use std::{
    ptr::{null, null_mut},
    str::from_utf8,
};

use glfw::{Action, Context, Key};
use learn_gl::render_timer::RenderTimer;
fn main() {
    let default_width = 500;
    let default_height = 500;

    let mut glfw = glfw::init(glfw::fail_on_errors).expect("msg");
    let (mut window, events) = glfw
        .create_window(
            default_width,
            default_height,
            "learn_gl",
            glfw::WindowMode::Windowed,
        )
        .expect("msg");

    window.set_key_polling(true);
    window.make_current();

    gl::load_with(|s| glfw.get_proc_address_raw(s).unwrap() as *const _);
    // gl::load_with(|s| window.get_proc_address(s).unwrap() as *const _);

    unsafe { gl::Viewport(0, 0, default_width as _, default_height as _) };
    window.set_framebuffer_size_callback(|_windows, width, height| {
        unsafe { gl::Viewport(0, 0, width as _, height as _) };
    });

    let mut render_timer = RenderTimer::new();

    // 编译着色器
    let vs_src = std::ffi::CString::new(include_str!(".\\shaders\\vs.vert")).unwrap_or_default();
    println!("Vs Shader:\n{}", vs_src.to_str().unwrap_or_default());
    let vs_ptr = vs_src.as_ptr() as *const i8;
    let vs = unsafe { gl::CreateShader(gl::VERTEX_SHADER) };
    unsafe { gl::ShaderSource(vs, 1, &vs_ptr as _, null()) };
    unsafe { gl::CompileShader(vs) };
    let mut success = 0;
    unsafe { gl::GetShaderiv(vs, gl::COMPILE_STATUS, &mut success) };
    if success == 0 {
        let mut log = [0; 512];
        unsafe { gl::GetShaderInfoLog(vs, 512, core::ptr::null_mut(), log.as_mut_ptr()) };
        let log_u8: [u8; 512] = unsafe { std::mem::transmute(log) };
        println!("{}", from_utf8(&log_u8).unwrap());
    }

    let fs_src = std::ffi::CString::new(include_str!(".\\shaders\\fs.frag")).unwrap_or_default();
    println!("Fs Shader:\n{}", fs_src.to_str().unwrap_or_default());
    let fs_ptr = fs_src.as_ptr() as *const i8;
    let fs = unsafe { gl::CreateShader(gl::FRAGMENT_SHADER) };
    unsafe { gl::ShaderSource(fs, 1, &fs_ptr as _, null()) };
    unsafe { gl::CompileShader(fs) };
    let mut success = 0;
    unsafe { gl::GetShaderiv(fs, gl::COMPILE_STATUS, &mut success) };
    if success == 0 {
        let mut log = [0; 512];
        unsafe { gl::GetShaderInfoLog(fs, 512, core::ptr::null_mut(), log.as_mut_ptr()) };
        let log_u8: [u8; 512] = unsafe { std::mem::transmute(log) };
        println!("{}", from_utf8(&log_u8).unwrap());
    }

    // 链接着色器
    let sp = unsafe { gl::CreateProgram() };
    unsafe { gl::AttachShader(sp, vs) };
    unsafe { gl::AttachShader(sp, fs) };
    unsafe { gl::LinkProgram(sp) };
    let mut success = 0;
    unsafe { gl::GetProgramiv(sp, gl::LINK_STATUS, &mut success) };
    if success == 0 {
        let mut log = [0; 512];
        unsafe { gl::GetProgramInfoLog(sp, 512, null_mut(), log.as_mut_ptr()) };
        let log_u8: [u8; 512] = unsafe { std::mem::transmute(log) };
        println!("{}", from_utf8(&log_u8).unwrap());
    }

    // 使用程序和删除着色器
    unsafe { gl::UseProgram(sp) };
    unsafe { gl::DeleteShader(vs) };
    unsafe { gl::DeleteShader(fs) };

    // 创建VAO
    let mut vao = 0;
    unsafe { gl::GenVertexArrays(1, &mut vao) };
    unsafe { gl::BindVertexArray(vao) };

    // 创建VBO
    let a: [f32; _] = [-0.5, -0.5, 0.0, 0.5, -0.5, 0.0, 0.0, 0.5, 0.0];
    let mut vbo: u32 = 0;
    unsafe { gl::GenBuffers(1, &mut vbo) };
    unsafe { gl::BindBuffer(gl::ARRAY_BUFFER, vbo) };
    unsafe {
        gl::BufferData(
            gl::ARRAY_BUFFER,
            size_of_val(&a) as _,
            a.as_ptr() as _,
            gl::STATIC_DRAW,
        )
    };

    // 链接顶点属性
    unsafe {
        gl::VertexAttribPointer(
            0,
            3,
            gl::FLOAT,
            gl::FALSE,
            (3 * size_of::<f32>()) as _,
            0 as _,
        )
    };
    unsafe { gl::EnableVertexAttribArray(0) };

    // 渲染循环
    while !window.should_close() {
        glfw.poll_events();
        for (_, event) in glfw::flush_messages(&events) {
            handle_window_event(&mut window, event);
        }

        render(&mut render_timer, sp ,vao);

        window.swap_buffers();
    }
}

fn handle_window_event(window: &mut glfw::Window, event: glfw::WindowEvent) {
    match event {
        glfw::WindowEvent::Key(Key::Escape, _, Action::Press, _) => window.set_should_close(true),
        _ => {}
    }
}

fn render(render_timer: &mut RenderTimer, sp: u32, vao: u32) {
    let t = render_timer.time_count() as f32 / 1000.0 as f32;
    unsafe { gl::ClearColor(t.sin() * 0.5 + 1.0, t.cos() * 0.5 + 1.0, 0.3, 1.0) };
    unsafe { gl::Clear(gl::COLOR_BUFFER_BIT) };

    unsafe { gl::UseProgram(sp) };
    unsafe { gl::BindVertexArray(vao) };
    unsafe { gl::DrawArrays(gl::TRIANGLES, 0, 3) };
}