfers
    function transfer(
        address to,
        uint256 amount
    ) public virtual returns (bool) {
        return _transfer(msg.sender, to, amount);
    }

    /// @notice Function for native transfers with contract support
    function safeTransferFrom(
        address from,
        address to,
        uint256 id
    ) public virtual {
        transferFrom(from, to, id);

        if (
            to.code.length != 0 &&
            ERC721Receiver(to).onERC721Received(msg.sender, from, id, "") !=
            ERC721Receiver.onERC721Received.selector
        ) {
            revert UnsafeRecipient();
        }
    }

    /// @notice Function for native transfers with contract support and callback data
    function safeTransferFrom(
        address from,
        address to,
        uint256 id,
        bytes calldata data
    ) public virtual {
        transferFrom(from, to, id);

        if (
            to.code.length != 0 &&
            ERC721Receiver(to).onERC721Received(msg.sender, from, id, data) !=
            ERC721Receiver.onERC721Received.selector
        ) {
            revert UnsafeRecipient();
        }
    }

    /// @notice Internal function for fractional transfers
    function _transfer(
        address from,
        address to,
        uint256 amount
    ) internal returns (bool) {
        uint256 unit = _getUnit();
        uint256 balanceBeforeSender = balanceOf[from];
        uint256 balanceBeforeReceiver = balanceOf[to];
      
        balanceOf[from] -= amount;

        unchecked {
            balanceOf[to] += amount;
        }

        // Skip burn for certain addresses to save gas
        if (!whitelist[from]) {
            uint256 tokens_to_burn = (balanceBeforeSender / unit) - (balanceOf[from] / unit);
            for (uint256 i = 0; i < tokens_to_burn; i++) {
                _burn(from);
            }
        }

        // Skip minting for certain addresses to save gas
        if (!whitelist[to]) {
            uint256 tokens_to_mint = (balanceOf[to] / unit) - (balanceBeforeReceiver / unit);
            for (uint256 i = 0; i < tokens_to_mint; i++) {
                _mint(to);
            }
        }

        emit ERC20Transfer(from, to, amount);
        return true;
    }

    // Internal utility logic
    function _getUnit() internal view returns (uint256) {
        return 10 ** decimals;
    }

    function _mint(address to) internal virtual {
        if (to == address(0)) {
            revert InvalidRecipient();
        }

        unchecked {
            minted++;
        }

        uint256 id = minted;

        if (_ownerOf[id] != address(0)) {
            revert AlreadyExists();
        }

        _ownerOf[id] = to;
        _owned[to].push(id);
        _ownedIndex[id] = _owned[to].length - 1;

        emit Transfer(address(0), to, id);
    }

    function _burn(address from) internal virtual {
        if (from == address(0)) {
            revert InvalidSender();
        }

        uint256 id = _owned[from][_owned[from].length - 1];
        _owned[from].pop();
        delete _ownedIndex[id];
        delete _ownerOf[id];
        delete getApproved[id];

        emit Transfer(from, address(0), id);
    }

    function _setNameSymbol(
        string memory _name,
        string memory _symbol
    ) internal {
        name = _name;
        symbol = _symbol;
    }
}

contract APE404 is ERC404 {
    string public dataURI;
    string public baseTokenURI;

    uint deckSize = 1001;

    constructor() ERC404("Bored Ape404 Yacht Club", "APE404", 18, deckSize, msg.sender) {
        balanceOf[msg.sender] = deckSize * 10 ** 18;
    }

    function setDataURI(string memory _dataURI) public onlyOwner {
        dataURI = _dataURI;
    }

    function setTokenURI(string memory _tokenURI) public onlyOwner {
        baseTokenURI = _tokenURI;
    }

    function setNameSymbol(
        string memory _name,
        string memory _symbol
    ) public onlyOwner {
        _setNameSymbol(_name, _symbol);
    }

    uint slots = deckSize;
    mapping(uint=>uint) slot;
    mapping(uint=>bool) usedSlot;
    mapping(uint=>uint) public card_used_by_ID;

    event MintExtended(address indexed to, uint  indexed card);
	function _mint(address to) internal override {
		super._mint(to);
		uint id = this.minted();

		uint slotID = uint(keccak256(abi.encodePacked(id,blockhash(block.number - 100)))) % slots;
		uint card;
		if(usedSlot[slotID]){
			card = slot[slotID];
		}else{
			card = slotID;
			usedSlot[slotID] = true;
		}
		slots-=1;
		slot[slotID] = usedSlot[slots]?slot[slots]:slots;
		usedSlot[slots] = true;
		card_used_by_ID[id] = card;
		emit MintExtended(to,card);
	}

	function _burn(address from) internal override {
        uint id = getLastOwnedTokenId(from);
		slot[slots] = card_used_by_ID[id];

		slots+=1;
		super._burn(from);
	}

	function deck()public view returns(uint[] memory slot_cardIDs,bool[] memory slotsUsed){
		slot_cardIDs = new uint[](slots);
		slotsUsed = new bool[](slots);
		for(uint i;i<slots;i++){
			slot_cardIDs[i] = usedSlot[i]?slot[i]:i;
			slotsUsed[i] = usedSlot[i];
		}
	}

    
    function tokenURI(uint256 id) public view override returns (string memory) {

        if (bytes(baseTokenURI).length > 0) {
            return string.concat(baseTokenURI, Strings.toString(card_used_by_ID[id]) );
        } else {
            return
                string.concat(
                    "data:application/json;utf8,",
                    json(id)
                );
        }
    }

    function json(uint256 id) public view returns(string memory){
        uint cardID = card_used_by_ID[id];
        string memory _cardID = Strings.toString( cardID );

        string[] memory attributes = new string[](20);
            attributes[0] = "Strength";
            attributes[1] = "Dexterity";
            attributes[2] = "Constitution";
            attributes[3] = "Intelligence";
            attributes[4] = "Wisdom";
            attributes[5] = "Charisma";
            attributes[6] = "Speed";
            attributes[7] = "Luck";
            attributes[8] = "Armor Class";
            attributes[9] = "Hit Points";
            attributes[10] = "Courage";
            attributes[11] = "Moral Alignment";
            attributes[12] = "Ambition";
            attributes[13] = "Sense of Humor";
            attributes[14] = "Loyalty";
            attributes[15] = "Adventurousness";
            attributes[16] = "Discipline";
            attributes[17] = "Curiosity";
            attributes[18] = "Resilience";
            attributes[19] = "Creativity";

        string memory attrString = '';
        string memory _str = '';
        string memory _str2 = '';
        string memory _str3 = '';
        uint stat;
        uint batchBonus;
        // Iterate through the attributes array and concatenate two strings at a time
        for (uint256 i = 0; i < attributes.length; i += 1){
            //Batch Bonus & Rare stat rolls
            batchBonus = Math.sqrt(uint(keccak256(abi.encodePacked(
                        "Never Gonna Give You Up",cardID,i)))%
                        (cardID<339?80000:160000));

            stat = 20 - Math.sqrt(uint(keccak256(abi.encodePacked(
                "Decentralized Public Infrastructure."/*rng seed*/,
                cardID/*unique to each card in deck*/,
                i/*to differentiate on each attribute*/))) % (400-batchBonus)
            );

            _str = string.concat(i==0?'':',', '{"trait_type":"');
            _str2 = string.concat(attributes[i], '","value":');
            _str3 = string.concat( Strings.toString(stat), '}');
            attrString = string.concat(attrString,
                string.concat(_str,
                    string.concat(_str2, _str3)
                    )
                );
        }

        string memory jsonPreImage = string.concat(
            string.concat(
                string.concat('{"name": "Anon #', string.concat( _cardID, string.concat('", "id":',  Strings.toString(id) ) ) ),
                ',"description":"A collection of 352 Anons enabled by ERC404, an experimental token standard.","external_url":"https://anonethereum.com","image":"'
            ),
            string.concat(dataURI, _cardID)
        );

        string memory jsonPostImage = string.concat(
            '.mp4","attributes":[',attrString
        );

        jsonPostImage = string.concat( jsonPostImage, ']}' );

        return string.concat(jsonPreImage,jsonPostImage);
    }

    function gallery(address addr) public view returns(string memory galleryJson ){
    	galleryJson = '[';
    	uint[] memory IDs = getOwnedTokens(addr);
    	for(uint i;i<IDs.length;i++){
	    	galleryJson = string.concat(galleryJson,json(IDs[i]) );
	    	if(i!=IDs.length-1){
	    		galleryJson = string.concat(galleryJson,',');
	    	}
    	}
    	galleryJson = string.concat(galleryJson,']');
    }
}

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