use std::io::{Read, Seek, SeekFrom};
use binrw::BinRead;
use crate::compression::no_header_decompress;
use crate::dat::{BlockHeader, CompressionMode};
pub fn read_data_block<T: Read + Seek>(mut buf: T, starting_position: u64) -> Option<Vec<u8>> {
buf.seek(SeekFrom::Start(starting_position)).ok()?;
let block_header = BlockHeader::read(&mut buf).unwrap();
match block_header.compression {
CompressionMode::Compressed {
compressed_length,
decompressed_length,
} => {
let mut compressed_data: Vec<u8> = vec![0; compressed_length as usize];
buf.read_exact(&mut compressed_data).ok()?;
let mut decompressed_data: Vec<u8> = vec![0; decompressed_length as usize];
if !no_header_decompress(&mut compressed_data, &mut decompressed_data) {
return None;
}
Some(decompressed_data)
}
CompressionMode::Uncompressed { file_size } => {
let mut local_data: Vec<u8> = vec![0; file_size as usize];
buf.read_exact(&mut local_data).ok()?;
Some(local_data)
}
}
}
pub fn read_data_block_patch<T: Read + Seek>(mut buf: T) -> Option<Vec<u8>> {
let block_header = BlockHeader::read(&mut buf).unwrap();
match block_header.compression {
CompressionMode::Compressed {
compressed_length,
decompressed_length,
} => {
let compressed_length: usize =
((compressed_length as usize + 143) & 0xFFFFFF80) - (block_header.size as usize);
let mut compressed_data: Vec<u8> = vec![0; compressed_length];
buf.read_exact(&mut compressed_data).ok()?;
let mut decompressed_data: Vec<u8> = vec![0; decompressed_length as usize];
if !no_header_decompress(&mut compressed_data, &mut decompressed_data) {
return None;
}
Some(decompressed_data)
}
CompressionMode::Uncompressed { file_size } => {
let new_file_size: usize = (file_size as usize + 143) & 0xFFFFFF80;
let mut local_data: Vec<u8> = vec![0; file_size as usize];
buf.read_exact(&mut local_data).ok()?;
buf.seek(SeekFrom::Current(
(new_file_size - block_header.size as usize - file_size as usize) as i64,
))
.ok()?;
Some(local_data)
}
}
}