use bevy::{
    asset::LoadState,
    core_pipeline::{
        bloom::{BloomCompositeMode, BloomPrefilterSettings, BloomSettings},
        fxaa::Fxaa,
        tonemapping::Tonemapping,
    },
    gltf::{self, Gltf},
    math::vec3,
    pbr::NotShadowCaster,
    prelude::*,
    reflect::{TypePath, TypeUuid},
    render::render_resource::{AsBindGroup, ShaderRef},
    utils::HashSet,
};
use bevy_mod_picking::PickableBundle;

use crate::{
    camera_controller::{CameraController, CameraControllerBundle, CameraMotionSystem},
    interaction::Selectable,
    skybox::SkyboxId,
};

pub struct ScenePlugin;

impl Plugin for ScenePlugin {
    fn build(&self, app: &mut App) {
        app.insert_resource(ClearColor(Color::hsl(0.0, 0.0, 0.25)))
            .insert_resource(Msaa::Off)
            .add_plugins(MaterialPlugin::<ProceduralGridMaterial>::default())
            .add_systems(Startup, initialize)
            .add_systems(
                Update,
                mark_scene_objects.run_if(
                    resource_exists::<NewGltf>()
                        .and_then(gltf_loaded)
                        .and_then(gltf_scene_spawned),
                ),
            )
            .add_systems(PostUpdate, move_plane_with_camera.after(CameraMotionSystem));
    }
}

#[derive(Component)]
struct WorldGridPlane;

#[derive(Resource, Deref, DerefMut)]
struct NewGltf(pub Handle<Gltf>);

fn initialize(
    mut cmd: Commands,
    assets: Res<AssetServer>,
    mut meshes: ResMut<Assets<Mesh>>,
    mut mat_proc_grid: ResMut<Assets<ProceduralGridMaterial>>,
) {
    // Skybox
    cmd.insert_resource(SkyboxId("test_scene".into()));

    // glTF scene
    cmd.insert_resource(NewGltf(assets.load("gltf/sample-room.gltf")));
    cmd.spawn((
        Name::new("Scene"),
        SceneBundle {
            scene: assets.load("gltf/sample-room.gltf#Scene0"),
            ..default()
        },
    ));

    // Camera, graphics settings
    let focus = vec3(0.35011, 0.5, -0.99576);
    let camera_xform = Transform::from_xyz(-2.5, 4.5, 5.0).looking_at(focus, Vec3::Y);
    cmd.spawn((
        Name::new("Main Camera"),
        Camera3dBundle {
            transform: camera_xform,
            tonemapping: Tonemapping::BlenderFilmic,
            camera: Camera {
                hdr: true,
                ..default()
            },
            ..default()
        },
        CameraControllerBundle::new(focus, camera_xform.translation),
        BloomSettings {
            composite_mode: BloomCompositeMode::EnergyConserving,
            intensity: 0.25,
            prefilter_settings: BloomPrefilterSettings {
                threshold: 0.8,
                threshold_softness: 0.5,
            },
            ..default()
        },
        Fxaa::default(),
    ));

    // Main light
    // TODO: get Blender to export enough metadata to automate light placements
    cmd.spawn((
        Name::new("Ceiling Light"),
        PointLightBundle {
            point_light: PointLight {
                color: Color::hex("FFE5B4").unwrap(),
                intensity: 200.,
                radius: 0.1,
                shadows_enabled: true,
                ..default()
            },
            transform: Transform::from_xyz(0.35263, 2.4348, 0.19601),
            ..default()
        },
    ));

    // Monitor glow
    cmd.spawn((
        Name::new("Monitor Glow"),
        PointLightBundle {
            point_light: PointLight {
                color: Color::WHITE,
                intensity: 6.,
                radius: 0.25,
                shadows_enabled: false,
                ..default()
            },
            transform: Transform::from_xyz(0.42615, 1.0706, -2.0705),
            ..default()
        },
    ));

    // Plane
    let plane = meshes.add(Mesh::from(shape::Plane {
        size: 200.0,
        subdivisions: 0,
    }));
    let proc_grid = mat_proc_grid.add(ProceduralGridMaterial {});

    cmd.spawn((
        Name::new("World Grid"),
        SpatialBundle::from_transform(Transform::IDENTITY),
        WorldGridPlane,
    ))
    .with_children(|parent| {
        parent.spawn((
            MaterialMeshBundle {
                mesh: plane.clone(),
                material: proc_grid.clone(),
                transform: Transform::IDENTITY,
                ..default()
            },
            NotShadowCaster,
        ));
        parent.spawn((
            MaterialMeshBundle {
                mesh: plane,
                material: proc_grid,
                transform: Transform::IDENTITY.looking_to(Vec3::Z, Vec3::NEG_Y),
                ..default()
            },
            NotShadowCaster,
        ));
    });
}

fn gltf_loaded(assets: Res<AssetServer>, gltf: Res<NewGltf>) -> bool {
    assets.get_load_state(&**gltf) == LoadState::Loaded
}

fn gltf_scene_spawned(
    r_assets: Res<AssetServer>,
    r_gltf: Res<NewGltf>,
    ra_gltfs: Res<Assets<Gltf>>,
    q_scenes: Query<&Handle<Scene>, (With<Name>, With<Children>)>,
) -> bool {
    let gltf = ra_gltfs.get(&r_gltf).unwrap();
    let Some(gltf_scene_path) = gltf
        .default_scene
        .as_ref()
        .and_then(|handle| r_assets.get_handle_path(handle))
    else {
        return false;
    };

    q_scenes.iter().any(|handle| {
        let Some(path) = r_assets.get_handle_path(handle) else {
            return false;
        };
        path == gltf_scene_path
    })
}

fn mark_scene_objects(
    mut cmd: Commands,
    r_gltf: Res<NewGltf>,
    r_assets: Res<AssetServer>,
    ra_gltfs: Res<Assets<Gltf>>,
    ra_gltf_nodes: Res<Assets<gltf::GltfNode>>,
    ra_gltf_meshes: Res<Assets<gltf::GltfMesh>>,
    q_parents: Query<(Entity, &Name, &Children), Without<Selectable>>,
    q_primitives: Query<&Handle<Mesh>>,
) {
    let gltf = ra_gltfs.get(&r_gltf).unwrap();

    for (ent_parent, name, children) in q_parents.iter() {
        // See if this name matches any of the meshes or nodes in our glTF scene
        let Some(gltf_mesh) = gltf
            .named_meshes
            .get(&**name)
            .cloned()
            .or_else(|| {
                gltf.named_nodes.get(&**name).and_then(|node_handle| {
                    ra_gltf_nodes
                        .get(node_handle)
                        .and_then(|node| node.mesh.clone())
                })
            })
            .and_then(|handle| ra_gltf_meshes.get(&handle))
        else {
            continue;
        };

        // Collect all of the mesh handles in the glTF mesh
        let prims_from_gltf = gltf_mesh
            .primitives
            .iter()
            .filter_map(|prim| r_assets.get_handle_path(&prim.mesh))
            .collect::<HashSet<_>>();

        // Collect all of the mesh handles in this entity's children
        let prims_from_ecs = children
            .iter()
            .filter_map(|ent_child| {
                q_primitives
                    .get(*ent_child)
                    .ok()
                    .and_then(|handle| r_assets.get_handle_path(handle))
            })
            .collect::<HashSet<_>>();

        // If the sets match, this is the entity that represents the glTF mesh
        if prims_from_gltf == prims_from_ecs {
            cmd.entity(ent_parent).insert(Selectable);

            for &ent_child in children.iter() {
                if q_primitives.contains(ent_child) {
                    cmd.entity(ent_child).insert(PickableBundle::default());
                }
            }
        }
    }

    cmd.remove_resource::<NewGltf>();
}

fn move_plane_with_camera(
    mut plane: Query<(&WorldGridPlane, &mut Transform)>,
    camera: Query<&CameraController, Changed<CameraController>>,
) {
    if let Ok(&CameraController { focus, .. }) = camera.get_single() {
        let (_, mut xform) = plane.single_mut();

        xform.translation.x = focus.x;
        xform.translation.z = focus.z;
    }
}

#[derive(AsBindGroup, Clone, TypePath, TypeUuid)]
#[uuid = "CE331A13-F247-4F5B-A75E-670B2BD5776A"]
struct ProceduralGridMaterial {}

impl Material for ProceduralGridMaterial {
    fn fragment_shader() -> ShaderRef {
        "shaders/procedural_grid.wgsl".into()
    }

    fn alpha_mode(&self) -> AlphaMode {
        AlphaMode::Blend
    }
}