lopdf 0.40.0

use crate::encodings;
use crate::encodings::cmap::ToUnicodeCMap;
use crate::encodings::Encoding;
use crate::error::DecompressError;
use crate::{Document, Error, Result};
use indexmap::IndexMap;
use log::warn;
use std::cmp::max;
use std::fmt;
use std::str;

/// Object identifier consists of two parts: object number and generation number.
pub type ObjectId = (u32, u16);

/// Dictionary object.
#[derive(Clone, Default, PartialEq)]
pub struct Dictionary(IndexMap<Vec<u8>, Object>);

/// Stream object
/// Warning - all streams must be indirect objects, while
/// the stream dictionary may be a direct object
#[derive(Debug, Clone, PartialEq)]
pub struct Stream {
    /// Associated stream dictionary
    pub dict: Dictionary,
    /// Contents of the stream in bytes
    pub content: Vec<u8>,
    /// Can the stream be compressed by the `Document::compress()` function?
    /// Font streams may not be compressed, for example
    pub allows_compression: bool,
    /// Stream data's position in PDF file.
    pub start_position: Option<usize>,
}

/// Basic PDF object types defined in an enum.
#[derive(Clone, PartialEq)]
pub enum Object {
    Null,
    Boolean(bool),
    Integer(i64),
    Real(f32),
    Name(Vec<u8>),
    String(Vec<u8>, StringFormat),
    Array(Vec<Object>),
    Dictionary(Dictionary),
    Stream(Stream),
    Reference(ObjectId),
}

/// String objects can be written in two formats.
#[derive(Debug, Clone, Copy, Default, PartialEq, Eq)]
pub enum StringFormat {
    #[default]
    Literal,
    Hexadecimal,
}

impl From<bool> for Object {
    fn from(value: bool) -> Self {
        Object::Boolean(value)
    }
}

impl From<i64> for Object {
    fn from(number: i64) -> Self {
        Object::Integer(number)
    }
}

macro_rules! from_smaller_ints {
	($( $Int: ty )+) => {
		$(
			impl From<$Int> for Object {
				fn from(number: $Int) -> Self {
					Object::Integer(i64::from(number))
				}
			}
		)+
	}
}

from_smaller_ints! {
    i8 i16 i32
    u8 u16 u32
}

impl From<f64> for Object {
    fn from(number: f64) -> Self {
        Object::Real(number as f32)
    }
}

impl From<f32> for Object {
    fn from(number: f32) -> Self {
        Object::Real(number)
    }
}

impl From<String> for Object {
    fn from(name: String) -> Self {
        Object::Name(name.into_bytes())
    }
}

impl<'a> From<&'a str> for Object {
    fn from(name: &'a str) -> Self {
        Object::Name(name.as_bytes().to_vec())
    }
}

impl From<Vec<Object>> for Object {
    fn from(array: Vec<Object>) -> Self {
        Object::Array(array)
    }
}

impl From<Dictionary> for Object {
    fn from(dict: Dictionary) -> Self {
        Object::Dictionary(dict)
    }
}

impl From<Stream> for Object {
    fn from(stream: Stream) -> Self {
        Object::Stream(stream)
    }
}

impl From<ObjectId> for Object {
    fn from(id: ObjectId) -> Self {
        Object::Reference(id)
    }
}

impl Object {
    pub fn string_literal<S: Into<Vec<u8>>>(s: S) -> Self {
        Object::String(s.into(), StringFormat::Literal)
    }

    pub fn is_null(&self) -> bool {
        matches!(*self, Object::Null)
    }

    pub fn as_bool(&self) -> Result<bool> {
        match self {
            Object::Boolean(value) => Ok(*value),
            _ => Err(Error::ObjectType {
                expected: "Boolean",
                found: self.enum_variant(),
            }),
        }
    }

    pub fn as_i64(&self) -> Result<i64> {
        match self {
            Object::Integer(value) => Ok(*value),
            _ => Err(Error::ObjectType {
                expected: "Integer",
                found: self.enum_variant(),
            }),
        }
    }

    pub fn as_f32(&self) -> Result<f32> {
        match self {
            Object::Real(value) => Ok(*value),
            _ => Err(Error::ObjectType {
                expected: "Real",
                found: self.enum_variant(),
            }),
        }
    }

    /// Get the object value as a float.
    /// Unlike [`Object::as_f32`] this will also cast an Integer to a Real.
    pub fn as_float(&self) -> Result<f32> {
        match self {
            Object::Integer(value) => Ok(*value as f32),
            Object::Real(value) => Ok(*value),
            _ => Err(Error::ObjectType {
                expected: "Integer or Real",
                found: self.enum_variant(),
            }),
        }
    }

    pub fn as_name(&self) -> Result<&[u8]> {
        match self {
            Object::Name(name) => Ok(name),
            _ => Err(Error::ObjectType {
                expected: "Name",
                found: self.enum_variant(),
            }),
        }
    }

    pub fn as_str(&self) -> Result<&[u8]> {
        match self {
            Object::String(string, _) => Ok(string),
            _ => Err(Error::ObjectType {
                expected: "String",
                found: self.enum_variant(),
            }),
        }
    }

    pub fn as_str_mut(&mut self) -> Result<&mut Vec<u8>> {
        match self {
            Object::String(string, _) => Ok(string),
            _ => Err(Error::ObjectType {
                expected: "String",
                found: self.enum_variant(),
            }),
        }
    }

    pub fn as_reference(&self) -> Result<ObjectId> {
        match self {
            Object::Reference(id) => Ok(*id),
            _ => Err(Error::ObjectType {
                expected: "Reference",
                found: self.enum_variant(),
            }),
        }
    }

    pub fn as_array(&self) -> Result<&Vec<Object>> {
        match self {
            Object::Array(arr) => Ok(arr),
            _ => Err(Error::ObjectType {
                expected: "Array",
                found: self.enum_variant(),
            }),
        }
    }

    pub fn as_array_mut(&mut self) -> Result<&mut Vec<Object>> {
        match self {
            Object::Array(arr) => Ok(arr),
            _ => Err(Error::ObjectType {
                expected: "Array",
                found: self.enum_variant(),
            }),
        }
    }

    pub fn as_dict(&self) -> Result<&Dictionary> {
        match self {
            Object::Dictionary(dict) => Ok(dict),
            _ => Err(Error::ObjectType {
                expected: "Dictionary",
                found: self.enum_variant(),
            }),
        }
    }

    pub fn as_dict_mut(&mut self) -> Result<&mut Dictionary> {
        match self {
            Object::Dictionary(dict) => Ok(dict),
            _ => Err(Error::ObjectType {
                expected: "Dictionary",
                found: self.enum_variant(),
            }),
        }
    }

    pub fn as_stream(&self) -> Result<&Stream> {
        match self {
            Object::Stream(stream) => Ok(stream),
            _ => Err(Error::ObjectType {
                expected: "Stream",
                found: self.enum_variant(),
            }),
        }
    }

    pub fn as_stream_mut(&mut self) -> Result<&mut Stream> {
        match self {
            Object::Stream(stream) => Ok(stream),
            _ => Err(Error::ObjectType {
                expected: "Stream",
                found: self.enum_variant(),
            }),
        }
    }

    // TODO: maybe remove
    pub fn type_name(&self) -> Result<&[u8]> {
        match self {
            Object::Dictionary(dict) => dict.get_type(),
            Object::Stream(stream) => stream.dict.get_type(),
            obj => Err(Error::ObjectType {
                expected: "Dictionary or Stream",
                found: obj.enum_variant(),
            }),
        }
    }

    pub fn enum_variant(&self) -> &'static str {
        match self {
            Object::Null => "Null",
            Object::Boolean(_) => "Boolean",
            Object::Integer(_) => "Integer",
            Object::Real(_) => "Real",
            Object::Name(_) => "Name",
            Object::String(_, _) => "String",
            Object::Array(_) => "Array",
            Object::Dictionary(_) => "Dictionary",
            Object::Stream(_) => "Stream",
            Object::Reference(_) => "Reference",
        }
    }
}

impl fmt::Debug for Object {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        match self {
            Object::Null => write!(f, "Null"),
            Object::Boolean(value) => write!(f, "{value}"),
            Object::Integer(value) => write!(f, "{value}"),
            Object::Real(value) => write!(f, "{value}"),
            Object::Name(name) => write!(f, "/{}", String::from_utf8_lossy(name)),
            Object::String(text, StringFormat::Literal) => write!(f, "({})", String::from_utf8_lossy(text)),
            Object::String(text, StringFormat::Hexadecimal) => {
                write!(f, "<")?;
                for b in text {
                    write!(f, "{b:02x}")?
                }
                write!(f, ">")
            }
            Object::Array(array) => {
                let items = array.iter().map(|item| format!("{item:?}")).collect::<Vec<String>>();
                write!(f, "[{}]", items.join(" "))
            }
            Object::Dictionary(dict) => write!(f, "{dict:?}"),
            Object::Stream(stream) => write!(f, "{:?}stream...endstream", stream.dict),
            Object::Reference(id) => write!(f, "{} {} R", id.0, id.1),
        }
    }
}

impl Dictionary {
    pub fn new() -> Dictionary {
        Dictionary(IndexMap::new())
    }

    pub fn has(&self, key: &[u8]) -> bool {
        self.0.contains_key(key)
    }

    pub fn get(&self, key: &[u8]) -> Result<&Object> {
        self.0
            .get(key)
            .ok_or(Error::DictKey(String::from_utf8_lossy(key).to_string()))
    }

    /// Extract object from dictionary, dereferencing
    /// the object if it is a reference.
    pub fn get_deref<'a>(&'a self, key: &[u8], doc: &'a Document) -> Result<&'a Object> {
        doc.dereference(self.get(key)?).map(|(_, object)| object)
    }

    pub fn get_mut(&mut self, key: &[u8]) -> Result<&mut Object> {
        self.0
            .get_mut(key)
            .ok_or(Error::DictKey(String::from_utf8_lossy(key).to_string()))
    }

    pub fn set<K, V>(&mut self, key: K, value: V)
    where
        K: Into<Vec<u8>>,
        V: Into<Object>,
    {
        self.0.insert(key.into(), value.into());
    }

    pub fn len(&self) -> usize {
        self.0.len()
    }

    pub fn is_empty(&self) -> bool {
        self.0.len() == 0
    }

    pub fn remove(&mut self, key: &[u8]) -> Option<Object> {
        self.0.swap_remove(key)
    }

    pub fn has_type(&self, type_name: &[u8]) -> bool {
        self.get(b"Type").and_then(|s| s.as_name()).ok() == Some(type_name)
    }

    pub fn get_type(&self) -> Result<&[u8]> {
        self.get(b"Type")
            .and_then(Object::as_name)
            .or_else(|_| self.get(b"Linearized").and(Ok(b"Linearized")))
    }

    pub fn iter(&'_ self) -> indexmap::map::Iter<'_, Vec<u8>, Object> {
        self.0.iter()
    }

    pub fn iter_mut(&'_ mut self) -> indexmap::map::IterMut<'_, Vec<u8>, Object> {
        self.0.iter_mut()
    }

    pub fn get_font_encoding(&'_ self, doc: &Document) -> Result<Encoding<'_>> {
        if !self.has_type(b"Font") {
            return Err(Error::DictType {
                expected: "Font",
                found: String::from_utf8_lossy(self.get_type().unwrap_or(b"None")).to_string(),
            });
        }

        // Note: currently not all encodings are handled, not implemented:
        // - dictionary differences encoding
        // - default base encoding in dictionary differences encoding
        // - TrueType cmap tables
        // - DescendantFonts in CID-Keyed fonts
        // - predefined CJK CMAP other than indicated in SimpleEncoding
        match self.get(b"Encoding").and_then(Object::as_name) {
            Ok(b"StandardEncoding") => Ok(Encoding::OneByteEncoding(&encodings::STANDARD_ENCODING)),
            Ok(b"MacRomanEncoding") => Ok(Encoding::OneByteEncoding(&encodings::MAC_ROMAN_ENCODING)),
            Ok(b"MacExpertEncoding") => Ok(Encoding::OneByteEncoding(&encodings::MAC_EXPERT_ENCODING)),
            Ok(b"WinAnsiEncoding") => Ok(Encoding::OneByteEncoding(&encodings::WIN_ANSI_ENCODING)),
            Ok(b"PDFDocEncoding") => {
                log::warn!("PDFDocEncoding is not a valid character encoding for a font");
                Ok(Encoding::OneByteEncoding(&encodings::PDF_DOC_ENCODING))
            }
            Ok(b"Identity-H") | Ok(b"Identity-V") => {
                let stream = self.get_deref(b"ToUnicode", doc)?.as_stream()?;
                self.get_encoding_from_to_unicode_cmap(stream)
            }
            Ok(name) => Ok(Encoding::SimpleEncoding(name)),
            Err(err) => {
                warn!(
                    "Could not parse the encoding, error: {err:#?}\nFont: {self:#?}\nTrying to retrieve ToUnicode."
                );
                let stream = self.get_deref(b"ToUnicode", doc).and_then(Object::as_stream);
                if let Ok(stream) = stream {
                    return self.get_encoding_from_to_unicode_cmap(stream);
                }

                warn!("Using standard encoding as a fallback!");
                Ok(Encoding::OneByteEncoding(&encodings::STANDARD_ENCODING))
            }
        }
    }

    fn get_encoding_from_to_unicode_cmap(&'_ self, stream: &Stream) -> Result<Encoding<'_>> {
        let content = stream.get_plain_content()?;
        let cmap = ToUnicodeCMap::parse(content)?;
        Ok(Encoding::UnicodeMapEncoding(cmap))
    }

    pub fn extend(&mut self, other: &Dictionary) {
        let keep_both_objects =
            |new_dict: &mut IndexMap<Vec<u8>, Object>, key: &Vec<u8>, value: &Object, old_value: Object| {
                let mut final_array;

                match value {
                    Object::Array(array) => {
                        final_array = Vec::with_capacity(array.len() + 1);
                        final_array.push(old_value);
                        final_array.extend(array.to_owned());
                    }
                    _ => {
                        final_array = vec![value.to_owned(), old_value];
                    }
                }

                new_dict.insert(key.to_owned(), Object::Array(final_array));
            };

        let mut new_dict = std::mem::take(&mut self.0);
        new_dict.reserve_exact(other.0.len());

        for (key, value) in other.0.iter() {
            if let Some(old_value) = new_dict.get(key) {
                let old_value = old_value.to_owned();
                match (&old_value, value) {
                    (Object::Dictionary(old_dict), Object::Dictionary(dict)) => {
                        let mut replaced_dict = old_dict.to_owned();
                        replaced_dict.extend(dict);
                        new_dict.insert(key.to_owned(), Object::Dictionary(replaced_dict));
                    }
                    (Object::Array(old_array), Object::Array(array)) => {
                        let mut replaced_array = old_array.to_owned();
                        replaced_array.extend(array.to_owned());
                        new_dict.insert(key.to_owned(), Object::Array(replaced_array));
                    }
                    (Object::Integer(old_id), Object::Integer(id)) => {
                        let array = vec![Object::Integer(*old_id), Object::Integer(*id)];
                        new_dict.insert(key.to_owned(), Object::Array(array));
                    }
                    (Object::Real(old_id), Object::Real(id)) => {
                        let array = vec![Object::Real(*old_id), Object::Real(*id)];
                        new_dict.insert(key.to_owned(), Object::Array(array));
                    }
                    (Object::String(old_ids, old_format), Object::String(ids, format)) => {
                        let array = vec![
                            Object::String(old_ids.to_owned(), old_format.to_owned()),
                            Object::String(ids.to_owned(), format.to_owned()),
                        ];
                        new_dict.insert(key.to_owned(), Object::Array(array));
                    }
                    (Object::Reference(old_object_id), Object::Reference(object_id)) => {
                        let array = vec![Object::Reference(*old_object_id), Object::Reference(*object_id)];
                        new_dict.insert(key.to_owned(), Object::Array(array));
                    }
                    (Object::Null, _) | (Object::Boolean(_), _) | (Object::Name(_), _) | (Object::Stream(_), _) => {
                        new_dict.insert(key.to_owned(), old_value);
                    }
                    (_, _) => keep_both_objects(&mut new_dict, key, value, old_value),
                }
            } else {
                new_dict.insert(key.to_owned(), value.to_owned());
            }
        }

        self.0 = new_dict;
    }

    /// Return a reference to the inner  [`IndexMap`].
    pub fn as_hashmap(&self) -> &IndexMap<Vec<u8>, Object> {
        &self.0
    }

    /// Return a mut reference to the inner [`IndexMap`].
    pub fn as_hashmap_mut(&mut self) -> &mut IndexMap<Vec<u8>, Object> {
        &mut self.0
    }
}

#[macro_export]
macro_rules! dictionary {
	() => {
		$crate::Dictionary::new()
	};
	($( $key: expr => $value: expr ),+ ,) => {
		dictionary!( $($key => $value),+ )
	};
	($( $key: expr => $value: expr ),*) => {{
		let mut dict = $crate::Dictionary::new();
		$(
			dict.set($key, $value);
		)*
		dict
	}}
}

impl fmt::Debug for Dictionary {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        let entries = self
            .into_iter()
            .map(|(key, value)| format!("/{} {:?}", String::from_utf8_lossy(key), value))
            .collect::<Vec<String>>();
        write!(f, "<<{}>>", entries.concat())
    }
}

impl IntoIterator for Dictionary {
    type Item = (Vec<u8>, Object);
    type IntoIter = indexmap::map::IntoIter<Vec<u8>, Object>;

    fn into_iter(self) -> Self::IntoIter {
        self.0.into_iter()
    }
}

impl<'a> IntoIterator for &'a Dictionary {
    type Item = (&'a Vec<u8>, &'a Object);
    type IntoIter = indexmap::map::Iter<'a, Vec<u8>, Object>;

    fn into_iter(self) -> Self::IntoIter {
        self.0.iter()
    }
}

impl<'a> IntoIterator for &'a mut Dictionary {
    type Item = (&'a Vec<u8>, &'a mut Object);
    type IntoIter = indexmap::map::IterMut<'a, Vec<u8>, Object>;

    fn into_iter(self) -> Self::IntoIter {
        self.0.iter_mut()
    }
}

use std::iter::FromIterator;
impl<K: Into<Vec<u8>>> FromIterator<(K, Object)> for Dictionary {
    fn from_iter<I: IntoIterator<Item = (K, Object)>>(iter: I) -> Self {
        let mut dict = Dictionary::new();
        for (k, v) in iter {
            dict.set(k, v);
        }
        dict
    }
}

impl Stream {
    pub fn new(mut dict: Dictionary, content: Vec<u8>) -> Stream {
        dict.set("Length", content.len() as i64);
        Stream {
            dict,
            content,
            allows_compression: true,
            start_position: None,
        }
    }

    pub fn with_position(dict: Dictionary, position: usize) -> Stream {
        Stream {
            dict,
            content: vec![],
            allows_compression: true,
            start_position: Some(position),
        }
    }

    /// Default is that the stream may be compressed. On font streams,
    /// set this to false, otherwise the font will be corrupt
    #[inline]
    pub fn with_compression(mut self, allows_compression: bool) -> Stream {
        self.allows_compression = allows_compression;
        self
    }

    pub fn filters(&self) -> Result<Vec<&[u8]>> {
        let filter = self.dict.get(b"Filter")?;

        if let Ok(name) = filter.as_name() {
            Ok(vec![name])
        } else if let Ok(names) = filter.as_array() {
            names.iter().map(Object::as_name).collect()
        } else {
            Err(Error::ObjectType {
                expected: "Name or Array",
                found: filter.enum_variant(),
            })
        }
    }

    pub fn set_content(&mut self, content: Vec<u8>) {
        self.content = content;
        self.dict.set("Length", self.content.len() as i64);
    }

    pub fn set_plain_content(&mut self, content: Vec<u8>) {
        self.dict.remove(b"DecodeParms");
        self.dict.remove(b"Filter");
        self.dict.set("Length", content.len() as i64);
        self.content = content;
    }

    pub fn get_plain_content(&self) -> Result<Vec<u8>> {
        match self.filters() {
            Ok(vec) if !vec.is_empty() => self.decompressed_content(),
            _ => Ok(self.content.clone()),
        }
    }

    pub fn compress(&mut self) -> Result<()> {
        use flate2::write::ZlibEncoder;
        use flate2::Compression;
        use std::io::prelude::*;

        if self.dict.get(b"Filter").is_err() {
            let mut encoder = ZlibEncoder::new(Vec::new(), Compression::best());
            encoder.write_all(self.content.as_slice())?;
            let compressed = encoder.finish()?;
            if compressed.len() + 19 < self.content.len() {
                self.dict.set("Filter", "FlateDecode");
                self.set_content(compressed);
            }
        }
        Ok(())
    }

    pub fn decompressed_content(&self) -> Result<Vec<u8>> {
        let params = self.dict.get(b"DecodeParms").and_then(Object::as_dict).ok();
        let filters = self.filters()?;

        let mut input = self.content.as_slice();
        let mut output = vec![];

        // Filters are in decoding order.
        for filter in filters {
            output = match filter {
                b"FlateDecode" => Self::decompress_zlib(input, params)?,
                b"LZWDecode" => Self::decompress_lzw(input, params)?,
                b"ASCII85Decode" => Self::decode_ascii85(input)?,
                _ => return Err(Error::Unimplemented("decompression algorithms")),
            };
            input = &output;
        }
        Ok(output)
    }

    fn decompress_lzw(input: &[u8], params: Option<&Dictionary>) -> Result<Vec<u8>> {
        use weezl::{decode::Decoder, BitOrder};
        const MIN_BITS: u8 = 9;

        let early_change = params
            .and_then(|p| p.get(b"EarlyChange").ok())
            .and_then(|p| Object::as_i64(p).ok())
            .map(|v| v != 0)
            .unwrap_or(true);

        let mut decoder = if early_change {
            Decoder::with_tiff_size_switch(BitOrder::Msb, MIN_BITS - 1)
        } else {
            Decoder::new(BitOrder::Msb, MIN_BITS - 1)
        };

        let output = Self::decompress_lzw_loop(input, &mut decoder);
        Self::decompress_predictor(output, params)
    }

    fn decompress_lzw_loop(input: &[u8], decoder: &mut weezl::decode::Decoder) -> Vec<u8> {
        let mut output = vec![];

        let result = decoder.into_stream(&mut output).decode_all(input);
        if let Err(err) = result.status {
            warn!("{err}");
        }

        output
    }

    fn decompress_zlib(input: &[u8], params: Option<&Dictionary>) -> Result<Vec<u8>> {
        use flate2::read::ZlibDecoder;
        use std::io::prelude::*;

        let mut output = Vec::with_capacity(input.len() * 2);

        if !input.is_empty() {
            let mut decoder = ZlibDecoder::new(input);
            if let Err(err) = decoder.read_to_end(&mut output) {
                warn!("{err}");
                // Zlib decompression failed (e.g. corrupt adler32 checksum in
                // encrypted PDFs). Retry with raw deflate, skipping the 2-byte
                // zlib header and ignoring the checksum.
                if output.is_empty() && input.len() > 2 {
                    use flate2::read::DeflateDecoder;
                    let mut raw_decoder = DeflateDecoder::new(&input[2..]);
                    if let Err(raw_err) = raw_decoder.read_to_end(&mut output) {
                        warn!("raw deflate fallback also failed: {raw_err}");
                    }
                }
            }
        }
        Self::decompress_predictor(output, params)
    }

    fn decode_ascii85(input: &[u8]) -> Result<Vec<u8>> {
        let mut output = vec![];
        let mut buffer: u32 = 0;
        let mut count = 0;
        // Check for EOD marker
        let input_no_eod = if input.len() >= 2 && &input[input.len() - 2..] == b"~>" {
            &input[..input.len() - 2]
        } else {
            log::warn!("ASCII85 stream is missing its EOD marker");
            input
        };
        for &ch in input_no_eod {
            if ch == b'z' {
                if count != 0 {
                    return Err(DecompressError::Ascii85("z character is not allowed in the middle of a group").into());
                }
                output.extend_from_slice(&[0, 0, 0, 0]);
                continue;
            }

            if ch.is_ascii_whitespace() {
                continue;
            }

            if !(b'!'..=b'u').contains(&ch) {
                break;
            }
            buffer = buffer
                .checked_mul(85)
                .ok_or(DecompressError::Ascii85("multiplication overflow"))?;
            buffer += (ch - b'!') as u32;
            count += 1;

            if count == 5 {
                output.extend_from_slice(&buffer.to_be_bytes());
                buffer = 0;
                count = 0;
            }
        }

        if count > 0 {
            for _ in count..5 {
                buffer = buffer
                    .checked_mul(85)
                    .ok_or(DecompressError::Ascii85("multiplication overflow"))?;
                buffer += 84;
            }

            let bytes = buffer.to_be_bytes();
            output.extend_from_slice(&bytes[..count - 1]);
        }

        Ok(output)
    }

    fn decompress_predictor(mut data: Vec<u8>, params: Option<&Dictionary>) -> Result<Vec<u8>> {
        use crate::filters::png;

        if let Some(params) = params {
            let predictor = params.get(b"Predictor").and_then(Object::as_i64).unwrap_or(1);
            if (10..=15).contains(&predictor) {
                let pixels_per_row = max(1, params.get(b"Columns").and_then(Object::as_i64).unwrap_or(1)) as usize;
                let colors = max(1, params.get(b"Colors").and_then(Object::as_i64).unwrap_or(1)) as usize;
                let bits = max(8, params.get(b"BitsPerComponent").and_then(Object::as_i64).unwrap_or(8)) as usize;
                let bytes_per_pixel = colors * bits / 8;
                data = png::decode_frame(data.as_slice(), bytes_per_pixel, pixels_per_row)?;
            }
            Ok(data)
        } else {
            Ok(data)
        }
    }

    pub fn decompress(&mut self) -> Result<()> {
        let data = self.decompressed_content()?;
        self.dict.remove(b"DecodeParms");
        self.dict.remove(b"Filter");
        self.set_content(data);
        Ok(())
    }

    pub fn is_compressed(&self) -> bool {
        self.dict.get(b"Filter").is_ok()
    }
}

#[cfg(test)]
mod test {
    use crate::{error::DecompressError, Error};

    use super::Stream;

    #[test]
    fn test_decode_ascii85() {
        let input = r#"9jqo^BlbD-BleB1DJ+*+F(f,q/0JhKF<GL>Cj@.4Gp$d7F!,L7@<6@)/0JDEF<G%<+EV:2F!,O<
            DJ+*.@<*K0@<6L(Df-\0Ec5e;DffZ(EZee.Bl.9pF"AGXBPCsi+DGm>@3BB/F*&OCAfu2/AKYi(
            DIb:@FD,*)+C]U=@3BN#EcYf8ATD3s@q?d$AftVqCh[NqF<G:8+EV:.+Cf>-FD5W8ARlolDIal(
            DId<j@<?3r@:F%a+D58'ATD4$Bl@l3De:,-DJs`8ARoFb/0JMK@qB4^F!,R<AKZ&-DfTqBG%G>u
            D.RTpAKYo'+CT/5+Cei#DII?(E,9)oF*2M7/c~>"#;
        let expected = "Man is distinguished, not only by his reason, but by this singular passion from other animals, which is a lust of the mind, that by a perseverance of delight in the continued and indefatigable generation of knowledge, exceeds the short vehemence of any carnal pleasure.";
        let output = Stream::decode_ascii85(input.as_bytes()).unwrap();
        println!("{}", String::from_utf8(output.clone()).unwrap());
        assert_eq!(&output, expected.as_bytes());
    }

    #[test]
    fn test_decode_ascii85_overflow() {
        let input = b"uuuuu~>";
        let output = Stream::decode_ascii85(input);
        // let expected: Result<Vec<u8>, Error> = Err(Error::ContentDecode);
        assert!(matches!(output, Err(Error::Decompress(DecompressError::Ascii85(_)))));
    }

    #[test]
    fn test_decompress_zlib_corrupt_checksum() {
        use flate2::write::ZlibEncoder;
        use flate2::Compression;
        use std::io::Write;

        let original = b"BT /F1 12 Tf (Hello World) Tj ET";

        // Compress with valid zlib
        let mut encoder = ZlibEncoder::new(Vec::new(), Compression::default());
        encoder.write_all(original).unwrap();
        let mut compressed = encoder.finish().unwrap();

        // Corrupt the adler32 checksum (last 4 bytes)
        let len = compressed.len();
        assert!(len >= 4);
        for byte in &mut compressed[len - 4..] {
            *byte ^= 0xFF;
        }

        // Normal zlib should fail, but our fallback should recover
        let result = Stream::decompress_zlib(&compressed, None).unwrap();
        assert_eq!(result, original);
    }
}