// SPDX-License-Identifier: MIT
// Copyright (c) 2021 the ethier authors (github.com/divergencetech/ethier)

pragma solidity ^0.8.22;

/// @title DynamicBuffer
/// @author David Huber (@cxkoda) and Simon Fremaux (@dievardump). See also
///         https://raw.githubusercontent.com/dievardump/solidity-dynamic-buffer
/// @notice This library is used to allocate a big amount of container memory
//          which will be subsequently filled without needing to reallocate
///         memory.
/// @dev First, allocate memory.
///      Then use `buffer.appendUnchecked(theBytes)` or `appendSafe()` if
///      bounds checking is required.
library DynamicBuffer {
    /// @notice Allocates container space for the DynamicBuffer
    /// @param capacity_ The intended max amount of bytes in the buffer
    /// @return buffer The memory location of the buffer
    /// @dev Allocates `capacity_ + 0x60` bytes of space
    ///      The buffer array starts at the first container data position,
    ///      (i.e. `buffer = container + 0x20`)
    function allocate(uint256 capacity_)
        internal
        pure
        returns (bytes memory buffer)
    {
        assembly {
            // Get next-free memory address
            let container := mload(0x40)

            // Allocate memory by setting a new next-free address
            {
                // Add 2 x 32 bytes in size for the two length fields
                // Add 32 bytes safety space for 32B chunked copy
                let size := add(capacity_, 0x60)
                let newNextFree := add(container, size)
                mstore(0x40, newNextFree)
            }

            // Set the correct container length
            {
                let length := add(capacity_, 0x40)
                mstore(container, length)
            }

            // The buffer starts at idx 1 in the container (0 is length)
            buffer := add(container, 0x20)

            // Init content with length 0
            mstore(buffer, 0)
        }

        return buffer;
    }

    /// @notice Appends data to buffer, and update buffer length
    /// @param buffer the buffer to append the data to
    /// @param data the data to append
    /// @dev Does not perform out-of-bound checks (container capacity)
    ///      for efficiency.
    function appendUnchecked(bytes memory buffer, bytes memory data)
        internal
        pure
    {
        assembly {
            let length := mload(data)
            for {
                data := add(data, 0x20)
                let dataEnd := add(data, length)
                let copyTo := add(buffer, add(mload(buffer), 0x20))
            } lt(data, dataEnd) {
                data := add(data, 0x20)
                copyTo := add(copyTo, 0x20)
            } {
                // Copy 32B chunks from data to buffer.
                // This may read over data array boundaries and copy invalid
                // bytes, which doesn't matter in the end since we will
                // later set the correct buffer length, and have allocated an
                // additional word to avoid buffer overflow.
                mstore(copyTo, mload(data))
            }

            // Update buffer length
            mstore(buffer, add(mload(buffer), length))
        }
    }

    /// @notice Appends data to buffer, and update buffer length
    /// @param buffer the buffer to append the data to
    /// @param data the data to append
    /// @dev Performs out-of-bound checks and calls `appendUnchecked`.
    function appendSafe(bytes memory buffer, bytes memory data) internal pure {
        checkOverflow(buffer, data.length);
        appendUnchecked(buffer, data);
    }

    /// @notice Appends data encoded as Base64 to buffer.
    /// @param fileSafe  Whether to replace '+' with '-' and '/' with '_'.
    /// @param noPadding Whether to strip away the padding.
    /// @dev Encodes `data` using the base64 encoding described in RFC 4648.
    /// See: https://datatracker.ietf.org/doc/html/rfc4648
    /// Author: Modified from Solady (https://github.com/vectorized/solady/blob/main/src/utils/Base64.sol)
    /// Author: Modified from Solmate (https://github.com/transmissions11/solmate/blob/main/src/utils/Base64.sol)
    /// Author: Modified from (https://github.com/Brechtpd/base64/blob/main/base64.sol) by Brecht Devos.
    function appendSafeBase64(
        bytes memory buffer,
        bytes memory data,
        bool fileSafe,
        bool noPadding
    ) internal pure {
        uint256 dataLength = data.length;

        if (data.length == 0) {
            return;
        }

        uint256 encodedLength;
        uint256 r;
        assembly {
            // For each 3 bytes block, we will have 4 bytes in the base64
            // encoding: `encodedLength = 4 * divCeil(dataLength, 3)`.
            // The `shl(2, ...)` is equivalent to multiplying by 4.
            encodedLength := shl(2, div(add(dataLength, 2), 3))

            r := mod(dataLength, 3)
            if noPadding {
                // if r == 0 => no modification
                // if r == 1 => encodedLength -= 2
                // if r == 2 => encodedLength -= 1
                encodedLength := sub(
                    encodedLength,
                    add(iszero(iszero(r)), eq(r, 1))
                )
            }
        }

        checkOverflow(buffer, encodedLength);

        assembly {
            let nextFree := mload(0x40)

            // Store the table into the scratch space.
            // Offsetted by -1 byte so that the `mload` will load the character.
            // We will rewrite the free memory pointer at `0x40` later with
            // the allocated size.
            mstore(0x1f, "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdef")
            mstore(
                0x3f,
                sub(
                    "ghijklmnopqrstuvwxyz0123456789-_",
                    // The magic constant 0x0230 will translate "-_" + "+/".
                    mul(iszero(fileSafe), 0x0230)
                )
            )

            // Skip the first slot, which stores the length.
            let ptr := add(add(buffer, 0x20), mload(buffer))
            let end := add(data, dataLength)

            // Run over the input, 3 bytes at a time.
            // prettier-ignore
            // solhint-disable-next-line no-empty-blocks
            for {} 1 {} {
                    data := add(data, 3) // Advance 3 bytes.
                    let input := mload(data)

                    // Write 4 bytes. Optimized for fewer stack operations.
                    mstore8(    ptr    , mload(and(shr(18, input), 0x3F)))
                    mstore8(add(ptr, 1), mload(and(shr(12, input), 0x3F)))
                    mstore8(add(ptr, 2), mload(and(shr( 6, input), 0x3F)))
                    mstore8(add(ptr, 3), mload(and(        input , 0x3F)))
                    
                    ptr := add(ptr, 4) // Advance 4 bytes.
                    // prettier-ignore
                    if iszero(lt(data, end)) { break }
                }

            if iszero(noPadding) {
                // Offset `ptr` and pad with '='. We can simply write over the end.
                mstore8(sub(ptr, iszero(iszero(r))), 0x3d) // Pad at `ptr - 1` if `r > 0`.
                mstore8(sub(ptr, shl(1, eq(r, 1))), 0x3d) // Pad at `ptr - 2` if `r == 1`.
            }

            mstore(buffer, add(mload(buffer), encodedLength))
            mstore(0x40, nextFree)
        }
    }

    /// @notice Appends data encoded as Base64 to buffer.
    /// @param fileSafe  Whether to replace '+' with '-' and '/' with '_'.
    /// @param noPadding Whether to strip away the padding.
    /// @dev Encodes `data` using the base64 encoding described in RFC 4648.
    /// See: https://datatracker.ietf.org/doc/html/rfc4648
    /// Author: Modified from Solady (https://github.com/vectorized/solady/blob/main/src/utils/Base64.sol)
    /// Author: Modified from Solmate (https://github.com/transmissions11/solmate/blob/main/src/utils/Base64.sol)
    /// Author: Modified from (https://github.com/Brechtpd/base64/blob/main/base64.sol) by Brecht Devos.
    function appendUncheckedBase64(
        bytes memory buffer,
        bytes memory data,
        bool fileSafe,
        bool noPadding
    ) internal pure {
        uint256 dataLength = data.length;

        if (data.length == 0) {
            return;
        }

        uint256 encodedLength;
        uint256 r;
        assembly {
            // For each 3 bytes block, we will have 4 bytes in the base64
            // encoding: `encodedLength = 4 * divCeil(dataLength, 3)`.
            // The `shl(2, ...)` is equivalent to multiplying by 4.
            encodedLength := shl(2, div(add(dataLength, 2), 3))

            r := mod(dataLength, 3)
            if noPadding {
                // if r == 0 => no modification
                // if r == 1 => encodedLength -= 2
                // if r == 2 => encodedLength -= 1
                encodedLength := sub(
                    encodedLength,
                    add(iszero(iszero(r)), eq(r, 1))
                )
            }
        }

        assembly {
            let nextFree := mload(0x40)

            // Store the table into the scratch space.
            // Offsetted by -1 byte so that the `mload` will load the character.
            // We will rewrite the free memory pointer at `0x40` later with
            // the allocated size.
            mstore(0x1f, "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdef")
            mstore(
                0x3f,
                sub(
                    "ghijklmnopqrstuvwxyz0123456789-_",
                    // The magic constant 0x0230 will translate "-_" + "+/".
                    mul(iszero(fileSafe), 0x0230)
                )
            )

            // Skip the first slot, which stores the length.
            let ptr := add(add(buffer, 0x20), mload(buffer))
            let end := add(data, dataLength)

            // Run over the input, 3 bytes at a time.
            // prettier-ignore
            // solhint-disable-next-line no-empty-blocks
            for {} 1 {} {
                    data := add(data, 3) // Advance 3 bytes.
                    let input := mload(data)

                    // Write 4 bytes. Optimized for fewer stack operations.
                    mstore8(    ptr    , mload(and(shr(18, input), 0x3F)))
                    mstore8(add(ptr, 1), mload(and(shr(12, input), 0x3F)))
                    mstore8(add(ptr, 2), mload(and(shr( 6, input), 0x3F)))
                    mstore8(add(ptr, 3), mload(and(        input , 0x3F)))
                    
                    ptr := add(ptr, 4) // Advance 4 bytes.
                    // prettier-ignore
                    if iszero(lt(data, end)) { break }
                }

            if iszero(noPadding) {
                // Offset `ptr` and pad with '='. We can simply write over the end.
                mstore8(sub(ptr, iszero(iszero(r))), 0x3d) // Pad at `ptr - 1` if `r > 0`.
                mstore8(sub(ptr, shl(1, eq(r, 1))), 0x3d) // Pad at `ptr - 2` if `r == 1`.
            }

            mstore(buffer, add(mload(buffer), encodedLength))
            mstore(0x40, nextFree)
        }
    }

    /// @notice Returns the capacity of a given buffer.
    function capacity(bytes memory buffer) internal pure returns (uint256) {
        uint256 cap;
        assembly {
            cap := sub(mload(sub(buffer, 0x20)), 0x40)
        }
        return cap;
    }

    /// @notice Reverts if the buffer will overflow after appending a given
    /// number of bytes.
    function checkOverflow(bytes memory buffer, uint256 addedLength)
        internal
        pure
    {
        uint256 cap = capacity(buffer);
        uint256 newLength = buffer.length + addedLength;
        if (cap < newLength) {
            revert("DynamicBuffer: Appending out of bounds.");
        }
    }
}