//! In-browser **deterministic byte-exact generation** — the create-side of the
//! integer contract, zero JS ML runtime.
//!
//! The same pure-i64 Rust that generates natively compiles straight to wasm32 and
//! produces the IDENTICAL bytes here: a generated image whose hash is portable, so
//! the page can pin "this prompt+seed under this model produces exactly these
//! bytes" and verify it client-side. No float, no ONNX — `wai.generate.spectral`.

use wasm_bindgen::prelude::*;

/// A generated image: RGB row-major, `width * height * 3` bytes.
#[wasm_bindgen]
pub struct GeneratedImage {
    rgb: Vec<u8>,
    width: u32,
    height: u32,
}

#[wasm_bindgen]
impl GeneratedImage {
    #[wasm_bindgen(getter)]
    pub fn rgb(&self) -> Box<[u8]> {
        self.rgb.clone().into_boxed_slice()
    }
    #[wasm_bindgen(getter)]
    pub fn width(&self) -> u32 {
        self.width
    }
    #[wasm_bindgen(getter)]
    pub fn height(&self) -> u32 {
        self.height
    }
}

/// Generate an image deterministically from `(model, prompt, seed, steps)`, in the
/// browser, integer-exact. `model_json` is the pinned model bundle
/// (`generate_spectral_model.json`); the output is byte-identical to the native
/// reference, so its FNV-1a is portable. No float, no ML runtime.
#[wasm_bindgen(js_name = generateSpectral)]
pub fn generate_spectral(
    model_json: &[u8], prompt: &str, seed: u32, steps: u32, w: u32, h: u32,
) -> Result<GeneratedImage, JsError> {
    let v: serde_json::Value =
        serde_json::from_slice(model_json).map_err(|e| JsError::new(&e.to_string()))?;
    let m = wai::generate::SpectralModel::from_value(&v);
    let rgb = wai::generate::generate(&m, prompt, seed as u64, steps as usize, h as usize, w as usize);
    Ok(GeneratedImage { rgb, width: w, height: h })
}

/// FNV-1a 64-bit of `bytes` as lowercase hex — the portable generation hash the
/// page pins and re-checks, the same checksum the native generator emits.
#[wasm_bindgen(js_name = fnv1aHex)]
pub fn fnv1a_hex(bytes: &[u8]) -> String {
    format!("{:016x}", wai::generate::fnv1a(bytes))
}