//! MIDI input: enumerate ports, connect/disconnect, and parse incoming messages.

use std::sync::Arc;
use std::time::Instant;

use audiofiles_browser::state::{MidiNoteEvent, SharedState};
use audiofiles_core::instrument::note_name;
use midir::{ConnectError, InitError, MidiInput, MidiInputConnection};
use thiserror::Error;
use tracing::instrument;

/// An active MIDI input connection. Dropping this disconnects.
pub struct MidiConnection {
    _conn: MidiInputConnection<()>,
}

/// Errors from MIDI port enumeration and connection.
#[derive(Error, Debug)]
pub enum MidiError {
    #[error("MIDI init: {0}")]
    Init(#[from] InitError),
    #[error("MIDI port index {idx} out of range ({count} ports available)")]
    PortOutOfRange { idx: usize, count: usize },
    #[error("MIDI connect: {0}")]
    Connect(#[from] ConnectError<MidiInput>),
}

/// List available MIDI input port names.
#[instrument(skip_all)]
pub fn list_input_ports() -> Vec<String> {
    let Ok(midi_in) = MidiInput::new("audiofiles-enumerate") else {
        return Vec::new();
    };
    midi_in
        .ports()
        .iter()
        .filter_map(|p| midi_in.port_name(p).ok())
        .collect()
}

/// Connect to a MIDI input port by index.
///
/// The callback parses note-on/note-off messages and calls `note_on`/`note_off`
/// on the instrument directly (low latency). Also pushes `MidiNoteEvent`s to
/// `shared.midi_recent_notes` for the GUI activity display.
#[instrument(skip_all)]
pub fn connect(port_index: usize, shared: Arc<SharedState>) -> Result<MidiConnection, MidiError> {
    let midi_in = MidiInput::new("audiofiles-input")?;
    let ports = midi_in.ports();
    let port = ports
        .get(port_index)
        .ok_or(MidiError::PortOutOfRange { idx: port_index, count: ports.len() })?;

    let shared_cb = shared.clone();
    let conn = midi_in
        .connect(
            port,
            "audiofiles-midi-in",
            move |_timestamp, message, _| {
                if message.len() < 3 {
                    return;
                }
                let status = message[0] & 0xF0;
                let note = message[1];
                let velocity = message[2];

                match status {
                    0x90 if velocity > 0 => {
                        // Note On
                        shared_cb.instrument.lock().note_on(note, velocity);
                        shared_cb.midi_recent_notes.lock().push(MidiNoteEvent {
                            note,
                            velocity,
                            note_name: note_name(note),
                            timestamp: Instant::now(),
                        });
                    }
                    0x80 | 0x90 => {
                        // Note Off (0x80 or 0x90 with velocity 0)
                        shared_cb.instrument.lock().note_off(note);
                    }
                    _ => {}
                }
            },
            (),
        )?;

    Ok(MidiConnection { _conn: conn })
}