Added the 'new' command which creates the scaffolding for a server instance

Cargo.toml

@@ -7,3 +7,5 @@ edition = "2021"
 
 [dependencies]
 clap = { version = "3.2", features = ["derive"] }
+reqwest = { version = "0.11", features = ["blocking"] }
+shellexpand = "2.1"

src/cmd/new.rs

@@ -1,3 +1,37 @@
-pub fn new_command(server_name: &str, minecraft_version: &str) {
+extern crate reqwest;
+
+use std::fs;
+use std::os::unix::fs::PermissionsExt;
+use std::io;
+use std::io::prelude::*;
+
+pub fn new_command(server_name: &str, minecraft_version: &str) -> Result<(), Box<dyn std::error::Error>> {
   println!("Creating new server with name '{}' using version '{}'.", server_name, minecraft_version);
+
+  let home_path = shellexpand::tilde("~");
+  let server_directory_path = format!("{}/{}", home_path, server_name);
+  let server_file_path = format!("{}/server_{}.jar", server_directory_path, minecraft_version);
+
+  // create the server directory
+  println!("Creating server directory {}.", server_directory_path);
+  fs::create_dir(&server_directory_path)?;
+
+  // download the Minecraft server JAR file
+  let server_jar_url = "https://piston-data.mojang.com/v1/objects/f69c284232d7c7580bd89a5a4931c3581eae1378/server.jar";
+  println!("Downloading {} to {}.", server_jar_url, server_file_path);
+  let mut resp = reqwest::blocking::get(server_jar_url)?;
+  let mut out = fs::File::create(server_file_path)?;
+  io::copy(&mut resp, &mut out)?;
+
+  // create the start.sh shell script
+  let script_file_path = format!("{}/start.sh", server_directory_path);
+  println!("Creating start.sh script.");
+  let mut script_file = fs::File::create(script_file_path)?;
+  let script_file_contents = format!("#!/bin/sh\n\ncd {}\njava -Xmx2048M -Xms2048M -jar server_{}.jar nogui", server_directory_path, minecraft_version);
+  script_file.write_all(script_file_contents.as_bytes())?;
+  // set the file permissions on the start.sh script
+  script_file.set_permissions(fs::Permissions::from_mode(0o755))?;
+
+  // return empty result to signify everything is okay
+  Ok(())
 }

src/main.rs

@@ -27,7 +27,12 @@ fn main() {
   let cli = Cli::parse();
 
   // map subcommands back to the main command
-  match &cli.command {
+  let res = match &cli.command {
     Commands::New { server_name, minecraft_version } => cmd::new::new_command(&server_name, &minecraft_version),
-  }
+  };
+
+  match res {
+    Ok(_) => {},
+    Err(e) => panic!("MCST ran into an error: {}", e),
+  };
 }