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use crate::Error;
use crate::Tag;
use byteorder::{ReadBytesExt, BE};
use flate2::read::{GzDecoder, ZlibDecoder};
use std::{collections::HashMap, io::Read};
impl Tag {
fn read_known(stream: &mut impl Read, id: u8) -> Result<Tag, Error> {
let tag = match id {
// Signifies the end of a TAG_Compound. It is only ever used inside
// a TAG_Compound, and is not named despite being in a TAG_Compound
0 => Tag::End,
// A single signed byte
1 => Tag::Byte(stream.read_i8().map_err(|_| Error::InvalidTag)?),
// A single signed, big endian 16 bit integer
2 => Tag::Short(stream.read_i16::<BE>().map_err(|_| Error::InvalidTag)?),
// A single signed, big endian 32 bit integer
3 => Tag::Int(stream.read_i32::<BE>().map_err(|_| Error::InvalidTag)?),
// A single signed, big endian 64 bit integer
4 => Tag::Long(stream.read_i64::<BE>().map_err(|_| Error::InvalidTag)?),
// A single, big endian IEEE-754 single-precision floating point
// number (NaN possible)
5 => Tag::Float(stream.read_f32::<BE>().map_err(|_| Error::InvalidTag)?),
// A single, big endian IEEE-754 double-precision floating point
// number (NaN possible)
6 => Tag::Double(stream.read_f64::<BE>().map_err(|_| Error::InvalidTag)?),
// A length-prefixed array of signed bytes. The prefix is a signed
// integer (thus 4 bytes)
7 => {
let length = stream.read_i32::<BE>().map_err(|_| Error::InvalidTag)?;
let mut bytes = Vec::new();
for _ in 0..length {
bytes.push(stream.read_i8().map_err(|_| Error::InvalidTag)?);
}
Tag::ByteArray(bytes)
}
// A length-prefixed modified UTF-8 string. The prefix is an
// unsigned short (thus 2 bytes) signifying the length of the
// string in bytes
8 => {
let length = stream.read_u16::<BE>().map_err(|_| Error::InvalidTag)?;
let mut bytes = Vec::new();
for _ in 0..length {
bytes.push(stream.read_u8().map_err(|_| Error::InvalidTag)?);
}
Tag::String(String::from_utf8(bytes).map_err(|_| Error::InvalidTag)?)
}
// A list of nameless tags, all of the same type. The list is
// prefixed with the Type ID of the items it contains (thus 1
// byte), and the length of the list as a signed integer (a further
// 4 bytes). If the length of the list is 0 or negative, the type
// may be 0 (TAG_End) but otherwise it must be any other type. (The
// notchian implementation uses TAG_End in that situation, but
// another reference implementation by Mojang uses 1 instead;
// parsers should accept any type if the length is <= 0).
9 => {
let type_id = stream.read_u8().map_err(|_| Error::InvalidTag)?;
let length = stream.read_i32::<BE>().map_err(|_| Error::InvalidTag)?;
let mut list = Vec::new();
for _ in 0..length {
list.push(Tag::read_known(stream, type_id)?);
}
Tag::List(list)
}
// Effectively a list of a named tags. Order is not guaranteed.
10 => {
let mut map = HashMap::new();
loop {
let tag_id = stream.read_u8().unwrap_or(0);
if tag_id == 0 {
break;
}
let name = match Tag::read_known(stream, 8)? {
Tag::String(name) => name,
_ => panic!("Expected a string tag"),
};
let tag = Tag::read_known(stream, tag_id).map_err(|_| Error::InvalidTag)?;
map.insert(name, tag);
}
Tag::Compound(map)
}
// A length-prefixed array of signed integers. The prefix is a
// signed integer (thus 4 bytes) and indicates the number of 4 byte
// integers.
11 => {
let length = stream.read_i32::<BE>().map_err(|_| Error::InvalidTag)?;
let mut ints = Vec::new();
for _ in 0..length {
ints.push(stream.read_i32::<BE>().map_err(|_| Error::InvalidTag)?);
}
Tag::IntArray(ints)
}
// A length-prefixed array of signed longs. The prefix is a signed
// integer (thus 4 bytes) and indicates the number of 8 byte longs.
12 => {
let length = stream.read_i32::<BE>().map_err(|_| Error::InvalidTag)?;
let mut longs = Vec::new();
for _ in 0..length {
longs.push(stream.read_i64::<BE>().map_err(|_| Error::InvalidTag)?);
}
Tag::LongArray(longs)
}
_ => return Err(Error::InvalidTagType(id)),
};
Ok(tag)
}
pub fn read(stream: &mut impl Read) -> Result<Tag, Error> {
// default to compound tag
Tag::read_known(stream, 10)
}
pub fn read_zlib(stream: &mut impl Read) -> Result<Tag, Error> {
let mut gz = ZlibDecoder::new(stream);
Tag::read(&mut gz)
}
pub fn read_gzip(stream: &mut impl Read) -> Result<Tag, Error> {
let mut gz = GzDecoder::new(stream);
Tag::read(&mut gz)
}
}
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