//! Sampler (currently 16bit WAVs at system rate; TODO convert/resample)

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

use symphonia::core::codecs::{DecoderOptions, CODEC_TYPE_NULL};
use symphonia::core::errors::Error;
use symphonia::core::formats::FormatOptions;
use symphonia::core::io::MediaSourceStream;
use symphonia::core::meta::MetadataOptions;
use symphonia::core::probe::Hint;

/// The sampler plugin plays sounds.
pub struct Sampler {
    pub name:        String,
    pub cursor:      (usize, usize),
    pub editing:     Option<Arc<RwLock<Sample>>>,
    pub mapped:      BTreeMap<u7, Arc<RwLock<Sample>>>,
    pub unmapped:    Vec<Arc<RwLock<Sample>>>,
    pub voices:      Vec<Voice>,
    pub ports:       JackPorts,
    pub buffer:      Vec<Vec<f32>>,
    pub output_gain: f32
}

render!(Sampler |self, buf, area| {
    let Rect { x, y, height, .. } = area;
    let style = Style::default().gray();
    let title = format!(" {} ({})", self.name, self.voices.len());
    title.blit(buf, x+1, y, Some(style.white().bold().not_dim()))?;
    let mut width = title.len() + 2;
    let mut y1 = 1;
    let mut j = 0;
    for (note, sample) in self.mapped.iter()
        .map(|(note, sample)|(Some(note), sample))
        .chain(self.unmapped.iter().map(|sample|(None, sample)))
    {
        if y1 >= height {
            break
        }
        let active = j == self.cursor.0;
        width = width.max(draw_sample(buf, x, y + y1, note, &*sample.read().unwrap(), active)?);
        y1 = y1 + 1;
        j = j + 1;
    }
    let height = ((2 + y1) as u16).min(height);
    Ok(Rect { x, y, width: (width as u16).min(area.width), height })
});

fn draw_sample (
    buf: &mut Buffer, x: u16, y: u16, note: Option<&u7>, sample: &Sample, focus: bool
) -> Usually<usize> {
    let style = if focus { Style::default().green() } else { Style::default() };
    if focus {
        "🬴".blit(buf, x+1, y, Some(style.bold()))?;
    }
    let label1 = format!("{:3} {:12}",
        note.map(|n|n.to_string()).unwrap_or(String::default()),
        sample.name);
    let label2 = format!("{:>6} {:>6}  +0.0",
        sample.start,
        sample.end);
    label1.blit(buf, x+2, y, Some(style.bold()))?;
    label2.blit(buf, x+3+label1.len()as u16, y, Some(style))?;
    Ok(label1.len() + label2.len() + 4)
}

handle!(Sampler |self, event| handle_keymap(self, event, KEYMAP_SAMPLER));

/// Key bindings for sampler device.
pub const KEYMAP_SAMPLER: &'static [KeyBinding<Sampler>] = keymap!(Sampler {
    [Up, NONE, "cursor_up", "move cursor up", |state: &mut Sampler| {
        state.cursor.0 = if state.cursor.0 == 0 {
            state.mapped.len() + state.unmapped.len() - 1
        } else {
            state.cursor.0 - 1
        };
        Ok(true)
    }],
    [Down, NONE, "cursor_down", "move cursor down", |state: &mut Sampler| {
        state.cursor.0 = (state.cursor.0 + 1) % (state.mapped.len() + state.unmapped.len());
        Ok(true)
    }],
    [Char('t'), NONE, "sample_play", "play current sample",  |state: &mut Sampler| {
        if let Some(sample) = state.sample() {
            state.voices.push(Sample::play(sample, 0, &100.into()))
        }
        Ok(true)
    }],
    [Char('a'), NONE, "sample_add", "add a new sample", |state: &mut Sampler| {
        let sample = Sample::new("", 0, 0, vec![]);
        *MODAL.lock().unwrap() = Some(Exit::boxed(AddSampleModal::new(&sample)?));
        state.unmapped.push(sample);
        Ok(true)
    }],
    [Char('r'), NONE, "sample_replace", "replace selected sample", |state: &mut Sampler| {
        if let Some(sample) = state.sample() {
            *MODAL.lock().unwrap() = Some(Exit::boxed(AddSampleModal::new(&sample)?));
        }
        Ok(true)
    }],
    [Enter, NONE, "sample_edit", "edit selected sample", |state: &mut Sampler| {
        if let Some(sample) = state.sample() {
            state.editing = Some(sample.clone());
        }
        Ok(true)
    }],
});

process!(Sampler = Sampler::process);

impl Sampler {
    pub fn new (name: &str, mapped: Option<BTreeMap<u7, Arc<RwLock<Sample>>>>) -> Usually<JackDevice> {
        Jack::new(name)?
            .midi_in("midi")
            .audio_in("recL")
            .audio_in("recR")
            .audio_out("outL")
            .audio_out("outR")
            .run(|ports|Box::new(Self {
                name:     name.into(),
                cursor:   (0, 0),
                editing:  None,
                mapped:   mapped.unwrap_or_else(||BTreeMap::new()),
                unmapped: vec![],
                voices:   vec![],
                ports,
                buffer:   vec![vec![0.0;16384];2],
                output_gain: 0.5,
            }))
    }

    /// Immutable reference to sample at cursor.
    pub fn sample (&self) -> Option<&Arc<RwLock<Sample>>> {
        for (i, sample) in self.mapped.values().enumerate() {
            if i == self.cursor.0 {
                return Some(sample)
            }
        }
        for (i, sample) in self.unmapped.iter().enumerate() {
            if i + self.mapped.len() == self.cursor.0 {
                return Some(sample)
            }
        }
        None
    }

    pub fn process (&mut self, _: &Client, scope: &ProcessScope) -> Control {
        self.process_midi_in(scope);
        self.clear_output_buffer();
        self.process_audio_out(scope);
        self.write_output_buffer(scope);
        Control::Continue
    }

    /// Create [Voice]s from [Sample]s in response to MIDI input.
    fn process_midi_in (&mut self, scope: &ProcessScope) {
        for RawMidi { time, bytes } in self.ports.midi_ins.get("midi").unwrap().iter(scope) {
            if let LiveEvent::Midi { message, .. } = LiveEvent::parse(bytes).unwrap() {
                if let MidiMessage::NoteOn { ref key, ref vel } = message {
                    if let Some(sample) = self.mapped.get(key) {
                        self.voices.push(Sample::play(sample, time as usize, vel));
                    }
                }
            }
        }
    }

    /// Zero the output buffer.
    fn clear_output_buffer (&mut self) {
        for buffer in self.buffer.iter_mut() {
            buffer.fill(0.0);
        }
    }

    /// Mix all currently playing samples into the output.
    fn process_audio_out (&mut self, scope: &ProcessScope) {
        let channel_count = self.buffer.len();
        self.voices.retain_mut(|voice|{
            for index in 0..scope.n_frames() as usize {
                if let Some(frame) = voice.next() {
                    for (channel, sample) in frame.iter().enumerate() {
                        // Averaging mixer:
                        //self.buffer[channel % channel_count][index] = (
                            //(self.buffer[channel % channel_count][index] + sample * self.output_gain) / 2.0
                        //);
                        self.buffer[channel % channel_count][index] +=
                            sample * self.output_gain;
                    }
                } else {
                    return false
                }
            }
            return true
        });
    }

    /// Write output buffer to output ports.
    fn write_output_buffer (&mut self, scope: &ProcessScope) {
        for (i, port) in self.ports.audio_outs.values_mut().enumerate() {
            let buffer = &self.buffer[i];
            for (i, value) in port.as_mut_slice(scope).iter_mut().enumerate() {
                *value = *buffer.get(i).unwrap_or(&0.0);
            }
        }
    }
}

/// Load sample from WAV and assign to MIDI note.
#[macro_export] macro_rules! sample {
    ($note:expr, $name:expr, $src:expr) => {{
        let (end, data) = read_sample_data($src)?;
        (
            u7::from_int_lossy($note).into(),
            Sample::new($name, 0, end, data).into()
        )
    }};
}

/// Read WAV from file
pub fn read_sample_data (src: &str) -> Usually<(usize, Vec<Vec<f32>>)> {
    let mut channels: Vec<wavers::Samples<f32>> = vec![];
    for channel in wavers::Wav::from_path(src)?.channels() {
        channels.push(channel);
    }
    let mut end = 0;
    let mut data: Vec<Vec<f32>> = vec![];
    for samples in channels.iter() {
        let channel = Vec::from(samples.as_ref());
        end = end.max(channel.len());
        data.push(channel);
    }
    Ok((end, data))
}

/// A sound sample.
pub struct Sample {
    pub name:     String,
    pub start:    usize,
    pub end:      usize,
    pub channels: Vec<Vec<f32>>,
}

impl Sample {
    pub fn new (
        name: &str, start: usize, end: usize, channels: Vec<Vec<f32>>
    ) -> Arc<RwLock<Self>> {
        Arc::new(RwLock::new(Self { name: name.to_string(), start, end, channels }))
    }
    pub fn play (sample: &Arc<RwLock<Self>>, after: usize, velocity: &u7) -> Voice {
        Voice {
            sample: sample.clone(),
            after,
            position: sample.read().unwrap().start,
            velocity: velocity.as_int() as f32 / 127.0
        }
    }
}

/// A currently playing instance of a sample.
pub struct Voice {
    pub sample:   Arc<RwLock<Sample>>,
    pub after:    usize,
    pub position: usize,
    pub velocity: f32,
}

impl Iterator for Voice {
    type Item = [f32;2];
    fn next (&mut self) -> Option<Self::Item> {
        if self.after > 0 {
            self.after = self.after - 1;
            return Some([0.0, 0.0])
        }
        let sample = self.sample.read().unwrap();
        if self.position < sample.end {
            let position = self.position;
            self.position = self.position + 1;
            return Some([
                sample.channels[0][position] * self.velocity,
                sample.channels[0][position] * self.velocity,
            ])
        }
        None
    }
}

pub struct AddSampleModal {
    exited:  bool,
    dir:     PathBuf,
    subdirs: Vec<OsString>,
    files:   Vec<OsString>,
    cursor:  usize,
    offset:  usize,
    sample:  Arc<RwLock<Sample>>,
    search:  Option<String>,
}

exit!(AddSampleModal);

render!(AddSampleModal |self,buf,area|{
    make_dim(buf);
    let area = center_box(
        area,
        64.max(area.width.saturating_sub(8)),
        20.max(area.width.saturating_sub(8)),
    );
    fill_fg(buf, area, Color::Reset);
    fill_bg(buf, area, Nord::bg_lo(true, true));
    fill_char(buf, area, ' ');
    format!("{}", &self.dir.to_string_lossy())
        .blit(buf, area.x+2, area.y+1, Some(Style::default().bold()))?;
    "Select sample:"
        .blit(buf, area.x+2, area.y+2, Some(Style::default().bold()))?;
    for (i, (is_dir, name)) in self.subdirs.iter()
        .map(|path|(true, path))
        .chain(self.files.iter().map(|path|(false, path)))
        .enumerate()
        .skip(self.offset)
    {
        if i >= area.height as usize - 4 {
            break
        }
        let t = if is_dir { "" } else { "" };
        let line = format!("{t} {}", name.to_string_lossy());
        let line = &line[..line.len().min(area.width as usize - 4)];
        line.blit(buf, area.x + 2, area.y + 3 + i as u16, Some(if i == self.cursor {
            Style::default().green()
        } else {
            Style::default().white()
        }))?;
    }
    Lozenge(Style::default()).draw(buf, area)
});

handle!(AddSampleModal |self,e|{
    if handle_keymap(self, e, KEYMAP_ADD_SAMPLE)? {
        return Ok(true)
    }
    Ok(true)
});

impl AddSampleModal {
    fn new (sample: &Arc<RwLock<Sample>>) -> Usually<Self> {
        let dir = std::env::current_dir()?;
        let (subdirs, files) = scan(&dir)?;
        Ok(Self {
            exited: false,
            dir,
            subdirs,
            files,
            cursor: 0,
            offset: 0,
            sample: sample.clone(),
            search: None
        })
    } 
    fn rescan (&mut self) -> Usually<()> {
        scan(&self.dir).map(|(subdirs, files)|{
            self.subdirs = subdirs;
            self.files = files;
        })
    }
    fn prev (&mut self) {
        self.cursor = self.cursor.saturating_sub(1);
    }
    fn next (&mut self) {
        self.cursor = self.cursor + 1;
    }
    fn try_preview (&mut self) -> Usually<()> {
        if let Some(path) = self.cursor_file() {
            let src = std::fs::File::open(&path)?;
            let mss = MediaSourceStream::new(Box::new(src), Default::default());
            let mut hint = Hint::new();
            if let Some(ext) = path.extension() {
                hint.with_extension(&ext.to_string_lossy());
            }
            let meta_opts: MetadataOptions = Default::default();
            let fmt_opts: FormatOptions = Default::default();
            if let Ok(mut probed) =  symphonia::default::get_probe()
                .format(&hint, mss, &fmt_opts, &meta_opts)
            {
                panic!("{:?}", probed.format.metadata());
            };
        }
        Ok(())
    }
    fn cursor_dir (&self) -> Option<PathBuf> {
        if self.cursor < self.subdirs.len() {
            Some(self.dir.join(&self.subdirs[self.cursor]))
        } else {
            None
        }
    }
    fn cursor_file (&self) -> Option<PathBuf> {
        if self.cursor < self.subdirs.len() {
            return None
        }
        let index = self.cursor.saturating_sub(self.subdirs.len());
        if index < self.files.len() {
            Some(self.dir.join(&self.files[index]))
        } else {
            None
        }
    }
    fn pick (&mut self) -> Usually<bool> {
        if self.cursor == 0 {
            if let Some(parent) = self.dir.parent() {
                self.dir = parent.into();
                self.rescan()?;
                self.cursor = 0;
                return Ok(false)
            }
        }
        if let Some(dir) = self.cursor_dir() {
            self.dir = dir;
            self.rescan()?;
            self.cursor = 0;
            return Ok(false)
        }
        if let Some(path) = self.cursor_file() {
            let (end, channels) = read_sample_data(&path.to_string_lossy())?;
            let mut sample = self.sample.write().unwrap();
            sample.name = path.file_name().unwrap().to_string_lossy().into();
            sample.end = end;
            sample.channels = channels;
            return Ok(true)
        }
        return Ok(false)
    }
}

pub const KEYMAP_ADD_SAMPLE: &'static [KeyBinding<AddSampleModal>] = keymap!(AddSampleModal {
    [Esc,   NONE, "sampler/add/close", "close help dialog",       |modal: &mut AddSampleModal|{
        modal.exit();
        Ok(true)
    }],
    [Up,    NONE, "sampler/add/prev",  "select previous entry",   |modal: &mut AddSampleModal|{
        modal.prev();
        Ok(true)
    }],
    [Down,  NONE, "sampler/add/next",  "select next entry",       |modal: &mut AddSampleModal|{
        modal.next();
        Ok(true)
    }],
    [Enter, NONE, "sampler/add/enter", "activate selected entry", |modal: &mut AddSampleModal|{
        if modal.pick()? {
            modal.exit();
        }
        Ok(true)
    }],
    [Char('p'), NONE, "sampler/add/preview", "preview selected entry", |modal: &mut AddSampleModal|{
        modal.try_preview()?;
        Ok(true)
    }]
});

fn scan (dir: &PathBuf) -> Usually<(Vec<OsString>, Vec<OsString>)> {
    let (mut subdirs, mut files) = read_dir(dir)?
        .fold((vec!["..".into()], vec![]), |(mut subdirs, mut files), entry|{
            let entry = entry.expect("failed to read drectory entry");
            let meta = entry.metadata().expect("failed to read entry metadata");
            if meta.is_file() {
                files.push(entry.file_name());
            } else if meta.is_dir() {
                subdirs.push(entry.file_name());
            }
            (subdirs, files)
        });
    subdirs.sort();
    files.sort();
    Ok((subdirs, files))
}

fn load_sample () {
    // Get the first command line argument.
    let args: Vec<String> = std::env::args().collect();
    let path = args.get(1).expect("file path not provided");

    // Open the media source.
    let src = std::fs::File::open(path).expect("failed to open media");

    // Create the media source stream.
    let mss = MediaSourceStream::new(Box::new(src), Default::default());

    // Create a probe hint using the file's extension. [Optional]
    let mut hint = Hint::new();
    hint.with_extension("mp3");

    // Use the default options for metadata and format readers.
    let meta_opts: MetadataOptions = Default::default();
    let fmt_opts: FormatOptions = Default::default();

    // Probe the media source.
    let probed = symphonia::default::get_probe()
        .format(&hint, mss, &fmt_opts, &meta_opts)
        .expect("unsupported format");

    // Get the instantiated format reader.
    let mut format = probed.format;

    // Find the first audio track with a known (decodeable) codec.
    let track = format
        .tracks()
        .iter()
        .find(|t| t.codec_params.codec != CODEC_TYPE_NULL)
        .expect("no supported audio tracks");

    // Use the default options for the decoder.
    let dec_opts: DecoderOptions = Default::default();

    // Create a decoder for the track.
    let mut decoder = symphonia::default::get_codecs()
        .make(&track.codec_params, &dec_opts)
        .expect("unsupported codec");

    // Store the track identifier, it will be used to filter packets.
    let track_id = track.id;

    // The decode loop.
    loop {
        // Get the next packet from the media format.
        let packet = match format.next_packet() {
            Ok(packet) => packet,
            Err(Error::ResetRequired) => {
                // The track list has been changed. Re-examine it and create a new set of decoders,
                // then restart the decode loop. This is an advanced feature and it is not
                // unreasonable to consider this "the end." As of v0.5.0, the only usage of this is
                // for chained OGG physical streams.
                unimplemented!();
            }
            Err(err) => {
                // A unrecoverable error occurred, halt decoding.
                panic!("{}", err);
            }
        };

        // Consume any new metadata that has been read since the last packet.
        while !format.metadata().is_latest() {
            // Pop the old head of the metadata queue.
            format.metadata().pop();

            // Consume the new metadata at the head of the metadata queue.
        }

        // If the packet does not belong to the selected track, skip over it.
        if packet.track_id() != track_id {
            continue;
        }

        // Decode the packet into audio samples.
        match decoder.decode(&packet) {
            Ok(_decoded) => {
                // Consume the decoded audio samples (see below).
            }
            Err(Error::IoError(_)) => {
                // The packet failed to decode due to an IO error, skip the packet.
                continue;
            }
            Err(Error::DecodeError(_)) => {
                // The packet failed to decode due to invalid data, skip the packet.
                continue;
            }
            Err(err) => {
                // An unrecoverable error occurred, halt decoding.
                panic!("{}", err);
            }
        }
    }
}