Working retrieval and saving of config file

Only tested on Windows so far

Cargo.toml

@@ -13,3 +13,9 @@ repository = "https://github.com/supleed2/omg-rs"
 # See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
 
 [dependencies]
+anyhow = "1.0.70"
+clap = { version = "4.2.2", features = ["derive"] }
+directories = "5.0.0"
+reqwest = { version = "0.11.16", features = ["blocking", "json"] }
+serde = { version = "1.0.160", features = ["derive"] }
+toml = "0.7.3"

src/main.rs

@@ -1,3 +1,99 @@
-fn main() {
-    println!("Hello, world!");
+use anyhow::Context;
+use clap::{Parser, Subcommand};
+use directories::ProjectDirs;
+use serde::{Deserialize, Serialize};
+use std::fs::read_to_string;
+
+#[derive(Default, Deserialize, Serialize)]
+struct Config {
+    api_key: Option<String>,
+    username: Option<String>,
 }
+
+#[derive(Parser)]
+struct Cli {
+    /// Set a custom username
+    #[clap(short, long)]
+    username: Option<String>,
+
+    #[clap(subcommand)]
+    command: Option<Commands>,
+
+    #[arg(short, long, action = clap::ArgAction::Count)]
+    verbose: u8,
+}
+
+#[derive(Subcommand)]
+enum Commands {
+    Auth {
+        api_key: String,
+    },
+    Weblog {
+        #[arg(short, long)]
+        yay: u8,
+
+        #[arg(short, long)]
+        nay: Option<u8>,
+    },
+    Status {
+        #[arg(long)]
+        message: String,
+
+        /// Does this explain it?
+        req: String,
+    },
+}
+
+fn main() -> anyhow::Result<()> {
+    let cli = Cli::parse();
+
+    if let Some(Commands::Auth { api_key }) = cli.command {
+        let config_path = ProjectDirs::from("com", "supleed2", "omg")
+            .context("Unable to access app config directory (while saving API key).")?
+            .config_dir().join("config.toml");
+        let _ = std::fs::create_dir_all(&config_path.parent().expect("Unable to get parent dir of config.toml"));
+        let Config { api_key: _, username } = read_to_string(&config_path).ok()
+            .and_then(|str| toml::from_str::<Config>(&str).ok())
+            .unwrap_or_default();
+        let toml_str = toml::to_string_pretty(&Config {
+            api_key: Some(api_key),
+            username,
+        })
+        .expect("Unable to convert updated config to TOML (when trying to save API key).");
+        match std::fs::write(&config_path, toml_str) {
+            Ok(_) => {
+                println!("Saved API key to config file: {}", config_path.display());
+                std::process::exit(0);
+            }
+            Err(_) => {
+                eprintln!(
+                    "Failed to save API key to config file: {}",
+                    config_path.display()
+                );
+                std::process::exit(1);
+            }
+        };
+    }
+
+    let config = ProjectDirs::from("com", "supleed2", "omg")
+        .and_then(|dirs| read_to_string(dirs.config_dir().join("config.toml")).ok())
+        .and_then(|str| toml::from_str::<Config>(&str).ok())
+        .context("Unable to parse config.json as config struct.")?;
+
+    let api_key = std::env::var("OMGLOL_API_KEY")
+        .ok()
+        .or(config.api_key)
+        .expect("omg.lol API key not provided as either environment variable or in config file");
+
+    let username = cli.username
+        .or(std::env::var("OMGLOL_USERNAME").ok())
+        .or(config.username)
+        .expect("omg.lol username not provided as command line option, environment variable or in config file");
+
+    println!("omg-rs, ready for @{username}");
+    println!("API key: {}", api_key);
+    Ok(())
+}
+
+// Tutorial at: https://docs.rs/clap/latest/clap/_derive/_tutorial/index.html
+// More info at: https://docs.rs/clap/latest/clap/_derive/index.html