Update for Nix module

src/main.rs

@@ -1,7 +1,8 @@
 mod commands;
 mod utils;
 
-use std::env;
+use std::env::{self, VarError};
+use lazy_static::lazy_static;
 
 type Error = Box<dyn std::error::Error + Send + Sync>;
 type Context<'a> = poise::Context<'a, Data, Error>;
@@ -12,6 +13,7 @@ pub struct Data {}
 use commands::{challenge::*, kanji::*, meta::*, owner::*};
 use poise::serenity_prelude as serenity;
 use poise::serenity_prelude::model::gateway::GatewayIntents;
+use clap::Parser;
 
 #[poise::command(prefix_command)]
 async fn register(ctx: Context<'_>) -> Result<(), Error> {
@@ -19,12 +21,50 @@ async fn register(ctx: Context<'_>) -> Result<(), Error> {
     Ok(())
 }
 
+#[derive(Parser)]
+#[clap(author, version, about)]
+struct Arguments {
+    #[clap(long, help = "Website domain", default_value = "tegakituesday.com")]
+    pub domain: String,
+    #[clap(long = "token", help = "Discord token")]
+    pub discord_token: String,
+    #[clap(long, help = "Traditional text command prefix, including space, if any", default_value = "-h")]
+    pub prefix: String,
+    #[clap(long, help = "Path to Hugo project where site rebuilds")]
+    pub hugo: String,
+    #[clap(long = "guilds", help = "Guild data JSON file", default_value = "guilds.json")]
+    pub guild_data: String,
+}
+
+impl Arguments {
+    fn from_dotenv() -> Result<Self, VarError> {
+        Ok(Self {
+            domain: env::var("DOMAIN")?,
+            discord_token: env::var("DISCORD_TOKEN")?,
+            prefix: env::var("PREFIX")?,
+            hugo: env::var("HUGO")?.into(),
+            guild_data: env::var("GUILD_DATA")?.into(),
+        })
+    }
+}
+
+lazy_static! {
+    static ref ARGS: Arguments = {
+        match env::args().count() {
+            1 => {
+                // This will load the environment variables located at `./.env`, relative to
+                // the CWD. See `./.env.example` for an example on how to structure this.
+                dotenv::dotenv().expect("Failed to load .env file");
+
+                Arguments::from_dotenv().unwrap()
+            },
+            _ => Arguments::parse(),
+        }
+    };
+}
+
 #[tokio::main]
 async fn main() {
-    // This will load the environment variables located at `./.env`, relative to
-    // the CWD. See `./.env.example` for an example on how to structure this.
-    dotenv::dotenv().expect("Failed to load .env file");
-
     // Initialize the logger to use environment variables.
     //
     // In this case, a good default is setting the environment variable
@@ -59,12 +99,12 @@ async fn main() {
                 so(),
             ],
             prefix_options: poise::PrefixFrameworkOptions {
-                prefix: Some(env::var("PREFIX").expect("Expected a prefix in the environment")),
+                prefix: Some(ARGS.prefix.clone()),
                 ..Default::default()
             },
             ..Default::default()
         })
-        .token(std::env::var("DISCORD_TOKEN").expect("Expected a token in the environment"))
+        .token(&ARGS.discord_token)
         .intents(
             GatewayIntents::GUILD_MESSAGES
                 | GatewayIntents::DIRECT_MESSAGES