use crate::renderer::camera::Camera;
use cgmath::{SquareMatrix, Vector3, InnerSpace};
use wgpu::util::DeviceExt;

#[repr(C)]
#[derive(Default, Debug, Copy, Clone, bytemuck::Pod, bytemuck::Zeroable)]
pub struct UniformValues {
    view_inv: [[f32; 4]; 4],
    proj_inv: [[f32; 4]; 4],
    cam_pos: [f32; 3],
    padding: f32,
    sun_dir: [f32; 3],
    //padding2: f32,
    time: f32
}

impl UniformValues {

    pub fn new() -> Self {

        let sun_vec: Vector3<f32> = (1.0, 1.0, 1.0).into();
        let sun_dir: [f32; 3] = sun_vec.normalize().into();
        Self { sun_dir, .. Default::default() }
    }

    pub fn update(&mut self, camera: &Camera, time: f32) {
        self.view_inv = camera.view_matrix().invert().unwrap().into();
        self.proj_inv = camera.proj_matrix().invert().unwrap().into();
        self.cam_pos = camera.position.into();
        self.time = time;
    }
}


pub struct UniformBuffer {
    pub values: UniformValues,
    pub buffer: wgpu::Buffer,
    pub bind_layout: wgpu::BindGroupLayout,
    pub bind_group: wgpu::BindGroup,
}

impl UniformBuffer {
    pub fn new(device: &wgpu::Device) -> Self {
        // Create values
        let values = UniformValues::new();

        // Create buffer
        let buffer = device.create_buffer_init(
            &wgpu::util::BufferInitDescriptor {
                label: Some("Uniform buffer"),
                contents: bytemuck::cast_slice(&[values]),
                usage: wgpu::BufferUsage::UNIFORM | wgpu::BufferUsage::COPY_DST,
            }
        );

        // Create bind group
        let bind_layout = device.create_bind_group_layout(&wgpu::BindGroupLayoutDescriptor {
            entries: &[
                wgpu::BindGroupLayoutEntry {
                    binding: 0,
                    visibility: wgpu::ShaderStage::FRAGMENT,
                    ty: wgpu::BindingType::Buffer {
                        ty: wgpu::BufferBindingType::Uniform,
                        has_dynamic_offset: false,
                        min_binding_size: None,
                    },
                    count: None,
                }
            ],
            label: Some("Uniform buffer layout"),
        });
        let bind_group = device.create_bind_group(&wgpu::BindGroupDescriptor {
            layout: &bind_layout,
            entries: &[
                wgpu::BindGroupEntry {
                    binding: 0,
                    resource: buffer.as_entire_binding(),
                }
            ],
            label: Some("Uniform buffer group"),
        });

        // Done
        UniformBuffer { buffer, values, bind_layout, bind_group }
    }
}