use std::sync::mpsc::Receiver;
use std::sync::Arc;

use glfw::{Context, Glfw, Window, WindowEvent};

use glow::HasContext;
use librashader_common::{Size, Viewport};

use librashader_runtime_gl::{FilterChainGL, GLFramebuffer, GLImage};

const WIDTH: u32 = 800;
const HEIGHT: u32 = 600;
const TITLE: &str = "librashader OpenGL 4.6";

pub fn setup() -> (
    Glfw,
    Window,
    Receiver<(f64, WindowEvent)>,
    glow::Program,
    glow::VertexArray,
    Arc<glow::Context>,
) {
    let mut glfw = glfw::init(glfw::FAIL_ON_ERRORS).unwrap();
    glfw.window_hint(glfw::WindowHint::ContextVersion(4, 6));
    glfw.window_hint(glfw::WindowHint::OpenGlProfile(
        glfw::OpenGlProfileHint::Core,
    ));
    glfw.window_hint(glfw::WindowHint::OpenGlForwardCompat(true));
    glfw.window_hint(glfw::WindowHint::Resizable(true));
    glfw.window_hint(glfw::WindowHint::OpenGlDebugContext(true));

    let (mut window, events) = glfw
        .create_window(WIDTH, HEIGHT, TITLE, glfw::WindowMode::Windowed)
        .unwrap();
    let (screen_width, screen_height) = window.get_framebuffer_size();

    window.make_current();
    window.set_key_polling(true);
    let mut gl = unsafe { glow::Context::from_loader_function(|ptr| window.get_proc_address(ptr)) };

    unsafe {
        gl.enable(glow::DEBUG_OUTPUT);
        gl.enable(glow::DEBUG_OUTPUT_SYNCHRONOUS);

        gl.debug_message_callback(super::debug_callback);

        gl.debug_message_control(glow::DONT_CARE, glow::DONT_CARE, glow::DONT_CARE, &[], true);
    }

    unsafe {
        gl.viewport(0, 0, screen_width, screen_height);
        gl.clear_color(0.4, 0.4, 0.4, 1.0);
    }
    // -------------------------------------------

    const VERT_SHADER: &str = "#version 330 core

layout (location = 0) in vec3 Position;
layout (location = 1) in vec3 Color;

out VS_OUTPUT {
    vec3 Color;
} OUT;

void main()
{
    gl_Position = vec4(Position, 1.0);
    OUT.Color = Color;
}";

    const FRAG_SHADER: &str = "#version 330 core

in VS_OUTPUT {
    vec3 Color;
} IN;

layout(location = 0) out vec4 Color;

void main()
{
    Color = vec4(IN.Color, 1.0f);
}";
    let shader_program = super::compile_program(&gl, VERT_SHADER, FRAG_SHADER);

    unsafe {
        gl.object_label(glow::SHADER, shader_program.0.get(), Some("color_shader"));
    }

    let vertices = &[
        // positions      // colors
        0.5f32, -0.5, 0.0, 1.0, 0.0, 0.0, // bottom right
        -0.5, -0.5, 0.0, 0.0, 1.0, 0.0, // bottom left
        0.0, 0.5, 0.0, 0.0, 0.0, 1.0, // top
    ];
    let vbo = unsafe { gl.create_named_buffer().unwrap() };

    unsafe {
        gl.object_label(glow::BUFFER, vbo.0.get(), Some("triangle_vbo"));
    }

    unsafe {
        gl.named_buffer_data_u8_slice(
            vbo,
            bytemuck::cast_slice(vertices),
            glow::STATIC_DRAW, // usage
        );
    }

    // set up vertex array object

    let vao = unsafe { gl.create_named_vertex_array().unwrap() };

    // todo: figure this shit out
    unsafe {
        // gl.object_label(glow::VERTEX_ARRAY, vao.0.get(), Some("triangle_vao"));

        gl.vertex_array_vertex_buffer(vao, 0, Some(vbo), 0, 6 * std::mem::size_of::<f32>() as i32);

        gl.enable_vertex_array_attrib(vao, 0); // this is "layout (location = 0)" in vertex shader
        gl.vertex_array_attrib_format_f32(vao, 0, 3, glow::FLOAT, false, 0);

        gl.enable_vertex_array_attrib(vao, 1);
        gl.vertex_array_attrib_format_f32(
            vao,
            1,
            3,
            glow::FLOAT,
            false,
            3 * std::mem::size_of::<f32>() as u32,
        );

        gl.vertex_array_attrib_binding_f32(vao, 0, 0);
        gl.vertex_array_attrib_binding_f32(vao, 1, 0);
    }

    // set up shared state for window

    unsafe {
        gl.viewport(0, 0, 900, 700);
        gl.clear_color(0.3, 0.3, 0.5, 1.0);
    }

    unsafe {
        // -------------------------------------------
        println!("OpenGL version: {}", gl.get_parameter_string(glow::VERSION));
        println!(
            "GLSL version: {}",
            gl.get_parameter_string(glow::SHADING_LANGUAGE_VERSION)
        );
    }

    (glfw, window, events, shader_program, vao, Arc::new(gl))
}

pub fn do_loop(
    gl: &Arc<glow::Context>,
    mut glfw: Glfw,
    mut window: Window,
    events: Receiver<(f64, WindowEvent)>,
    triangle_program: glow::Program,
    triangle_vao: glow::VertexArray,
    filter: &mut FilterChainGL,
) {
    let mut framecount = 0;
    let rendered_framebuffer;
    let rendered_texture;
    let quad_vbuf;

    let output_texture;
    let output_framebuffer_handle;
    let output_quad_vbuf;

    unsafe {
        // do frmaebuffer
        rendered_framebuffer = gl.create_named_framebuffer().unwrap();
        gl.object_label(
            glow::FRAMEBUFFER,
            rendered_framebuffer.0.get(),
            Some("rendered_framebuffer"),
        );

        rendered_texture = gl.create_named_texture(glow::TEXTURE_2D).unwrap();
        gl.object_label(
            glow::TEXTURE,
            rendered_texture.0.get(),
            Some("rendered_texture"),
        );

        // empty image
        gl.texture_storage_2d(
            rendered_texture,
            1,
            glow::RGBA8,
            WIDTH as i32,
            HEIGHT as i32,
        );

        gl.texture_parameter_i32(
            rendered_texture,
            glow::TEXTURE_MAG_FILTER,
            glow::NEAREST as i32,
        );
        gl.texture_parameter_i32(
            rendered_texture,
            glow::TEXTURE_MIN_FILTER,
            glow::NEAREST as i32,
        );
        gl.texture_parameter_i32(
            rendered_texture,
            glow::TEXTURE_WRAP_S,
            glow::CLAMP_TO_EDGE as i32,
        );
        gl.texture_parameter_i32(
            rendered_texture,
            glow::TEXTURE_WRAP_T,
            glow::CLAMP_TO_EDGE as i32,
        );

        // set color attachment
        gl.named_framebuffer_texture(
            Some(rendered_framebuffer),
            glow::COLOR_ATTACHMENT0,
            Some(rendered_texture),
            0,
        );

        gl.named_framebuffer_draw_buffer(Some(rendered_framebuffer), glow::COLOR_ATTACHMENT0);

        if gl.check_named_framebuffer_status(Some(rendered_framebuffer), glow::FRAMEBUFFER)
            != glow::FRAMEBUFFER_COMPLETE
        {
            panic!("failed to create fbo")
        }

        let fullscreen_fbo = [
            -1.0f32, -1.0, 0.0, 1.0, -1.0, 0.0, -1.0, 1.0, 0.0, -1.0, 1.0, 0.0, 1.0, -1.0, 0.0,
            1.0, 1.0, 0.0,
        ];

        quad_vbuf = gl.create_named_buffer().unwrap();

        gl.named_buffer_data_u8_slice(
            quad_vbuf,
            bytemuck::cast_slice(&fullscreen_fbo),
            glow::STATIC_DRAW,
        );
    }

    unsafe {
        // do frmaebuffer
        output_framebuffer_handle = gl.create_named_framebuffer().unwrap();

        gl.object_label(
            glow::FRAMEBUFFER,
            output_framebuffer_handle.0.get(),
            Some("output_framebuffer"),
        );

        // make tetxure
        output_texture = gl.create_named_texture(glow::TEXTURE_2D).unwrap();
        //
        gl.object_label(
            glow::TEXTURE,
            output_texture.0.get(),
            Some("output_texture"),
        );

        gl.texture_storage_2d(output_texture, 1, glow::RGBA8, WIDTH as i32, HEIGHT as i32);

        gl.texture_parameter_i32(
            output_texture,
            glow::TEXTURE_MAG_FILTER,
            glow::NEAREST as i32,
        );
        gl.texture_parameter_i32(
            output_texture,
            glow::TEXTURE_MIN_FILTER,
            glow::NEAREST as i32,
        );
        gl.texture_parameter_i32(
            output_texture,
            glow::TEXTURE_WRAP_S,
            glow::CLAMP_TO_EDGE as i32,
        );
        gl.texture_parameter_i32(
            output_texture,
            glow::TEXTURE_WRAP_T,
            glow::CLAMP_TO_EDGE as i32,
        );

        // set color attachment
        gl.named_framebuffer_texture(
            Some(output_framebuffer_handle),
            glow::COLOR_ATTACHMENT0,
            Some(output_texture),
            0,
        );

        gl.named_framebuffer_draw_buffer(Some(output_framebuffer_handle), glow::COLOR_ATTACHMENT0);

        if gl.check_named_framebuffer_status(Some(output_framebuffer_handle), glow::FRAMEBUFFER)
            != glow::FRAMEBUFFER_COMPLETE
        {
            panic!("failed to create fbo")
        }

        let fullscreen_fbo = [
            -1.0f32, -1.0, 0.0, 1.0, -1.0, 0.0, -1.0, 1.0, 0.0, -1.0, 1.0, 0.0, 1.0, -1.0, 0.0,
            1.0, 1.0, 0.0,
        ];

        output_quad_vbuf = gl.create_named_buffer().unwrap();
        gl.named_buffer_data_u8_slice(
            output_quad_vbuf,
            bytemuck::cast_slice(&fullscreen_fbo),
            glow::STATIC_DRAW,
        );
    }

    const VERT_SHADER: &str = r"#version 150 core
out vec2 v_tex;

const vec2 pos[4]=vec2[4](vec2(-1.0, 1.0),
                          vec2(-1.0,-1.0),
                          vec2( 1.0, 1.0),
                          vec2( 1.0,-1.0));

void main()
{
    v_tex=0.5*pos[gl_VertexID] + vec2(0.5);
    gl_Position=vec4(pos[gl_VertexID], 0.0, 1.0);
}
";

    const FRAG_SHADER: &str = r"
#version 150 core
in vec2 v_tex;
uniform sampler2D texSampler;
out vec4 color;
void main()
{
    color=texture(texSampler, v_tex);
}";

    let quad_programid = super::compile_program(gl, VERT_SHADER, FRAG_SHADER);
    let quad_vao = unsafe { gl.create_named_vertex_array().unwrap() };

    let (fb_width, fb_height) = window.get_framebuffer_size();
    let (vp_width, vp_height) = window.get_size();

    let output = GLFramebuffer::new_from_raw(
        Arc::clone(gl),
        Some(output_texture),
        output_framebuffer_handle,
        glow::RGBA8,
        Size::new(vp_width as u32, vp_height as u32),
        1,
    );

    while !window.should_close() {
        glfw.poll_events();
        for (_, event) in glfw::flush_messages(&events) {
            glfw_handle_event(&mut window, event);
        }

        unsafe {
            // render to fb

            gl.clear_named_framebuffer_f32_slice(
                Some(rendered_framebuffer),
                glow::COLOR,
                0,
                &[0.3f32, 0.4, 0.6, 1.0],
            );
            gl.bind_framebuffer(glow::FRAMEBUFFER, Some(rendered_framebuffer));
            gl.viewport(0, 0, vp_width, vp_height);

            // do the drawing
            gl.use_program(Some(triangle_program));
            // select vertices
            gl.bind_vertex_array(Some(triangle_vao));

            // draw to bound target
            gl.draw_arrays(glow::TRIANGLES, 0, 3);

            // unselect vertices
            gl.bind_vertex_array(None);

            // unselect fbo
            gl.bind_framebuffer(glow::FRAMEBUFFER, None);
        }

        let viewport = Viewport {
            x: 0f32,
            y: 0f32,
            output: &output,
            mvp: None,
        };

        let rendered = GLImage {
            handle: Some(rendered_texture),
            format: glow::RGBA8,
            size: Size {
                width: fb_width as u32,
                height: fb_height as u32,
            },
        };

        unsafe {
            filter
                .frame(&rendered, &viewport, framecount, None)
                .unwrap();
        }

        unsafe {
            // texture is done now.
            // draw quad to screen
            gl.use_program(Some(quad_programid));

            gl.bind_texture_unit(0, Some(output_texture));

            gl.bind_vertex_array(Some(quad_vao));
            gl.draw_arrays(glow::TRIANGLE_STRIP, 0, 4);
        }

        framecount += 1;
        window.swap_buffers();
    }
}
fn glfw_handle_event(window: &mut glfw::Window, event: glfw::WindowEvent) {
    use glfw::Action;
    use glfw::Key;
    use glfw::WindowEvent as Event;

    match event {
        Event::Key(Key::Escape, _, Action::Press, _) => {
            window.set_should_close(true);
        }
        Event::Size(width, height) => window.set_size(width, height),
        _ => {}
    }
}