use bevy_app::{App, Plugin};
use bevy_ecs::{
    entity::Entity,
    query::With,
    resource::Resource,
    system::{Commands, Query, Res},
};
use bevy_log::error;
use bevy_math::Isometry3d;
use bevy_mod_xr::{
    session::{XrPreDestroySession, XrSessionCreated},
    spaces::{XrPrimaryReferenceSpace, XrReferenceSpace},
};
use bevy_render::{RenderApp, extract_resource::ExtractResourcePlugin};

use crate::session::OxrSession;

pub struct OxrReferenceSpacePlugin {
    pub default_primary_ref_space: openxr::ReferenceSpaceType,
}
impl Default for OxrReferenceSpacePlugin {
    fn default() -> Self {
        Self {
            default_primary_ref_space: openxr::ReferenceSpaceType::STAGE,
        }
    }
}

/// Resource specifying what the type should used be for the [`XrPrimaryReferenceSpace`]. Set through [`OxrReferenceSpacePlugin`].
#[derive(Resource)]
struct OxrDefaultPrimaryReferenceSpaceType(openxr::ReferenceSpaceType);

impl Plugin for OxrReferenceSpacePlugin {
    fn build(&self, app: &mut App) {
        app.add_plugins(ExtractResourcePlugin::<XrPrimaryReferenceSpace>::default())
            .insert_resource(OxrDefaultPrimaryReferenceSpaceType(
                self.default_primary_ref_space,
            ))
            .add_systems(XrSessionCreated, set_primary_ref_space)
            .add_systems(XrPreDestroySession, cleanup);

        let render_app = app.sub_app_mut(RenderApp);

        render_app.add_systems(XrPreDestroySession, cleanup);
    }
}

fn cleanup(query: Query<Entity, With<XrReferenceSpace>>, mut cmds: Commands) {
    cmds.remove_resource::<XrPrimaryReferenceSpace>();
    for e in &query {
        cmds.entity(e).remove::<XrReferenceSpace>();
    }
}

fn set_primary_ref_space(
    session: Res<OxrSession>,
    space_type: Res<OxrDefaultPrimaryReferenceSpaceType>,
    mut cmds: Commands,
) {
    match session.create_reference_space(space_type.0, Isometry3d::IDENTITY) {
        Ok(space) => {
            cmds.insert_resource(XrPrimaryReferenceSpace(space));
        }
        Err(openxr::sys::Result::ERROR_EXTENSION_NOT_PRESENT) => {
            error!("Required Extension for Reference Space not loaded");
        }
        Err(err) => error!("Error while creating reference space: {}", err.to_string()),
    };
}