Definition of NymConfig trait + default methods

Cargo.lock

@@ -349,6 +349,15 @@ dependencies = [
  "winapi 0.3.8",
 ]
 
+[[package]]
+name = "config"
+version = "0.1.0"
+dependencies = [
+ "handlebars",
+ "serde",
+ "toml",
+]
+
 [[package]]
 name = "constant_time_eq"
 version = "0.1.5"
@@ -1369,13 +1378,13 @@ dependencies = [
  "bs58",
  "built",
  "clap",
+ "config",
  "crypto",
  "curve25519-dalek",
  "directory-client",
  "dirs",
  "dotenv",
  "futures 0.3.1",
- "handlebars",
  "healthcheck",
  "log",
  "mix-client",

Cargo.toml

@@ -9,6 +9,7 @@ members = [
     "common/clients/provider-client",
     "common/clients/validator-client",
     "common/addressing",
+    "common/config",
     "common/crypto",
     "common/healthcheck",
     "common/pemstore",

common/config/Cargo.toml

@@ -0,0 +1,12 @@
+[package]
+name = "config"
+version = "0.1.0"
+authors = ["Jedrzej Stuczynski <andrew@nymtech.net>"]
+edition = "2018"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]
+handlebars = "3.0.1"
+serde = { version = "1.0.104", features = ["derive"] }
+toml = "0.5.6"

common/config/src/lib.rs

@@ -0,0 +1,46 @@
+use handlebars::Handlebars;
+use serde::de::DeserializeOwned;
+use serde::Serialize;
+use std::path::{Path, PathBuf};
+use std::{fs, io};
+
+pub trait NymConfig: Default + Serialize + DeserializeOwned {
+    fn template() -> &'static str;
+
+    fn default_root_directory() -> PathBuf;
+
+    // default, most probable, implementations; can be easily overridden where required
+    fn default_config_directory() -> PathBuf {
+        Self::default_root_directory().join("config")
+    }
+
+    fn default_data_directory() -> PathBuf {
+        Self::default_root_directory().join("data")
+    }
+
+    fn root_directory(&self) -> PathBuf;
+    fn config_directory(&self) -> PathBuf;
+    fn data_directory(&self) -> PathBuf;
+
+    fn save_to_file(&self, custom_location: Option<PathBuf>) -> io::Result<()> {
+        let reg = Handlebars::new();
+        // it's whoever is implementing the trait responsibility to make sure you can execute your own template on your data
+        let templated_config = reg.render_template(Self::template(), self).unwrap();
+
+        fs::write(
+            custom_location.unwrap_or(self.config_directory().join("config.toml")),
+            templated_config,
+        )
+    }
+
+    fn load_from_file(custom_location: Option<PathBuf>) -> io::Result<Self> {
+        let config_contents = fs::read_to_string(
+            custom_location.unwrap_or(Self::default_config_directory().join("config.toml")),
+        )?;
+
+        let parsing_result = toml::from_str(&config_contents)
+            .map_err(|toml_err| io::Error::new(io::ErrorKind::Other, toml_err));
+
+        parsing_result
+    }
+}