use cgmath::prelude::*;

#[cfg(not(target_arch="wasm32"))]
use rayon::prelude::*;
use ::render::graphics_renderer::GraphicsRenderer;
use wgpu::{util::DeviceExt, Queue};
use winit::event::{DeviceEvent, ElementState, Event, KeyboardInput, MouseButton, WindowEvent};

use crate::{
    camera,
    model::{self, DrawLight, DrawModel},
    render, resources, texture, CameraUniform, Instance, LightUniform, NUM_INSTANCES_PER_ROW,
};

pub struct DefaultState {
    obj_model: model::Model,
    camera: camera::Camera,
    projection: camera::Projection,
    camera_controller: camera::CameraController,
    camera_uniform: CameraUniform,
    camera_buffer: wgpu::Buffer,
    camera_bind_group: wgpu::BindGroup,
    instances: Vec<Instance>,
    #[allow(dead_code)]
    instance_buffer: wgpu::Buffer,
    depth_texture: texture::Texture,
    light_uniform: LightUniform,
    light_buffer: wgpu::Buffer,
    light_bind_group: wgpu::BindGroup,
    #[allow(dead_code)]
    debug_material: model::Material,
    mouse_pressed: bool,
    pipelines: render::Pipelines,
}

impl DefaultState {
    pub async fn new(renderer: &GraphicsRenderer) -> Self
    {
        let global_bind_layout = render::GlobalBindLayout::new(&renderer.device);
        let pipelines =
            render::Pipelines::new(&global_bind_layout, &renderer.device, &renderer.config);

        let camera = camera::Camera::new((0.0, 5.0, 10.0), cgmath::Deg(-90.0), cgmath::Deg(-20.0));
        let projection = camera::Projection::new(
            renderer.config.width,
            renderer.config.height,
            cgmath::Deg(45.0),
            0.1,
            100.0,
        );
        let camera_controller = camera::CameraController::new(4.0, 0.4);

        let mut camera_uniform = CameraUniform::new();
        camera_uniform.update_view_proj(&camera, &projection);

        let camera_buffer = renderer
            .device
            .create_buffer_init(&wgpu::util::BufferInitDescriptor {
                label: Some("Camera Buffer"),
                contents: bytemuck::cast_slice(&[camera_uniform]),
                usage: wgpu::BufferUsages::UNIFORM | wgpu::BufferUsages::COPY_DST,
            });

        const SPACE_BETWEEN: f32 = 3.0;
        let iter = {
            cfg_if::cfg_if! {
                if #[cfg(target_arch = "wasm32")] {
                    (0..NUM_INSTANCES_PER_ROW)
                    .into_iter()
                } else {
                    (0..NUM_INSTANCES_PER_ROW)
                    .into_par_iter()
                }
            }
        };
        let instances = iter
            .clone()
            .flat_map(|z| {
                // UPDATED!
                iter.clone().map(move |x| {
                    let x = SPACE_BETWEEN * (x as f32 - NUM_INSTANCES_PER_ROW as f32 / 2.0);
                    let z = SPACE_BETWEEN * (z as f32 - NUM_INSTANCES_PER_ROW as f32 / 2.0);

                    let position = cgmath::Vector3 { x, y: 0.0, z };

                    let rotation = if position.is_zero() {
                        cgmath::Quaternion::from_axis_angle(
                            cgmath::Vector3::unit_z(),
                            cgmath::Deg(0.0),
                        )
                    } else {
                        cgmath::Quaternion::from_axis_angle(position.normalize(), cgmath::Deg(45.0))
                    };

                    Instance { position, rotation }
                })
            })
            .collect::<Vec<_>>();

        let instance_data = instances.iter().map(Instance::to_raw).collect::<Vec<_>>();
        let instance_buffer =
            (&renderer.device).create_buffer_init(&wgpu::util::BufferInitDescriptor {
                label: Some("Instance Buffer"),
                contents: bytemuck::cast_slice(&instance_data),
                usage: wgpu::BufferUsages::VERTEX,
            });

        let camera_bind_group = renderer
            .device
            .create_bind_group(&wgpu::BindGroupDescriptor {
                layout: global_bind_layout.get_camera_bind_layout(),
                entries: &[wgpu::BindGroupEntry {
                    binding: 0,
                    resource: camera_buffer.as_entire_binding(),
                }],
                label: Some("camera_bind_group"),
            });

        let obj_model = resources::load_model(
            "cube.obj",
            &renderer.device,
            &renderer.queue,
            global_bind_layout.get_texture_bind_layout(),
        ).await.unwrap();

        let light_uniform = LightUniform {
            position: [2.0, 2.0, 2.0],
            _padding: 0,
            color: [1.0, 1.0, 1.0],
            _padding2: 0,
        };

        let light_buffer = renderer
            .device
            .create_buffer_init(&wgpu::util::BufferInitDescriptor {
                label: Some("Light VB"),
                contents: bytemuck::cast_slice(&[light_uniform]),
                usage: wgpu::BufferUsages::UNIFORM | wgpu::BufferUsages::COPY_DST,
            });

        let light_bind_group = renderer
            .device
            .create_bind_group(&wgpu::BindGroupDescriptor {
                layout: global_bind_layout.get_light_bind_layout(),
                entries: &[wgpu::BindGroupEntry {
                    binding: 0,
                    resource: light_buffer.as_entire_binding(),
                }],
                label: None,
            });

        let depth_texture = texture::Texture::create_depth_texture(
            &renderer.device,
            &renderer.config,
            "depth_texture",
        );

        let debug_material = {
            let diffuse_bytes = include_bytes!("../../../res/cobble-diffuse.png");
            let normal_bytes = include_bytes!("../../../res/cobble-normal.png");

            let diffuse_texture = texture::Texture::from_bytes(
                &renderer.device,
                &renderer.queue,
                diffuse_bytes,
                "res/alt-diffuse.png",
                false,
            )
            .unwrap();
            let normal_texture = texture::Texture::from_bytes(
                &renderer.device,
                &renderer.queue,
                normal_bytes,
                "res/alt-normal.png",
                true,
            )
            .unwrap();

            model::Material::new(
                &renderer.device,
                "alt-material",
                diffuse_texture,
                normal_texture,
                global_bind_layout.get_texture_bind_layout(),
            )
        };

        Self {
            obj_model,
            camera,
            projection,
            camera_controller,
            camera_buffer,
            camera_bind_group,
            camera_uniform,
            instances,
            instance_buffer,
            depth_texture,
            light_uniform,
            light_buffer,
            light_bind_group,
            #[allow(dead_code)]
            debug_material,
            mouse_pressed: false,
            pipelines,
        }
    }
}

impl super::State for DefaultState {
    fn resize(
        &mut self,
        device: &wgpu::Device,
        config: &wgpu::SurfaceConfiguration,
        new_size: winit::dpi::PhysicalSize<u32>,
    ) {
        self.projection.resize(new_size.width, new_size.height);
        self.depth_texture =
            texture::Texture::create_depth_texture(&device, &config, "depth_texture");
    }

    fn input(&mut self, event: &Event<()>) -> bool {
        match event {
            Event::DeviceEvent {
                event: DeviceEvent::MouseMotion { delta },
                ..
            } => {
                if self.mouse_pressed {
                    self.camera_controller.process_mouse(delta.0, delta.1);
                }
                true
            }
            Event::WindowEvent { ref event, .. } => match event {
                WindowEvent::KeyboardInput {
                    input:
                        KeyboardInput {
                            virtual_keycode: Some(key),
                            state,
                            ..
                        },
                    ..
                } => self.camera_controller.process_keyboard(*key, *state),
                WindowEvent::MouseWheel { delta, .. } => {
                    self.camera_controller.process_scroll(delta);
                    true
                }
                WindowEvent::MouseInput {
                    button: MouseButton::Left,
                    state,
                    ..
                } => {
                    self.mouse_pressed = *state == ElementState::Pressed;
                    true
                }
                _ => false,
            },
            _ => false,
        }
    }

    fn update(&mut self, queue: &Queue, dt: instant::Duration) {
        self.camera_controller.update_camera(&mut self.camera, dt);
        self.camera_uniform
            .update_view_proj(&self.camera, &self.projection);
        queue.write_buffer(
            &self.camera_buffer,
            0,
            bytemuck::cast_slice(&[self.camera_uniform]),
        );

        // Update the light
        let old_position: cgmath::Vector3<_> = self.light_uniform.position.into();
        self.light_uniform.position =
            (cgmath::Quaternion::from_axis_angle((0.0, 1.0, 0.0).into(), cgmath::Deg(1.0))
                * old_position)
                .into();
        queue.write_buffer(
            &self.light_buffer,
            0,
            bytemuck::cast_slice(&[self.light_uniform]),
        );
    }

    fn render(
        &self,
        view: &wgpu::TextureView,
        encoder: &mut wgpu::CommandEncoder,
    ) -> Result<(), wgpu::SurfaceError> {
        let mut render_pass = encoder.begin_render_pass(&wgpu::RenderPassDescriptor {
            label: Some("Render Pass"),
            color_attachments: &[Some(wgpu::RenderPassColorAttachment {
                view: &view,
                resolve_target: None,
                ops: wgpu::Operations {
                    load: wgpu::LoadOp::Clear(wgpu::Color {
                        r: 0.1,
                        g: 0.2,
                        b: 0.3,
                        a: 1.0,
                    }),
                    store: true,
                },
            })],
            depth_stencil_attachment: Some(wgpu::RenderPassDepthStencilAttachment {
                view: &self.depth_texture.view,
                depth_ops: Some(wgpu::Operations {
                    load: wgpu::LoadOp::Clear(1.0),
                    store: true,
                }),
                stencil_ops: None,
            }),
        });

        render_pass.set_vertex_buffer(1, self.instance_buffer.slice(..));
        render_pass.set_pipeline(self.pipelines.get_light_pipeline());
        render_pass.draw_light_model(
            &self.obj_model,
            &self.camera_bind_group,
            &self.light_bind_group,
        );

        render_pass.set_pipeline(self.pipelines.get_render_pipeline());
        render_pass.draw_model_instanced(
            &self.obj_model,
            0..self.instances.len() as u32,
            &self.camera_bind_group,
            &self.light_bind_group,
        );

        Ok(())
    }
}
