//! Voltage-controlled oscillator (VCO).
//!
//! Waveforms: Sine, Saw, Square, Triangle, Pulse (variable width).
//! Uses phase accumulation; bandlimited variants (BLEP/BLAMP) to follow.

use crate::{AudioProcessor, CVProcessor, config::SampleRate};

#[derive(Clone, Copy, Debug, PartialEq)]
pub enum Waveform {
    Sine,
    Saw,
    Square,
    Triangle,
    Pulse(f32), // pulse width 0.0–1.0
}

pub struct Vco {
    pub waveform: Waveform,
    pub freq_hz: f32,
    phase: f32,
    sample_rate: SampleRate,
}

impl Vco {
    pub fn new(sample_rate: SampleRate, freq_hz: f32, waveform: Waveform) -> Self {
        Self { waveform, freq_hz, phase: 0.0, sample_rate }
    }

    #[inline]
    fn next_sample(&mut self) -> f32 {
        let p = self.phase;
        let sample = match self.waveform {
            Waveform::Sine     => libm::sinf(p * core::f32::consts::TAU),
            Waveform::Saw      => 2.0 * p - 1.0,
            Waveform::Square   => if p < 0.5 { 1.0 } else { -1.0 },
            Waveform::Triangle => 4.0 * (p - libm::floorf(p + 0.5)).abs() - 1.0,
            Waveform::Pulse(w) => if p < w { 1.0 } else { -1.0 },
        };
        let next = p + self.freq_hz * self.sample_rate.period();
        self.phase = next - libm::floorf(next);
        sample
    }
}

impl<const B: usize> AudioProcessor<B> for Vco {
    fn process(&mut self, out: &mut [f32; B]) {
        for s in out.iter_mut() {
            *s = self.next_sample();
        }
    }

    fn reset(&mut self) {
        self.phase = 0.0;
    }
}

impl<const B: usize> CVProcessor<B> for Vco {
    /// CV is 1 V/oct: 0 V = 440 Hz, +1 V = 880 Hz, −1 V = 220 Hz.
    fn set_cv(&mut self, cv: f32) {
        self.freq_hz = 440.0 * libm::powf(2.0, cv);
    }
}