feat: create digest engine with Sha256/Md5/None and integrate with save mode

src/digest_engine.rs

@@ -0,0 +1,37 @@
+use std::io;
+use std::path::PathBuf;
+
+use log::*;
+use strum::IntoEnumIterator;
+
+pub mod none;
+pub mod sha2;
+pub mod program;
+
+use crate::digest_engine::none::DigestEngineNone;
+use crate::digest_engine::sha2::DigestEngineSha256;
+use crate::digest_engine::program::DigestEngineProgram;
+
+#[derive(Debug, Eq, PartialEq, Clone, strum::EnumIter, strum::Display, strum::EnumString, Enum)]
+#[strum(ascii_case_insensitive)]
+pub enum DigestType {
+    Sha256,
+    Md5,
+    None,
+}
+
+pub trait DigestEngine {
+    fn create(&self) -> Box<dyn DigestEngine>;
+    
+    fn update(&mut self, data: &[u8]) -> io::Result<()>;
+    
+    fn finalize(&mut self) -> io::Result<String>;
+}
+
+pub fn get_engine(digest_type: DigestType) -> Box<dyn DigestEngine> {
+    match digest_type {
+        DigestType::Sha256 => Box::new(DigestEngineSha256::new()),
+        DigestType::Md5 => Box::new(DigestEngineProgram::new("md5sum")),
+        DigestType::None => Box::new(DigestEngineNone::new()),
+    }
+}