From b1ceaaf636cd21098ad77bc1d75ae88684252373 Mon Sep 17 00:00:00 2001
From: Draklaw <drakdiv@gmail.com>
Date: Sun, 5 Sep 2021 01:09:59 +0200
Subject: [PATCH] Implement RefStore for SimpleCas.

---
 cas-core/src/lib.rs   |  2 +-
 cas-simple/src/cas.rs | 75 ++++++++++++++++++++++++++++++++++++++++++-
 2 files changed, 75 insertions(+), 2 deletions(-)

diff --git a/cas-core/src/lib.rs b/cas-core/src/lib.rs
index 9d8bacd..5db84a5 100644
--- a/cas-core/src/lib.rs
+++ b/cas-core/src/lib.rs
@@ -39,6 +39,6 @@ pub use crate::{
     object_type::{ObjectType},
     object_metadata::{ObjectMetadata},
     pipeline::{Pipeline, DefaultPipeline, Reader, Writer, ReadWrapper, WriteWrapper},
-    cas::{Cas},
+    cas::{Cas, RefStore},
 };
 
diff --git a/cas-simple/src/cas.rs b/cas-simple/src/cas.rs
index 9d3714d..52e5360 100644
--- a/cas-simple/src/cas.rs
+++ b/cas-simple/src/cas.rs
@@ -21,7 +21,7 @@ use digest::DynDigest;
 use toml::Value;
 use cas_core::{
     Cas, DefaultPipeline, Error, ObjectId, ObjectMetadata, ObjectType,
-    Pipeline, Reader, ReadWrapper, Result, Writer,
+    Pipeline, Reader, ReadWrapper, RefStore, Result, Writer,
 };
 
 use crate::utils::{
@@ -162,6 +162,57 @@ impl Cas for SimpleCas {
     }
 }
 
+impl RefStore for SimpleCas {
+    fn get_ref<P: AsRef<Path>>(&self, key: P) -> Result<ObjectId> {
+        let path = ref_dir(&self.db_path).join(key.as_ref());
+        if !path.exists() {
+            Error::err(format!("reference {} does not exists", key.as_ref().to_string_lossy()))
+        }
+        else if !path.is_file() {
+            Error::err(format!("reference {} is not a file", key.as_ref().to_string_lossy()))
+        }
+        else {
+            let file = std::fs::read(path).or_else(|err|
+                Error::err(format!("failed to read reference file for {}: {}", key.as_ref().to_string_lossy(), err))
+            )?;
+            Ok(
+                ObjectId::from_str(
+                    std::str::from_utf8(&file).or_else(|err|
+                        Error::err(format!("invalid reference file at {}: {}", key.as_ref().to_string_lossy(), err))
+                    )?
+                )?
+            )
+        }
+    }
+
+    fn set_ref<P: AsRef<Path>>(&mut self, key: P, value: &ObjectId) -> Result<()> {
+        let path = ref_dir(&self.db_path).join(key.as_ref());
+        std::fs::create_dir_all(path.parent().ok_or_else(||
+            Error::error(format!("reference file {} has no parent dir?", key.as_ref().to_string_lossy()))
+        )?).or_else(|err|
+            Error::err(format!("failed to create reference dir for {}: {}", key.as_ref().to_string_lossy(), err))
+        )?;
+        std::fs::write(path, value.to_string()).or_else(|err|
+            Error::err(format!("failed to write reference {}: {}", key.as_ref().to_string_lossy(), err))
+        )
+    }
+
+    fn remove_ref<P: AsRef<Path>>(&mut self, key: P) -> Result<()> {
+        let path = ref_dir(&self.db_path).join(key.as_ref());
+        if !path.exists() {
+            Error::err(format!("reference {} does not exists", key.as_ref().to_string_lossy()))
+        }
+        else if !path.is_file() {
+            Error::err(format!("reference {} is not a file", key.as_ref().to_string_lossy()))
+        }
+        else {
+            std::fs::remove_file(path).or_else(|err|
+                Error::err(format!("failed to remove reference file {}: {}", key.as_ref().to_string_lossy(), err))
+            )
+        }
+    }
+}
+
 
 pub struct ObjectIdIterator {
     root_dirs: Vec<PathBuf>,
@@ -560,4 +611,26 @@ mod tests {
             .collect::<Result<Vec<_>>>().unwrap();
         assert_eq!(objects, oids);
     }
+
+    #[test]
+    fn test_reference() {
+        let dir = tempfile::tempdir().expect("failed to create temp test dir");
+        let cas_path = get_cas_path(dir.path());
+        let config = get_config();
+
+        let mut cas = SimpleCas::create(cas_path.clone(), config)
+            .expect("failed to create SimpleCas object");
+
+        let oid_0 = ObjectId::from_str("f731f6bc6a6a73bad170e56452473ef6930b7a0ab33cc54be44221a89b49d786").unwrap();
+
+        assert!(cas.get_ref("foo/bar").is_err());
+        assert!(cas.remove_ref("foo/bar").is_err());
+
+        cas.set_ref("foo/bar", &oid_0).unwrap();
+        assert_eq!(cas.get_ref("foo/bar").unwrap(), oid_0);
+
+        cas.remove_ref("foo/bar").unwrap();
+
+        assert!(cas.get_ref("foo/bar").is_err());
+    }
 }