refactor: reduce quality findings

adapters/src/unity/unity_2021_3.rs

@@ -5,6 +5,9 @@
 use super::adapter::{ParsedAssetBundle, RawAssetBundle, UnityAdapter, VersionRange};
 use async_trait::async_trait;
 
+const PARSE_NOT_IMPLEMENTED: &str = "parse() 将在 Phase 2 实现";
+const SERIALIZE_NOT_IMPLEMENTED: &str = "serialize() 将在 Phase 2 实现";
+
 /// Unity 2021.3 Adapter
 pub struct Unity2021_3Adapter;
 
@@ -14,35 +17,30 @@ impl Unity2021_3Adapter {
         Self
     }
 
-    /// 检测 Unity 版本（从文件头）
-    fn detect_unity_version(data: &[u8]) -> Option<String> {
-        // UnityFS 文件头结构：
-        // 0x00-0x06: "UnityFS\0"
-        // 0x08-0x0B: format version
-        // 0x0C-...: Unity version string
-
+    fn unity_version_bytes(data: &[u8]) -> Option<&[u8]> {
         if data.len() < 20 {
             return None;
         }
 
-        // 检查签名
         if &data[0..7] != b"UnityFS" {
             return None;
         }
 
-        // 读取 Unity 版本字符串
-        // 版本字符串从偏移 0x14 开始（可能因格式版本不同而变化）
-        if let Some(version_start) = data.windows(7).position(|w| w.starts_with(b"2021.3.")) {
-            // 读取版本字符串直到 null 或非 ASCII
-            let version_bytes = &data[version_start..];
-            if let Some(end) = version_bytes.iter().position(|&b| b == 0 || !b.is_ascii()) {
-                if let Ok(version) = std::str::from_utf8(&version_bytes[..end]) {
-                    return Some(version.to_string());
-                }
-            }
-        }
+        let version_start = data.windows(7).position(|window| window == b"2021.3.")?;
+        let version_bytes = &data[version_start..];
+        let version_end = version_bytes
+            .iter()
+            .position(|&byte| byte == 0 || !byte.is_ascii())?;
 
-        None
+        Some(&version_bytes[..version_end])
+    }
+
+    /// 检测 Unity 版本（从文件头）
+    fn detect_unity_version(data: &[u8]) -> Option<String> {
+        let version_bytes = Self::unity_version_bytes(data)?;
+        std::str::from_utf8(version_bytes)
+            .map(ToOwned::to_owned)
+            .ok()
     }
 }
 
@@ -78,7 +76,7 @@ impl UnityAdapter for Unity2021_3Adapter {
         // 2. 解压缩数据块
         // 3. 解析 TypeTree
         // 4. 提取 Asset 对象
-        Err("parse() 将在 Phase 2 实现".to_string())
+        Err(PARSE_NOT_IMPLEMENTED.to_string())
     }
 
     async fn serialize(&self, _parsed: &ParsedAssetBundle) -> Result<Vec<u8>, String> {
@@ -88,7 +86,7 @@ impl UnityAdapter for Unity2021_3Adapter {
         // 2. 重新构建 TypeTree
         // 3. 压缩数据块
         // 4. 写入 UnityFS 文件头
-        Err("serialize() 将在 Phase 2 实现".to_string())
+        Err(SERIALIZE_NOT_IMPLEMENTED.to_string())
     }
 }