app: improve config loading and merging

crates/app/src/config.rs

@@ -1,6 +1,10 @@
 use clap::Parser;
 
-use self::{cli::Args, config_file::Configs};
+use self::{
+    cli::Args,
+    config_file::{find_config_file, Configs},
+    error::ConfigError,
+};
 
 mod cli;
 mod config_file;
@@ -11,14 +15,49 @@ pub struct Config {
 }
 
 impl Config {
-    pub fn read() -> Self {
+    pub fn read() -> Result<Self, ConfigError> {
         let args = Args::parse();
-        let cfg = Configs::read(args.config_file);
+        let config_path = if let Some(config_path) = args.config_path {
+            config_path
+        } else {
+            find_config_file()?
+        };
+        let file_config = Configs::read(config_path)?;
 
-        Self {
+        Ok(Self {
             // this is negated because to an outward api, the negative is more intuitive,
             // while in the source the other way around is more intuitive
-            startup_msg: !(args.no_startup_message || cfg.no_startup_message),
+            startup_msg: !(args.no_startup_message || file_config.no_startup_message),
+        })
+    }
+}
+
+pub mod error {
+    #[derive(Debug)]
+    pub enum ConfigError {
+        NoConfigDir,
+        NoConfigFileFound,
+        IoError(std::io::Error),
+        UnknownExtension(Option<String>),
+        SerdeJsonError(serde_json::Error),
+        SerdeRonError(ron::error::SpannedError),
+    }
+
+    impl From<std::io::Error> for ConfigError {
+        fn from(value: std::io::Error) -> Self {
+            Self::IoError(value)
+        }
+    }
+
+    impl From<serde_json::Error> for ConfigError {
+        fn from(value: serde_json::Error) -> Self {
+            Self::SerdeJsonError(value)
+        }
+    }
+
+    impl From<ron::error::SpannedError> for ConfigError {
+        fn from(value: ron::error::SpannedError) -> Self {
+            Self::SerdeRonError(value)
         }
     }
 }

crates/app/src/config/cli.rs

@@ -6,7 +6,7 @@ use clap::Parser;
 pub(crate) struct Args {
     /// Read this config file.
     #[arg(short, long)]
-    pub config_file: Option<PathBuf>,
+    pub config_path: Option<PathBuf>,
     #[arg(long, env = "NO_STARTUP_MESSAGE", default_value = "false")]
     pub no_startup_message: bool,
 }

crates/app/src/config/config_file.rs

@@ -1,12 +1,11 @@
 use std::{
     fs,
     path::{Path, PathBuf},
-    process,
 };
 
 use serde::{Deserialize, Serialize};
 
-use crate::error_reporting::{report_serde_json_err, report_serde_ron_err};
+use super::error::ConfigError;
 
 #[derive(Debug, Serialize, Deserialize)]
 pub struct Configs {
@@ -17,59 +16,37 @@ pub struct Configs {
 }
 
 /// what the fuck serde why do i need this
-pub(crate) fn default_example_value() -> i32 {
+fn default_example_value() -> i32 {
     43
 }
 
-pub(crate) fn default_no_startup_msg() -> bool {
+fn default_no_startup_msg() -> bool {
     false
 }
 
-impl Configs {
-    pub fn read(custom_path: Option<PathBuf>) -> Self {
-        use owo_colors::OwoColorize;
-        let p = match custom_path {
-            Some(p) => p,
-            None => {
-                let config_path = dirs::config_dir().expect("config dir should exist");
+pub(super) fn find_config_file() -> Result<PathBuf, ConfigError> {
+    let Some(config_path) = dirs::config_dir() else {
+        return Err(ConfigError::NoConfigDir);
+    };
 
     let ron_path = config_path.with_file_name("config.ron");
     let json_path = config_path.with_file_name("config.json");
 
     if Path::new(&ron_path).exists() {
-                    ron_path
+        Ok(ron_path)
     } else if Path::new(&json_path).exists() {
-                    json_path
+        Ok(json_path)
     } else {
-                    eprintln!("{}: couldn't find config file", "Fatal error".red());
-                    process::exit(1)
+        Err(ConfigError::NoConfigFileFound)
     }
-            }
-        };
+}
 
+impl Configs {
+    pub fn read(p: PathBuf) -> Result<Self, ConfigError> {
         match p.extension().map(|v| v.to_str().unwrap()) {
-            Some("ron") => Self::read_json(&fs::read_to_string(p).unwrap()),
-            Some("json") => Self::read_ron(&fs::read_to_string(p).unwrap()),
-            None | Some(_) => {
-                eprintln!(
-                    "{}: couldn't determine config file type",
-                    "Fatal error".red()
-                );
-                process::exit(1)
-            }
-        }
-    }
-    pub fn read_json(config_text: &str) -> Configs {
-        match serde_json::from_str(config_text) {
-            Ok(c) => c,
-            Err(e) => report_serde_json_err(config_text, e),
-        }
-    }
-
-    pub fn read_ron(config_text: &str) -> Configs {
-        match ron::from_str(config_text) {
-            Ok(c) => c,
-            Err(e) => report_serde_ron_err(config_text, e),
+            Some("ron") => Ok(serde_json::from_str(&fs::read_to_string(p)?)?),
+            Some("json") => Ok(ron::from_str(&fs::read_to_string(p)?)?),
+            e => Err(ConfigError::UnknownExtension(e.map(|v| v.to_owned()))),
         }
     }
 }

crates/app/src/main.rs

@@ -2,11 +2,14 @@ use config::Config;
 use welcome_msg::print_startup_msg;
 
 mod config;
+
+#[allow(unused)]
 mod error_reporting;
 mod welcome_msg;
 
 fn main() {
-    let cfg = Config::read();
+    // TODO: proper error handling
+    let cfg = Config::read().unwrap();
 
     if cfg.startup_msg {
         print_startup_msg();