Added WIP initial toml merging

mcmpmgr/src/file_merge.rs

@@ -244,8 +244,119 @@ fn test_merge_yaml() {
     );
 }
 
+fn merge_toml(
+    src: &toml::Value,
+    dst: &mut toml::Value,
+    overwrite_existing: bool,
+) -> anyhow::Result<()> {
+    if src.is_table() && dst.is_table() {
+        let src = src.as_table().unwrap();
+        let dst = dst.as_table_mut().unwrap();
+
+        for (k, v) in src.iter() {
+            if v.is_table() {
+                let dst_v = dst.entry(k.clone()).or_insert(serde_yaml::from_str("{}")?);
+                merge_toml(v, dst_v, overwrite_existing)?;
+            } else {
+                if overwrite_existing || !dst.contains_key(k) {
+                    dst.insert(k.clone(), v.clone());
+                }
+            }
+        }
+    } else {
+        // TODO: Keep track of path for better errors
+        anyhow::bail!("Cannot merge non-objects: {src:#?} and {dst:#?}")
+    }
+    Ok(())
+}
+
+#[test]
+fn test_merge_toml() {
+    let src: toml::Value = toml::from_str(
+        r#"
+        a = 3
+
+        [b]
+        [b.x]
+
+        [b.y]
+        test = "thing"
+
+        [c]
+    "#,
+    )
+    .unwrap();
+
+    let mut dst: toml::Value = toml::from_str(
+        r#"
+        [b]
+        [b.y]
+        test = "something"
+
+        [c]
+        foo = "bar"
+    "#,
+    )
+    .unwrap();
+
+    let mut merged_overwrite = dst.clone();
+    let mut merged_retained = dst.clone();
+    merge_toml(&src, &mut merged_overwrite, true).unwrap();
+    merge_toml(&src, &mut merged_retained, false).unwrap();
+
+    assert!(
+        merged_overwrite["b"]["y"]["test"] == "thing".into(),
+        "//b/y/test wasn't overwritten with \"thing\". src={:#?}, dst={:#?}",
+        src,
+        merged_overwrite
+    );
+    assert!(
+        merged_overwrite["a"] == 3.into(),
+        "//a was not set to 3. src={:#?}, dst={:#?}",
+        src,
+        merged_overwrite
+    );
+    assert!(
+        merged_overwrite["b"]["x"].is_table(),
+        "//b/x is not a mapping. src={:#?}, dst={:#?}",
+        src,
+        merged_overwrite
+    );
+    assert!(
+        merged_overwrite["c"]["foo"] == "bar".into(),
+        "//c/foo != bar. src={:#?}, dst={:#?}",
+        src,
+        merged_overwrite
+    );
+
+    assert!(
+        merged_retained["b"]["y"]["test"] == "something".into(),
+        "//b/y/test was overwritten. src={:#?}, dst={:#?}",
+        src,
+        merged_retained
+    );
+    assert!(
+        merged_retained["a"] == 3.into(),
+        "//a was not set to 3. src={:#?}, dst={:#?}",
+        src,
+        merged_retained
+    );
+    assert!(
+        merged_retained["b"]["x"].is_table(),
+        "//b/x is not a mapping. src={:#?}, dst={:#?}",
+        src,
+        merged_retained
+    );
+    assert!(
+        merged_retained["c"]["foo"] == "bar".into(),
+        "//c/foo != bar. src={:#?}, dst={:#?}",
+        src,
+        merged_retained
+    );
+}
+
 /// Merge `src` into `dst` if it is a supported file type
-fn merge_files(
+pub fn merge_files(
     src: &str,
     dst: &str,
     overwrite_existing: bool,
@@ -264,6 +375,11 @@ fn merge_files(
             merge_yaml(&src_val, &mut dst_val, overwrite_existing)?;
             serde_yaml::to_string(&dst_val)?
         }
-        FileType::Toml => todo!(),
+        FileType::Toml => {
+            let src_val: toml::Value = toml::from_str(src)?;
+            let mut dst_val: toml::Value = toml::from_str(dst)?;
+            merge_toml(&src_val, &mut dst_val, overwrite_existing)?;
+            dst_val.to_string()
+        }
     })
 }