use glow::HasContext;
use wasm_bindgen::{prelude::Closure, JsCast};
use web_sys::{Event, HtmlCanvasElement};
use winit::{application::ApplicationHandler, dpi::LogicalSize, event::WindowEvent, event_loop::ActiveEventLoop, platform::web::{WindowAttributesExtWebSys, WindowExtWebSys}, raw_window_handle::HasWindowHandle, window::{Window, WindowAttributes}};

pub mod init;

#[derive(Default)]
pub struct App {
    window: Option<Window>,
    program: glow::Program,
    vertex_array: glow::VertexArray,
    vertex_buffer: glow::Buffer,
    element_buffer: glow::Buffer,
    gl: Option<glow::Context>,
}

const VERTICES: [f32; 8] = [
    -1.0, -1.0,
    1.0, -1.0,
    1.0, 1.0,
    -1.0, 1.0,
];
const INDICES: [u32; 6] = [
    0, 1, 2,
    2, 3, 0,
];

impl ApplicationHandler for App {
    fn resumed(&mut self, event_loop: &ActiveEventLoop) {
        #[cfg(target_arch = "wasm32")]
        let attributes = {
            let document = web_sys::window().unwrap().document().unwrap();
            let canvas = document.get_element_by_id("canvas").unwrap();
            let canvas = canvas.dyn_into::<web_sys::HtmlCanvasElement>()
                .map_err(|_| ()).unwrap();
            canvas.set_width(web_sys::window().unwrap().inner_width().unwrap().as_f64().unwrap() as u32);
            canvas.set_height(web_sys::window().unwrap().inner_height().unwrap().as_f64().unwrap() as u32);
            Window::default_attributes()
                .with_title("StarKingdoms.TK")
                .with_canvas(Some(canvas))
        };
        #[cfg(not(target_arch = "wasm32"))]
        let attributes = {
            Window::default_attributes().with_title("StarKingdoms.TK");
        };
        self.window = Some(event_loop.create_window(attributes).unwrap());
        let window = self.window.as_ref().unwrap();
        #[cfg(target_arch = "wasm32")]
        let context = window.canvas().unwrap().get_context("webgl2")
            .unwrap().unwrap()
            .dyn_into::<web_sys::WebGl2RenderingContext>()
            .unwrap();
        #[cfg(not(target_arch = "wasm32"))]
        unsafe {
        }
        let (gl, shader_version) = (glow::Context::from_webgl2_context(context), "#version 300 es");
        unsafe {
            let shaders = [
                ("vertex", include_str!("../shaders/vertex.glsl"), glow::VERTEX_SHADER),
                ("fragment", include_str!("../shaders/fragment.glsl"), glow::FRAGMENT_SHADER),
            ];
            let program = gl.create_program().expect("Failed to create program");

            for (name, source, shader_type) in shaders {
                let shader = gl.create_shader(shader_type).expect("Failed to create vertex shader");
                gl.shader_source(shader, &format!("{}\n{}", shader_version, source));
                gl.compile_shader(shader);
                if !gl.get_shader_compile_status(shader) {
                    tracing::error!("error in {} shader: {}", name, gl.get_shader_info_log(shader));
                }
                gl.attach_shader(program, shader);
                gl.delete_shader(shader);
            }
            gl.link_program(program);

            gl.use_program(Some(program));

            let vertex_array = gl.create_vertex_array().expect("Failed to create vertex array");
            gl.bind_vertex_array(Some(vertex_array));
            let vertex_buffer = gl.create_buffer().expect("Failed to create vertex buffer");
            gl.bind_buffer(glow::ARRAY_BUFFER, Some(vertex_buffer));
            let element_buffer = gl.create_buffer().expect("Failed to create element buffer");
            gl.bind_buffer(glow::ELEMENT_ARRAY_BUFFER, Some(element_buffer));
            gl.buffer_data_u8_slice(glow::ARRAY_BUFFER,
                std::slice::from_raw_parts(VERTICES.as_ptr() as *const u8, 8*4),
                glow::STATIC_DRAW);
            gl.buffer_data_u8_slice(glow::ELEMENT_ARRAY_BUFFER,
                std::slice::from_raw_parts(INDICES.as_ptr() as *const u8, 6*4),
                glow::STATIC_DRAW);

            gl.vertex_attrib_pointer_f32(0, 2, glow::FLOAT, false, 2*std::mem::size_of::<f32>() as i32, 0);
            gl.enable_vertex_attrib_array(0);

            gl.clear_color(1.0, 1.0, 1.0, 1.0);
            gl.viewport(0, 0, window.inner_size().width as i32, window.inner_size().height as i32);

            self.program = program;
            self.vertex_array = vertex_array;
            self.vertex_buffer = vertex_buffer;
            self.element_buffer = element_buffer;
        }
        #[cfg(target_arch = "wasm32")]
        web_sys::window().unwrap().set_onresize(Some(Closure::<dyn Fn(Event)>::new(move |_| {
            let document = web_sys::window().unwrap().document().unwrap();
            let canvas = document.get_element_by_id("canvas").unwrap();
            let canvas = canvas.dyn_into::<web_sys::HtmlCanvasElement>()
                .map_err(|_| ()).unwrap();
            canvas.set_width(web_sys::window().unwrap().inner_width().unwrap().as_f64().unwrap() as u32);
            canvas.set_height(web_sys::window().unwrap().inner_height().unwrap().as_f64().unwrap() as u32);
        }).into_js_value().as_ref().unchecked_ref()));
        self.gl = Some(gl);
    }
    fn window_event(
        &mut self,
        event_loop: &ActiveEventLoop,
        window_id: winit::window::WindowId,
        event: winit::event::WindowEvent,
    ) {
        match event {
            WindowEvent::Resized(size) => {
                unsafe {
                    self.gl.as_ref().unwrap().viewport(0, 0, size.width as i32, size.height as i32);
                }
            }
            WindowEvent::RedrawRequested => {
                let window = self.window.as_ref().unwrap();
                let gl = self.gl.as_ref().unwrap();

                unsafe {
                    gl.clear(glow::COLOR_BUFFER_BIT);
                    gl.draw_elements(glow::TRIANGLES, 6, glow::UNSIGNED_INT, 0);
                }

                window.request_redraw();
            }
            _ => {}
        }
    }
}