1 files changed, 227 insertions, 0 deletions
diff --git a/libnres/src/reader.rs b/libnres/src/reader.rs
new file mode 100644
index 0000000..2a450ee
--- /dev/null
+++ b/libnres/src/reader.rs
@@ -0,0 +1,227 @@
+use std::io::{Read, Seek};
+
+use byteorder::ByteOrder;
+
+use crate::error::ReaderError;
+use crate::{converter, FILE_TYPE_1, FILE_TYPE_2, LIST_ELEMENT_SIZE, MINIMUM_FILE_SIZE};
+
+#[derive(Debug)]
+pub struct ListElement {
+    /// Unknown parameter
+    _unknown0: i32,
+    /// Unknown parameter
+    _unknown1: i32,
+    /// Unknown parameter
+    _unknown2: i32,
+    /// File extension
+    pub extension: String,
+    /// Identifier or sequence number
+    pub index: u32,
+    /// File name
+    pub name: String,
+    /// Position in the file
+    pub position: u32,
+    /// File size (in bytes)
+    pub size: u32,
+}
+
+impl ListElement {
+    /// Get full name of the file
+    pub fn get_filename(&self) -> String {
+        format!("{}.{}", self.name, self.extension)
+    }
+}
+
+#[derive(Debug)]
+pub struct FileHeader {
+    /// File size
+    size: u32,
+    /// Number of files
+    total: u32,
+    /// First constant value
+    type1: u32,
+    /// Second constant value
+    type2: u32,
+}
+
+/// Get a packed file data
+pub fn get_file(file: &std::fs::File, element: &ListElement) -> Result<Vec<u8>, ReaderError> {
+    let size = get_file_size(file)?;
+    check_file_size(size)?;
+
+    let header = get_file_header(file)?;
+    check_file_header(&header, size)?;
+
+    let data = get_element_data(file, element)?;
+    Ok(data)
+}
+
+/// Get a list of packed files
+pub fn get_list(file: &std::fs::File) -> Result<Vec<ListElement>, ReaderError> {
+    let mut list: Vec<ListElement> = Vec::new();
+
+    let size = get_file_size(file)?;
+    check_file_size(size)?;
+
+    let header = get_file_header(file)?;
+    check_file_header(&header, size)?;
+
+    get_file_list(file, &header, &mut list)?;
+
+    Ok(list)
+}
+
+fn check_file_header(header: &FileHeader, size: u32) -> Result<(), ReaderError> {
+    if header.type1 != FILE_TYPE_1 || header.type2 != FILE_TYPE_2 {
+        return Err(ReaderError::IncorrectHeader);
+    }
+
+    if header.size != size {
+        return Err(ReaderError::IncorrectSizeFile {
+            expected: size,
+            received: header.size,
+        });
+    }
+
+    Ok(())
+}
+
+fn check_file_size(size: u32) -> Result<(), ReaderError> {
+    if size < MINIMUM_FILE_SIZE {
+        return Err(ReaderError::SmallFile {
+            expected: MINIMUM_FILE_SIZE,
+            received: size,
+        });
+    }
+
+    Ok(())
+}
+
+fn get_element_data(file: &std::fs::File, element: &ListElement) -> Result<Vec<u8>, ReaderError> {
+    let position = converter::u32_to_u64(element.position)?;
+    let size = converter::u32_to_usize(element.size)?;
+
+    let mut reader = std::io::BufReader::new(file);
+    let mut buffer = vec![0u8; size];
+
+    if let Err(error) = reader.seek(std::io::SeekFrom::Start(position)) {
+        return Err(ReaderError::ReadFile(error));
+    };
+
+    if let Err(error) = reader.read_exact(&mut buffer) {
+        return Err(ReaderError::ReadFile(error));
+    };
+
+    Ok(buffer)
+}
+
+fn get_element_position(index: u32) -> Result<(usize, usize), ReaderError> {
+    let from = converter::u32_to_usize(index * LIST_ELEMENT_SIZE)?;
+    let to = converter::u32_to_usize((index * LIST_ELEMENT_SIZE) + LIST_ELEMENT_SIZE)?;
+    Ok((from, to))
+}
+
+fn get_file_header(file: &std::fs::File) -> Result<FileHeader, ReaderError> {
+    let mut reader = std::io::BufReader::new(file);
+    let mut buffer = vec![0u8; MINIMUM_FILE_SIZE as usize];
+
+    if let Err(error) = reader.seek(std::io::SeekFrom::Start(0)) {
+        return Err(ReaderError::ReadFile(error));
+    };
+
+    if let Err(error) = reader.read_exact(&mut buffer) {
+        return Err(ReaderError::ReadFile(error));
+    };
+
+    let header = FileHeader {
+        size: byteorder::LittleEndian::read_u32(&buffer[12..16]),
+        total: byteorder::LittleEndian::read_u32(&buffer[8..12]),
+        type1: byteorder::LittleEndian::read_u32(&buffer[0..4]),
+        type2: byteorder::LittleEndian::read_u32(&buffer[4..8]),
+    };
+
+    buffer.clear();
+    Ok(header)
+}
+
+fn get_file_list(
+    file: &std::fs::File,
+    header: &FileHeader,
+    list: &mut Vec<ListElement>,
+) -> Result<(), ReaderError> {
+    let (start_position, list_size) = get_list_position(header)?;
+    let mut reader = std::io::BufReader::new(file);
+    let mut buffer = vec![0u8; list_size];
+
+    if let Err(error) = reader.seek(std::io::SeekFrom::Start(start_position)) {
+        return Err(ReaderError::ReadFile(error));
+    };
+
+    if let Err(error) = reader.read_exact(&mut buffer) {
+        return Err(ReaderError::ReadFile(error));
+    }
+
+    let buffer_size = converter::usize_to_u32(buffer.len())?;
+
+    if buffer_size % LIST_ELEMENT_SIZE != 0 {
+        return Err(ReaderError::IncorrectSizeList {
+            expected: LIST_ELEMENT_SIZE,
+            received: buffer_size,
+        });
+    }
+
+    for i in 0..(buffer_size / LIST_ELEMENT_SIZE) {
+        let (from, to) = get_element_position(i)?;
+        let chunk: &[u8] = &buffer[from..to];
+
+        let element = get_list_element(chunk)?;
+        list.push(element);
+    }
+
+    buffer.clear();
+    Ok(())
+}
+
+fn get_file_size(file: &std::fs::File) -> Result<u32, ReaderError> {
+    let metadata = match file.metadata() {
+        Err(error) => return Err(ReaderError::ReadFile(error)),
+        Ok(value) => value,
+    };
+
+    let result = converter::u64_to_u32(metadata.len())?;
+    Ok(result)
+}
+
+fn get_list_element(buffer: &[u8]) -> Result<ListElement, ReaderError> {
+    let index = byteorder::LittleEndian::read_u32(&buffer[60..64]);
+    let position = byteorder::LittleEndian::read_u32(&buffer[56..60]);
+    let size = byteorder::LittleEndian::read_u32(&buffer[12..16]);
+    let unknown0 = byteorder::LittleEndian::read_i32(&buffer[4..8]);
+    let unknown1 = byteorder::LittleEndian::read_i32(&buffer[8..12]);
+    let unknown2 = byteorder::LittleEndian::read_i32(&buffer[16..20]);
+
+    let extension = String::from_utf8_lossy(&buffer[0..4])
+        .trim_matches(char::from(0))
+        .to_string();
+
+    let name = String::from_utf8_lossy(&buffer[20..56])
+        .trim_matches(char::from(0))
+        .to_string();
+
+    Ok(ListElement {
+        _unknown0: unknown0,
+        _unknown1: unknown1,
+        _unknown2: unknown2,
+        extension,
+        index,
+        name,
+        position,
+        size,
+    })
+}
+
+fn get_list_position(header: &FileHeader) -> Result<(u64, usize), ReaderError> {
+    let position = converter::u32_to_u64(header.size - (header.total * LIST_ELEMENT_SIZE))?;
+    let size = converter::u32_to_usize(header.total * LIST_ELEMENT_SIZE)?;
+    Ok((position, size))
+}