tek/src/devices/sequencer.rs

//! Phrase editor.

use crate::{core::*, model::*, view::*};

/// Key bindings for phrase editor.
pub const KEYMAP_SEQUENCER: &'static [KeyBinding<App>] = keymap!(App {
    [Up,    NONE, "seq_cursor_up",    "move cursor up", |app: &mut App| {
        match app.sequencer.entered {
            true  => { app.sequencer.note_axis.point_dec(); },
            false => { app.sequencer.note_axis.start_dec(); },
        }
        Ok(true)
    }],
    [Down,  NONE, "seq_cursor_down",  "move cursor down", |app: &mut App| {
        match app.sequencer.entered {
            true  => { app.sequencer.note_axis.point_inc(); },
            false => { app.sequencer.note_axis.start_inc(); },
        }
        Ok(true)
    }],
    [Left,  NONE, "seq_cursor_left",  "move cursor up", |app: &mut App| {
        match app.sequencer.entered {
            true  => { app.sequencer.time_axis.point_dec(); },
            false => { app.sequencer.time_axis.start_dec(); },
        }
        Ok(true)
    }],
    [Right, NONE, "seq_cursor_right", "move cursor up", |app: &mut App| {
        match app.sequencer.entered {
            true  => { app.sequencer.time_axis.point_inc(); },
            false => { app.sequencer.time_axis.start_inc(); },
        }
        Ok(true)
    }],
    [Char('`'), NONE, "seq_mode_switch", "switch the display mode", |app: &mut App| {
        app.sequencer.mode   = !app.sequencer.mode;
        Ok(true)
    }],
    /*
    [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],
    */
});

pub type PhraseData = Vec<Vec<MidiMessage>>;

#[derive(Debug)]
/// A MIDI sequence.
pub struct Phrase {
    pub name:   String,
    pub length: usize,
    pub notes:  PhraseData,
    pub looped: Option<(usize, usize)>,
    /// Immediate note-offs in view
    pub percussive: bool
}

impl Default for Phrase {
    fn default () -> Self {
        Self::new("", 0, None)
    }
}

impl Phrase {
    pub fn new (name: &str, length: usize, notes: Option<PhraseData>) -> Self {
        Self {
            name:   name.to_string(),
            length,
            notes:  notes.unwrap_or(vec![Vec::with_capacity(16);length]),
            looped: Some((0, length)),
            percussive: true,
        }
    }
    pub fn record_event (&mut self, pulse: usize, message: MidiMessage) {
        if pulse >= self.length {
            panic!("extend phrase first")
        }
        self.notes[pulse].push(message);
    }
    /// Check if a range `start..end` contains MIDI Note On `k`
    pub fn contains_note_on (&self, k: u7, start: usize, end: usize) -> bool {
        //panic!("{:?} {start} {end}", &self);
        for events in self.notes[start.max(0)..end.min(self.notes.len())].iter() {
            for event in events.iter() {
                match event {
                    MidiMessage::NoteOn {key,..} => {
                        if *key == k {
                            return true
                        }
                    }
                    _ => {}
                }
            }
        }
        return false
    }
    /// Write a chunk of MIDI events to an output port.
    pub fn process_out (
        &self,
        output:   &mut MIDIChunk,
        notes_on: &mut [bool;128],
        timebase: &Arc<Timebase>,
        (frame0, frames, _): (usize, usize, f64),
    ) {
        let mut buf = Vec::with_capacity(8);
        for (time, tick) in Ticks(timebase.pulse_per_frame()).between_frames(
            frame0, frame0 + frames
        ) {
            let tick = tick % self.length;
            for message in self.notes[tick].iter() {
                buf.clear();
                let channel = 0.into();
                let message = *message;
                LiveEvent::Midi { channel, message }.write(&mut buf).unwrap();
                output[time as usize].push(buf.clone());
                match message {
                    MidiMessage::NoteOn  { key, .. } => notes_on[key.as_int() as usize] = true,
                    MidiMessage::NoteOff { key, .. } => notes_on[key.as_int() as usize] = false,
                    _ => {}
                }
            }
        }
    }
}

/// Phrase editor.
pub struct Sequencer {
    pub mode:      bool,
    pub focused:   bool,
    pub entered:   bool,

    pub phrase:    Option<Arc<RwLock<Phrase>>>,
    pub buffer:    Buffer,
    pub keys:      Buffer,
    /// Highlight input keys
    pub keys_in:  [bool; 128],
    /// Highlight output keys
    pub keys_out: [bool; 128],

    pub now:       usize,
    pub ppq:       usize,
    pub note_axis: FixedAxis<u16>,
    pub time_axis: ScaledAxis<u16>,

}

render!(Sequencer |self, buf, area| {
    fill_bg(buf, area, Nord::bg_lo(self.focused, self.entered));
    self.horizontal_draw(buf, area)?;
    if self.focused && self.entered {
        Corners(Style::default().green().not_dim()).draw(buf, area)?;
    }
    Ok(area)
});

impl Sequencer {
    pub fn new () -> Self {
        Self {
            buffer:    Buffer::empty(Rect::default()),
            keys:      keys_vert(),
            entered:   false,
            focused:   false,
            mode:      false,
            keys_in:  [false;128],
            keys_out: [false;128],
            phrase:    None,
            now:       0,
            ppq:       96,
            note_axis: FixedAxis {
                start: 12,
                point: Some(36)
            },
            time_axis: ScaledAxis {
                start: 0,
                scale: 24,
                point: Some(0)
            },
        }
    }
    /// Select which pattern to display. This pre-renders it to the buffer at full resolution.
    /// FIXME: Support phrases longer that 65536 ticks
    pub fn show (&mut self, phrase: Option<&Arc<RwLock<Phrase>>>) -> Usually<()> {
        self.phrase = phrase.map(Clone::clone);
        if let Some(ref phrase) = self.phrase {
            let width = u16::MAX.min(phrase.read().unwrap().length as u16);
            let mut buffer = Buffer::empty(Rect { x: 0, y: 0, width, height: 64 });
            let phrase = phrase.read().unwrap();
            fill_seq_bg(&mut buffer, phrase.length, self.ppq)?;
            fill_seq_fg(&mut buffer, &phrase)?;
            self.buffer = buffer;
        } else {
            self.buffer = Buffer::empty(Rect::default())
        }
        Ok(())
    }

    fn style_focus (&self) -> Option<Style> {
        Some(if self.focused {
            Style::default().green().not_dim()
        } else {
            Style::default().green().dim()
        })
    }

    fn style_timer_step (now: usize, step: usize, next_step: usize) -> Style {
        if step <= now && now < next_step {
            Style::default().yellow().bold().not_dim()
        } else {
            Style::default()
        }
    }

    fn index_to_color (&self, index: u16, default: Color) -> Color {
        let index = index as usize;
        if self.keys_in[index] && self.keys_out[index] {
            Color::Yellow
        } else if self.keys_in[index] {
            Color::Red
        } else if self.keys_out[index] {
            Color::Green
        } else {
            default
        }
    }

    const H_KEYS_OFFSET: u16 = 5;

    fn horizontal_draw (&self, buf: &mut Buffer, area: Rect) -> Usually<()> {
        self.horizontal_keys(buf, area)?;
        if let Some(ref phrase) = self.phrase {
            self.horizontal_timer(buf, area, phrase)?;
        }
        self.horizontal_notes(buf, area)?;
        self.horizontal_cursor(buf, area)?;
        self.horizontal_quant(buf, area)?;
        Ok(())
    }

    fn horizontal_notes (&self, buf: &mut Buffer, area: Rect) -> Usually<Rect> {
        if area.height < 2 {
            return Ok(area)
        }
        let area = Rect {
            x:      area.x + Self::H_KEYS_OFFSET,
            y:      area.y + 1,
            width:  area.width - Self::H_KEYS_OFFSET,
            height: area.height - 2
        };
        buffer_update(buf, area, &|cell, x, y|{
            let src_x = (x + self.time_axis.start) * self.time_axis.scale;
            let src_y = y + self.note_axis.start;
            if src_x < self.buffer.area.width && src_y < self.buffer.area.height - 1 {
                let src = self.buffer.get(src_x, self.buffer.area.height - src_y);
                cell.set_symbol(src.symbol());
                cell.set_fg(src.fg);
            }
        });
        Ok(area)
    }

    fn horizontal_keys (&self, buf: &mut Buffer, area: Rect) -> Usually<Rect> {
        if area.height < 2 {
            return Ok(area)
        }
        let area = Rect {
            x: area.x,
            y: area.y + 1,
            width: 5,
            height: area.height - 2
        };
        buffer_update(buf, area, &|cell, x, y|{
            let y = y + self.note_axis.start;
            if x < self.keys.area.width && y < self.keys.area.height {
                *cell = self.keys.get(x, y).clone()
            }
        });
        Ok(area)
    }

    fn horizontal_quant (&self, buf: &mut Buffer, area: Rect) -> Usually<Rect> {
        let quant = ppq_to_name(self.time_axis.scale);
        let quant_x = area.x + area.width - 1 - quant.len() as u16;
        let quant_y = area.y + area.height - 2;
        quant.blit(buf, quant_x, quant_y, self.style_focus())
    }

    fn horizontal_cursor (&self, buf: &mut Buffer, area: Rect) -> Usually<Rect> {
        if let (Some(time), Some(note)) = (self.time_axis.point, self.note_axis.point) {
            let x = area.x + Self::H_KEYS_OFFSET + time as u16;
            let y = area.y + 1 + note as u16 / 2;
            let c = if note % 2 == 0 { "▀" } else { "▄" };
            c.blit(buf, x, y, self.style_focus())
        } else {
            Ok(Rect::default())
        }
    }

    fn horizontal_timer (
        &self, buf: &mut Buffer, area: Rect, phrase: &RwLock<Phrase>
    ) -> Usually<Rect> {
        let phrase = phrase.read().unwrap();
        let (time0, time_z, now) = (self.time_axis.start, self.time_axis.scale, self.now % phrase.length);
        let Rect { x, width, .. } = area;
        for x in x+Self::H_KEYS_OFFSET..x+width {
            let step = (time0 + (x-Self::H_KEYS_OFFSET)) * time_z;
            let next_step = (time0 + (x-Self::H_KEYS_OFFSET) + 1) * time_z;
            let style = Self::style_timer_step(now, step as usize, next_step as usize);
            "-".blit(buf, x, area.y, Some(style))?;
        }
        return Ok(Rect { x: area.x, y: area.y, width: area.width, height: 1 })
    }
}

fn keys_vert () -> Buffer {
    let area = Rect { x: 0, y: 0, width: 5, height: 64 };
    let mut buffer = Buffer::empty(area);
    buffer_update(&mut buffer, area, &|cell, x, y| {
        let y = 63 - y;
        match x {
            0 => {
                cell.set_char('▀');
                let (fg, bg) = key_colors(6 - y % 6);
                cell.set_fg(fg);
                cell.set_bg(bg);
            },
            1 => {
                cell.set_char('▀');
                cell.set_fg(Color::White);
                cell.set_bg(Color::White);
            },
            2 => if y % 6 == 0 {
                cell.set_char('C');
            },
            3 => if y % 6 == 0 {
                cell.set_symbol(nth_octave(y / 6));
            },
            _ => {}
        }
    });
    buffer
}

fn nth_octave (index: u16) -> &'static str {
    match index {
        0  =>  "-1",
        1  =>  "0",
        2  =>  "1",
        3  =>  "2",
        4  =>  "3",
        5  =>  "4",
        6  =>  "5",
        7  =>  "6",
        8  =>  "7",
        9  =>  "8",
        10 =>  "9",
        _  => unreachable!()
    }
}

fn key_colors (index: u16) -> (Color, Color) {
    match index % 6 {
        0 => (Color::White, Color::Black),
        1 => (Color::White, Color::Black),
        2 => (Color::White, Color::White),
        3 => (Color::Black, Color::White),
        4 => (Color::Black, Color::White),
        5 => (Color::Black, Color::White),
        _ => unreachable!()
    }
}

fn fill_seq_bg (buf: &mut Buffer, length: usize, ppq: usize) -> Usually<()> {
    for x in 0 .. buf.area.width - buf.area.x {
        if x as usize >= length {
            break
        }
        let style = Style::default();
        let cell = buf.get_mut(x, buf.area.y);
        cell.set_char('-');
        cell.set_style(style);
        for y in 0 .. buf.area.height - buf.area.y {
            let cell = buf.get_mut(x, y);
            cell.set_char(char_seq_bg(ppq, x));
            cell.set_fg(Color::Gray);
            cell.modifier = Modifier::DIM;
        }
    }
    Ok(())
}

fn char_seq_bg (ppq: usize, x: u16) -> char {
    if ppq == 0 {
        '·'
    } else if x % (4 * ppq as u16) == 0 {
        '│'
    } else if x % ppq as u16 == 0 {
        '╎'
    } else {
        '·'
    }
}

fn fill_seq_fg (buf: &mut Buffer, phrase: &Phrase) -> Usually<()> {
    let mut notes_on = [false;128];
    for x in 0 .. buf.area.width - buf.area.x {
        if x as usize >= phrase.length {
            break
        }
        if let Some(notes) = phrase.notes.get(x as usize) {
            for note in notes {
                if phrase.percussive {
                    match note {
                        MidiMessage::NoteOn { key, .. } =>
                            notes_on[key.as_int() as usize] = true,
                        _ => {}
                    }
                } else {
                    match note {
                        MidiMessage::NoteOn { key, .. } =>
                            notes_on[key.as_int() as usize] = true,
                        MidiMessage::NoteOff { key, .. } =>
                            notes_on[key.as_int() as usize] = false,
                        _ => {}
                    }
                }
            }
            for y in 0 .. (buf.area.height - buf.area.y) / 2 {
                if y >= 64 {
                    break
                }
                if let Some(block) = half_block(
                    notes_on[y as usize * 2],
                    notes_on[y as usize * 2 + 1],
                ) {
                    let cell = buf.get_mut(x, y);
                    cell.set_char(block);
                    cell.set_fg(Color::White);
                }
            }
            if phrase.percussive {
                notes_on.fill(false);
            }
        }
    }
    Ok(())
}