use std::rc::Rc;
use std::cell::RefCell;
use std::io;

#[cfg(feature="threads")]
use std::sync::{Arc, Mutex};

use crate::lib8::RGB8;
use crate::geometry::*;

pub trait Shader: Send {
    fn draw(&self, surface_coords: VirtualCoordinates) -> RGB8;
}

pub trait Surface: Default + Clone {
    fn with_shader<F: FnMut(&dyn Shader)>(&self, f: F);
    fn set_shader(&mut self, shader: Box<dyn Shader>);
    fn clear_shader(&mut self);
}

pub trait Surfaces<T: Surface> {
    fn new_surface(&mut self) -> Result<T, io::Error>;
}

pub trait Display<T: Surface>: Surfaces<T> {
    fn start_frame(&mut self) {}
    fn end_frame(&mut self) {}
    fn render_frame(&mut self);
}

pub struct ShaderBinding {
    shader: Option<Box<dyn Shader>>,
}

#[derive(Clone)]
pub struct BoundSurface<T> {
    pub binding: T
}

pub type SimpleSurface = BoundSurface<Rc<RefCell<ShaderBinding>>>;

impl Default for BoundSurface<Rc<RefCell<ShaderBinding>>>{
    fn default() -> Self {
        Self {
            binding: Rc::new(RefCell::new(ShaderBinding {
                shader: None,
            })),
        }
    }
}

impl Surface for BoundSurface<Rc<RefCell<ShaderBinding>>> {
    fn with_shader<F: FnMut(&dyn Shader)>(&self, mut f: F) {
        if let Some(ref shader) = self.binding.borrow().shader {
            f(shader.as_ref());
        }
    }

    fn set_shader(&mut self, shader: Box<dyn Shader>) {
        self.binding.borrow_mut().shader = Some(shader);
    }

    fn clear_shader(&mut self) {
        self.binding.borrow_mut().shader = None;
    }
}

#[cfg(feature="threads")]
pub type SharedSurface = BoundSurface<Arc<Mutex<ShaderBinding>>>;


#[cfg(feature="threads")]
impl Default for BoundSurface<Arc<Mutex<ShaderBinding>>> {
    fn default() -> Self {
        Self {
            binding: Arc::new(Mutex::new(ShaderBinding {
                shader: None,
            })),
        }
    }
}

#[cfg(feature="threads")]
impl Surface for BoundSurface<Arc<Mutex<ShaderBinding>>> {
    fn with_shader<F: FnMut(&dyn Shader)>(&self, mut f: F) {
        if let Some(ref shader) = self.binding.lock().unwrap().shader {
            f(shader.as_ref());
        }
    }

    fn set_shader(&mut self, shader: Box<dyn Shader>) {
        self.binding.lock().unwrap().shader = Some(shader);
    }

    fn clear_shader(&mut self) {
        self.binding.lock().unwrap().shader = None;
    }
}

pub struct SurfacePool<S: Surface + Default> {
    surfaces: Vec<S>
}

impl<S: Surface + Default> SurfacePool<S> {
    pub const fn new() -> Self {
        Self {
            surfaces: Vec::new()
        }
    }

    pub fn iter(&self) -> std::slice::Iter<S> {
        self.surfaces.iter()
    }
}

impl<S: Surface + Default + Clone> Surfaces<S> for SurfacePool<S> {
    fn new_surface(&mut self) -> Result<S, io::Error> {
        let surface = S::default();
        self.surfaces.push(surface.clone());
        return Ok(surface);
    }
}