#[repr(C)]
#[derive(Copy, Clone, bytemuck::Pod, bytemuck::Zeroable)]
pub struct Globals {
    pub view_proj: [[f32; 4]; 4],
}

#[derive(Clone, Copy, Debug, PartialEq, Eq, Hash)]
pub enum Shape {
    Polygon,
    Circle,
}

pub struct Geometry {
    pub(crate) vertex_buffer: wgpu::Buffer,
    pub(crate) index_buffer: wgpu::Buffer,
    pub(crate) index_count: u32,
}

pub struct RenderInstance {
    pub position: cgmath::Vector3<f32>,
    pub rotation: cgmath::Quaternion<f32>,
    pub color: [f32; 3],
    pub scale: f32,
    pub shape: Shape,
}

impl RenderInstance {
    pub fn to_raw(&self) -> InstanceRaw {
        let model = cgmath::Matrix4::from_translation(self.position)
            * cgmath::Matrix4::from(self.rotation)
            * cgmath::Matrix4::from_scale(self.scale);
        InstanceRaw {
            model: model.into(),
            color: self.color,
        }
    }
}

#[repr(C)]
#[derive(Copy, Clone, bytemuck::Pod, bytemuck::Zeroable)]
pub struct InstanceRaw {
    model: [[f32; 4]; 4],
    color: [f32; 3],
}

impl InstanceRaw {
    pub(crate) fn desc() -> wgpu::VertexBufferLayout<'static> {
        wgpu::VertexBufferLayout {
            array_stride: size_of::<InstanceRaw>() as wgpu::BufferAddress,
            step_mode: wgpu::VertexStepMode::Instance,
            attributes: &[
                wgpu::VertexAttribute { offset: 0, shader_location: 5, format: wgpu::VertexFormat::Float32x4 },
                wgpu::VertexAttribute { offset: 16, shader_location: 6, format: wgpu::VertexFormat::Float32x4 },
                wgpu::VertexAttribute { offset: 32, shader_location: 7, format: wgpu::VertexFormat::Float32x4 },
                wgpu::VertexAttribute { offset: 48, shader_location: 8, format: wgpu::VertexFormat::Float32x4 },
                wgpu::VertexAttribute { offset: 64, shader_location: 9, format: wgpu::VertexFormat::Float32x3 },
            ],
        }
    }
}


pub struct SampleCount(pub u32);

impl SampleCount {
    pub fn get(&self) -> u32 {
        self.0
    }
}

#[repr(C)]
#[derive(Copy, Clone, Debug, bytemuck::Pod, bytemuck::Zeroable)]
pub struct Vertex {
    pub(crate) position: [f32; 3],
    pub(crate) color: [f32; 3],
}

impl Vertex {
    const ATTRIBS: [wgpu::VertexAttribute; 2] =
        wgpu::vertex_attr_array![0 => Float32x3, 1 => Float32x3];

    pub(crate) fn desc() -> wgpu::VertexBufferLayout<'static> {
        wgpu::VertexBufferLayout {
            array_stride: size_of::<Self>() as wgpu::BufferAddress,
            step_mode: wgpu::VertexStepMode::Vertex,
            attributes: &Self::ATTRIBS,
        }
    }
}

pub fn create_circle_vertices(segment_count: usize, radius: f32, color: [f32; 3]) -> (Vec<Vertex>, Vec<u16>) {
    let mut vertices = vec![Vertex { position: [0.0, 0.0, 0.0], color }];
    let mut indices = vec![];

    for i in 0..=segment_count {
        let theta = (i as f32) / (segment_count as f32) * std::f32::consts::TAU;
        let x = radius * theta.cos();
        let y = radius * theta.sin();
        vertices.push(Vertex { position: [x, y, 0.0], color });
    }

    for i in 1..=segment_count {
        indices.push(0);
        indices.push(i as u16);
        indices.push((i % segment_count + 1) as u16);
    }

    (vertices, indices)
}