Support ~ and $HOME components in path option (#278)

* Support ~ and $HOME components in path option

* Clean up error handling, canonicalize after replacing components

* Clean up error handling further

src/config.rs

@@ -1,9 +1,10 @@
 //! This module contains the config specification and functionality for creating a config.
 
+use anyhow::Result;
 use clap::ValueEnum;
 use serde::{Deserialize, Serialize};
-use std::path::PathBuf;
-use std::{env, fs, io};
+use std::path::{Path, PathBuf};
+use std::{env, fs};
 
 /// This struct is the actual config type consumed through the codebase. It is boostrapped via its
 /// public methods and uses [`EntryConfig`], a private struct, under the hood in order to
@@ -22,7 +23,7 @@ impl Config {
     /// This method tries to deserialize the config file (empty, non-existent, partial or complete)
     /// and uses [`EntryConfig`] as an intermediary struct. This is the primary method used when
     /// creating a config.
-    pub fn try_config() -> anyhow::Result<Self> {
+    pub fn try_config() -> Result<Self> {
         // Within this method, we check if the config file is empty before deserializing it. Users
         // should be able to proceed with empty config files. If empty or not found, then we fall
         // back to the "EntryConfig" default before conversion.
@@ -37,7 +38,7 @@ impl Config {
 
         let path = match paths.into_iter().find(|p| p.exists()) {
             Some(path) => path,
-            None => return Ok(Self::try_config_default()?),
+            None => return Self::try_config_default(),
         };
 
         let contents = fs::read_to_string(path)?;
@@ -46,25 +47,25 @@ impl Config {
         } else {
             toml::from_str(&contents)?
         };
-        Ok(Self::from_entry_config(&entry_config)?)
+        Self::from_entry_config(&entry_config)
     }
 
     /// This method does not look for the config file and uses [`EntryConfig`]'s defaults instead.
     /// Use this method when the user wishes to skip config file lookup.
-    pub fn try_config_default() -> io::Result<Self> {
+    pub fn try_config_default() -> Result<Self> {
         Self::from_entry_config(&EntryConfig::default())
     }
 
     /// This method prints the full config (merged with config file, as needed) as valid, pretty TOML.
-    pub fn print(self) -> std::result::Result<(), toml::ser::Error> {
+    pub fn print(self) -> Result<(), toml::ser::Error> {
         print!("{}", toml::to_string_pretty(&self)?);
         Ok(())
     }
 
-    fn from_entry_config(entry_config: &EntryConfig) -> io::Result<Self> {
+    fn from_entry_config(entry_config: &EntryConfig) -> Result<Self> {
         Ok(Config {
             path: match &entry_config.path {
-                Some(path) => path.clone(),
+                Some(path) => normalize_path(path)?,
                 None => env::current_dir()?.canonicalize()?,
             },
             display_mode: match &entry_config.display_mode {
@@ -79,6 +80,17 @@ impl Config {
     }
 }
 
+fn normalize_path(path: &Path) -> Result<PathBuf> {
+    Ok(match path
+        .strip_prefix("~")
+        .or_else(|_| path.strip_prefix("$HOME"))
+    {
+        Ok(stripped) => user_dirs::home_dir()?.join(stripped),
+        Err(_) => path.to_path_buf(),
+    }
+    .canonicalize()?)
+}
+
 /// This struct is a reflection of [`Config`] with its fields wrapped with [`Option`], which
 /// ensures that we can deserialize from partial config file contents and populate empty fields
 /// with defaults. Moreover, enum fields cannot set defaults values currently, so we need to