use std::io::stdin;

use anyhow::{anyhow, Result};
use midir::{MidiInput, MidiInputPort};

fn main() {
    match run() {
        Ok(_) => {}
        Err(err) => {
            println!("Ended with error: {}", err);
        }
    }
}

fn run() -> Result<()> {
    let midi_in = MidiInput::new("keyboard")?;

    let midi_device = find_first_midi_device(&midi_in)?;
    let port_name = midi_in.port_name(&midi_device)?;

    let _midi_connection = match midi_in.connect(&midi_device, &port_name, handle_midi_event, ()) {
        Ok(m) => m,
        Err(err) => return Err(anyhow!("failed to connect to device: {}", err)),
    };

    // TODO: instead, listen for a signal like control-d
    let mut buf = String::new();
    stdin().read_line(&mut buf)?;

    Ok(())
}

fn handle_midi_event(timestamp: u64, message: &[u8], _extra_data: &mut ()) {
    let hex_msg = hex::encode(message);
    println!("{timestamp} > {hex_msg}");
}

/// Finds the first MIDI input port which corresponds to a physical MIDI device
/// connected to this computer.
fn find_first_midi_device(midi_in: &MidiInput) -> Result<MidiInputPort> {
    let ports = midi_in.ports();

    // "Midi Through" is automatically created by the snd-seq-dummy kernel module.
    // We can ignore it, since it's not a physical MIDI device, which is what we
    // are looking for.
    //
    // Source: https://www.reddit.com/r/linuxaudio/comments/jsrl31/comment/gc16qwu/
    let mut physical_ports = ports.iter().filter(|p| {
        midi_in
            .port_name(p)
            .map_or(false, |n| !n.starts_with("Midi Through:"))
    });

    physical_ports
        .next()
        .cloned()
        .ok_or(anyhow!("no physical MIDI devices found"))
}