binarygcode/components/

deserialiser.rs

use core::{array::TryFromSliceError, fmt};

use alloc::{borrow::ToOwned, boxed::Box, vec::Vec};
use base64::{prelude::BASE64_STANDARD, Engine};
use embedded_heatshrink::{
    HSDFinishRes, HSDPollRes, HSDSinkRes, HeatshrinkDecoder,
};
use meatpack::Unpacker;
use miniz_oxide::inflate::decompress_to_vec_zlib;

use crate::components::common::{
    crc32, BinaryGcodeError, BlockKind, Checksum, CompressionAlgorithm,
    Encoding, MAGIC,
};

/// A utility enum to keep track of the state of the deserialiser
/// instance when digesting some bytes.
enum DeserialiserState {
    FileHeader,
    Block,
}

/// The possible outputs from a call to deserialise().
#[derive(Debug)]
pub enum DeserialisedResult {
    FileHeader(DeserialisedFileHeader),
    MoreBytesRequired(usize),
    Block(DeserialisedBlock),
}

/// A struct containing the header details of the bgcode.
#[derive(Debug)]
pub struct DeserialisedFileHeader {
    pub magic: u32,
    pub version: u32,
    pub checksum: Checksum,
}

/// A utility function to take a generic slice and return a slice of a specific size.
pub(crate) fn try_from_slice<const N: usize>(
    buf: &[u8]
) -> Result<[u8; N], BinaryGcodeError> {
    let bytes: Result<[u8; N], TryFromSliceError> = buf.try_into();
    match bytes {
        Ok(bytes) => Ok(bytes),
        Err(_) => Err(BinaryGcodeError::TryFromSliceError),
    }
}

/// A binarygcode deserialiser that can parse a bgcode file. It can
/// digest data in chunks and returns header and blocks when available.
/// The block remain compressed so the user can decide which ones they
/// which to decompress.
pub struct Deserialiser {
    pub inner: Vec<u8>,
    state: DeserialiserState,
    checksum: Checksum,
}

impl Default for Deserialiser {
    fn default() -> Self {
        Self {
            inner: Vec::new(),
            state: DeserialiserState::FileHeader,
            checksum: Checksum::None,
        }
    }
}

impl Deserialiser {
    /// Provide some more bytes for the deserialiser to process/
    pub fn digest(
        &mut self,
        buf: &[u8],
    ) {
        self.inner.extend(buf);
    }

    /// Reset the deserialisor to its default state.
    pub fn reset(&mut self) {
        self.inner.clear();
        self.state = DeserialiserState::FileHeader;
    }

    /// Try and deserialised either a file header or block element from the
    /// current digest.
    pub fn deserialise(
        &mut self
    ) -> Result<DeserialisedResult, BinaryGcodeError> {
        match self.state {
            DeserialiserState::FileHeader => self.deserialise_file_header(),
            DeserialiserState::Block => self.deserialise_block(),
        }
    }

    /// An internal function to deserialise the file header.
    fn deserialise_file_header(
        &mut self
    ) -> Result<DeserialisedResult, BinaryGcodeError> {
        if self.inner.len() < 10 {
            return Ok(DeserialisedResult::MoreBytesRequired(
                10 - self.inner.len(),
            ));
        }
        // We have enough data to read the file header
        let bytes = try_from_slice::<4>(&self.inner[0..=3])?;
        let magic = u32::from_le_bytes(bytes);
        if magic != MAGIC {
            return Err(BinaryGcodeError::InvalidMagic(magic));
        }

        let bytes = try_from_slice::<4>(&self.inner[4..=7])?;
        let version = u32::from_le_bytes(bytes);

        let bytes = try_from_slice::<2>(&self.inner[8..=9])?;
        let checksum_value = u16::from_le_bytes(bytes);

        let checksum = match checksum_value {
            1 => Checksum::Crc32,
            0 => Checksum::None,
            v => return Err(BinaryGcodeError::InvalidChecksumType(v)),
        };

        let fh = DeserialisedFileHeader {
            magic,
            version,
            checksum: checksum.clone(),
        };

        self.checksum = checksum;
        self.state = DeserialiserState::Block;
        self.inner.drain(..10);

        Ok(DeserialisedResult::FileHeader(fh))
    }

    /// An internal function to deserialise a block from the digest.
    fn deserialise_block(
        &mut self
    ) -> Result<DeserialisedResult, BinaryGcodeError> {
        // Check if we have enough data to read the block header
        if self.inner.len() < 12 {
            return Ok(DeserialisedResult::MoreBytesRequired(
                12 - self.inner.len(),
            ));
        }

        // Check the header
        let bytes = try_from_slice::<2>(&self.inner[0..=1])?;
        let kind = BlockKind::from_le_bytes(bytes)?;

        let bytes = try_from_slice::<2>(&self.inner[2..=3])?;
        let compression = CompressionAlgorithm::from_le_bytes(bytes)?;

        let bytes = try_from_slice::<4>(&self.inner[4..=7])?;
        let data_uncompressed_len = u32::from_le_bytes(bytes) as usize;

        let data_compressed_len: Option<usize> = match compression {
            CompressionAlgorithm::None => None,
            _ => {
                let bytes = try_from_slice::<4>(&self.inner[8..=11])?;
                Some(u32::from_le_bytes(bytes) as usize)
            }
        };

        let param_len = match kind {
            BlockKind::Thumbnail => 6,
            _ => 2,
        };

        // Have we collected all the data we need?
        let block_len = match data_compressed_len {
            Some(compressed_len) => {
                // header + parameters + comrpessed_len
                let mut block_len = 12 + param_len + compressed_len;
                if self.checksum == Checksum::Crc32 {
                    block_len += 4;
                }
                if self.inner.len() < block_len {
                    return Ok(DeserialisedResult::MoreBytesRequired(
                        block_len - self.inner.len(),
                    ));
                }
                block_len
            }
            None => {
                let mut block_len = 8 + param_len + data_uncompressed_len;
                if self.checksum == Checksum::Crc32 {
                    block_len += 4;
                }
                if self.inner.len() < block_len {
                    return Ok(DeserialisedResult::MoreBytesRequired(
                        block_len - self.inner.len(),
                    ));
                }
                block_len
            }
        };

        // Checksum check
        match self.checksum {
            Checksum::None => {}
            Checksum::Crc32 => {
                let bytes =
                    try_from_slice::<4>(&self.inner[block_len - 4..block_len])?;
                let c = u32::from_le_bytes(bytes);
                let chk = crc32(&self.inner[..block_len - 4]);
                if c != chk {
                    return Err(BinaryGcodeError::InvalidChecksum(c, chk));
                }
            }
        }

        let param_start = match data_compressed_len {
            Some(_) => 12,
            None => 8,
        };

        let encoding = &self.inner[param_start..param_start + 2];
        let encoding = try_from_slice::<2>(encoding)?;
        let encoding = Encoding::from_le_bytes(encoding, &kind)?;

        let parameters = self.inner[param_start..param_start + param_len]
            .to_owned()
            .into_boxed_slice();
        let data = self.inner[param_start + param_len..block_len - 4]
            .to_owned()
            .into_boxed_slice();

        // Pass out the block
        let b = DeserialisedBlock {
            kind,
            data_compressed_len,
            data_uncompressed_len,
            compression,
            encoding,
            parameters,
            data,
        };

        self.inner.drain(..block_len);

        Ok(DeserialisedResult::Block(b))
    }
}

#[derive(Debug)]
pub enum BlockError {
    DecodeError(&'static str),
}

/// A struct representing a deserialised binary gcode block.
#[derive(Debug)]
pub struct DeserialisedBlock {
    pub kind: BlockKind,
    pub data_compressed_len: Option<usize>,
    pub data_uncompressed_len: usize,
    pub compression: CompressionAlgorithm,
    pub encoding: Encoding,
    pub parameters: Box<[u8]>,
    pub data: Box<[u8]>,
}

impl fmt::Display for DeserialisedBlock {
    fn fmt(
        &self,
        f: &mut fmt::Formatter<'_>,
    ) -> fmt::Result {
        write!(
			f,
			"{:?}  {{ compressed_len: {:?}, uncompressed_len: {}, compression: {:?}, encoding: {:?} }}",
			self.kind, self.data_compressed_len, self.data_uncompressed_len, self.compression, self.encoding
		)
    }
}

impl DeserialisedBlock {
    /// Internal function to decompress the data given the compression algorithm.
    pub fn decompress(&self) -> Result<Box<[u8]>, BlockError> {
        match self.compression {
            CompressionAlgorithm::None => Ok(self.data.clone()),
            CompressionAlgorithm::Deflate => {
                let output = decompress_to_vec_zlib(&self.data);
                if let Ok(o) = output {
                    Ok(o.into_boxed_slice())
                } else {
                    Err(BlockError::DecodeError("deflate"))
                }
            }
            CompressionAlgorithm::Heatshrink11_4 => {
                unshrink(&self.data, self.data_uncompressed_len, 11, 4)
            }
            CompressionAlgorithm::Heatshrink12_4 => {
                unshrink(&self.data, self.data_uncompressed_len, 12, 4)
            }
        }
    }

    /// Pumps the decompressed ascii representation of the gcode block into a buffer. The user can define whether they want to include our block comments so they can see the decomposition of blocks in the gcode.
    pub fn to_ascii(
        &mut self,
        buf: &mut Vec<u8>,
        with_block_comments: bool,
    ) -> Result<(), BinaryGcodeError> {
        let data = self.decompress().unwrap();
        match self.kind {
            BlockKind::FileMetadata => {
                if with_block_comments {
                    buf.extend("; [FILE_METADATA_BLOCK_START]\n".as_bytes());
                }
                buf.extend(data);
                if with_block_comments {
                    // Add a new line.
                    buf.extend("\n; [FILE_METADATA_BLOCK_END]\n".as_bytes());
                }
            }
            BlockKind::PrinterMetadata => {
                if with_block_comments {
                    buf.extend("; [PRINTER_METADATA_BLOCK_START]\n".as_bytes());
                }
                buf.extend(data);
                if with_block_comments {
                    buf.extend("\n; [PRINTER_METADATA_BLOCK_END]\n".as_bytes());
                }
            }
            BlockKind::PrintMetadata => {
                if with_block_comments {
                    buf.extend("; [PRINT_METADATA_BLOCK_START]\n".as_bytes());
                }
                buf.extend(data);
                if with_block_comments {
                    buf.extend("\n; [PRINT_METADATA_BLOCK_END]\n".as_bytes());
                }
            }
            BlockKind::SlicerMetadata => {
                if with_block_comments {
                    buf.extend("; [SLICER_METADATA_BLOCK_START]\n".as_bytes());
                }
                buf.extend(data);
                if with_block_comments {
                    buf.extend("\n; [SLICER_METADATA_BLOCK_END]\n".as_bytes());
                }
            }
            BlockKind::Thumbnail => {
                //buf.resize_with(buf.len() + data.len(), Default::default);
                let width = try_from_slice::<2>(&self.parameters[2..=3])?;
                let width = u16::from_le_bytes(width);
                let height = try_from_slice::<2>(&self.parameters[4..=5])?;
                let height = u16::from_le_bytes(height);

                if with_block_comments {
                    buf.extend("; [THUMBNAIL_BLOCK_START]\n".as_bytes());
                }
                let r = BASE64_STANDARD.encode(&data).into_bytes();
                match self.encoding {
                    Encoding::Png => {
                        let header = format!(
                            "; thumbnail begin {}x{} {}\n",
                            width,
                            height,
                            r.len()
                        );
                        buf.extend(header.as_bytes());
                    }
                    Encoding::Jpg => {
                        let header = format!(
                            "; thumbnail_JPG begin {}x{} {}\n",
                            width,
                            height,
                            r.len()
                        );
                        buf.extend(header.as_bytes());
                    }
                    Encoding::Qoi => {
                        let header = format!(
                            "; thumbnail_QOI begin {}x{} {}\n",
                            width,
                            height,
                            r.len()
                        );
                        buf.extend(header.as_bytes());
                    }
                    _ => {}
                }
                // Taking the max row length of 78 from libbgcode
                for chunk in r.chunks(78) {
                    buf.extend("; ".as_bytes());
                    buf.extend(chunk);
                    buf.push(b'\n');
                }
                match self.encoding {
                    Encoding::Png => {
                        buf.extend("; thumbnail end \n\n".as_bytes())
                    }
                    Encoding::Jpg => {
                        buf.extend("; thumbnail_JPG end \n\n".as_bytes())
                    }
                    Encoding::Qoi => {
                        buf.extend("; thumbnail_QOI end \n\n".as_bytes())
                    }
                    _ => {}
                }
                if with_block_comments {
                    buf.extend("; [THUMBNAIL_BLOCK_END]\n".as_bytes());
                }
            }
            BlockKind::GCode => {
                if with_block_comments {
                    buf.extend("; [GCODE_BLOCK_START]\n".as_bytes());
                }
                match self.encoding {
                    Encoding::Ascii => buf.extend(data),
                    Encoding::Meatpack => {
                        // Use the Meatpack crate to re-encode back to ASCII Gcode.
                        if let Some(e) =
                            Unpacker::<64>::unpack_slice(&data, buf).err()
                        {
                            return Err(BinaryGcodeError::Meatpack(e));
                        }
                    }
                    Encoding::MeatpackWithComments => {
                        if let Some(e) =
                            Unpacker::<64>::unpack_slice(&data, buf).err()
                        {
                            return Err(BinaryGcodeError::Meatpack(e));
                        }
                    }
                    _ => {}
                }
                if with_block_comments {
                    buf.extend("; [GCODE_BLOCK_END]\n".as_bytes());
                }
            }
        }
        Ok(())
    }
}

/// An internal function wrapping around the heatshrink decoder.
fn unshrink(
    input: &[u8],
    uncompressed_len: usize,
    window: u8,
    lookahead: u8,
) -> Result<Box<[u8]>, BlockError> {
    let input_buffer_size = input.len();
    let mut decoder =
        HeatshrinkDecoder::new(input_buffer_size as u16, window, lookahead)
            .unwrap();
    let mut uncompressed: Vec<u8> = vec![0; uncompressed_len];
    let mut sunk: usize = 0;
    let mut polled: usize = 0;

    while sunk < input_buffer_size {
        match decoder.sink(&input[sunk..]) {
            HSDSinkRes::Ok(sz) => {
                sunk += sz;
            }
            HSDSinkRes::Full => {
                return Err(BlockError::DecodeError("HSDSinkRes::Full"))
            }
            HSDSinkRes::ErrorNull => {
                return Err(BlockError::DecodeError("HSDSinkRes::ErrorNull"))
            }
        }
        loop {
            let res = decoder.poll(&mut uncompressed[polled..]);
            match res {
                HSDPollRes::Empty(sz) => {
                    polled += sz;
                    if sz == 0 {
                        break;
                    }
                }
                // Panics after looping for more. Is there a bug where
                // More is Empty and Empty is More or my interpretation
                // of what they mean?
                HSDPollRes::More(sz) => {
                    polled += sz;
                    break;
                }
                HSDPollRes::ErrorNull => {
                    return Err(BlockError::DecodeError(
                        "HSDPollRes::ErrorNull",
                    ))
                }
                HSDPollRes::ErrorUnknown => {
                    return Err(BlockError::DecodeError(
                        "HSDPollRes::ErrorUnknown",
                    ))
                }
            }
        }
    }

    loop {
        match decoder.finish() {
            HSDFinishRes::Done => break,
            HSDFinishRes::More => {
                match decoder.poll(&mut uncompressed[polled..]) {
                    HSDPollRes::Empty(sz) => {
                        polled += sz;
                        if sz == 0 {
                            break;
                        }
                    }
                    HSDPollRes::More(sz) => {
                        polled += sz;
                    }
                    HSDPollRes::ErrorUnknown => {
                        return Err(BlockError::DecodeError(
                            "HSDPollRes::ErrorUnknown",
                        ))
                    }
                    HSDPollRes::ErrorNull => {
                        return Err(BlockError::DecodeError(
                            "HSDPollRes::ErrorNull",
                        ))
                    }
                }
            }
            HSDFinishRes::ErrorNull => {
                return Err(BlockError::DecodeError("HSDFinishRes::ErrorNull"))
            }
        }
    }

    Ok(uncompressed.into_boxed_slice())
}