use std::ops::Range;

use crate::core::texture::Texture;

pub struct Material {
    pub name: String,
    pub diffuse_texture: Texture,
    pub normal_texture: Texture,
    pub metallic_roughness_texture: Texture,
    pub metallic_factor: f32,  // TODO pass to shader
    pub roughness_factor: f32, // TODO pass to shader
    pub bind_group: wgpu::BindGroup,
}

impl Material {
    pub fn new(
        device: &wgpu::Device,
        name: &str,
        diffuse_texture: Texture,
        normal_texture: Texture,
        metallic_roughness_texture: Texture,
        metallic_factor: f32,
        roughness_factor: f32,
        layout: &wgpu::BindGroupLayout,
    ) -> Self {
        let bind_group = device.create_bind_group(&wgpu::BindGroupDescriptor {
            layout,
            entries: &[
                // diffuse
                wgpu::BindGroupEntry {
                    binding: 0,
                    resource: wgpu::BindingResource::TextureView(&diffuse_texture.view),
                },
                wgpu::BindGroupEntry {
                    binding: 1,
                    resource: wgpu::BindingResource::Sampler(&diffuse_texture.sampler),
                },
                // normal
                wgpu::BindGroupEntry {
                    binding: 2,
                    resource: wgpu::BindingResource::TextureView(&normal_texture.view),
                },
                wgpu::BindGroupEntry {
                    binding: 3,
                    resource: wgpu::BindingResource::Sampler(&normal_texture.sampler),
                },
                // metallic roughness
                wgpu::BindGroupEntry {
                    binding: 4,
                    resource: wgpu::BindingResource::TextureView(&metallic_roughness_texture.view),
                },
                wgpu::BindGroupEntry {
                    binding: 5,
                    resource: wgpu::BindingResource::Sampler(&metallic_roughness_texture.sampler),
                },
            ],
            label: None,
        });

        Self {
            name: String::from(name),
            diffuse_texture,
            normal_texture,
            metallic_roughness_texture,
            metallic_factor,
            roughness_factor,
            bind_group,
        }
    }
}

pub struct Mesh {
    pub name: String,
    pub vertex_buffer: wgpu::Buffer,
    pub index_buffer: wgpu::Buffer,
    pub num_elements: u32,
    pub material: usize,
}

pub struct Model {
    pub meshes: Vec<Mesh>,
    pub materials: Vec<Material>,
}

pub trait Vertex {
    fn desc<'a>() -> wgpu::VertexBufferLayout<'a>;
}

#[repr(C)]
#[derive(Copy, Clone, Debug, Default, bytemuck::Pod, bytemuck::Zeroable)]
pub struct ModelVertex {
    pub position: [f32; 3],
    pub tex_coords: [f32; 2],
    pub normal: [f32; 3],
    pub tangent: [f32; 3],
    pub bitangent: [f32; 3],
}

impl Vertex for ModelVertex {
    fn desc<'a>() -> wgpu::VertexBufferLayout<'a> {
        use std::mem;
        wgpu::VertexBufferLayout {
            array_stride: mem::size_of::<ModelVertex>() as wgpu::BufferAddress,
            step_mode: wgpu::VertexStepMode::Vertex,
            attributes: &[
                // position
                wgpu::VertexAttribute {
                    offset: 0,
                    shader_location: 0,
                    format: wgpu::VertexFormat::Float32x3,
                },
                // tex_coords
                wgpu::VertexAttribute {
                    offset: mem::size_of::<[f32; 3]>() as wgpu::BufferAddress,
                    shader_location: 1,
                    format: wgpu::VertexFormat::Float32x2,
                },
                // normal
                wgpu::VertexAttribute {
                    offset: mem::size_of::<[f32; 5]>() as wgpu::BufferAddress,
                    shader_location: 2,
                    format: wgpu::VertexFormat::Float32x3,
                },
                // tangent
                wgpu::VertexAttribute {
                    offset: mem::size_of::<[f32; 8]>() as wgpu::BufferAddress,
                    shader_location: 3,
                    format: wgpu::VertexFormat::Float32x3,
                },
                // bitangent
                wgpu::VertexAttribute {
                    offset: mem::size_of::<[f32; 11]>() as wgpu::BufferAddress,
                    shader_location: 4,
                    format: wgpu::VertexFormat::Float32x3,
                },
            ],
        }
    }
}

pub trait DrawModel<'a> {
    fn draw_mesh(
        &mut self,
        mesh: &'a Mesh,
        material: &'a Material,
        bind_groups: Vec<&'a wgpu::BindGroup>,
    );
    fn draw_mesh_instanced(
        &mut self,
        mesh: &'a Mesh,
        material: &'a Material,
        instances: Range<u32>,
        bind_groups: Vec<&'a wgpu::BindGroup>,
    );

    fn draw_model(
        &mut self,
        model: &'a Model,
        bind_groups: Vec<&'a wgpu::BindGroup>,
    );
    fn draw_model_instanced(
        &mut self,
        model: &'a Model,
        instances: Range<u32>,
        bind_groups: Vec<&'a wgpu::BindGroup>,
    );
}

impl<'a, 'b> DrawModel<'b> for wgpu::RenderPass<'a>
where
    'b: 'a,
{
    fn draw_mesh(
        &mut self,
        mesh: &'b Mesh,
        material: &'b Material,
        bind_groups: Vec<&'a wgpu::BindGroup>,
    ) {
        self.draw_mesh_instanced(mesh, material, 0..1, bind_groups);
    }

    fn draw_mesh_instanced(
        &mut self,
        mesh: &'b Mesh,
        material: &'b Material,
        instances: Range<u32>,
        bind_groups: Vec<&'a wgpu::BindGroup>,
    ) {
        self.set_vertex_buffer(0, mesh.vertex_buffer.slice(..));
        self.set_index_buffer(mesh.index_buffer.slice(..), wgpu::IndexFormat::Uint32);
        for i in 0..bind_groups.len() {
            self.set_bind_group(i as u32, bind_groups[i], &[]);
        }
        self.set_bind_group(bind_groups.len() as u32, &material.bind_group, &[]);
        self.draw_indexed(0..mesh.num_elements, 0, instances);
    }

    fn draw_model(
        &mut self,
        model: &'b Model,
        bind_groups: Vec<&'a wgpu::BindGroup>,
    ) {
        self.draw_model_instanced(model, 0..1, bind_groups);
    }

    fn draw_model_instanced(
        &mut self,
        model: &'b Model,
        instances: Range<u32>,
        bind_groups: Vec<&'a wgpu::BindGroup>,
    ) {
        for mesh in &model.meshes {
            let material = &model.materials[mesh.material];
            self.draw_mesh_instanced(
                mesh,
                material,
                instances.clone(),
                bind_groups.clone(),
            );
        }
    }
}