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use super::{flags::Flags, scope::Scope, FlagsError, Packet, ScopeError};
use byteorder::{NetworkEndian, ReadBytesExt, WriteBytesExt};
use std::io::{Read, Write};
#[derive(Debug, thiserror::Error)]
pub enum StartPacketError {
#[error("wrong data_part len")]
DataPartLength,
#[error("couldn't read full data_part")]
ReadFullDataPart,
#[error(transparent)]
Flags(#[from] FlagsError),
#[error(transparent)]
Scope(#[from] ScopeError),
#[error(transparent)]
Io(#[from] std::io::Error),
}
type Result<T> = std::result::Result<T, StartPacketError>;
#[derive(Debug, PartialEq, Eq)]
pub struct StartPacket {
pub stream_id: u8,
pub scope: Scope,
pub data_length: u16,
pub data_part: Vec<u8>,
}
impl StartPacket {
pub const DATA_PART_LENGTH: usize = 64 - 2 * 2 - 1;
pub fn new<S: Into<Scope>>(
stream_id: u8,
scope: S,
data_length: u16,
data_part: Vec<u8>,
) -> Result<Self> {
if data_part.len() != Self::DATA_PART_LENGTH {
return Err(StartPacketError::DataPartLength);
}
Ok(Self {
stream_id,
scope: scope.into(),
data_length,
data_part,
})
}
pub fn new_reader<S: Into<Scope>>(
stream_id: u8,
scope: S,
data_length: u16,
data_stream: &mut impl Read,
) -> Result<Self> {
let mut data_part = Vec::with_capacity(Packet::DATA_LENGTH);
let mut buf = [0; Self::DATA_PART_LENGTH];
let n = data_stream.read(&mut buf)?;
data_part.write_all(&buf[..n])?;
data_part.resize(Self::DATA_PART_LENGTH, 0);
Self::new(stream_id, scope, data_length, data_part)
}
pub fn encode(&self) -> Result<Vec<u8>> {
let mut data = Vec::with_capacity(Packet::DATA_LENGTH);
data.write_all(
&Flags {
is_packet_start: true,
stream_id: self.stream_id,
}
.encode()?,
)?;
data.write_all(&self.scope.encode()?)?;
data.write_u16::<NetworkEndian>(self.data_length)?;
data.write_all(&self.data_part)?;
Ok(data)
}
pub(crate) fn decode(stream_id: u8, data_stream: &mut impl Read) -> Result<Self> {
let scope = Scope::decode(data_stream)?;
let data_length = data_stream.read_u16::<NetworkEndian>()?;
let mut data_part = [0; Self::DATA_PART_LENGTH];
let n = data_stream.read(&mut data_part)?;
if n != Self::DATA_PART_LENGTH {
return Err(StartPacketError::ReadFullDataPart);
}
Ok(Self {
stream_id,
scope,
data_length,
data_part: data_part.to_vec(),
})
}
}