// Copyright Jeron A. Lau 2018.
// Dual-licensed under either the MIT License or the Boost Software License,
// Version 1.0.  (See accompanying file LICENSE_1_0.txt or copy at
// https://www.boost.org/LICENSE_1_0.txt)

//! OpenGL implementation for adi_gpu.

extern crate asi_opengl;
extern crate adi_gpu_base;

use std::mem;

pub use base::Shape;
pub use base::Gradient;
pub use base::Model;
pub use base::TexCoords;
pub use base::Texture;

use adi_gpu_base as base;
use asi_opengl::{
	OpenGL, OpenGLBuilder, VertexData, Program, Buffer, UniformData,
	Feature, Topology,
};
use adi_gpu_base::*;

const SHADER_SOLID_FRAG: &'static [u8] = include_bytes!("shaders/solid-frag.glsl");
const SHADER_SOLID_VERT: &'static [u8] = include_bytes!("shaders/solid-vert.glsl");
const SHADER_GRADIENT_FRAG: &'static [u8] = include_bytes!("shaders/gradient-frag.glsl");
const SHADER_GRADIENT_VERT: &'static [u8] = include_bytes!("shaders/gradient-vert.glsl");
const SHADER_TEX_FRAG: &'static [u8] = include_bytes!("shaders/texture-frag.glsl");
const SHADER_TEX_VERT: &'static [u8] = include_bytes!("shaders/texture-vert.glsl");
const SHADER_FADED_VERT: &'static [u8] = include_bytes!("shaders/faded-vert.glsl");
const SHADER_TINTED_FRAG: &'static [u8] = include_bytes!("shaders/tinted-frag.glsl");
const SHADER_COMPLEX_VERT: &'static [u8] = include_bytes!("shaders/complex-vert.glsl");
const SHADER_COMPLEX_FRAG: &'static [u8] = include_bytes!("shaders/complex-frag.glsl");

const STYLE_GRADIENT: usize = 0;
const STYLE_TEXTURE: usize = 1;
const STYLE_FADED: usize = 2;
const STYLE_TINTED: usize = 3;
const STYLE_SOLID: usize = 4;
const STYLE_COMPLEX: usize = 5;

struct Style {
	shader: Program,
	matrix_uniform: UniformData,
	has_camera: UniformData,
	camera_uniform: UniformData,
	has_fog: UniformData,
	fog: UniformData,
	range: UniformData,
	alpha: UniformData,
	color: UniformData,
	position: VertexData,
	texpos: VertexData,
	acolor: VertexData,
}

impl Style {
	// Create a new style.
	fn new(context: &OpenGL, vert: &[u8], frag: &[u8]) -> Style {
		let shader = Program::new(context, vert, frag);
		let matrix_uniform = shader.uniform(b"models_tfm\0");
		let has_camera = shader.uniform(b"has_camera\0");
		let camera_uniform = shader.uniform(b"matrix\0");
		let has_fog = shader.uniform(b"has_fog\0");
		let fog = shader.uniform(b"fog\0");
		let range = shader.uniform(b"range\0");
		let alpha = shader.uniform(b"alpha\0");
		let color = shader.uniform(b"color\0");
		let position = shader.vertex_data(b"position\0");
		let texpos = shader.vertex_data(b"texpos\0");
		let acolor = shader.vertex_data(b"acolor\0");

		Style {
			shader, matrix_uniform, has_camera, camera_uniform, fog,
			range, position, texpos, alpha, has_fog, color, acolor,
		}
	}
}

struct ShapeData {
	style: usize,
	buffers: [Option<Buffer>; 2],
	has_fog: bool,
	alpha: Option<f32>,
	color: Option<[f32; 4]>,
	transform: Transform, // Transformation matrix.
	texture: Option<asi_opengl::Texture>,
	vertex_buffer: Buffer,
	fans: Vec<(u32, u32)>,
}

impl ::adi_gpu_base::Point for ShapeData {
	fn point(&self) -> Vec3 {
		// Position vector at origin * object transform.
		(self.transform.0 * vec4!(0f32, 0f32, 0f32, 1f32)).xyz()
	}
}

struct ModelData {
	vertex_buffer: Buffer,
	// TODO alot could be in base as duplicate
	vertex_count: u32,
	fans: Vec<(u32, u32)>,
}

struct TexcoordsData {
	vertex_buffer: Buffer,
	vertex_count: u32,
}

struct GradientData {
	vertex_buffer: Buffer,
	vertex_count: u32,
}

struct TextureData {
	t: asi_opengl::Texture,
}

/// To render anything with adi_gpu, you have to make a `Display`
pub struct Display {
	window: adi_gpu_base::Window,
	context: OpenGL,
	color: (f32, f32, f32),
	opaque_ind: Vec<u32>,
	alpha_ind: Vec<u32>,
	opaque_vec: Vec<ShapeData>,
	alpha_vec: Vec<ShapeData>,
	gui_vec: Vec<ShapeData>,
	models: Vec<ModelData>,
	texcoords: Vec<TexcoordsData>,
	gradients: Vec<GradientData>,
	textures: Vec<TextureData>,
	styles: [Style; 6],
	xyz: Vec3,
	rotate_xyz: Vec3,
	ar: f32,
	projection: Transform,
}

pub fn new(title: &str, icon: &afi::Video) -> Result<Box<Display>, &'static str>
{
	if let Some(tuple) = OpenGLBuilder::new() {
		let (builder, v) = tuple;
		let window = adi_gpu_base::Window::new(title, icon, Some(v));

		let context = builder.to_opengl(match window.get_connection() {
			WindowConnection::Xcb(_, window) => // |
			//	WindowConnection::Windows(_, window) =>
			{
				unsafe {mem::transmute(window as usize)}
			},
			WindowConnection::Windows(_, window) => {
				window
			}
			WindowConnection::Wayland => return Err(
				"OpenGL support on Wayland is WIP"),
			WindowConnection::DirectFB => return Err(
				"OpenGL support on DirectFB is WIP"),
			WindowConnection::Android => return Err(
				"OpenGL support on Android is WIP"),
			WindowConnection::IOS => return Err(
				"OpenGL support on iOS is WIP"),
			WindowConnection::AldaronsOS => return Err(
				"AldaronsOS doesn't support OpenGL"),
			WindowConnection::Arduino => return Err(
				"Arduino doesn't support OpenGL"),
			WindowConnection::Switch => return Err(
				"Nintendo Switch doesn't support OpenGL"),
			WindowConnection::Web => return Err(
				"WebGL support is WIP"),
			WindowConnection::NoOS => return Err(
				"NoOS doesn't support OpenGL"),
		});

		// Set the settings.
		context.disable(Feature::Dither);
		context.enable(Feature::CullFace);
		context.enable(Feature::Blend);
		context.blend();

		// Load shaders
		let style_solid = Style::new(&context,
			SHADER_SOLID_VERT, SHADER_SOLID_FRAG);
		let style_gradient = Style::new(&context,
			SHADER_GRADIENT_VERT, SHADER_GRADIENT_FRAG);
		let style_texture = Style::new(&context,
			SHADER_TEX_VERT, SHADER_TEX_FRAG);
		let style_faded = Style::new(&context,
			SHADER_FADED_VERT, SHADER_TEX_FRAG);
		let style_tinted = Style::new(&context,
			SHADER_TEX_VERT, SHADER_TINTED_FRAG);
		let style_complex = Style::new(&context,
			SHADER_COMPLEX_VERT, SHADER_COMPLEX_FRAG);

		let wh = window.wh();
		let ar = wh.0 as f32 / wh.1 as f32;

		let projection = base::projection(ar, 0.5 * PI);

		// Adjust the viewport
		context.viewport(wh.0, wh.1);

		let mut display = ::Display {
			window,
			context,
			color: (0.0, 0.0, 0.0),
			alpha_ind: vec![],
			opaque_ind: vec![],
			alpha_vec: vec![],
			opaque_vec: vec![],
			gui_vec: vec![],
			models: vec![],
			texcoords: vec![],
			gradients: vec![],
			textures: vec![],
			styles: [
				style_gradient,
				style_texture,
				style_faded,
				style_tinted,
				style_solid,
				style_complex,
			],
			xyz: vec3!(0.0, 0.0, 0.0),
			rotate_xyz: vec3!(0.0, 0.0, 0.0),
			ar,
			projection,
		};

		use base::Display;
		display.camera(vec3!(0.0, 0.0, 0.0), vec3!(0.0, 0.0, 0.0));

		Ok(Box::new(display))
	} else {
		Err("Couldn't find OpenGL!")
	}
}

impl base::Display for Display {
	fn color(&mut self, color: (f32, f32, f32)) {
		self.color = color;
		self.context.color(color.0, color.1, color.2);
	}

	fn update(&mut self) -> Option<adi_gpu_base::Input> {
		if let Some(input) = self.window.update() {
			return Some(input);
		}

		// Update Window:
		// TODO: This is copied pretty much from adi_gpu_vulkan.  Move
		// to the base.

		// Opaque & Alpha Shapes need a camera.
		for i in (&self.styles).iter() {
			i.has_camera.set_int1(1);
		}

		// Enable for 3D depth testing
		self.context.enable(Feature::DepthTest);

		// sort nearest
		::adi_gpu_base::zsort(&mut self.opaque_ind, &self.opaque_vec,
			true, self.xyz);
		for shape in self.opaque_vec.iter() {
			draw_shape(&self.styles[shape.style], shape);
		}

		// sort farthest
		::adi_gpu_base::zsort(&mut self.alpha_ind, &self.alpha_vec,
			false, self.xyz);
		for shape in self.alpha_vec.iter() {
			draw_shape(&self.styles[shape.style], shape);
		}

		// Disable Depth Testing for GUI
		self.context.disable(Feature::DepthTest);

		// Gui Elements don't want a camera.
		for i in (&self.styles).iter() {
			i.has_camera.set_int1(0);
		}

		// No need to sort gui elements.
		for shape in self.gui_vec.iter() {
			draw_shape(&self.styles[shape.style], shape);
		}

		// end todo

		self.context.update();
		// Return None, there was no input, updated screen.
		None
	}

	fn camera(&mut self, xyz: Vec3, rotate_xyz: Vec3) {
		// Set Camera
		self.xyz = xyz;
		self.rotate_xyz = rotate_xyz;

		// Write To Camera Uniforms.  TODO: only before use (not here).
		// TODO this assignment copied from vulkan implementation.  Put
		// in the base library.
		let cam = Transform::IDENTITY
			.t(vec3!()-self.xyz) // Move camera - TODO: negation operator?
			.r(vec3!()-self.rotate_xyz) // Rotate camera - TODO: negation operator?
			.m(self.projection.0); // Apply projection to camera

		for i in (&self.styles).iter() {
			i.camera_uniform.set_mat4(cam.into());
		}
	}

	fn model(&mut self, vertices: &[f32], fans: Vec<(u32, u32)>) -> Model {
		// TODO most is duplicate from other implementation.
		let index = self.models.len();

		let buffer = Buffer::new(&self.context);

		let vertex_buffer = buffer;
		vertex_buffer.set(vertices);


		self.models.push(ModelData {
			vertex_buffer, vertex_count: vertices.len() as u32 / 4,
			fans
		});

		Model(index)
	}

	fn fog(&mut self, fog: Option<(f32, f32)>) -> () {
		let fogc = [self.color.0, self.color.1, self.color.2, 1.0];
		let fogr = if let Some(fog) = fog {
			[fog.0, fog.1]
		} else {
			[::std::f32::MAX, 0.0]
		};

		for i in (&self.styles).iter() {
			i.fog.set_vec4(&fogc);
			i.range.set_vec2(&fogr);
		}
	}

	fn texture(&mut self, wh: (u16,u16), graphic: &VFrame) -> Texture {
		let (w, h) = wh;
		let pixels = graphic.0.as_slice();

		let t = self.context.texture();

		t.set(w, h, pixels);

		let a = self.textures.len();

		self.textures.push(TextureData { t });

		Texture(a, w, h)
	}

	fn gradient(&mut self, colors: &[f32]) -> Gradient {
		// TODO: A lot of duplication here from adi_gpu_vulkan.  Put in
		// base.
		let vertex_buffer = Buffer::new(&self.context);
		vertex_buffer.set(colors);

		let a = self.gradients.len();

		self.gradients.push(GradientData {
			vertex_buffer,
			vertex_count: colors.len() as u32 / 4,
		});

		Gradient(a)
	}

	fn texcoords(&mut self, texcoords: &[f32]) -> TexCoords {
		// TODO: A lot of duplication here from adi_gpu_vulkan.  Put in
		// base.
		let vertex_buffer = Buffer::new(&self.context);
		vertex_buffer.set(texcoords);

		let a = self.texcoords.len();

		self.texcoords.push(TexcoordsData {
			vertex_buffer,
			vertex_count: texcoords.len() as u32 / 4,
		});

		TexCoords(a)
	}

	fn set_texture(&mut self, texture: &mut Texture, wh: (u16,u16),
		graphic: &VFrame)
	{
		self.textures[texture.0].t.set(wh.0, wh.1,
			graphic.0.as_slice());
	}

	#[inline(always)]
	fn shape_solid(&mut self, model: &Model, transform: Transform,
		color: [f32; 4], blending: bool, fog: bool, camera: bool)
		-> Shape
	{
		let shape = ShapeData {
			style: STYLE_SOLID,
			buffers: [None, None],
			has_fog: fog,
			alpha: None,
			color: Some(color),
			texture: None,
			vertex_buffer: self.models[model.0].vertex_buffer.clone(),
			transform, // Transformation matrix.
			fans: self.models[model.0].fans.clone(),
		};

		base::new_shape(if !camera && !fog {
			let index = self.gui_vec.len() as u32;
			self.gui_vec.push(shape);
			base::ShapeHandle::Gui(index)
		} else if blending {
			let index = self.alpha_vec.len() as u32;
			self.alpha_vec.push(shape);
			self.alpha_ind.push(index);
			base::ShapeHandle::Alpha(index)
		} else {
			let index = self.opaque_vec.len() as u32;
			self.opaque_vec.push(shape);
			self.opaque_ind.push(index);
			base::ShapeHandle::Opaque(index)
		})
	}

	#[inline(always)]
	fn shape_gradient(&mut self, model: &Model, transform: Transform,
		colors: Gradient, blending: bool, fog: bool, camera: bool)
		-> Shape
	{
		// TODO: is copied from adi_gpu_vulkan, move to base
		if self.models[model.0].vertex_count
			!= self.gradients[colors.0].vertex_count
		{
			panic!("TexCoord length doesn't match gradient length");
		}

		let shape = ShapeData {
			style: STYLE_GRADIENT,
			buffers: [
				Some(self.gradients[colors.0].vertex_buffer.clone()),
				None
			],
			has_fog: fog,
			alpha: None,
			color: None,
			texture: None,
			vertex_buffer: self.models[model.0].vertex_buffer.clone(),
			transform, // Transformation matrix.
			fans: self.models[model.0].fans.clone(),
		};

		base::new_shape(if !camera && !fog {
			let index = self.gui_vec.len() as u32;
			self.gui_vec.push(shape);
			base::ShapeHandle::Gui(index)
		} else if blending {
			let index = self.alpha_vec.len() as u32;
			self.alpha_vec.push(shape);
			self.alpha_ind.push(index);
			base::ShapeHandle::Alpha(index)
		} else {
			let index = self.opaque_vec.len() as u32;
			self.opaque_vec.push(shape);
			self.opaque_ind.push(index);
			base::ShapeHandle::Opaque(index)
		})
	}

	#[inline(always)]
	fn shape_texture(&mut self, model: &Model, transform: Transform,
		texture: &Texture, tc: TexCoords, blending: bool, fog: bool,
		camera: bool) -> Shape
	{
		// TODO: from adi_gpu_vulkan, move to the base
		if self.models[model.0].vertex_count
			!= self.texcoords[tc.0].vertex_count
		{
			panic!("TexCoord length doesn't match vertex length");
		}

		let shape = ShapeData {
			style: STYLE_TEXTURE,
			buffers: [
				Some(self.texcoords[tc.0].vertex_buffer.clone()),
				None
			],
			has_fog: fog,
			alpha: None,
			color: None,
			texture: Some(self.textures[texture.0].t.clone()),
			vertex_buffer: self.models[model.0].vertex_buffer.clone(),
			transform, // Transformation matrix.
			fans: self.models[model.0].fans.clone(),
		};

		base::new_shape(if !camera && !fog {
			let index = self.gui_vec.len() as u32;
			self.gui_vec.push(shape);
			base::ShapeHandle::Gui(index)
		} else if blending {
			let index = self.alpha_vec.len() as u32;
			self.alpha_vec.push(shape);
			self.alpha_ind.push(index);
			base::ShapeHandle::Alpha(index)
		} else {
			let index = self.opaque_vec.len() as u32;
			self.opaque_vec.push(shape);
			self.opaque_ind.push(index);
			base::ShapeHandle::Opaque(index)
		})
	}

	#[inline(always)]
	fn shape_faded(&mut self, model: &Model, transform: Transform,
		texture: &Texture, tc: TexCoords, alpha: f32, fog: bool,
		camera: bool) -> Shape
	{
		// TODO: from adi_gpu_vulkan, move to the base
		if self.models[model.0].vertex_count
			!= self.texcoords[tc.0].vertex_count
		{
			panic!("TexCoord length doesn't match vertex length");
		}

		let shape = ShapeData {
			style: STYLE_FADED,
			buffers: [
				Some(self.texcoords[tc.0].vertex_buffer.clone()),
				None
			],
			has_fog: fog,
			alpha: Some(alpha),
			color: None,
			texture: Some(self.textures[texture.0].t.clone()),
			vertex_buffer: self.models[model.0].vertex_buffer.clone(),
			transform, // Transformation matrix.
			fans: self.models[model.0].fans.clone(),
		};

		base::new_shape(if !camera && !fog {
			let index = self.gui_vec.len() as u32;
			self.gui_vec.push(shape);
			base::ShapeHandle::Gui(index)
		} else {
			let index = self.alpha_vec.len() as u32;
			self.alpha_vec.push(shape);
			self.alpha_ind.push(index);
			base::ShapeHandle::Alpha(index)
		})
	}

	#[inline(always)]
	fn shape_tinted(&mut self, model: &Model, transform: Transform,
		texture: &Texture, tc: TexCoords, tint: [f32; 4], blending: bool,
		fog: bool, camera: bool) -> Shape
	{
		// TODO: from adi_gpu_vulkan, move to the base
		if self.models[model.0].vertex_count
			!= self.texcoords[tc.0].vertex_count
		{
			panic!("TexCoord length doesn't match vertex length");
		}

		let shape = ShapeData {
			style: STYLE_TINTED,
			buffers: [
				Some(self.texcoords[tc.0].vertex_buffer.clone()),
				None,
			],
			has_fog: fog,
			alpha: None,
			color: Some(tint),
			texture: Some(self.textures[texture.0].t.clone()),
			vertex_buffer: self.models[model.0].vertex_buffer.clone(),
			transform, // Transformation matrix.
			fans: self.models[model.0].fans.clone(),
		};

		base::new_shape(if !camera && !fog {
			let index = self.gui_vec.len() as u32;
			self.gui_vec.push(shape);
			base::ShapeHandle::Gui(index)
		} else if blending {
			let index = self.alpha_vec.len() as u32;
			self.alpha_vec.push(shape);
			self.alpha_ind.push(index);
			base::ShapeHandle::Alpha(index)
		} else {
			let index = self.opaque_vec.len() as u32;
			self.opaque_vec.push(shape);
			self.opaque_ind.push(index);
			base::ShapeHandle::Opaque(index)
		})
	}

	#[inline(always)]
	fn shape_complex(&mut self, model: &Model, transform: Transform,
		texture: &Texture, tc: TexCoords, tints: Gradient,
		blending: bool, fog: bool, camera: bool) -> Shape
	{
		// TODO: from adi_gpu_vulkan, move to the base
		if self.models[model.0].vertex_count
			!= self.texcoords[tc.0].vertex_count
		{
			panic!("TexCoord length doesn't match vertex length");
		}

		// TODO: is copied from adi_gpu_vulkan, move to base
		if self.models[model.0].vertex_count
			!= self.gradients[tints.0].vertex_count
		{
			panic!("TexCoord length doesn't match gradient length");
		}

		let shape = ShapeData {
			style: STYLE_COMPLEX,
			buffers: [
				Some(self.texcoords[tc.0].vertex_buffer.clone()),
				Some(self.gradients[tints.0].vertex_buffer.clone()),
			],
			has_fog: fog,
			alpha: None,
			color: None,
			texture: Some(self.textures[texture.0].t.clone()),
			vertex_buffer: self.models[model.0].vertex_buffer.clone(),
			transform, // Transformation matrix.
			fans: self.models[model.0].fans.clone(),
		};

		base::new_shape(if !camera && !fog {
			let index = self.gui_vec.len() as u32;
			self.gui_vec.push(shape);
			base::ShapeHandle::Gui(index)
		} else if blending {
			let index = self.alpha_vec.len() as u32;
			self.alpha_vec.push(shape);
			self.alpha_ind.push(index);
			base::ShapeHandle::Alpha(index)
		} else {
			let index = self.opaque_vec.len() as u32;
			self.opaque_vec.push(shape);
			self.opaque_ind.push(index);
			base::ShapeHandle::Opaque(index)
		})
	}

	#[inline(always)]
	fn drop_shape(&mut self, shape: &Shape) {
		match get_shape(&shape) {
			ShapeHandle::Opaque(x) => {
				let index = self.opaque_ind.iter()
					.position(|y| *y == x).unwrap();
				self.opaque_ind.remove(index);
			},
			ShapeHandle::Alpha(x) => {
				let index = self.alpha_ind.iter()
					.position(|y| *y == x).unwrap();
				self.alpha_ind.remove(index);
			},
			ShapeHandle::Gui(_x) => {
				// TODO: make it obvious that there's only meant
				// to be 1 GUI object.
				self.gui_vec.clear();
			},
		}
	}

	fn transform(&mut self, shape: &Shape, transform: Transform) {
		// TODO: put in base, some is copy from vulkan implementation.
		match base::get_shape(shape) {
			ShapeHandle::Opaque(x) => {
				let x = x as usize; // for indexing
				self.opaque_vec[x].transform = transform;
			},
			ShapeHandle::Alpha(x) => {
				let x = x as usize; // for indexing
				self.alpha_vec[x].transform = transform;
			},
			ShapeHandle::Gui(x) => {
				let x = x as usize; // for indexing
				self.gui_vec[x].transform = transform;
			},
		}
	}

	fn resize(&mut self, wh: (u16, u16)) -> () {
		let xyz = self.xyz;
		let rotate_xyz = self.rotate_xyz;

		self.ar = wh.0 as f32 / wh.1 as f32;
		self.context.viewport(wh.0, wh.1);

		self.projection = ::base::projection(self.ar, 0.5 * PI);
		self.camera(xyz, rotate_xyz);
	}

	fn wh(&self) -> (u16, u16) {
		self.window.wh()
	}
}

fn draw_shape(style: &Style, shape: &ShapeData) {
	style.matrix_uniform.set_mat4(shape.transform.into());

	if !style.texpos.is_none() {
		// Set texpos for the program from the texpos buffer.
		style.texpos.set(shape.buffers[0].as_ref().unwrap());
		// Bind the texture
		shape.texture.as_ref().unwrap().bind();
	}

	if !style.acolor.is_none() {
		// Set colors for the program from the color buffer.
		// TODO: probably shouldn't be same buffer as texpos.
		style.acolor.set(shape.buffers[0].as_ref().unwrap());
	}

	if !style.alpha.is_none() {
		style.alpha.set_vec1(shape.alpha.unwrap());
	}

	if !style.color.is_none() {
		style.color.set_vec4(&shape.color.unwrap());
	}

	if shape.has_fog {
		style.has_fog.set_int1(1);
	} else {
		style.has_fog.set_int1(0);
	}

	// Set vertices for the program from the vertex buffer.
	style.position.set(&shape.vertex_buffer);
	for i in shape.fans.iter() {
		style.shader.draw_arrays(Topology::TriangleFan, i.0..i.1);
	}
}