use crate::prelude::*;
use ratatui::style::Stylize;

type Sequence = std::collections::BTreeMap<u32, Vec<::midly::MidiMessage>>;

pub struct Sequencer {
    name:       String,
    /// JACK transport handle.
    transport:  ::jack::Transport,
    /// Holds info about tempo
    timebase:   Arc<Timebase>,
    /// Sequencer resolution, e.g. 16 steps per beat.
    resolution: usize,
    /// Steps in sequence, e.g. 64 16ths = 4 beat loop.
    steps:      usize,

    /// JACK MIDI input port that will be created.
    input_port:     Port<MidiIn>,
    /// Port name patterns to connect to.
    input_connect:  Vec<String>,
    /// Play input through output.
    monitoring:     bool,
    /// Red keys on piano roll.
    notes_on:       Vec<bool>,
    /// Write input to sequence.
    recording:      bool,
    /// Sequence selector
    sequence:       usize,
    /// Map: tick -> MIDI events at tick
    sequences:      Vec<Sequence>,
    /// Don't delete when recording.
    overdub:        bool,
    /// Play sequence to output.
    playing:        bool,
    /// JACK MIDI output port that will be created.
    output_port:    Port<MidiOut>,
    /// Port name patterns to connect to.
    output_connect: Vec<String>,

    /// Display mode
    mode:        SequencerView,
    /// Range of notes to display
    note_axis:   (u16, u16),
    /// Position of cursor within note range
    note_cursor: u16,
    /// Range of time steps to display
    time_axis:   (u16, u16),
    /// Position of cursor within time range
    time_cursor: u16,
}

#[derive(Debug, Clone)]
enum SequencerView {
    Tiny,
    Compact,
    Horizontal,
    Vertical,
}

impl Sequencer {
    pub fn new (name: &str, timebase: &Arc<Timebase>) -> Usually<DynamicDevice<Self>> {
        let (client, _status) = Client::new(name, ClientOptions::NO_START_SERVER)?;
        DynamicDevice::new(render, handle, Self::process, Self {
            name:            name.into(),
            transport:       client.transport(),
            timebase:        timebase.clone(),
            steps:           64,
            resolution:      8,

            input_port:      client.register_port("in", MidiIn::default())?,
            input_connect:   vec!["nanoKEY Studio * (capture): *".into()],
            monitoring:      true,
            notes_on:        vec![false;128],
            recording:       false,
            overdub:         true,
            sequence:        0,
            sequences:       vec![std::collections::BTreeMap::new();8],
            playing:         true,
            output_port:     client.register_port("out", MidiOut::default())?,
            output_connect:  vec![],

            mode:            SequencerView::Horizontal,
            note_axis:       (36, 68),
            note_cursor:     0,
            time_axis:       (0,  64),
            time_cursor:     0,
        }).activate(client)
    }

    fn process (&mut self, _: &Client, scope: &ProcessScope) -> Control {
        let transport = self.transport.query().unwrap();
        process_out(self, scope, &transport);
        process_in(self, scope, &transport);
        Control::Continue
    }
}

fn process_in (s: &mut Sequencer, scope: &ProcessScope, transport: &::jack::TransportStatePosition) {
    if !s.recording {
        return
    }
    let pos   = &transport.pos;
    let usecs = s.timebase.frame_to_usec(pos.frame() as usize);
    let steps = usecs / s.timebase.usec_per_step(s.resolution as usize);
    let step  = steps % s.steps;
    let tick  = step * s.timebase.ppq() / s.resolution;
    let mut sequence = &mut s.sequences[s.sequence];
    for event in s.input_port.iter(scope) {
        match midly::live::LiveEvent::parse(event.bytes).unwrap() {

            midly::live::LiveEvent::Midi { channel: _, message } => match message {

                midly::MidiMessage::NoteOn { key, vel: _ } => {
                    s.notes_on[key.as_int() as usize] = true;
                    let contains = sequence.contains_key(&(tick as u32));
                    if contains {
                        sequence.get_mut(&(tick as u32)).unwrap().push(message.clone());
                    } else {
                        sequence.insert(tick as u32, vec![message.clone()]);
                    }
                },

                midly::MidiMessage::NoteOff { key, vel: _ } => {
                    s.notes_on[key.as_int() as usize] = false;
                    let contains = sequence.contains_key(&(tick as u32));
                    if contains {
                        sequence.get_mut(&(tick as u32)).unwrap().push(message.clone());
                    } else {
                        sequence.insert(tick as u32, vec![message.clone()]);
                    }
                },

                _ => {}

            },

            _ => {}

        }
    }
}

fn process_out (s: &mut Sequencer, scope: &ProcessScope, transport: &::jack::TransportStatePosition) {
    if !s.playing {
        return
    }
    if transport.state != ::jack::TransportState::Rolling {
        return
    }
    let frame = transport.pos.frame() as usize;
    let ticks = s.timebase.frames_to_ticks(
        frame,
        frame + scope.n_frames() as usize,
        s.timebase.fpb() as usize * s.steps / s.resolution
    );
    let mut writer = s.output_port.writer(scope);
    for (time, tick) in ticks.iter() {
        if let Some(events) = s.sequences[s.sequence].get(&(*tick as u32)) {
            for message in events.iter() {
                let mut buf = vec![];
                ::midly::live::LiveEvent::Midi {
                    channel: 1.into(),
                    message: *message,
                }.write(&mut buf).unwrap();
                let midi = ::jack::RawMidi {
                    time: *time as u32,
                    bytes: &buf
                };
                writer.write(&midi).expect(&format!("{midi:?}"))
            }
        }
    }
}

fn render (s: &Sequencer, buf: &mut Buffer, mut area: Rect) -> Usually<Rect> {
    let Rect { x, y, width, .. } = area;
    let (time0, time1) = s.time_axis;
    let (note0, note1) = s.note_axis;
    let pos   = s.transport.query().unwrap().pos;
    let frame = pos.frame();
    let usecs = s.timebase.frame_to_usec(frame as usize);
    let usec_per_step = s.timebase.usec_per_step(s.resolution as usize);
    let steps = usecs / usec_per_step;
    let header = draw_header(s, buf, area, steps)?;
    let piano = match s.mode {
        SequencerView::Tiny =>
            Rect { x, y, width, height: 0 },
        SequencerView::Compact =>
            Rect { x, y, width, height: 0 },
        SequencerView::Vertical => draw_vertical(s, buf, Rect {
            x,
            y: y + header.height,
            width:  3 + note1 - note0,
            height: 3 + time1 - time0,
        }, steps)?,
        SequencerView::Horizontal => draw_horizontal(s, buf, Rect {
            x,
            y: y + header.height,
            width:  area.width.max(3 + time1 - time0),
            height: 3 + note1 - note0,
        })?,
    };
    Ok(draw_box(buf, Rect {
        x,
        y,
        width:  header.width.max(piano.width),
        height: header.height + piano.height
    }))
}

fn draw_header (s: &Sequencer, buf: &mut Buffer, area: Rect, beat: usize) -> Usually<Rect> {
    let rep   = beat / s.steps;
    let step  = beat % s.steps;
    let reps  = s.steps / s.resolution;
    let steps = s.steps % s.resolution;
    let Rect { x, y, width, .. } = area;
    let style = Style::default().gray();
    let timer = format!("{rep}.{step:02} / {reps}.{steps}");
    buf.set_string(x + width - 2 - timer.len() as u16, y + 1, &timer, style.bold().not_dim());
    buf.set_string(x + 2, y + 1, &format!("⏹ STOP"), if s.playing {
        style.dim().bold()
    } else {
        style.not_dim().white().bold()
    });
    buf.set_string(x, y + 2, format!("├{}┤", "-".repeat((area.width - 2).into())), style.dim());
    //buf.set_string(x + 2, y + 2,
        //&format!("▶ PLAY"), if s.playing {
            //Style::default().green()
        //} else {
            //Style::default().dim()
        //});
    buf.set_string(x + 10, y + 1,
        &format!("⏺ MON"), if s.monitoring {
            Style::default().bold().green()
        } else {
            Style::default().bold().dim()
        });
    buf.set_string(x + 17, y + 1,
        &format!("⏺ REC"), if s.recording {
            Style::default().bold().red()
        } else {
            Style::default().bold().dim()
        });
    buf.set_string(x + 24, y + 1,
        &format!("⏺ DUB"), if s.overdub {
            Style::default().bold().yellow()
        } else {
            Style::default().bold().dim()
        });
    let clips = draw_clips(s, buf, area)?;
    Ok(Rect { x, y, width: area.width, height: 3 })
}

fn draw_clips (s: &Sequencer, buf: &mut Buffer, area: Rect) -> Usually<Rect> {
    let Rect { x, y, .. } = area;
    let style = Style::default().gray();
    for i in 0..8 {
        buf.set_string(x + 2, y + 3 + i*2, &format!("▶ {}", &s.name), if i as usize == s.sequence {
            if s.playing {
                style.white().bold()
            } else {
                style.not_dim().bold()
            }
        } else {
            style.dim()
        });
    }
    Ok(Rect { x, y, width: 14, height: 14 })
}

const KEYS_VERTICAL: [&'static str; 6] = [
    "▀", "▀", "▀", "█", "▄", "▄",
];

fn draw_keys_vertical (s: &Sequencer, buf: &mut Buffer, mut area: Rect, beat: usize) {
    let ppq = s.timebase.ppq() as u32;
    let Rect { x, y, .. } = area;
    let (note0, note1) = s.note_axis;
    for key in note0..note1 {
        let x = x + 5 + key - note0;
        if key % 12 == 0 {
            let octave = format!("C{}", (key / 12) as i8 - 4);
            buf.set_string(x, y, &octave, Style::default());
        }
        let mut color = KEY_STYLE[key as usize % 12];
        let mut is_on = s.notes_on[key as usize];
        let step = beat % s.steps;
        let (a, b, c) = (
            (step + 0) as u32 * ppq / s.resolution as u32,
            (step + 1) as u32 * ppq / s.resolution as u32,
            (step + 2) as u32 * ppq / s.resolution as u32,
        );
        let key = ::midly::num::u7::from(key as u8);
        is_on = is_on || contains_note_on(&s.sequences[s.sequence], key, a, b);
        is_on = is_on || contains_note_on(&s.sequences[s.sequence], key, b, c);
        if is_on {
            color = Style::default().red();
        }
        buf.set_string(x, y - 1, &format!("▄"), color);
    }
}

fn draw_vertical (s: &Sequencer, buf: &mut Buffer, mut area: Rect, beat: usize) -> Usually<Rect> {
    let ppq = s.timebase.ppq() as u32;
    area.x = area.x + 13;
    let Rect { x, y, .. } = area;
    let (time0, time1) = s.time_axis;
    let (note0, note1) = s.note_axis;
    let bw = Style::default().dim().on_black();
    let bg = Style::default().on_black();
    draw_keys_vertical(s, buf, area, beat);
    for step in time0..time1 {
        let y = y - time0 + step / 2;
        let step = step as usize;
        //buf.set_string(x + 5, y, &" ".repeat(32.max(note1-note0)as usize), bg);
        if step % s.resolution == 0 {
            buf.set_string(x + 2, y, &format!("{:2} ", step + 1), Style::default());
        }
        for k in note0..note1 {
            let key = ::midly::num::u7::from_int_lossy(k as u8);
            if step % 2 == 0 {
                let (a, b, c) = (
                    (step + 0) as u32 * ppq / s.resolution as u32,
                    (step + 1) as u32 * ppq / s.resolution as u32,
                    (step + 2) as u32 * ppq / s.resolution as u32,
                );
                let (character, style) = match (
                    contains_note_on(&s.sequences[s.sequence], key, a, b),
                    contains_note_on(&s.sequences[s.sequence], key, b, c),
                ) {
                    (true, true)   => ("█", bg),
                    (true, false)  => ("▀", bg),
                    (false, true)  => ("▄", bg),
                    (false, false) => ("·", bw),
                };
                buf.set_string(x + 5 + k - note0, y, character, style);
            }
        }
        if beat % s.steps == step as usize {
            buf.set_string(x + 4, y, if beat % 2 == 0 { "▀" } else { "▄" }, Style::default().yellow());
            for key in note0..note1 {
                let _color = if s.notes_on[key as usize] {
                    Style::default().red()
                } else {
                    KEY_STYLE[key as usize % 12]
                };
            }
        }
    }
    let height = (time1-time0)/2;
    buf.set_string(x + 2, y + height + 1, format!(
        "Q 1/{} | N {} ({}-{}) | T {} ({}-{})",
        4 * s.resolution,
        s.note_axis.0 + s.note_cursor,
        s.note_axis.0,
        s.note_axis.1 - 1,
        s.time_axis.0 + s.time_cursor + 1,
        s.time_axis.0 + 1,
        s.time_axis.1,
    ), Style::default().dim());
    buf.set_string(
        x + 5 + s.note_cursor,
        y + s.time_cursor / 2,
        if s.time_cursor % 2 == 0 { "▀" } else { "▄" },
        Style::default()
    );
    Ok(Rect { x, y, width: area.width, height: height + 1 })
}

fn contains_note_on (sequence: &Sequence, k: ::midly::num::u7, start: u32, end: u32) -> bool {
    for (_, (_, events)) in sequence.range(start..end).enumerate() {
        for event in events.iter() {
            match event {
                ::midly::MidiMessage::NoteOn {key,..} => {
                    if *key == k {
                        return true
                    }
                }
                _ => {}
            }
        }
    }
    return false
}


const KEY_WHITE: Style = Style {
    fg: Some(Color::Gray),
    bg: None,
    underline_color: None,
    add_modifier: ::ratatui::style::Modifier::empty(),
    sub_modifier: ::ratatui::style::Modifier::empty(),
};

const KEY_BLACK: Style = Style {
    fg: Some(Color::Black),
    bg: None,
    underline_color: None,
    add_modifier: ::ratatui::style::Modifier::empty(),
    sub_modifier: ::ratatui::style::Modifier::empty(),
};

const KEY_STYLE: [Style;12] = [
    KEY_WHITE, KEY_BLACK, KEY_WHITE, KEY_BLACK, KEY_WHITE,
    KEY_WHITE, KEY_BLACK, KEY_WHITE, KEY_BLACK, KEY_WHITE, KEY_BLACK, KEY_WHITE,
];

fn draw_keys_horizontal (s: &Sequencer, buf: &mut Buffer, mut area: Rect) -> Usually<Rect> {
    let Rect { x, y, .. } = area;
    let (note0, note1) = s.note_axis;
    let (time0, time1) = s.time_axis;
    let bw = Style::default().dim();
    let bg = Style::default().on_black();
    for i in 0..32.max(note1-note0)/2 {
        let y = y + i;
        buf.set_string(x + 2, y, KEYS_VERTICAL[(i % 6) as usize], bw);
        buf.set_string(x + 3, y, "█", bw);
        buf.set_string(x + 6, y, &"·".repeat((time1 - time0) as usize), bg.dim());
        if i % 6 == 0 {
            let octave = format!("C{}", ((note1 - i) / 6) as i8 - 4);
            buf.set_string(x + 4, y, &octave, Style::default());
        }
    }
    Ok(area)
}

fn draw_horizontal (s: &Sequencer, buf: &mut Buffer, mut area: Rect) -> Usually<Rect> {
    area.x = area.x + 13;
    let Rect { x, y, width, .. } = area;
    let (time0, time1) = s.time_axis;
    let (note0, note1) = s.note_axis;
    let bw = Style::default().dim();
    let bg = Style::default().on_black();
    draw_keys_horizontal(s, buf, area)?;
    for step in time0..time1 {
        let time_start = step as u32 * s.timebase.ppq() as u32;
        let time_end   = (step + 1) as u32 * s.timebase.ppq() as u32;
        for (_, (_, events)) in s.sequences[s.sequence].range(time_start..time_end).enumerate() {
            if events.len() > 0 {
                buf.set_string(x + 5 + step as u16, y, "█", bw);
            }
        }
    }
    let height = 32.max(note1 - note0) / 2;
    buf.set_string(x - 13, y + height, format!("├{}┤", "-".repeat((width - 2).into())),
        Style::default().dim());
    buf.set_string(x - 11, y + height + 1, format!(
        "Sync 4/4   Quantize 1/{}   Notes {} ({}-{})   Time {} ({}-{})",
        4 * s.resolution,
        s.note_axis.0 + s.note_cursor,
        s.note_axis.0,
        s.note_axis.1 - 1,
        s.time_axis.0 + s.time_cursor + 1,
        s.time_axis.0 + 1,
        s.time_axis.1,
    ), Style::default().not_dim());
    buf.set_string(
        x + 6 + s.time_cursor,
        y + s.note_cursor / 2,
        if s.note_cursor % 2 == 0 { "▀" } else { "▄" },
        Style::default()
    );
    Ok(Rect {
        x: x - 13,
        y,
        width: time1 - time0 + 19,
        height: height + 3
    })
}

pub fn handle (s: &mut Sequencer, event: &AppEvent) -> Usually<bool> {
    handle_keymap(s, event, KEYMAP)
}

pub const KEYMAP: &'static [KeyBinding<Sequencer>] = keymap!(Sequencer {
    [Up,        NONE,  "cursor_up",       "move cursor up",           cursor_up],
    [Down,      NONE,  "cursor_down",     "move cursor down",         cursor_down],
    [Left,      NONE,  "cursor_left",     "move cursor left",         cursor_left],
    [Right,     NONE,  "cursor_right",    "move cursor right",        cursor_right],
    [Char(']'), NONE,  "cursor_inc",      "increase note duration",   cursor_duration_inc],
    [Char('['), NONE,  "cursor_dec",      "decrease note duration",   cursor_duration_dec],
    [Char('`'), NONE,  "mode_next",       "Next view mode",           mode_next],
    [Char('+'), NONE,  "zoom_in",         "Zoom in",                  nop],
    [Char('-'), NONE,  "zoom_out",        "Zoom out",                 nop],
    [Char('a'), NONE,  "note_add",        "Add note",                 note_add],
    [Char('z'), NONE,  "note_del",        "Delete note",              note_del],
    [CapsLock,  NONE,  "advance",         "Toggle auto advance",      nop],
    [Char('w'), NONE,  "rest",            "Advance by note duration", nop],
    [Char('r'), NONE,  "toggle_record",   "Toggle recording",         toggle_record],
    [Char('d'), NONE,  "toggle_overdub",  "Toggle overdub",           toggle_overdub],
    [Char(' '), NONE,  "toggle_play",     "Toggle play/pause",        toggle_play],
    [Char('s'), NONE,  "stop_and_rewind", "Stop and rewind",          stop_and_rewind],
    [Char('q'), NONE,  "quantize_next",   "Next quantize value",      quantize_next],
    [Char('Q'), SHIFT, "quantize_prev",   "Previous quantize value",  quantize_prev],
    [Char('n'), NONE,  "note_axis",       "Focus note axis",          nop],
    [Char('t'), NONE,  "time_axis",       "Focus time axis",          nop],
    [Char('v'), NONE,  "variations",      "Focus variation selector", nop],
    [Char('s'), SHIFT, "sync",            "Focus sync selector",      nop],
    [Char('1'), NONE,  "seq_1",           "Sequence 1",               focus_seq(0)],
    [Char('2'), NONE,  "seq_2",           "Sequence 2",               focus_seq(1)],
    [Char('3'), NONE,  "seq_3",           "Sequence 3",               focus_seq(2)],
    [Char('4'), NONE,  "seq_4",           "Sequence 4",               focus_seq(3)],
    [Char('5'), NONE,  "seq_5",           "Sequence 5",               focus_seq(4)],
    [Char('6'), NONE,  "seq_6",           "Sequence 6",               focus_seq(5)],
    [Char('7'), NONE,  "seq_7",           "Sequence 7",               focus_seq(6)],
    [Char('8'), NONE,  "seq_8",           "Sequence 8",               focus_seq(7)],
});

const fn focus_seq (i: usize) -> impl Fn(&mut Sequencer)->Usually<bool> {
    move |s: &mut Sequencer| {
        s.sequence = i;
        Ok(true)
    }
}

fn nop (_: &mut Sequencer) -> Usually<bool> {
    Ok(false)
}
fn note_add (s: &mut Sequencer) -> Usually<bool> {
    let pos      = s.transport.query().unwrap().pos;
    let usecs    = s.timebase.frame_to_usec(pos.frame() as usize);
    let step     = (s.time_axis.0 + s.time_cursor) as u32;
    let start    = (step as usize * s.timebase.ppq() / s.resolution) as u32;
    let end      = ((step + 1) as usize * s.timebase.ppq() / s.resolution) as u32;
    let key      = ::midly::num::u7::from_int_lossy((s.note_cursor + s.note_axis.0) as u8);
    let note_on  = ::midly::MidiMessage::NoteOn { key, vel: 100.into() };
    let note_off = ::midly::MidiMessage::NoteOff { key, vel: 100.into() };
    let mut sequence = &mut s.sequences[s.sequence];
    if sequence.contains_key(&start) {
        sequence.get_mut(&start).unwrap().push(note_on.clone());
    } else {
        sequence.insert(start, vec![note_on]);
    }
    if sequence.contains_key(&end) {
        sequence.get_mut(&end).unwrap().push(note_off.clone());
    } else {
        sequence.insert(end, vec![note_off]);
    };
    Ok(true)
}
fn note_del (_: &mut Sequencer) -> Usually<bool> {
    Ok(true)
}
fn time_cursor_inc (s: &mut Sequencer) -> Usually<bool> {
    let time = s.time_axis.1 - s.time_axis.0;
    s.time_cursor = ((time + s.time_cursor) + 1) % time;
    Ok(true)
}
fn time_cursor_dec (s: &mut Sequencer) -> Usually<bool> {
    let time = s.time_axis.1 - s.time_axis.0;
    s.time_cursor = ((time + s.time_cursor) - 1) % time;
    Ok(true)
}
fn note_cursor_inc (s: &mut Sequencer) -> Usually<bool> {
    let note = s.note_axis.1 - s.note_axis.0;
    s.note_cursor = ((note + s.note_cursor) + 1) % note;
    Ok(true)
}
fn note_cursor_dec (s: &mut Sequencer) -> Usually<bool> {
    let note = s.note_axis.1 - s.note_axis.0;
    s.note_cursor = ((note + s.note_cursor) - 1) % note;
    Ok(true)
}
fn cursor_up (s: &mut Sequencer) -> Usually<bool> {
    match s.mode {
        SequencerView::Vertical   => time_cursor_dec(s),
        SequencerView::Horizontal => note_cursor_dec(s),
        _ => Ok(false)
    };
    Ok(true)
}
fn cursor_down (s: &mut Sequencer) -> Usually<bool> {
    match s.mode {
        SequencerView::Vertical   => time_cursor_inc(s),
        SequencerView::Horizontal => note_cursor_inc(s),
        _ => Ok(false)
    };
    Ok(true)
}
fn cursor_left (s: &mut Sequencer) -> Usually<bool> {
    match s.mode {
        SequencerView::Vertical   => note_cursor_dec(s),
        SequencerView::Horizontal => time_cursor_dec(s),
        _ => Ok(false)
    };
    Ok(true)
}
fn cursor_right (s: &mut Sequencer) -> Usually<bool> {
    match s.mode {
        SequencerView::Vertical   => note_cursor_inc(s),
        SequencerView::Horizontal => time_cursor_inc(s),
        _ => Ok(false)
    };
    Ok(true)
}
fn cursor_duration_inc (_: &mut Sequencer) -> Usually<bool> {
    //s.cursor.2 = s.cursor.2 + 1
    Ok(true)
}
fn cursor_duration_dec (_: &mut Sequencer) -> Usually<bool> {
    //if s.cursor.2 > 0 { s.cursor.2 = s.cursor.2 - 1 }
    Ok(true)
}
fn mode_next (s: &mut Sequencer) -> Usually<bool> {
    s.mode = s.mode.next();
    Ok(true)
}
impl SequencerView {
    fn next (&self) -> Self {
        match self {
            Self::Horizontal => Self::Vertical,
            Self::Vertical   => Self::Tiny,
            Self::Tiny       => Self::Horizontal,
            _ => self.clone()
        }
    }
}
fn stop_and_rewind (s: &mut Sequencer) -> Usually<bool> {
    s.playing = false;
    Ok(true)
}
fn toggle_play (s: &mut Sequencer) -> Usually<bool> {
    s.playing = !s.playing;
    if s.playing {
        s.transport.start()?;
    } else {
        s.transport.stop()?;
        s.transport.locate(0)?;
    }
    Ok(true)
}
fn toggle_record (s: &mut Sequencer) -> Usually<bool> {
    s.recording = !s.recording;
    Ok(true)
}
fn toggle_overdub (s: &mut Sequencer) -> Usually<bool> {
    s.overdub = !s.overdub;
    Ok(true)
}
fn quantize_next (s: &mut Sequencer) -> Usually<bool> {
    if s.resolution < 64 {
        s.resolution = s.resolution * 2;
    }
    Ok(true)
}
fn quantize_prev (s: &mut Sequencer) -> Usually<bool> {
    if s.resolution > 1 {
        s.resolution = s.resolution / 2;
    }
    Ok(true)
}

#[cfg(test)] mod test {
    use super::*;

    #[test]
    fn test_sequencer_output () -> Usually<()> {
        let sequencer = Sequencer::new("test")?;
        let mut s = sequencer.state.lock().unwrap();
        s.rate  = Hz(48000);
        s.tempo = Tempo(240_000);
        println!("F/S = {:.03}", s.fps());
        println!("B/S = {:.03}", s.bps());
        println!("F/B = {:.03}", s.fpb());
        println!("T/B = {:.03}", s.tpb());
        println!("F/T = {:.03}", s.fpt());
        println!("F/L = {:.03}", s.fpl());
        println!("T/L = {:.03}", s.tpl());
        let fpt = s.fpt();
        let frames_per_chunk = 240;
        let chunk = |chunk: usize| s.frames_to_ticks(
            chunk * frames_per_chunk,
            (chunk + 1) * frames_per_chunk
        );
        //for i in 0..2000 {
            //println!("{i} {:?}", chunk(i));
        //}
        assert_eq!(chunk(0), vec![(0, 0), (125, 1)]);
        assert_eq!(chunk(1), vec![(10, 2), (135, 3)]);
        assert_eq!(chunk(12), vec![(120, 24)]);
        assert_eq!(chunk(412), vec![(120, 24)]);
        assert_eq!(chunk(413), vec![(5, 25), (130, 26)]);
        Ok(())
    }
}