write a metadata to uncompressed pak

src/app.rs

@@ -24,7 +24,7 @@ use ree_pak_core::{
     write::FileOptions,
 };
 
-use crate::{chunk::ChunkName, util::human_bytes};
+use crate::{chunk::ChunkName, metadata::PakMetadata, util::human_bytes};
 
 const FILE_NAME_LIST: &[u8] = include_bytes!("../assets/MHWs_STM_Release.list.zst");
 const AUTO_CHUNK_SELECTION_SIZE_THRESHOLD: usize = 50 * 1024 * 1024; // 50MB
@@ -111,7 +111,15 @@ impl App {
             .truncate(true)
             .write(true)
             .open(output_path)?;
-        let pak_writer = ree_pak_core::write::PakWriter::new(out_file, entries.len() as u64);
+        let mut pak_writer = ree_pak_core::write::PakWriter::new(out_file, entries.len() as u64);
+
+        // write metadata
+        let metadata = PakMetadata {
+            version: 1,
+            is_uncompressed_patch: true,
+        };
+        metadata.write_to_pak(&mut pak_writer)?;
+
         let pak_writer_mtx = Arc::new(Mutex::new(pak_writer));
 
         let bar = ProgressBar::new(entries.len() as u64);

src/main.rs

@@ -1,5 +1,6 @@
 mod app;
 mod chunk;
+mod metadata;
 mod util;
 
 use colored::Colorize;

src/metadata.rs

@@ -0,0 +1,61 @@
+//! Extended metadata for generated pak files.
+
+use std::io::{self, Read, Write};
+
+use ree_pak_core::{
+    filename::{FileNameExt, FileNameFull},
+    pak::PakArchive,
+    read::archive::PakArchiveReader,
+    write::{FileOptions, PakWriter},
+};
+use serde::{Deserialize, Serialize};
+
+const METADATA_KEY: &str = "__TEX_DECOMPRESSOR_METADATA__";
+
+#[derive(Debug, Clone, Serialize, Deserialize)]
+pub struct PakMetadata {
+    pub version: u32,
+    pub is_uncompressed_patch: bool,
+}
+
+impl PakMetadata {
+    pub fn from_pak_archive<R>(
+        reader: R,
+        pak_archive: &PakArchive,
+    ) -> color_eyre::Result<Option<Self>>
+    where
+        R: io::Read + io::Seek,
+    {
+        let key_name = FileNameFull::new(METADATA_KEY);
+        let entry = pak_archive
+            .entries()
+            .iter()
+            .find(|entry| entry.hash() == key_name.hash_mixed());
+
+        if let Some(entry) = entry {
+            // read file
+            let mut archive_reader = PakArchiveReader::new(reader, pak_archive);
+            let mut entry_reader = archive_reader.owned_entry_reader(entry.clone())?;
+            let mut buf = Vec::new();
+            entry_reader.read_to_end(&mut buf)?;
+
+            let metadata = serde_json::from_slice(&buf)?;
+            Ok(Some(metadata))
+        } else {
+            Ok(None)
+        }
+    }
+
+    pub fn write_to_pak<W>(&self, pak_writer: &mut PakWriter<W>) -> color_eyre::Result<()>
+    where
+        W: io::Write + io::Seek,
+    {
+        let json_str = serde_json::to_string(self)?;
+        let json_bytes = json_str.as_bytes();
+
+        pak_writer.start_file(METADATA_KEY, FileOptions::default())?;
+        pak_writer.write_all(json_bytes)?;
+
+        Ok(())
+    }
+}