use std::ffi::{c_void, CString};
use std::process::abort;

use glfw::WindowSize;

use crate::vector::Vec2;

pub fn initialize(window: &glfw::Window) -> Result<(), Error>
{
    gl::load_with(|symbol| {
        let proc_name = unsafe { CString::from_vec_unchecked(symbol.into()) };

        match window.get_proc_address(proc_name.as_c_str()) {
            Ok(addr) => addr as *const c_void,
            Err(err) => {
                println!(
                    "FATAL ERROR: Failed to get adress of OpenGL function {}. {}",
                    symbol, err
                );

                abort();
            }
        }
    });

    let window_size = window.size().map_err(Error::GetWindowSizeFailed)?;

    set_viewport(&Vec2 { x: 0, y: 0 }, &window_size);

    Ok(())
}

pub fn render()
{
    unsafe {
        gl::Clear(gl::COLOR_BUFFER_BIT | gl::DEPTH_BUFFER_BIT);
    }
}

pub fn set_viewport(position: &Vec2<u32>, size: &WindowSize)
{
    unsafe {
        #[allow(clippy::cast_possible_wrap)]
        gl::Viewport(
            position.x as i32,
            position.y as i32,
            size.width as i32,
            size.height as i32,
        );
    }
}

/// Renderer error.
#[derive(Debug, thiserror::Error)]
pub enum Error
{
    #[error("Failed to get window size")]
    GetWindowSizeFailed(#[source] glfw::Error),
}