//! Minimal declarative workflow, no explicit WGPU handling in this file.
//! `AppBuilder` creates the event loop, then `App::run` opens the window, builds the `Context`/`Renderer`
//! and drives the update → render → present loop. Since the winit 0.30 migration, the GPU only exists
//! after `resumed`: that is why shader registration + mesh/material/entity creation live in
//! the `AppHandler::setup` hook, called once the context is ready. Since Step 7 the PipelineCache
//! lives in the scene (`Scene::init_gpu`, called in `resumed`): go through `register_shader` +
//! `add_material_shader` + `create_mesh` + `add_entity`, the material being bound to the mesh. Since Step 8
//! (DRAFT 8.4/8.5) the mesh is declared from a **`Geometry`**: per-vertex positions + colors
//! for the unlit quad. The scene renders automatically: the default `render()` method calls
//! `app.render_scene(frame.view())`.
use wsg_lib::AppHandler;
use wsg_lib::app::AppBuilder;
use wsg_lib::resources::Geometry;
use wsg_lib::utils::WsgError;

struct MonQuad;

impl AppHandler for MonQuad {
    fn setup(&mut self, app: &mut wsg_lib::App) {
        // Flat 2D example: the `standard` shader in **unlit** mode (options.x = 1) returns the vertex
        // color as-is. Flat 2D is thus a special case of 3D — a single pipeline for all.
        app.renderer_mut().set_unlit(true);
        app.scene
            .register_shader("standard", wsg_lib::utils::STANDARD_SHADER_PATH)
            .unwrap();

        let geometry = Geometry::new(vec![
            [-0.5, 0.5, 0.0],  // top-left
            [0.5, 0.5, 0.0],   // top-right
            [0.5, -0.5, 0.0],  // bottom-right
            [-0.5, -0.5, 0.0], // bottom-left
        ])
        .with_normals(vec![[0.0, 0.0, 1.0]; 4])
        .with_colors(vec![
            [1.0, 0.0, 0.0, 1.0], // top-left (red)
            [0.0, 1.0, 0.0, 1.0], // top-right (green)
            [0.0, 0.0, 1.0, 1.0], // bottom-right (blue)
            [1.0, 1.0, 0.0, 1.0], // bottom-left (yellow)
        ])
        .with_indices(vec![0, 1, 2, 0, 2, 3]);

        // Default material: `None` lets the Scene inject its `standard` at render time
        // (`Scene::default_material`, DRAFT Step 7.3.5) — this exercises the default path.
        app.scene.create_mesh("quad_mesh", geometry, None).unwrap();
        app.scene.add_entity("quad", "quad_mesh").unwrap();
    }
}

#[pollster::main]
async fn main() -> Result<(), WsgError> {
    let app = AppBuilder::new().title("WSG Simple").build().await?;
    app.run(MonQuad)
}