// 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, NodeExecContext};
use crate::dsp::{NodeId, SAtom, ProcBuf, DspNode, LedPhaseVals};
use crate::dsp::helpers::{DelayBuffer, crossfade, DCBlockFilter};

#[macro_export]
macro_rules! fa_dly_s { ($formatter: expr, $v: expr, $denorm_v: expr) => { {
        let s =
            match ($v.round() as usize) {
                0  => "Zero",
                1  => "One",
                2  => "Two",
                3  => "Three",
                4  => "Four",
                5  => "Five",
                6  => "Six",
                7  => "Seven",
                8  => "Eigth",
                9  => "Nine",
                10 => "Ten",
                _  => "?",
            };
        write!($formatter, "{}", s)
} } }

/// A simple amplifier
#[derive(Debug, Clone)]
pub struct Delay {
    buffer:    Box<DelayBuffer>,
    fb_sample: f32,
    dcblock:   DCBlockFilter,
}

impl Delay {
    pub fn new(_nid: &NodeId) -> Self {
        Self {
            buffer:     Box::new(DelayBuffer::new()),
            fb_sample:  0.0,
            dcblock:    DCBlockFilter::new(),
        }
    }

    pub const inp  : &'static str =
        "Delay inp\nThe signal input for the delay. You can mix in this \
         input to the output with the 'mix' parameter.\nRange: (-1..1)";
    pub const time : &'static str =
        "Delay time\nThe delay time. It can be freely modulated to your \
         likings.\nRange: (0..1)";
    pub const fb   : &'static str =
        "Delay fb\nThe feedback amount of the delay output to it's input. \
        \nRange: (0..1)";
    pub const mix  : &'static str =
        "Delay mix\nThe dry/wet mix of the delay.\nRange: (0..1)";
    pub const sig  : &'static str =
        "Delay sig\nThe output of the dry/wet mix.\nRange: (-1..1)";

    pub const DESC : &'static str =
r#"Simple Delay Line

This is a very simple single buffer delay node.
It provides an internal feedback and dry/wet mix.
"#;
pub const HELP : &'static str =
r#"Delay - A Simple Delay Line

This node provides a very simple delay line with the bare minimum of
parameters. Most importantly a freely modulateable 'time' parameter
and a feedback 'fb' parameter.

Via the 'mix' parameter you can mix in the input signal to the output.

You can use this node to delay any kind of signal, from a simple control
signal to an audio signal.

For other kinds of delay/feedback please see also the 'FbWr'/'FbRd' nodes.
"#;
}

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

    fn set_sample_rate(&mut self, srate: f32) {
        self.buffer.set_sample_rate(srate);
        self.dcblock.set_sample_rate(srate);
    }

    fn reset(&mut self) {
        self.buffer.reset();
        self.dcblock.reset();
    }

    #[inline]
    fn process<T: NodeAudioContext>(
        &mut self, ctx: &mut T, _ectx: &mut NodeExecContext,
        _atoms: &[SAtom], _params: &[ProcBuf], inputs: &[ProcBuf],
        outputs: &mut [ProcBuf], _led: LedPhaseVals)
    {
        use crate::dsp::{out, inp, denorm};

        let buffer  = &mut *self.buffer;
        let dcblock = &mut self.dcblock;

        let inp  = inp::Delay::inp(inputs);
        let time = inp::Delay::time(inputs);
        let fb   = inp::Delay::fb(inputs);
        let mix  = inp::Delay::mix(inputs);
        let out  = out::Delay::sig(outputs);

        let mut fb_s = self.fb_sample;

        for frame in 0..ctx.nframes() {
            let dry = inp.read(frame);
            buffer.feed(
                dry + fb_s * denorm::Delay::fb(fb, frame));

            let out_sample =
                buffer.cubic_interpolate_at(
                    denorm::Delay::time(time, frame));

            out.write(frame,
                dcblock.next(
                    crossfade(dry, out_sample,
                        denorm::Delay::mix(mix, frame).clamp(0.0, 1.0))));

            fb_s = out_sample;
        }

        self.fb_sample = fb_s;
    }
}