#![no_std]
extern crate alloc;
use alloc::{boxed::Box, vec, vec::Vec};
use engine_internals::engine_startup;
use pixel_format::{Rgba64, RGBA};
// use core::fmt::Result;
use core::result::Result;
use rhai::{EvalAltResult, Scope};

mod engine_internals;
pub mod pixel_format;

pub const SHADER: &str = include_str!("../shaders/simple.shade");

pub fn rhai_test() -> Result<Vec<RGBA>, Box<EvalAltResult>>
//                          ^^^^^^^^^^^^^^^^^^
//                          Rhai API error type
{
    // Create an 'Engine'

    let engine = engine_startup();

    let ast = engine.compile(SHADER)?;
    let mut scope = Scope::new();

    let a = vec![
        RGBA {
            r: 255,
            g: 0,
            b: 0,
            a: 0,
        },
        RGBA {
            r: 0,
            g: 255,
            b: 0,
            a: 0,
        },
        RGBA {
            r: 0,
            g: 0,
            b: 255,
            a: 0,
        },
        RGBA {
            r: 0,
            g: 0,
            b: 0,
            a: 255,
        },
    ];

    let mut result_rgba = vec![];

    for pixel in a {
        /*
        scope.push("PIXEL_X", 0);
        scope.push("PIXEL_Y", index);
        */
        scope.push("PIXEL_RGBA", pixel);

        let result: RGBA = engine.call_fn(&mut scope, &ast, "main", ())?;
        result_rgba.push(result);
    }

    // Done!
    Ok(result_rgba)
}

pub fn evaluate_shader(pixel: u8) -> Result<Rgba64, Box<EvalAltResult>> {
    let engine = engine_startup();

    let ast = engine.compile(SHADER)?;
    let mut scope = Scope::new();

    scope.push("PIXEL_RGBA", pixel);

    let result: RGBA = engine.call_fn(&mut scope, &ast, "main", ())?;

    Ok(8)
}