// Copyright (c) 2021 Weird Constructor <weirdconstructor@gmail.com>
// This is a part of HexoDSP. Released under (A)GPLv3 or any later.
// See README.md and COPYING for details.

use crate::nodes::NodeAudioContext;
use crate::dsp::{SAtom, ProcBuf, DspNode, LedPhaseVals};

/// A simple amplifier
#[derive(Debug, Clone)]
pub struct Sampl {
    phase: f64,
    srate: f64,
}

impl Sampl {
    pub fn new() -> Self {
        Self {
            phase: 0.0,
            srate: 44100.0,
        }
    }
    pub const freq : &'static str =
        "Sampl freq\nPitch input for the sampler, giving the playback speed of the \
        sample.\nRange: (-1..1)\n";

    pub const trig : &'static str =
        "Sampl trig\nThe trigger input causes a resync of the playback phase \
         and triggers the playback if the 'pmode' is 'OneShot'";
    pub const spos : &'static str =
        "Sampl spos\nStart position offset.\nRange: (-1..1)\n";
    pub const epos : &'static str =
        "Sampl epos\nEnd position offset.\nRange: (-1..1)\n";

    pub const sample : &'static str =
        "Sampl sample\nThe audio sample that is played back.\nRange: (-1..1)\n";

    pub const pmode : &'static str =
        "Sampl pmode\nThe playback mode of the sampler.\n\
        - 'Loop' constantly plays back the sample. You can reset/sync the phase \
        using the 'trig' input in this case.\n\
        - 'OneShot' plays back the sample if a trigger is received on 'trig' input.\n";
    pub const dclick : &'static str =
        "Sampl dclick\nIf this is enabled and the 'pmode' is 'OneShot' \
         this will enable short fade in and out ramps.\n\
         This if useful if you don't want to add an envelope just for \
         getting rid of the clicks if spos and epos are modulated.";

    pub const sig : &'static str =
        "Sampl sig\nSampler audio output\nRange: (-1..1)\n";
}

impl DspNode for Sampl {
    fn outputs() -> usize { 1 }

    fn set_sample_rate(&mut self, srate: f32) { self.srate = srate.into(); }
    fn reset(&mut self) { }

    #[inline]
    fn process<T: NodeAudioContext>(
        &mut self, ctx: &mut T, atoms: &[SAtom], _params: &[ProcBuf],
        inputs: &[ProcBuf], outputs: &mut [ProcBuf], ctx_vals: LedPhaseVals)
    {
        use crate::dsp::{out, at, inp, denorm}; //, inp, denorm, denorm_v, inp_dir, at};

        let sample = at::Sampl::sample(atoms);
        let freq   = inp::Sampl::freq(inputs);
        let out    = out::Sampl::sig(outputs);

        if let SAtom::AudioSample((_, Some(sample_data))) = sample {
            let sd_len   = sample_data.len() - 1;
            let sd_len_f = sd_len as f64;

            let sample_srate = sample_data[0] as f64;
            let sample_data  = &sample_data[1..];

            let sr_factor = sample_srate / self.srate;

            for frame in 0..ctx.nframes() {
                let playback_speed =
                    denorm::Sampl::freq(freq, frame) / 440.0;

                let i = self.phase.floor() as usize + sd_len;

                // Hermite interpolation, take from 
                // https://github.com/eric-wood/delay/blob/main/src/delay.rs#L52
                //
                // Thanks go to Eric Wood!
                //
                // For the interpolation code:
                // MIT License, Copyright (c) 2021 Eric Wood
                let xm1 = sample_data[(i - 1) % sd_len];
                let x0  = sample_data[i       % sd_len];
                let x1  = sample_data[(i + 1) % sd_len];
                let x2  = sample_data[(i + 2) % sd_len];

                let c     = (x1 - xm1) * 0.5;
                let v     = x0 - x1;
                let w     = c + v;
                let a     = w + v + (x2 - x0) * 0.5;
                let b_neg = w + a;

                let f = self.phase.fract() as f32;

                let out_sample = (((a * f) - b_neg) * f + c) * f + x0;
                out.write(frame, out_sample);

                self.phase += sr_factor * playback_speed as f64;
            }
        } else {
            for frame in 0..ctx.nframes() {
                out.write(frame, 0.0);
            }
        }

        ctx_vals[0].set(1.0);
//        let neg  = at::Amp::neg_att(atoms);
//
//        let last_frame   = ctx.nframes() - 1;
//
//        let last_val =
//            if neg.i() > 0 {
//                for frame in 0..ctx.nframes() {
//                    out.write(frame,
//                        inp.read(frame)
//                        * denorm_v::Amp::att(
//                            inp_dir::Amp::att(att, frame)
//                            .max(0.0))
//                        * denorm::Amp::gain(gain, frame));
//                }
//
//                inp.read(last_frame)
//                * denorm_v::Amp::att(
//                    inp_dir::Amp::att(att, last_frame)
//                    .max(0.0))
//                * denorm::Amp::gain(gain, last_frame)
//
//            } else {
//                for frame in 0..ctx.nframes() {
//                    out.write(frame,
//                        inp.read(frame)
//                        * denorm_v::Amp::att(
//                            inp_dir::Amp::att(att, frame).abs())
//                        * denorm::Amp::gain(gain, frame));
//                }
//
//                inp.read(last_frame)
//                * denorm_v::Amp::att(
//                    inp_dir::Amp::att(att, last_frame).abs())
//                * denorm::Amp::gain(gain, last_frame)
//            };
    }
}