use crate::*;

/// The sampler plugin plays sounds.
pub struct Sampler<E: Engine> {
    _engine:         PhantomData<E>,
    pub jack:        Arc<RwLock<JackClient>>,
    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:      Arc<RwLock<Vec<Voice>>>,
    pub ports:       JackPorts,
    pub buffer:      Vec<Vec<f32>>,
    pub modal:       Arc<Mutex<Option<Box<dyn Exit + Send>>>>,
    pub output_gain: f32
}

impl<E: Engine> Sampler<E> {
    pub fn new (
        jack: &Arc<RwLock<JackClient>>,
        name: &str,
        mapped: Option<BTreeMap<u7, Arc<RwLock<Sample>>>>
    ) -> Usually<JackDevice<E>> {
        Jack::new(name)?
            .midi_in("midi")
            .audio_in("recL")
            .audio_in("recR")
            .audio_out("outL")
            .audio_out("outR")
            .run(|ports|Box::new(Self {
                _engine:  Default::default(),
                jack:     jack.clone(),
                name:     name.into(),
                cursor:   (0, 0),
                editing:  None,
                mapped:   mapped.unwrap_or_else(||BTreeMap::new()),
                unmapped: vec![],
                voices:   Arc::new(RwLock::new(vec![])),
                ports,
                buffer:   vec![vec![0.0;16384];2],
                output_gain: 0.5,
                modal:    Default::default()
            }))
    }
    /// 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
    }
    /// Create [Voice]s from [Sample]s in response to MIDI input.
    pub 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.write().unwrap().push(Sample::play(sample, time as usize, vel));
                    }
                }
            }
        }
    }
    /// Zero the output buffer.
    pub 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.
    pub fn process_audio_out (&mut self, scope: &ProcessScope) {
        let channel_count = self.buffer.len();
        self.voices.write().unwrap().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.
    pub 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);
            }
        }
    }
}

/// A sound sample.
#[derive(Default, Debug)]
pub struct Sample {
    pub name:     String,
    pub start:    usize,
    pub end:      usize,
    pub channels: Vec<Vec<f32>>,
    pub rate:     Option<usize>,
}

impl Sample {
    pub fn new (name: &str, start: usize, end: usize, channels: Vec<Vec<f32>>) -> Self {
        Self { name: name.to_string(), start, end, channels, rate: None }
    }
    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,
        }
    }
}


/// 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))
}

use std::fs::File;
use symphonia::core::codecs::CODEC_TYPE_NULL;
use symphonia::core::errors::Error;
use symphonia::core::io::MediaSourceStream;
use symphonia::core::probe::Hint;
use symphonia::core::audio::SampleBuffer;
use symphonia::default::get_codecs;

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

impl Exit for AddSampleModal {
    fn exited (&self) -> bool {
        self.exited
    }
    fn exit (&mut self) {
        self.exited = true
    }
}

impl AddSampleModal {
    pub fn new (
        sample: &Arc<RwLock<Sample>>,
        voices: &Arc<RwLock<Vec<Voice>>>
    ) -> 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(),
            voices: voices.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() {
            if let Ok(sample) = Sample::from_file(&path) {
                *self.sample.write().unwrap() = sample;
                self.voices.write().unwrap().push(
                    Sample::play(&self.sample, 0, &u7::from(100u8))
                );
            }
            //load_sample(&path)?;
            //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))
}

impl Sample {
    fn from_file (path: &PathBuf) -> Usually<Self> {
        let mut sample = Self::default();
        sample.name = path.file_name().unwrap().to_string_lossy().into();
        // Use file extension if present
        let mut hint = Hint::new();
        if let Some(ext) = path.extension() {
            hint.with_extension(&ext.to_string_lossy());
        }
        let probed = symphonia::default::get_probe().format(
            &hint,
            MediaSourceStream::new(
                Box::new(File::open(path)?),
                Default::default(),
            ),
            &Default::default(),
            &Default::default()
        )?;
        let mut format = probed.format;
        let mut decoder = get_codecs().make(
            &format.tracks().iter()
                .find(|t| t.codec_params.codec != CODEC_TYPE_NULL)
                .expect("no tracks found")
                .codec_params,
            &Default::default()
        )?;
        loop {
            match format.next_packet() {
                Ok(packet) => {
                    // Decode a packet
                    let decoded = match decoder.decode(&packet) {
                        Ok(decoded) => decoded,
                        Err(err) => { return Err(err.into()); }
                    };
                    // Determine sample rate
                    let spec = *decoded.spec();
                    if let Some(rate) = sample.rate {
                        if rate != spec.rate as usize {
                            panic!("sample rate changed");
                        }
                    } else {
                        sample.rate = Some(spec.rate as usize);
                    }
                    // Determine channel count
                    while sample.channels.len() < spec.channels.count() {
                        sample.channels.push(vec![]);
                    }
                    // Load sample
                    let mut samples = SampleBuffer::new(
                        decoded.frames() as u64,
                        spec
                    );
                    if samples.capacity() > 0 {
                        samples.copy_interleaved_ref(decoded);
                        for frame in samples.samples().chunks(spec.channels.count()) {
                            for (chan, frame) in frame.iter().enumerate() {
                                sample.channels[chan].push(*frame)
                            }
                        }
                    }
                },
                Err(Error::IoError(_)) => break decoder.last_decoded(),
                Err(err) => return Err(err.into()),
            };
        };
        sample.end = sample.channels.iter().fold(0, |l, c|l + c.len());
        Ok(sample)
    }
}

/// 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 sample.channels[0].get(position).map(|_amplitude|[
                sample.channels[0][position] * self.velocity,
                sample.channels[0][position] * self.velocity,
            ])
        }
        None
    }
}