Day 2!

src/args.rs

@@ -0,0 +1,74 @@
+use clap::{App,Arg,SubCommand};
+use crate::machine::Computer;
+use std::fs;
+
+pub enum Command {
+    ComputeFuel(Vec<u64>),
+    RunComputer(Computer),
+}
+
+fn is_number(s: String) -> Result<(), String> {
+    match u64::from_str_radix(&s, 10) {
+        Ok(_) => Ok(()),
+        Err(e) => Err(e.to_string()),
+    }
+}
+
+fn is_file(s: String) -> Result<(), String> {
+    match fs::metadata(&s) {
+        Err(e) => Err(e.to_string()),
+        Ok(md) if md.is_file() => Ok(()),
+        _      => Err(format!("{} is not a file.", s))
+    }
+}
+
+impl Command {
+    pub fn get() -> Command {
+        let matches = App::new("My Advent of Code Thing")
+                          .version("1.0")
+                          .author("Adam Wick <awick@uhsure.com>")
+                          .about("Runs advent of code programs")
+                          .subcommand(SubCommand::with_name("fuel")
+                                        .about("runs the fuel computation from day1")
+                                        .arg(Arg::with_name("NUM")
+                                                 .help("The mass of the ship")
+                                                 .multiple(true)
+                                                 .validator(is_number))
+                                        )
+                          .subcommand(SubCommand::with_name("compute")
+                                        .about("run the given computer")
+                                        .arg(Arg::with_name("START_POSITION")
+                                                 .short("p")
+                                                 .long("start-position")
+                                                 .help("The starting position to execute from.")
+                                                 .default_value("0")
+                                                 .validator(is_number))
+                                        .arg(Arg::with_name("COMPUTER")
+                                                 .index(1)
+                                                 .help("The computer to run.")
+                                                 .required(true)
+                                                 .validator(is_file))
+                                        )
+                          .get_matches();
+    
+        if let Some(problem1) = matches.subcommand_matches("fuel") {
+            match problem1.values_of("NUM") {
+                None =>
+                    println!("ERROR: No values to compute fuel for!"),
+                Some(masses) => {
+                    let args = masses.map(|x| u64::from_str_radix(x, 10).unwrap()).collect();
+                    return Command::ComputeFuel(args);
+               }
+            }
+        }
+    
+        if let Some(problem2) = matches.subcommand_matches("compute") {
+            let start_pos_str = problem2.value_of("START_POSITION").unwrap();
+            let start_pos = usize::from_str_radix(&start_pos_str, 10).unwrap();
+            let mut computer = Computer::load(problem2.value_of("COMPUTER").unwrap(), start_pos);
+            return Command::RunComputer(computer);
+        }
+    
+        panic!("Failed to run a reasonable command.");
+    }
+}