use glow::*;
use std::fs;
use std::ffi::{CString, CStr};
use std::rc::Rc;
use std::str;
use cgmath::prelude::*;
    /// Shader Struct for creating and using shaders in the Context of engine
    ///
    pub struct shader {

      pub ID: NativeProgram,
      gl: Rc<glow::Context>
    }



    impl shader
        {
            /// Shader Constructor, will read, Compile and Create GLSL Program for use
            ///
            /// # Example
            /// `new(String::from("Example"))`
            /// if the String given was "Example" the Program expects both shaders to be in the directory "resources/shaders/Example/"
            /// with the vertex shader being called "shader.vert" and fragment "shader.frag"
            pub fn new(path: &str, gl: Rc<glow::Context>) -> shader
                {
                    //read file contents
                    let VERT_SHADER = fs::read_to_string(format!("resources/shaders/{path}/shader.vert")).unwrap();
                    let FRAG_SHADER = fs::read_to_string(format!("resources/shaders/{path}/shader.frag")).unwrap();

                    //create vertex shader
                    let vertex_shader = unsafe {gl.create_shader(glow::VERTEX_SHADER).unwrap() };
                    unsafe {
                      gl.shader_source(vertex_shader, &VERT_SHADER);
                      gl.compile_shader(vertex_shader);

                    }
                  // create fragment shader
                  let fragment_shader = unsafe{gl.create_shader(glow::FRAGMENT_SHADER).unwrap()};
                  unsafe {
                    gl.shader_source(fragment_shader, &FRAG_SHADER);
                    gl.compile_shader(fragment_shader);
                    if !gl.get_shader_compile_status(fragment_shader) {
                      panic!("Error, Compiling Fragment Shader: {}", gl.get_shader_info_log(fragment_shader));
                    }

                    let shader_program = gl.create_program().unwrap();

                    gl.attach_shader(shader_program, vertex_shader);
                    gl.attach_shader(shader_program, fragment_shader);
                    gl.link_program(shader_program);
                    if !gl.get_program_link_status(shader_program) {
                      panic!("Error, Linking Shader Program {}", gl.get_program_info_log(shader_program));
                    }
                    gl.detach_shader(shader_program, vertex_shader);
                    gl.detach_shader(shader_program, fragment_shader);
                    gl.delete_shader(vertex_shader);
                    gl.delete_shader(fragment_shader);

                    shader {
                      ID: shader_program,
                      gl: Rc::clone(&gl),
                    };
                  }
                }



          // return program

            /// uses Shader
            pub fn Use(&self, gl: glow::Context)
            {
                unsafe {gl.use_program(Some(self.ID));}
            }

            // BOILERPLATE JUMPSCARE
          /*
          pub fn setBool(&self, name: &str, value: bool )
          {unsafe {self.gl.uniform_1_bool(self.gl.get_uniform_location(self.ID, name).as_ref(), value);}}
           */
          pub fn setInt(&self, name: &str, value: i32 )
          {unsafe {self.gl.uniform_1_i32(self.gl.get_uniform_location(self.ID, name).as_ref(), value);}}

          pub fn setFloat(&self, name: &str, value: f32 )
          {unsafe {self.gl.uniform_1_f32(self.gl.get_uniform_location(self.ID, name).as_ref(), value);}}

          pub fn setVector2(&self, name: &str, value: cgmath::Vector2<f32> )
          {unsafe {self.gl.uniform_2_f32(self.gl.get_uniform_location(self.ID, name).as_ref(), value[0], value[1]);}}

          pub fn setVector2d(&self, name: &str, x: f32, y: f32)
          {unsafe {self.gl.uniform_2_f32(self.gl.get_uniform_location(self.ID, name).as_ref(), x, y);}}

          pub fn setVector3(&self, name: &str, value: cgmath::Vector3<f32> )
          {unsafe {self.gl.uniform_3_f32(self.gl.get_uniform_location(self.ID, name).as_ref(), value[0], value[1], value[2]);}}

          pub fn setVector3d(&self, name: &str, x: f32, y: f32, z: f32 )
          {unsafe {self.gl.uniform_3_f32(self.gl.get_uniform_location(self.ID, name).as_ref(), x, y, z);}}

          pub fn setVector4(&self, name: &str, value: &cgmath::Vector4<f32> )
          {unsafe {self.gl.uniform_4_f32(self.gl.get_uniform_location(self.ID, name).as_ref(), value[0], value[1], value[2], value[3]);}}

          pub fn setVector4d(&self, name: &str, x: f32, y: f32, z: f32, w: f32)
          {unsafe {self.gl.uniform_4_f32(self.gl.get_uniform_location(self.ID, name).as_ref(), x, y, z, w);}}

          //pub fn setMat2(&self, name: &str, value: cgmath::Matrix2<f32>)

          pub fn setMat3(&self, name: &str, value: cgmath::Matrix3<f32>)
          {
            let nums = vec![value.x.x, value.x.y, value.x.z,
            value.y.x, value.y.y, value.y.z,
            value.z.x, value.z.y, value.z.z];
            unsafe
            {
              self.gl.uniform_matrix_3_f32_slice(self.gl.get_uniform_location(self.ID, name).as_ref(), false, nums.as_ref());
            }
          }

          pub fn setMat4(&self, name: &str, value: &cgmath::Matrix4<f32>)
          {
            let nums = vec![value.x.x, value.x.y, value.x.z, value.x.w,
            value.y.x, value.y.y, value.y.z, value.y.w,
            value.z.x, value.z.y, value.z.z, value.z.w,
            value.w.x, value.w.y, value.w.z, value.w.w];
            unsafe
            {
              self.gl.uniform_matrix_4_f32_slice(self.gl.get_uniform_location(self.ID, name).as_ref(), false, nums.as_ref());
            }
          }

        }
#[cfg(test)]
  mod tests {
      use glfw;
      use glfw::Context;
      use gl;
      use super::*;

      #[test]
      fn ShaderLoading()  {

          // initialize GLFW
              let mut glfw = glfw::init(glfw::FAIL_ON_ERRORS).unwrap();
          // set window hints
          glfw.window_hint(glfw::WindowHint::ContextVersion(3, 3));
          glfw.window_hint(glfw::WindowHint::OpenGlProfile(glfw::OpenGlProfileHint::Core));
          glfw.window_hint(glfw::WindowHint::OpenGlForwardCompat(true));
          glfw.window_hint(glfw::WindowHint::Resizable(false));

          //create Window
          let (mut window, events) = glfw.create_window(480, 320, "Shader Test", glfw::WindowMode::Windowed).unwrap();
          let (screen_width, screen_height) = window.get_framebuffer_size();

          // setup window
          window.make_current();
          window.set_key_polling(true);
          // initialize gl
          gl::load_with(|ptr| window.get_proc_address(ptr) as *const _);

          let Shader = shader::new("basic");
          Shader.Use();
      }
  }