Add infra for commands

Cargo.toml

@@ -6,6 +6,8 @@ authors = ["Matthew Maxwell"]
 description = "CLI tool for converting frequencies and musical notes"
 
 [dependencies]
+async-trait = "0.1.83"
+regex = "1.11.1"
 structopt = "0.3.26"
 thiserror = "1.0.65"
 tokio = { version = "1.41.0", features = ["full"] }

README.md

@@ -1,7 +1,7 @@
 # `fnote`
 
-[![Format](https://github.com/blackboxaudio/fnote/actions/workflows/ci.fmt.yml/badge.svg)](https://github.com/blackboxaudio/fnote/actions/workflows/ci.fmt.yml)
 [![Lint](https://github.com/blackboxaudio/fnote/actions/workflows/ci.lint.yml/badge.svg)](https://github.com/blackboxaudio/fnote/actions/workflows/ci.lint.yml)
+[![Format](https://github.com/blackboxaudio/fnote/actions/workflows/ci.fmt.yml/badge.svg)](https://github.com/blackboxaudio/fnote/actions/workflows/ci.fmt.yml)
 [![Version: v0.1.0](https://img.shields.io/badge/Version-v0.1.0-blue.svg)](https://github.com/blackboxaudio/fnote)
 [![License](https://img.shields.io/badge/License-MIT-yellow)](https://github.com/blackboxaudio/fnote/blob/develop/LICENSE)
 

src/cli.rs

@@ -0,0 +1,30 @@
+use async_trait::async_trait;
+
+use crate::{commands::midi::MidiCommand, error::FNoteResult};
+
+/// Represents an `fnote` program command.
+#[async_trait]
+pub trait Command {
+    /// Executes the corresponding command.
+    async fn run(&self) -> FNoteResult<()>;
+}
+
+/// Commands supported by `fnote`.
+#[derive(structopt::StructOpt)]
+#[structopt(
+    author = "Matthew Maxwell",
+    version = env!("CARGO_PKG_VERSION"),
+)]
+pub enum FNoteCommand {
+    /// Extracts the frequency and musical note from a MIDI note number (0-127).
+    Midi(MidiCommand),
+}
+
+#[async_trait]
+impl Command for FNoteCommand {
+    async fn run(&self) -> FNoteResult<()> {
+        match self {
+            Self::Midi(cmd) => cmd.run().await,
+        }
+    }
+}

src/commands/midi.rs

@@ -0,0 +1,34 @@
+use async_trait::async_trait;
+use regex::Regex;
+
+use crate::{
+    cli::Command,
+    error::{FNoteError, FNoteResult},
+};
+
+/// Extracts the frequency and musical note from a MIDI note number (0-127).
+#[derive(structopt::StructOpt)]
+pub struct MidiCommand {
+    /// The MIDI note number to use.
+    #[structopt(parse(try_from_str = try_midi_note_number_from_str))]
+    pub midi_note_number: usize,
+}
+
+#[async_trait]
+impl Command for MidiCommand {
+    async fn run(&self) -> FNoteResult<()> {
+        println!("Converting MIDI note number: {:?}", self.midi_note_number);
+
+        Ok(())
+    }
+}
+
+/// Parses a MIDI note number from a string.
+fn try_midi_note_number_from_str(arg: &str) -> FNoteResult<usize> {
+    let regex = Regex::new(r"^(?:\d|[1-9]\d|1[01]\d|12[0-7])$").unwrap();
+    if regex.is_match(arg) {
+        Ok(arg.parse::<usize>().unwrap())
+    } else {
+        Err(FNoteError::InvalidMidiNoteNumber(arg.to_string()))
+    }
+}

src/commands/mod.rs

@@ -0,0 +1 @@
+pub(crate) mod midi;

src/error.rs

@@ -3,4 +3,10 @@ pub type FNoteResult<T> = std::result::Result<T, FNoteError>;
 
 /// Error variants for the `fnote` program.
 #[derive(Debug, PartialEq, thiserror::Error)]
-pub enum FNoteError {}
+pub enum FNoteError {
+    #[error("Unknown command")]
+    UnknownCommand,
+
+    #[error("Invalid MIDI note number \"{0}\"")]
+    InvalidMidiNoteNumber(String),
+}

src/lib.rs

@@ -1 +1,4 @@
-pub(crate) mod error;
+pub mod cli;
+pub mod error;
+
+pub(crate) mod commands;

src/main.rs

@@ -1,8 +1,13 @@
-use crate::error::FNoteResult;
-
-mod error;
+use fnote::{
+    cli::{Command, FNoteCommand},
+    error::{FNoteError, FNoteResult},
+};
+use structopt::StructOpt;
 
 #[tokio::main]
 async fn main() -> FNoteResult<()> {
-    Ok(())
+    match FNoteCommand::from_args().run().await {
+        Ok(_) => Ok(()),
+        Err(_) => panic!("{:?}", FNoteError::UnknownCommand),
+    }
 }