//! Plugin providing an [`AssetLoader`](bevy_asset::AssetLoader) and type definitions
//! for loading glTF 2.0 (a standard 3D scene definition format) files in Bevy.
//!
//! The [glTF 2.0 specification](https://registry.khronos.org/glTF/specs/2.0/glTF-2.0.html) defines the format of the glTF files.

#[cfg(feature = "bevy_animation")]
use bevy_animation::AnimationClip;
use bevy_utils::HashMap;

mod loader;
mod vertex_attributes;
pub use loader::*;

use bevy_app::prelude::*;
use bevy_asset::{Asset, AssetApp, Handle};
use bevy_ecs::{prelude::Component, reflect::ReflectComponent};
use bevy_pbr::StandardMaterial;
use bevy_reflect::{Reflect, TypePath};
use bevy_render::{
    mesh::{Mesh, MeshVertexAttribute},
    renderer::RenderDevice,
    texture::CompressedImageFormats,
};
use bevy_scene::Scene;

/// Adds support for glTF file loading to the app.
#[derive(Default)]
pub struct GltfPlugin {
    custom_vertex_attributes: HashMap<String, MeshVertexAttribute>,
}

impl GltfPlugin {
    /// Register a custom vertex attribute so that it is recognized when loading a glTF file with the [`GltfLoader`].
    ///
    /// `name` must be the attribute name as found in the glTF data, which must start with an underscore.
    /// See [this section of the glTF specification](https://registry.khronos.org/glTF/specs/2.0/glTF-2.0.html#meshes-overview)
    /// for additional details on custom attributes.
    pub fn add_custom_vertex_attribute(
        mut self,
        name: &str,
        attribute: MeshVertexAttribute,
    ) -> Self {
        self.custom_vertex_attributes
            .insert(name.to_string(), attribute);
        self
    }
}

impl Plugin for GltfPlugin {
    fn build(&self, app: &mut App) {
        app.register_type::<GltfExtras>()
            .init_asset::<Gltf>()
            .init_asset::<GltfNode>()
            .init_asset::<GltfPrimitive>()
            .init_asset::<GltfMesh>()
            .preregister_asset_loader::<GltfLoader>(&["gltf", "glb"]);
    }

    fn finish(&self, app: &mut App) {
        let supported_compressed_formats = match app.world.get_resource::<RenderDevice>() {
            Some(render_device) => CompressedImageFormats::from_features(render_device.features()),

            None => CompressedImageFormats::NONE,
        };
        app.register_asset_loader(GltfLoader {
            supported_compressed_formats,
            custom_vertex_attributes: self.custom_vertex_attributes.clone(),
        });
    }
}

/// Representation of a loaded glTF file.
#[derive(Asset, Debug, TypePath)]
pub struct Gltf {
    /// All scenes loaded from the glTF file.
    pub scenes: Vec<Handle<Scene>>,
    /// Named scenes loaded from the glTF file.
    pub named_scenes: HashMap<String, Handle<Scene>>,
    /// All meshes loaded from the glTF file.
    pub meshes: Vec<Handle<GltfMesh>>,
    /// Named meshes loaded from the glTF file.
    pub named_meshes: HashMap<String, Handle<GltfMesh>>,
    /// All materials loaded from the glTF file.
    pub materials: Vec<Handle<StandardMaterial>>,
    /// Named materials loaded from the glTF file.
    pub named_materials: HashMap<String, Handle<StandardMaterial>>,
    /// All nodes loaded from the glTF file.
    pub nodes: Vec<Handle<GltfNode>>,
    /// Named nodes loaded from the glTF file.
    pub named_nodes: HashMap<String, Handle<GltfNode>>,
    /// Default scene to be displayed.
    pub default_scene: Option<Handle<Scene>>,
    /// All animations loaded from the glTF file.
    #[cfg(feature = "bevy_animation")]
    pub animations: Vec<Handle<AnimationClip>>,
    /// Named animations loaded from the glTF file.
    #[cfg(feature = "bevy_animation")]
    pub named_animations: HashMap<String, Handle<AnimationClip>>,
    /// The gltf root of the gltf asset, see <https://docs.rs/gltf/latest/gltf/struct.Gltf.html>. Only has a value when `GltfLoaderSettings::include_source` is true.
    pub source: Option<gltf::Gltf>,
}

/// A glTF node with all of its child nodes, its [`GltfMesh`],
/// [`Transform`](bevy_transform::prelude::Transform) and an optional [`GltfExtras`].
///
/// See [the relevant glTF specification section](https://registry.khronos.org/glTF/specs/2.0/glTF-2.0.html#reference-node).
#[derive(Asset, Debug, Clone, TypePath)]
pub struct GltfNode {
    /// Direct children of the node.
    pub children: Vec<GltfNode>,
    /// Mesh of the node.
    pub mesh: Option<Handle<GltfMesh>>,
    /// Local transform.
    pub transform: bevy_transform::prelude::Transform,
    /// Additional data.
    pub extras: Option<GltfExtras>,
}

/// A glTF mesh, which may consist of multiple [`GltfPrimitives`](GltfPrimitive)
/// and an optional [`GltfExtras`].
///
/// See [the relevant glTF specification section](https://registry.khronos.org/glTF/specs/2.0/glTF-2.0.html#reference-mesh).
#[derive(Asset, Debug, Clone, TypePath)]
pub struct GltfMesh {
    /// Primitives of the glTF mesh.
    pub primitives: Vec<GltfPrimitive>,
    /// Additional data.
    pub extras: Option<GltfExtras>,
}

/// Part of a [`GltfMesh`] that consists of a [`Mesh`], an optional [`StandardMaterial`] and [`GltfExtras`].
///
/// See [the relevant glTF specification section](https://registry.khronos.org/glTF/specs/2.0/glTF-2.0.html#reference-mesh-primitive).
#[derive(Asset, Debug, Clone, TypePath)]
pub struct GltfPrimitive {
    /// Topology to be rendered.
    pub mesh: Handle<Mesh>,
    /// Material to apply to the `mesh`.
    pub material: Option<Handle<StandardMaterial>>,
    /// Additional data.
    pub extras: Option<GltfExtras>,
    /// Additional data of the `material`.
    pub material_extras: Option<GltfExtras>,
}

/// Additional untyped data that can be present on most glTF types.
///
/// See [the relevant glTF specification section](https://registry.khronos.org/glTF/specs/2.0/glTF-2.0.html#reference-extras).
#[derive(Clone, Debug, Reflect, Default, Component)]
#[reflect(Component)]
pub struct GltfExtras {
    /// Content of the extra data.
    pub value: String,
}