use std::rc::Rc;

use anyhow::Result;
use bytemuck;
use galactica_content::Content;
use glyphon::{FontSystem, SwashCache, TextAtlas, TextRenderer};
use log::debug;
use wgpu;
use winit;

use crate::{
	globaluniform::{GlobalDataContent, GlobalUniform},
	pipeline::PipelineBuilder,
	renderscene::{LandedScene, RenderScene, SystemScene},
	shaderprocessor::preprocess_shader,
	starfield::Starfield,
	texturearray::TextureArray,
	ui::{UiManager, UiScene},
	RenderInput, RenderScenes, RenderState, VertexBuffers,
};

/// A high-level GPU wrapper. Reads game state (via RenderInput), produces pretty pictures.
pub struct GPUState {
	pub(crate) device: wgpu::Device,
	pub(crate) config: wgpu::SurfaceConfiguration,
	pub(crate) surface: wgpu::Surface,
	pub(crate) object_pipeline: wgpu::RenderPipeline,
	pub(crate) starfield_pipeline: wgpu::RenderPipeline,
	pub(crate) ui_pipeline: wgpu::RenderPipeline,
	pub(crate) radialbar_pipeline: wgpu::RenderPipeline,
	pub(crate) starfield: Starfield,
	pub(crate) texture_array: TextureArray,
	pub(crate) state: RenderState,
	pub(crate) ui: UiManager,
	pub(crate) scene: RenderScenes,
}

impl GPUState {
	/// Make a new GPUState that draws on `window`
	pub async fn new(window: winit::window::Window, ct: Rc<Content>) -> Result<Self> {
		let window_size = window.inner_size();
		let window_aspect = window_size.width as f32 / window_size.height as f32;

		let instance = wgpu::Instance::new(wgpu::InstanceDescriptor {
			backends: wgpu::Backends::all(),
			..Default::default()
		});

		let surface = unsafe { instance.create_surface(&window) }.unwrap();

		// Basic setup
		let device;
		let queue;
		let config;

		{
			let adapter = instance
				.request_adapter(&wgpu::RequestAdapterOptions {
					power_preference: wgpu::PowerPreference::default(),
					compatible_surface: Some(&surface),
					force_fallback_adapter: false,
				})
				.await
				.unwrap();

			(device, queue) = adapter
					.request_device(
						&wgpu::DeviceDescriptor {
							// TODO: remove nonuniform sampled textures
							features: wgpu::Features::TEXTURE_BINDING_ARRAY | wgpu::Features::SAMPLED_TEXTURE_AND_STORAGE_BUFFER_ARRAY_NON_UNIFORM_INDEXING,
							// We may need limits if we compile for wasm
							limits: wgpu::Limits::default(),
							label: Some("gpu device"),
						},
						None,
					)
					.await
					.unwrap();

			// Assume sRGB
			let surface_caps = surface.get_capabilities(&adapter);
			let surface_format = surface_caps
				.formats
				.iter()
				.copied()
				.filter(|f| f.is_srgb())
				.filter(|f| f.has_stencil_aspect())
				.next()
				.unwrap_or(surface_caps.formats[0]);

			config = wgpu::SurfaceConfiguration {
				usage: wgpu::TextureUsages::RENDER_ATTACHMENT,
				format: surface_format,
				width: window_size.width,
				height: window_size.height,
				present_mode: surface_caps.present_modes[0],
				alpha_mode: surface_caps.alpha_modes[0],
				view_formats: vec![],
			};

			surface.configure(&device, &config);
		}

		let vertex_buffers = VertexBuffers::new(&device, &ct);

		// Load uniforms
		let global_uniform = GlobalUniform::new(&device);
		let texture_array = TextureArray::new(&device, &queue, &ct)?;

		// Make sure these match the indices in each shader
		let bind_group_layouts = &[
			&texture_array.bind_group_layout,
			&global_uniform.bind_group_layout,
		];

		// Text renderer
		let mut text_atlas = TextAtlas::new(&device, &queue, wgpu::TextureFormat::Bgra8UnormSrgb);
		let mut text_font_system = FontSystem::new_with_locale_and_db(
			"en-US".to_string(),
			glyphon::fontdb::Database::new(),
		);

		let conf = ct.get_config();
		for font in &conf.font_files {
			text_font_system.db_mut().load_font_file(font)?;
		}

		// TODO: nice error if no family with this name is found
		text_font_system
			.db_mut()
			.set_sans_serif_family(conf.font_sans.clone());
		text_font_system
			.db_mut()
			.set_serif_family(conf.font_serif.clone());
		text_font_system
			.db_mut()
			.set_monospace_family(conf.font_mono.clone());
		//text_font_system
		//	.db_mut()
		//	.set_cursive_family(conf.font_cursive.clone());
		//text_font_system
		//	.db_mut()
		//	.set_fantasy_family(conf.font_fantasy.clone());

		let text_cache = SwashCache::new();
		let text_renderer = TextRenderer::new(
			&mut text_atlas,
			&device,
			wgpu::MultisampleState::default(),
			None,
		);

		// Create render pipelines
		let object_pipeline = PipelineBuilder::new("object", &device)
			.set_shader(&preprocess_shader(
				&include_str!(concat!(
					env!("CARGO_MANIFEST_DIR"),
					"/shaders/",
					"object.wgsl"
				)),
				&global_uniform,
				1,
			))
			.set_format(config.format)
			.set_triangle(true)
			.set_vertex_buffer(vertex_buffers.get_object())
			.set_bind_group_layouts(bind_group_layouts)
			.build();

		let starfield_pipeline = PipelineBuilder::new("starfield", &device)
			.set_shader(&preprocess_shader(
				&include_str!(concat!(
					env!("CARGO_MANIFEST_DIR"),
					"/shaders/",
					"starfield.wgsl"
				)),
				&global_uniform,
				1,
			))
			.set_format(config.format)
			.set_triangle(true)
			.set_vertex_buffer(vertex_buffers.get_starfield())
			.set_bind_group_layouts(bind_group_layouts)
			.build();

		let ui_pipeline = PipelineBuilder::new("ui", &device)
			.set_shader(&preprocess_shader(
				&include_str!(concat!(env!("CARGO_MANIFEST_DIR"), "/shaders/", "ui.wgsl")),
				&global_uniform,
				1,
			))
			.set_format(config.format)
			.set_triangle(true)
			.set_vertex_buffer(vertex_buffers.get_ui())
			.set_bind_group_layouts(bind_group_layouts)
			.build();

		let radialbar_pipeline = PipelineBuilder::new("radialbar", &device)
			.set_shader(&preprocess_shader(
				&include_str!(concat!(
					env!("CARGO_MANIFEST_DIR"),
					"/shaders/",
					"radialbar.wgsl"
				)),
				&global_uniform,
				1,
			))
			.set_format(config.format)
			.set_triangle(true)
			.set_vertex_buffer(vertex_buffers.get_radialbar())
			.set_bind_group_layouts(bind_group_layouts)
			.build();

		let mut starfield = Starfield::new();
		starfield.regenerate(&ct);

		return Ok(Self {
			ui: UiManager::new(ct),
			device,
			config,
			surface,
			starfield,
			texture_array,
			object_pipeline,
			starfield_pipeline,
			ui_pipeline,
			radialbar_pipeline,
			scene: RenderScenes::Landed,

			state: RenderState {
				queue,
				window,
				window_size,
				window_aspect,
				global_uniform,
				vertex_buffers,
				text_atlas,
				text_cache,
				text_font_system,
				text_renderer,
			},
		});
	}
}

impl GPUState {
	/// Get the window we are attached to
	pub fn window(&self) -> &winit::window::Window {
		&self.state.window
	}

	/// Change the current scenection
	pub fn set_scene(&mut self, scene: RenderScenes) {
		debug!("switching to {:?}", scene);

		match scene {
			RenderScenes::Landed => self.ui.set_scene(&mut self.state, UiScene::Landed).unwrap(),
			RenderScenes::System => self.ui.set_scene(&mut self.state, UiScene::Flying).unwrap(),
		};

		self.scene = scene;
	}

	/// Update window size.
	/// This should be called whenever our window is resized.
	pub fn resize(&mut self, ct: &Content) {
		let new_size = self.state.window.inner_size();
		if new_size.width > 0 && new_size.height > 0 {
			self.state.window_size = new_size;
			self.state.window_aspect = new_size.width as f32 / new_size.height as f32;
			self.config.width = new_size.width;
			self.config.height = new_size.height;
			self.surface.configure(&self.device, &self.config);
		}
		self.starfield.update_buffer(ct, &mut self.state);
	}

	/// Initialize the rendering engine
	pub fn init(&mut self, ct: &Content) {
		// Update global values
		self.state.queue.write_buffer(
			&self.state.global_uniform.atlas_buffer,
			0,
			bytemuck::cast_slice(&[self.texture_array.texture_atlas]),
		);

		self.starfield.update_buffer(ct, &mut self.state);
	}

	/// Main render function. Draws sprites on a window.
	pub fn render(&mut self, input: RenderInput) -> Result<(), wgpu::SurfaceError> {
		// Update global values
		self.state.queue.write_buffer(
			&self.state.global_uniform.data_buffer,
			0,
			bytemuck::cast_slice(&[GlobalDataContent {
				camera_position_x: input.camera_pos.x,
				camera_position_y: input.camera_pos.y,
				camera_zoom: input.camera_zoom,
				camera_zoom_min: input.ct.get_config().zoom_min,
				camera_zoom_max: input.ct.get_config().zoom_max,
				window_size_w: self.state.window_size.width as f32,
				window_size_h: self.state.window_size.height as f32,
				window_scale: self.state.window.scale_factor() as f32,
				window_aspect: self.state.window_aspect,
				starfield_sprite: input.ct.get_config().starfield_texture.into(),
				starfield_tile_size: input.ct.get_config().starfield_size,
				starfield_size_min: input.ct.get_config().starfield_min_size,
				starfield_size_max: input.ct.get_config().starfield_max_size,
			}]),
		);

		self.state.frame_reset();

		match self.scene {
			RenderScenes::System => SystemScene::render(self, &input).unwrap(),
			RenderScenes::Landed => LandedScene::render(self, &input).unwrap(),
		}

		return Ok(());
	}
}