//! Synthesiser parameter model — mirrors synth-core state.
//! Serialised as JSON for postMessage() across the AudioWorklet MessagePort.

use wasm_bindgen::prelude::*;
use serde::{Serialize, Deserialize};

#[wasm_bindgen]
#[derive(Clone, Debug, Serialize, Deserialize)]
pub struct SynthParams {
    pub osc_freq:      f32, // Hz
    pub osc_wave:      u8,  // 0=Sine 1=Saw 2=Square 3=Triangle
    pub filter_cutoff: f32, // Hz
    pub filter_res:    f32, // 0.0–1.0
    pub env_attack:    f32, // seconds
    pub env_decay:     f32,
    pub env_sustain:   f32, // 0.0–1.0
    pub env_release:   f32,
    pub lfo_rate:      f32, // Hz
    pub lfo_depth:     f32, // 0.0–1.0
    pub master_gain:   f32, // 0.0–1.0
}

#[wasm_bindgen]
impl SynthParams {
    #[wasm_bindgen(constructor)]
    pub fn new() -> Self {
        Self {
            osc_freq:      440.0,
            osc_wave:      1,
            filter_cutoff: 2000.0,
            filter_res:    0.3,
            env_attack:    0.01,
            env_decay:     0.1,
            env_sustain:   0.7,
            env_release:   0.3,
            lfo_rate:      2.0,
            lfo_depth:     0.0,
            master_gain:   0.8,
        }
    }

    pub fn to_json(&self) -> String {
        // serde_json would pull in std; for WASM we use the js glue instead.
        // This is a simple manual serialisation for the scaffold.
        format!(
            r#"{{"osc_freq":{:.2},"osc_wave":{},"filter_cutoff":{:.2},"filter_res":{:.3},"env_attack":{:.4},"env_decay":{:.4},"env_sustain":{:.3},"env_release":{:.4},"lfo_rate":{:.3},"lfo_depth":{:.3},"master_gain":{:.3}}}"#,
            self.osc_freq, self.osc_wave, self.filter_cutoff, self.filter_res,
            self.env_attack, self.env_decay, self.env_sustain, self.env_release,
            self.lfo_rate, self.lfo_depth, self.master_gain
        )
    }
}