Initialize Butchunker project structure and policy system

1 files changed, 88 insertions, 0 deletions

diff --git a/src/chunker/rw/storage.rs b/src/chunker/rw/storage.rs
new file mode 100644
index 0000000..13452d0
--- /dev/null
+++ b/src/chunker/rw/storage.rs
@@ -0,0 +1,88 @@
+pub mod build;
+pub mod write;
+
+pub use build::build;
+pub use write::write;
+
+use std::path::{Path, PathBuf};
+
+/// Information about a chunk for index file
+#[derive(Debug, Clone)]
+pub struct ChunkInfo {
+    /// Index of the chunk in the file
+    pub index: usize,
+    /// Hash of the chunk (hex string)
+    pub hash: String,
+    /// Size of the chunk in bytes
+    pub size: usize,
+    /// Start position in the original file
+    pub start: usize,
+    /// End position in the original file (exclusive)
+    pub end: usize,
+}
+
+/// 根据hash值计算chunk文件的存储路径
+///
+/// # 参数
+/// - `storage_dir`: 存储目录
+/// - `hash_hex`: chunk的hash值（16进制字符串）
+///
+/// # 返回
+/// 返回chunk文件的完整路径
+pub fn get_chunk_path(storage_dir: &Path, hash_hex: &str) -> PathBuf {
+    let first_slice = &hash_hex[0..2];
+    let second_slice = &hash_hex[2..4];
+    storage_dir
+        .join(first_slice)
+        .join(second_slice)
+        .join(hash_hex)
+}
+
+/// 根据hash字节数组计算chunk文件的存储路径
+///
+/// # 参数
+/// - `storage_dir`: 存储目录
+/// - `hash_bytes`: chunk的hash值（字节数组）
+///
+/// # 返回
+/// 返回chunk文件的完整路径
+pub fn get_chunk_path_from_bytes(storage_dir: &Path, hash_bytes: &[u8; 32]) -> PathBuf {
+    let hash_hex = hex::encode(hash_bytes);
+    get_chunk_path(storage_dir, &hash_hex)
+}
+
+/// 生成唯一的文件路径，如果文件已存在则添加数字后缀
+///
+/// # 参数
+/// - `output_dir`: 输出目录
+/// - `desired_filename`: 期望的文件名
+///
+/// # 返回
+/// 返回唯一的文件路径
+pub fn generate_unique_path(output_dir: &Path, desired_filename: &str) -> PathBuf {
+    let desired_path = output_dir.join(desired_filename);
+    let mut candidate = desired_path.clone();
+
+    let mut counter = 1;
+    while candidate.exists() {
+        let path_buf = PathBuf::from(desired_filename);
+        if let Some(stem) = path_buf.file_stem() {
+            if let Some(ext) = path_buf.extension() {
+                let ext_str = ext.to_string_lossy();
+                let new_name = if ext_str.is_empty() {
+                    format!("{}_{}", stem.to_string_lossy(), counter)
+                } else {
+                    format!("{}.{}_{}", stem.to_string_lossy(), ext_str, counter)
+                };
+                candidate = output_dir.join(new_name);
+            } else {
+                candidate = output_dir.join(format!("{}_{}", stem.to_string_lossy(), counter));
+            }
+        } else {
+            candidate = output_dir.join(format!("{}_{}", desired_filename, counter));
+        }
+        counter += 1;
+    }
+
+    candidate
+}