use crate::vertex::Vertex;
use wgpu::util::DeviceExt;

pub struct Mesh {
    pub vertex_buffer: wgpu::Buffer,
    pub index_buffer: Option<wgpu::Buffer>,
    pub num_vertices: u32,
    pub num_indices: u32,
}

impl Mesh {
    pub fn new(device: &wgpu::Device, vertices: &[Vertex], indices: Option<&[u16]>) -> Self {
        let vertex_buffer = device.create_buffer_init(&wgpu::util::BufferInitDescriptor {
            label: Some("Mesh Vertex Buffer"),
            contents: bytemuck::cast_slice(vertices),
            usage: wgpu::BufferUsages::VERTEX,
        });

        let (index_buffer, num_indices) = if let Some(data) = indices {
            let buffer = device.create_buffer_init(&wgpu::util::BufferInitDescriptor {
                label: Some("Mesh Index Buffer"),
                usage: wgpu::BufferUsages::INDEX,
                contents: bytemuck::cast_slice(data),
            });
            (Some(buffer), data.len() as u32)
        } else {
            (None, 0)
        };
        Self {
            vertex_buffer,
            index_buffer,
            num_vertices: vertices.len() as u32,
            num_indices,
        }
    }
}