//! GPUState routines for drawing the world

use bytemuck;
use cgmath::{EuclideanSpace, InnerSpace, Point2, Vector2};
use galactica_world::{
	objects::{ProjectileWorldObject, ShipWorldObject},
	util,
};

use crate::{
	globaluniform::ObjectData,
	vertexbuffer::{types::ObjectInstance, BufferObject},
	GPUState, RenderState,
};

impl GPUState {
	pub(super) fn world_push_ship(
		&mut self,
		state: &RenderState,
		// NE and SW corners of screen
		screen_clip: (Point2<f32>, Point2<f32>),
		s: &ShipWorldObject,
	) {
		let r = state.world.get_rigid_body(s.rigid_body).unwrap();
		let ship = state.data.get_ship(s.data_handle);
		let ship_pos = util::rigidbody_position(&r);
		let ship_rot = util::rigidbody_rotation(r);
		let ship_ang = -ship_rot.angle(Vector2 { x: 0.0, y: 1.0 }); // TODO: inconsistent angles. Fix!
		let ship_cnt = state.content.get_ship(s.data_handle.content_handle());

		// Position adjusted for parallax
		// TODO: adjust parallax for zoom?
		// 1.0 is z-coordinate, which is constant for ships
		let pos: Point2<f32> = (ship_pos - state.camera_pos.to_vec()) / 1.0;

		// Game dimensions of this sprite post-scale.
		// Post-scale width or height, whichever is larger.
		// This is in game units.
		//
		// We take the maximum to account for rotated sprites.
		let m = (ship_cnt.size / 1.0) * ship_cnt.sprite.aspect.max(1.0);

		// Don't draw sprites that are off the screen
		if pos.x < screen_clip.0.x - m
			|| pos.y > screen_clip.0.y + m
			|| pos.x > screen_clip.1.x + m
			|| pos.y < screen_clip.1.y - m
		{
			return;
		}

		let idx = self.vertex_buffers.object_counter;
		// Write this object's location data
		self.queue.write_buffer(
			&self.global_uniform.object_buffer,
			ObjectData::SIZE * idx as u64,
			bytemuck::cast_slice(&[ObjectData {
				xpos: ship_pos.x,
				ypos: ship_pos.y,
				zpos: 1.0,
				angle: ship_ang.0,
				size: ship_cnt.size,
				parent: 0,
				is_child: 0,
				_padding: Default::default(),
			}]),
		);

		// Enforce buffer limit
		if self.vertex_buffers.object_counter as u64
			> galactica_constants::OBJECT_SPRITE_INSTANCE_LIMIT
		{
			// TODO: no panic, handle this better.
			panic!("Sprite limit exceeded!")
		}

		// Push this object's instance
		self.queue.write_buffer(
			&self.vertex_buffers.object.instances,
			ObjectInstance::SIZE * self.vertex_buffers.object_counter,
			bytemuck::cast_slice(&[ObjectInstance {
				sprite_index: ship_cnt.sprite.get_index(),
				object_index: idx as u32,
			}]),
		);
		self.vertex_buffers.object_counter += 1;

		/*
		// Draw engine flares if necessary
		//if s.controls.thrust && !s.ship.is_dead() {
		if s.controls.thrust {
			for f in s.ship.outfits.iter_enginepoints() {
				let flare = match s.ship.outfits.get_flare_sprite() {
					None => continue,
					Some(s) => s,
				};

				self.queue.write_buffer(
					&self.global_uniform.object_buffer,
					ObjectData::SIZE * self.vertex_buffers.object_counter as u64,
					bytemuck::cast_slice(&[ObjectData {
						xpos: f.pos.x,
						ypos: f.pos.y - f.size / 2.0,
						zpos: 1.0,
						angle: 0.0,
						size: f.size,
						parent: idx as u32,
						is_child: 1,
						_padding: Default::default(),
					}]),
				);

				// Enforce buffer limit
				if self.vertex_buffers.object_counter as u64
					> galactica_constants::OBJECT_SPRITE_INSTANCE_LIMIT
				{
					// TODO: no panic, handle this better.
					panic!("Sprite limit exceeded!")
				}

				self.queue.write_buffer(
					&self.vertex_buffers.object.instances,
					ObjectInstance::SIZE * self.vertex_buffers.object_counter,
					bytemuck::cast_slice(&[ObjectInstance {
						sprite_index: flare.get_index(),
						object_index: self.vertex_buffers.object_counter as u32,
					}]),
				);
				self.vertex_buffers.object_counter += 1;
			}
		}
		*/
	}

	pub(super) fn world_push_projectile(
		&mut self,
		state: &RenderState,
		// NE and SW corners of screen
		screen_clip: (Point2<f32>, Point2<f32>),
		p: &ProjectileWorldObject,
	) {
		let r = state.world.get_rigid_body(p.rigid_body).unwrap();
		let proj_pos = util::rigidbody_position(&r);
		let proj_rot = util::rigidbody_rotation(r);
		let proj_ang = -proj_rot.angle(Vector2 { x: 1.0, y: 0.0 });
		let proj_cnt = &p.content; // TODO: don't clone this?

		// Position adjusted for parallax
		// TODO: adjust parallax for zoom?
		// 1.0 is z-coordinate, which is constant for ships
		let pos: Point2<f32> = (proj_pos - state.camera_pos.to_vec()) / 1.0;

		// Game dimensions of this sprite post-scale.
		// Post-scale width or height, whichever is larger.
		// This is in game units.
		//
		// We take the maximum to account for rotated sprites.
		let m = (proj_cnt.size / 1.0) * proj_cnt.sprite.aspect.max(1.0);

		// Don't draw sprites that are off the screen
		if pos.x < screen_clip.0.x - m
			|| pos.y > screen_clip.0.y + m
			|| pos.x > screen_clip.1.x + m
			|| pos.y < screen_clip.1.y - m
		{
			return;
		}

		let idx = self.vertex_buffers.object_counter;
		// Write this object's location data
		self.queue.write_buffer(
			&self.global_uniform.object_buffer,
			ObjectData::SIZE * idx as u64,
			bytemuck::cast_slice(&[ObjectData {
				xpos: proj_pos.x,
				ypos: proj_pos.y,
				zpos: 1.0,
				angle: proj_ang.0,
				size: 0f32.max(proj_cnt.size + p.size_rng),
				parent: 0,
				is_child: 0,
				_padding: Default::default(),
			}]),
		);

		// Enforce buffer limit
		if self.vertex_buffers.object_counter as u64
			> galactica_constants::OBJECT_SPRITE_INSTANCE_LIMIT
		{
			// TODO: no panic, handle this better.
			panic!("Sprite limit exceeded!")
		}

		// Push this object's instance
		self.queue.write_buffer(
			&self.vertex_buffers.object.instances,
			ObjectInstance::SIZE * self.vertex_buffers.object_counter,
			bytemuck::cast_slice(&[ObjectInstance {
				sprite_index: proj_cnt.sprite.get_index(),
				object_index: idx as u32,
			}]),
		);
		self.vertex_buffers.object_counter += 1;
	}
}