maolan-engine 0.2.20

use serde::{Deserialize, Serialize};

#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash, Serialize, Deserialize)]
pub enum ModulatorController {
    Volume,
    Balance,
}

#[derive(Debug, Clone, Copy, PartialEq, Eq, Serialize, Deserialize, Default)]
pub enum ModulatorShape {
    #[default]
    Sine,
    Triangle,
    Saw,
    Square,
    SampleHold,
}

impl std::fmt::Display for ModulatorShape {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        match self {
            Self::Sine => write!(f, "Sine"),
            Self::Triangle => write!(f, "Triangle"),
            Self::Saw => write!(f, "Saw"),
            Self::Square => write!(f, "Square"),
            Self::SampleHold => write!(f, "Sample & Hold"),
        }
    }
}

#[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
pub enum ModulatorTarget {
    TrackVolume {
        track_name: String,
        min: f32,
        max: f32,
    },
    TrackBalance {
        track_name: String,
        min: f32,
        max: f32,
    },
    HwOutVolume {
        min: f32,
        max: f32,
    },
    HwOutBalance {
        min: f32,
        max: f32,
    },
}

impl ModulatorTarget {
    pub fn track_name(&self) -> Option<&str> {
        match self {
            Self::TrackVolume { track_name, .. } | Self::TrackBalance { track_name, .. } => {
                Some(track_name)
            }
            Self::HwOutVolume { .. } | Self::HwOutBalance { .. } => None,
        }
    }
}

#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct Modulator {
    pub id: usize,
    pub name: String,
    pub shape: ModulatorShape,
    pub rate_hz: f32,
    pub phase: f32,
    pub bipolar: bool,
    pub enabled: bool,
    pub targets: Vec<ModulatorTarget>,
}

impl Modulator {
    pub fn new(id: usize) -> Self {
        Self {
            id,
            name: format!("Modulator {id}"),
            shape: ModulatorShape::default(),
            rate_hz: 1.0,
            phase: 0.0,
            bipolar: false,
            enabled: true,
            targets: Vec::new(),
        }
    }

    /// Evaluate the modulator at a given transport sample and sample rate.
    /// Returns a normalized value in `[0, 1]` regardless of the `bipolar` flag.
    pub fn value_at(&self, sample: usize, sample_rate: f64) -> f32 {
        let cycles = sample as f64 / sample_rate * self.rate_hz as f64 + self.phase as f64;
        let phase = cycles.rem_euclid(1.0) as f32;
        let raw = match self.shape {
            ModulatorShape::Sine => (phase * 2.0 * std::f32::consts::PI).sin(),
            ModulatorShape::Triangle => {
                if phase < 0.5 {
                    4.0 * phase - 1.0
                } else {
                    3.0 - 4.0 * phase
                }
            }
            ModulatorShape::Saw => 2.0 * phase - 1.0,
            ModulatorShape::Square => {
                if phase < 0.5 {
                    1.0
                } else {
                    -1.0
                }
            }
            ModulatorShape::SampleHold => {
                let step = (phase * 16.0).floor() as i32;
                let mut hasher = std::collections::hash_map::DefaultHasher::new();
                use std::hash::{Hash, Hasher};
                step.hash(&mut hasher);
                let h = hasher.finish();
                ((h as f32 / u64::MAX as f32) * 2.0) - 1.0
            }
        };
        ((raw + 1.0) / 2.0).clamp(0.0, 1.0)
    }
}