app: unify config handling stuff a bit

crates/app/src/config/cli.rs

@@ -0,0 +1,12 @@
+use std::path::PathBuf;
+
+use clap::Parser;
+
+#[derive(Parser)]
+pub(crate) struct Args {
+    /// Read this config file.
+    #[arg(short, long)]
+    pub config_file: Option<PathBuf>,
+    #[arg(long, env = "NO_STARTUP_MESSAGE", default_value = "false")]
+    pub no_startup_message: bool,
+}

crates/app/src/config/config_file.rs

@@ -0,0 +1,75 @@
+use std::{
+    fs,
+    path::{Path, PathBuf},
+    process,
+};
+
+use serde::{Deserialize, Serialize};
+
+use crate::error_reporting::{report_serde_json_err, report_serde_ron_err};
+
+#[derive(Debug, Serialize, Deserialize)]
+pub struct Configs {
+    #[serde(default = "default_example_value")]
+    pub example_value: i32,
+    #[serde(default = "default_no_startup_msg")]
+    pub no_startup_message: bool,
+}
+
+/// what the fuck serde why do i need this
+pub(crate) fn default_example_value() -> i32 {
+    43
+}
+
+pub(crate) 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");
+
+                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
+                } else if Path::new(&json_path).exists() {
+                    json_path
+                } else {
+                    eprintln!("{}: couldn't find config file", "Fatal error".red());
+                    process::exit(1)
+                }
+            }
+        };
+
+        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),
+        }
+    }
+}