Add README, update usage, add (unused) logo :)

Author: bew

README.md

@@ -0,0 +1,23 @@
+# AdventOfCode 2021 - Learning Rust :heart: again ^^
+
+This is my take on the [advent of code challenges](https://adventofcode.com/2021/) of 2021.
+
+I already tried doing them in Rust [last year](https://github.com/bew/adventofcode-2020), but didn't go too far, because (for learning
+purpose) I wanted to not use any libs, so I learned about cumbersome parsing and having to
+re-write a simple generic error wrapper :)
+
+Now I want to actually do somthing in Rust, so I'm using a few libraries, mainly:
+- [`anyhow`](https://crates.io/crates/anyhow) for error wrapping, without having to deal with specific errors
+- [`chumsky`](https://crates.io/crates/chumsky) for input parsing using combinators that build incrementally the AST of the input :heart:. I discovered this lib not long ago, and I fell in love, it's time to try it _for real_ now!
+
+
+## Workflow
+
+* `cargo run last`: Run the last available day, display results.
+  It's very handy when I'm working on the next day :smiley:
+
+* `cargo run all`: Run all days, display results
+
+* `cargo run list`: List available days
+
+* `cargo run dayNN`: Run specific day

logo.txt

@@ -0,0 +1,13 @@
+|             ___             ___     ___      __     ___      _    |
+|     o O O  /   \    ___    / __|   |_  )    /  \   |_  )    / |   |
+|    o       | - |   / _ \  | (__     / /    | () |   / /     | |   |
+|   TS__[O]  |_|_|   \___/   \___|   /___|   _\__/   /___|   _|_|_  |
+|  {======|_|"""""|_|"""""|_|"""""|_|"""""|_|"""""|_|"""""|_|"""""|_|
+| ./o--000'"`-0-0-'"`-0-0-'"`-0-0-'"`-0-0-'"`-0-0-'"`-0-0-'"`-0-0-'"|
+|                                                                   |
+|    _                      ___                     _               |
+|   (_)    _ _             | _ \   _  _     ___    | |_   O O o     |
+|   | |   | ' \            |   /  | \| |   (_-<    |  _|       o    |
+|  _|_|_  |_||_|   _____   |_|_\   \_,_|   /__/_   _\__|  [O]__ST   |
+|_|"""""|_|"""""|_|     |_|"""""|_|"""""|_|"""""|_|"""""|_|======}  |
+|"`-0-0-'"`-0-0-'"'-0-0-`"`-0-0-'"`-0-0-'"`-0-0-'"`-0-0-'"'000--o\. |

src/main.rs

@@ -54,11 +54,20 @@ static DAYS: &[Day] = &[
 fn print_usage() {
     let prog_name = env::args().next().unwrap_or("prog".to_string());
     let day_names: Vec<_> = DAYS.iter().map(|d| d.name).collect();
-    println!("Usage: {} <day> [<custom_input_path>]", prog_name);
-    println!(
-        "Where <day> is either 'all', 'last' or one of: {}",
-        day_names.join(", ")
-    );
+    println!("Usage:");
+    println!("  {} <cmd>", prog_name);
+    println!("  {} <day> [<custom_input_path>]", prog_name);
+    println!("");
+
+    println!("<cmd> can be:");
+    println!("  all   - run all available days");
+    println!("  last  - run the last available day (used while dev)");
+    println!("  list  - list available days");
+    println!("");
+
+    let joined_days = day_names.join(", ");
+    println!("<day> can be one of: {}", joined_days);
+    println!("");
     exit(1);
 }
 
@@ -92,10 +101,10 @@ fn main() -> anyhow::Result<()> {
     // TODO: Use clap to parse params to structured opts!
     let prog_args: Vec<String> = env::args().collect();
     let first_arg = prog_args.get(1);
-    // Converts Option<String> to Option<&str> so I can match on `Some("all")`
-    // (necessary because matching on `Some("all".to_string())` does not work
-    // and matching on `Some(xyz) if xyz == "all"` is ugly..).
-    match first_arg.and_then(|s| Some(s.as_str())) {
+
+    // NOTE: We convert Option<String> to Option<&str> to be able to match on `Some("all")`,
+    //       instead of matching `Some(xyz) if xyz == "all"` many times, which is quite ugly.
+    match first_arg.map(String::as_str) {
         Some("all") => {
             for day in DAYS {
                 run_day(day)?;
@@ -104,6 +113,14 @@ fn main() -> anyhow::Result<()> {
         Some("last") => {
             run_day(&DAYS.last().unwrap())?;
         }
+        Some("list") => {
+            println!("Available days:");
+            for day in DAYS {
+                println!("- {}", day.name);
+                // TODO: Display how finish that day it, by running it without displaying anything
+                //       (need to return proper enum with all statuses)
+            }
+        }
         Some(wanted_day) => {
             let matching_day = DAYS.iter().find(|day| day.name == wanted_day);
             match matching_day {