use galactica_util::constants::{IMAGE_LIMIT, OBJECT_SPRITE_INSTANCE_LIMIT};
use wgpu;

use super::{object::ObjectLocationArray, AtlasArray, GlobalDataContent};

pub struct GlobalUniform {
	pub data_buffer: wgpu::Buffer,
	pub atlas_buffer: wgpu::Buffer,
	pub object_buffer: wgpu::Buffer,
	pub bind_group: wgpu::BindGroup,
	pub bind_group_layout: wgpu::BindGroupLayout,
	pub content: GlobalDataContent,
}

impl GlobalUniform {
	pub fn shader_header(&self, group: u32) -> String {
		let mut out = String::new();

		// Global game data
		out.push_str(&format!("@group({group}) @binding(0)\n"));
		out.push_str(
			r#"
			var<uniform> global_data: GlobalData;
			struct GlobalData {
				camera_position_x: f32,
				camera_position_y: f32,
				camera_zoom: f32,
				camera_zoom_min: f32,
				camera_zoom_max: f32,
				window_size_w: f32,
				window_size_h: f32,
				window_scale: f32,
				window_aspect: f32,
				starfield_sprite: u32,
				starfield_tile_size: f32,
				starfield_size_min: f32,
				starfield_size_max: f32,
			};
			"#,
		);
		out.push_str("\n");

		// Atlas image locations
		out.push_str(&format!(
			r#"
			@group({group}) @binding(1)
			var<uniform> global_atlas: array<AtlasImageLocation, {IMAGE_LIMIT}>;
			"#
		));
		out.push_str("\n");
		out.push_str(
			r#"
			struct AtlasImageLocation {
				xpos: f32,
				ypos: f32,
				width: f32,
				height: f32,

				atlas_texture: u32,

				padding_a: f32,
				padding_b: f32,
				padding_c: f32,
			};
			"#,
		);
		out.push_str("\n");

		// TODO: document
		// wgpu uniforms require constant item sizes.
		// if you get an error like the following,check!
		// `Buffer is bound with size 3456 where the shader expects 5184 in group[1] compact index 2`
		// More notes are in datacontent

		// Object location data
		out.push_str(&format!(
			r#"
			@group({group}) @binding(2)
			var<uniform> objects: array<ObjectData, {OBJECT_SPRITE_INSTANCE_LIMIT}>;
			"#
		));
		out.push_str("\n");
		out.push_str(
			r#"
			struct ObjectData {
				xpos: f32,
				ypos: f32,
				zpos: f32,
				angle: f32,
				size: f32,
				parent: u32,
				is_child: u32,

				padding_a: f32,
			};
			"#,
		);
		out.push_str("\n");

		return out;
	}

	pub fn new(device: &wgpu::Device) -> Self {
		let data_buffer = device.create_buffer(&wgpu::BufferDescriptor {
			label: Some("global uniform data buffer"),
			size: GlobalDataContent::SIZE,
			usage: wgpu::BufferUsages::UNIFORM | wgpu::BufferUsages::COPY_DST,
			mapped_at_creation: false,
		});

		let atlas_buffer = device.create_buffer(&wgpu::BufferDescriptor {
			label: Some("global uniform atlas buffer"),
			size: AtlasArray::SIZE,
			usage: wgpu::BufferUsages::UNIFORM | wgpu::BufferUsages::COPY_DST,
			mapped_at_creation: false,
		});

		let object_buffer = device.create_buffer(&wgpu::BufferDescriptor {
			label: Some("global uniform object buffer"),
			size: ObjectLocationArray::SIZE,
			usage: wgpu::BufferUsages::UNIFORM | wgpu::BufferUsages::COPY_DST,
			mapped_at_creation: false,
		});

		let bind_group_layout = device.create_bind_group_layout(&wgpu::BindGroupLayoutDescriptor {
			entries: &[
				wgpu::BindGroupLayoutEntry {
					binding: 0,
					visibility: wgpu::ShaderStages::VERTEX_FRAGMENT,
					ty: wgpu::BindingType::Buffer {
						ty: wgpu::BufferBindingType::Uniform,
						has_dynamic_offset: false,
						min_binding_size: None,
					},
					count: None,
				},
				wgpu::BindGroupLayoutEntry {
					binding: 1,
					visibility: wgpu::ShaderStages::VERTEX_FRAGMENT,
					ty: wgpu::BindingType::Buffer {
						ty: wgpu::BufferBindingType::Uniform,
						has_dynamic_offset: false,
						min_binding_size: None,
					},
					count: None,
				},
				wgpu::BindGroupLayoutEntry {
					binding: 2,
					visibility: wgpu::ShaderStages::VERTEX_FRAGMENT,
					ty: wgpu::BindingType::Buffer {
						ty: wgpu::BufferBindingType::Uniform,
						has_dynamic_offset: false,
						min_binding_size: None,
					},
					count: None,
				},
			],
			label: Some("global uniform bind group layout"),
		});

		let bind_group = device.create_bind_group(&wgpu::BindGroupDescriptor {
			layout: &bind_group_layout,
			entries: &[
				wgpu::BindGroupEntry {
					binding: 0,
					resource: data_buffer.as_entire_binding(),
				},
				wgpu::BindGroupEntry {
					binding: 1,
					resource: atlas_buffer.as_entire_binding(),
				},
				wgpu::BindGroupEntry {
					binding: 2,
					resource: object_buffer.as_entire_binding(),
				},
			],
			label: Some("global uniform bind group"),
		});

		return Self {
			data_buffer,
			atlas_buffer,
			object_buffer,
			bind_group,
			bind_group_layout,
			content: GlobalDataContent::default(),
		};
	}
}