use bytemuck::{Pod, Zeroable};
use rand::Rng;
use wgpu::{VertexAttribute, VertexBufferLayout};
use std::{default, vec::Vec};


#[repr(C)]
#[derive(Debug, Clone, Copy)]
pub struct Pos([f32; 3]);

#[repr(C)]
#[derive(Debug, Clone, Copy)]
pub struct Col([f32; 3]);

impl Pos {
    pub fn new(x: f32, y: f32, z: f32) -> Self {
        Self([x, y, z])
    }
}

unsafe impl Zeroable for Pos {}
unsafe impl Pod for Pos {}

impl Col {
    pub fn new(r: f32, g: f32, b: f32) -> Self {
        Self([r, g, b])
    }
    pub fn random() -> Self {
        Self::new(rand::thread_rng().gen_range(0.0..=1.0), rand::thread_rng().gen_range(0.0..=1.0), rand::thread_rng().gen_range(0.0..=1.0))
    }
}

unsafe impl Zeroable for Col {}
unsafe impl Pod for Col {}

#[repr(C)]
#[derive(Debug, Clone, Copy)]
pub struct Vertex {
    position: Pos,
    color: Col,
}

impl Vertex {
    pub fn new(position: Pos, color: Col) -> Self {
        Vertex { position: position, color: color }
    }

    pub fn desc() -> wgpu::VertexBufferLayout<'static> {
        wgpu::VertexBufferLayout {
            array_stride: std::mem::size_of::<Self>() as wgpu::BufferAddress,
            step_mode: wgpu::VertexStepMode::Vertex,
            attributes: &[VertexAttribute {
                format: wgpu::VertexFormat::Float32x3,
                offset: 0,
                shader_location: 0,
            },
            VertexAttribute {
                format: wgpu::VertexFormat::Float32x3,
                offset: std::mem::size_of::<[f32; 3]>() as u64,
                shader_location: 1,
            }],
        }
    }
}

unsafe impl Zeroable for Vertex {}
unsafe impl Pod for Vertex {}






#[derive(Debug)]
pub enum PolyError {
    NotEnoughSides,
    SidesAndTriangeNumberArentConsistant
}


#[repr(C)]
pub struct Polygon{
    triangles: Vec<Triangle>,
    n_sides: usize,
}

impl Polygon {
    pub fn new_from_center(center: Vertex, radius: f32, n_sides: usize) -> Self {
        //let theta = (360.0 / n_sides as f32).to_radians();
        let mut vec_tris: Vec<Triangle> = Vec::with_capacity(n_sides);

        let center_x = center.position.0[0];
        let center_y = center.position.0[1];

        for v in 0..n_sides {
            let theta_current = (v as f32 / n_sides as f32) * 2.0 * std::f32::consts::PI;
            let theta_next = ((v+1) as f32 / n_sides as f32) * 2.0 * std::f32::consts::PI;
            let triangle = Triangle::new(Vertex::new(Pos::new((theta_current.cos() * radius) + center_x, (theta_current.sin() * radius) + center_y, 0.0), Col::random()), Vertex::new(Pos::new((theta_next.cos() * radius) + center_x, (theta_next.sin() * radius) + center_y, 0.0), Col::random()), center);
            vec_tris.push(triangle);
        };
        Self::new_from_tris(vec_tris, n_sides).unwrap()
    }


    pub fn new_from_side(len_side: f32, n_sides: usize, color: Option<Col>) -> Self {
        todo!();
    //     let color = color.unwrap_or(Col::random());
    //     let theta = 360.0 / n_sides as f32;
        
    //     let center = Pos::new(
    //         // ((180.0 - theta) / 2.0).to_radians().cos() * radius,
    //         // ((180.0 - theta) / 2.0).to_radians().sin() * radius,
    //         (theta / 2.0).to_radians().cos() * radius,
    //         (theta / 2.0).to_radians().sin() * radius,
    //         0.0
    //     );

    //     let nsides_poly = NSides::new(center, radius, n_sides, color).unwrap();
    //     nsides_poly.verts.polish_tris(nsides_poly.center, color)
    }

    fn new_from_tris(triangles: Vec<Triangle>, n_sides: usize) -> Result<Self, PolyError> {
        if triangles.len() != n_sides {
            return Err(PolyError::SidesAndTriangeNumberArentConsistant)
        }
        
        Ok(Self {
            triangles,
            n_sides
        })
    }

    pub fn get_tris(&self) -> Vec<Triangle> {
        self.triangles.clone()
    }

    pub fn uniform(&self) -> &[u8] {
        self.get_tris();
        todo!()
    }
}


#[repr(C)]
#[derive(Debug, Clone)]
pub struct Triangle([Vertex; 3]);

impl Triangle {
    pub fn new(vertex1: Vertex, vertex2: Vertex, vertex3: Vertex) -> Self {
        Self([vertex1, vertex2, vertex3])
    }

    pub fn verts(&self) -> [Vertex; 3] {
        self.0
    } 
}


pub type VertexVector = Vec<Vertex>;

trait VertexVectorMethods {
    fn polish_tris(&self, center_position: Pos, center_color: Col) -> Polygon;
    fn get_next(&self, index: usize) -> Vertex;
}

impl VertexVectorMethods for VertexVector {
    fn polish_tris(&self, center_position: Pos, center_color: Col) -> Polygon {
        let start_verts = self;
        let mut vec_tris = Vec::with_capacity(self.len());
        for (vx, indx) in self.iter().zip(0..self.len()) {
            vec_tris.push(Triangle::new(vx.to_owned(), self.get_next(indx), Vertex { position: center_position, color: Col::random() }));
        };
        Polygon::new_from_tris(vec_tris, self.len()).unwrap()
    }

    fn get_next(&self, index: usize) -> Vertex {
        if index != self.len()-1 {
            return self[index+1];
        } else {
            return self[0];
        }
    }
}


#[repr(C)]
pub struct NSides {
    center: Pos,
    radius: f32,
    n_sides: usize,
    color: Col,
    verts: VertexVector
}

impl NSides {
    #[allow(private_interfaces)]
    pub fn new(center: Pos, radius: f32, n_sides: usize, color: Col) -> Result<Self, PolyError> {
        if n_sides < 3 {
            return Err(PolyError::NotEnoughSides)
        }

        let verts = Self::calc_vertecies(n_sides, radius, color);

        return Ok(Self {
            center,
            radius,
            n_sides,
            color,
            verts,
        })
    }

    pub fn get_verts(&self) -> VertexVector {
        self.verts.clone()
    }

    #[allow(private_interfaces)]
    fn calc_vertecies(n_sides: usize, radius: f32, color: Col) -> VertexVector{
        let mut verts: Vec<Vertex> = Vec::with_capacity(n_sides);
        let float_sides = n_sides as f32;
        for x in 0..n_sides {
            let x = x as f32;
            let theta = (x / float_sides) * 2.0 * 3.14159265359;
            verts.push(Vertex::new(Pos::new(theta.cos() * radius, theta.sin() * radius, 0.0), color));
        }

        verts
    }
}