use std::cell::RefCell;
use std::ffi::{c_int, CStr, CString};
use std::hint::unreachable_unchecked;
use std::panic::catch_unwind;
use std::ptr::null_mut;

use crate::init::{initialize, Glfw};
use crate::{get_glfw_error, Error};

#[derive(Debug)]
pub struct Window
{
    _init: Glfw,
    handle: *mut crate::ffi::GLFWwindow,
}

impl Window
{
    /// Makes the context of the window current for the calling thread.
    ///
    /// # Errors
    /// Will return `Err` if a GLFW platform error occurs or if no OpenGL context is
    /// present.
    pub fn make_context_current(&self) -> Result<(), Error>
    {
        unsafe { crate::ffi::glfwMakeContextCurrent(self.handle) };

        get_glfw_error()?;

        Ok(())
    }

    /// Returns the address of the specified OpenGL function, if it is supported by the
    /// current context.
    ///
    /// # Errors
    /// Will return `Err` if a GLFW platform error occurs or if no current context has
    /// been set.
    pub fn get_proc_address(
        &self,
        proc_name: &CStr,
    ) -> Result<unsafe extern "C" fn(), Error>
    {
        let proc_addr = unsafe { crate::ffi::glfwGetProcAddress(proc_name.as_ptr()) };

        get_glfw_error()?;

        // SAFETY: Is only None when a error has occured and that case is handled above
        Ok(unsafe { proc_addr.unwrap_unchecked() })
    }

    /// Processes all pending events.
    ///
    /// # Errors
    /// Will return `Err` if a GLFW platform error occurs.
    pub fn poll_events(&self) -> Result<(), Error>
    {
        // SAFETY: The initialize function (called when the window is created) makes sure
        // the current thread is the main thread
        unsafe { crate::ffi::glfwPollEvents() };

        get_glfw_error()?;

        Ok(())
    }

    /// Swaps the front and back buffers of the window.
    ///
    /// # Errors
    /// Will return `Err` if a GLFW platform error occurs or if no OpenGL window context
    /// is present.
    pub fn swap_buffers(&self) -> Result<(), Error>
    {
        unsafe {
            crate::ffi::glfwSwapBuffers(self.handle);
        };

        get_glfw_error()?;

        Ok(())
    }

    /// Returns whether or not the window should close.
    #[must_use]
    pub fn should_close(&self) -> bool
    {
        let should_close = unsafe { crate::ffi::glfwWindowShouldClose(self.handle) };

        should_close == crate::ffi::GLFW_TRUE
    }

    /// Retrieves the size of the window.
    ///
    /// # Errors
    /// Will return `Err` if a GLFW platform error occurs.
    pub fn size(&self) -> Result<Size, Error>
    {
        let mut width = 0;
        let mut height = 0;

        // SAFETY: The initialize function (called when the window is created) makes sure
        // the current thread is the main thread
        unsafe { crate::ffi::glfwGetWindowSize(self.handle, &mut width, &mut height) };

        get_glfw_error()?;

        #[allow(clippy::cast_sign_loss)]
        Ok(Size {
            width: width as u32,
            height: height as u32,
        })
    }

    pub fn set_framebuffer_size_callback(&self, callback: impl Fn(Size) + 'static)
    {
        FRAMEBUFFER_SIZE_CB.with_borrow_mut(|framebuffer_size_cb| {
            *framebuffer_size_cb = Some(Box::new(callback));
        });

        // SAFETY: The initialize function (called when the window is created) makes sure
        // the current thread is the main thread
        unsafe {
            crate::ffi::glfwSetFramebufferSizeCallback(
                self.handle,
                Some(framebuffer_size_callback),
            );
        }
    }

    /// Returns the last reported state of a keyboard key.
    ///
    /// # Errors
    /// Will return `Err` if a GLFW error occurs.
    pub fn get_key(&self, key: Key) -> Result<KeyState, Error>
    {
        // SAFETY: The initialize function (called when the window is created) makes sure
        // the current thread is the main thread
        let state = unsafe { crate::ffi::glfwGetKey(self.handle, key as i32) };

        get_glfw_error()?;

        Ok(match state {
            crate::ffi::GLFW_PRESS => KeyState::Pressed,
            crate::ffi::GLFW_RELEASE => KeyState::Released,
            _ => {
                // SAFETY: glfwGetKey can only return GLFW_PRESS or GLFW_RELEASE
                unsafe {
                    unreachable_unchecked();
                }
            }
        })
    }
}

/// [`Window`] builder.
#[derive(Debug, Clone, Default)]
pub struct Builder
{
    hints: Vec<(Hint, i32)>,
}

impl Builder
{
    #[must_use]
    pub fn new() -> Self
    {
        Self { hints: Vec::new() }
    }

    /// Adds a window creation hint to set.
    #[must_use]
    pub fn hint(mut self, hint: Hint, value: i32) -> Self
    {
        self.hints.push((hint, value));

        self
    }

    /// Sets the window hints to set.
    pub fn hints(mut self, hints: impl IntoIterator<Item = (Hint, i32)>)
    {
        self.hints = hints.into_iter().collect();
    }

    /// Creates a new window.
    ///
    /// # Errors
    /// Will return `Err` if
    /// - The title contains an internal nul byte
    /// - A GLFW error occurs
    pub fn create(&self, size: &Size, title: &str) -> Result<Window, Error>
    {
        let c_title =
            CString::new(title).map_err(|_| Error::InternalNulByteInWindowTitle)?;

        let init = initialize()?;

        for (hint, value) in &self.hints {
            // SAFETY: The initialize function makes sure the current thread is the main
            // thread
            //
            // Error is not checked for after since the two possible errors
            // (GLFW_NOT_INITIALIZED and GLFW_INVALID_ENUM) cannot occur.
            unsafe {
                crate::ffi::glfwWindowHint(hint.to_glfw(), *value);
            }
        }

        // SAFETY: The initialize function makes sure the current thread is the main
        // thread
        let handle = unsafe {
            #[allow(clippy::cast_possible_wrap)]
            crate::ffi::glfwCreateWindow(
                size.width as i32,
                size.height as i32,
                c_title.as_ptr(),
                null_mut(),
                null_mut(),
            )
        };

        get_glfw_error()?;

        Ok(Window {
            _init: init,
            handle,
        })
    }
}

/// Window creation hint
#[derive(Debug, Clone, Copy)]
pub enum Hint
{
    OpenGLDebugContext,
}

impl Hint
{
    fn to_glfw(self) -> c_int
    {
        match self {
            Self::OpenGLDebugContext => crate::ffi::GLFW_OPENGL_DEBUG_CONTEXT,
        }
    }
}

/// Window size.
#[derive(Debug, Clone, PartialEq, Eq)]
pub struct Size
{
    pub width: u32,
    pub height: u32,
}

#[derive(Debug, Clone, Copy)]
#[repr(i32)]
pub enum Key
{
    // Unknown = crate::ffi::GLFW_KEY_UNKNOWN,
    Space = crate::ffi::GLFW_KEY_SPACE,
    Apostrophe = crate::ffi::GLFW_KEY_APOSTROPHE,
    Comma = crate::ffi::GLFW_KEY_COMMA,
    Minus = crate::ffi::GLFW_KEY_MINUS,
    Period = crate::ffi::GLFW_KEY_PERIOD,
    Slash = crate::ffi::GLFW_KEY_SLASH,
    Digit0 = crate::ffi::GLFW_KEY_0,
    Digit1 = crate::ffi::GLFW_KEY_1,
    Digit2 = crate::ffi::GLFW_KEY_2,
    Digit3 = crate::ffi::GLFW_KEY_3,
    Digit4 = crate::ffi::GLFW_KEY_4,
    Digit5 = crate::ffi::GLFW_KEY_5,
    Digit6 = crate::ffi::GLFW_KEY_6,
    Digit7 = crate::ffi::GLFW_KEY_7,
    Digit8 = crate::ffi::GLFW_KEY_8,
    Digit9 = crate::ffi::GLFW_KEY_9,
    Semicolon = crate::ffi::GLFW_KEY_SEMICOLON,
    Equal = crate::ffi::GLFW_KEY_EQUAL,
    A = crate::ffi::GLFW_KEY_A,
    B = crate::ffi::GLFW_KEY_B,
    C = crate::ffi::GLFW_KEY_C,
    D = crate::ffi::GLFW_KEY_D,
    E = crate::ffi::GLFW_KEY_E,
    F = crate::ffi::GLFW_KEY_F,
    G = crate::ffi::GLFW_KEY_G,
    H = crate::ffi::GLFW_KEY_H,
    I = crate::ffi::GLFW_KEY_I,
    J = crate::ffi::GLFW_KEY_J,
    K = crate::ffi::GLFW_KEY_K,
    L = crate::ffi::GLFW_KEY_L,
    M = crate::ffi::GLFW_KEY_M,
    N = crate::ffi::GLFW_KEY_N,
    O = crate::ffi::GLFW_KEY_O,
    P = crate::ffi::GLFW_KEY_P,
    Q = crate::ffi::GLFW_KEY_Q,
    R = crate::ffi::GLFW_KEY_R,
    S = crate::ffi::GLFW_KEY_S,
    T = crate::ffi::GLFW_KEY_T,
    U = crate::ffi::GLFW_KEY_U,
    V = crate::ffi::GLFW_KEY_V,
    W = crate::ffi::GLFW_KEY_W,
    X = crate::ffi::GLFW_KEY_X,
    Y = crate::ffi::GLFW_KEY_Y,
    Z = crate::ffi::GLFW_KEY_Z,
    LeftBracket = crate::ffi::GLFW_KEY_LEFT_BRACKET,
    Backslash = crate::ffi::GLFW_KEY_BACKSLASH,
    RightBracket = crate::ffi::GLFW_KEY_RIGHT_BRACKET,
    GraveAccent = crate::ffi::GLFW_KEY_GRAVE_ACCENT,
    World1 = crate::ffi::GLFW_KEY_WORLD_1,
    World2 = crate::ffi::GLFW_KEY_WORLD_2,
    Escape = crate::ffi::GLFW_KEY_ESCAPE,
    Enter = crate::ffi::GLFW_KEY_ENTER,
    Tab = crate::ffi::GLFW_KEY_TAB,
    Backspace = crate::ffi::GLFW_KEY_BACKSPACE,
    Insert = crate::ffi::GLFW_KEY_INSERT,
    Delete = crate::ffi::GLFW_KEY_DELETE,
    Right = crate::ffi::GLFW_KEY_RIGHT,
    Left = crate::ffi::GLFW_KEY_LEFT,
    Down = crate::ffi::GLFW_KEY_DOWN,
    Up = crate::ffi::GLFW_KEY_UP,
    PageUp = crate::ffi::GLFW_KEY_PAGE_UP,
    PageDown = crate::ffi::GLFW_KEY_PAGE_DOWN,
    Home = crate::ffi::GLFW_KEY_HOME,
    End = crate::ffi::GLFW_KEY_END,
    CapsLock = crate::ffi::GLFW_KEY_CAPS_LOCK,
    ScrollLock = crate::ffi::GLFW_KEY_SCROLL_LOCK,
    NumLock = crate::ffi::GLFW_KEY_NUM_LOCK,
    PrintScreen = crate::ffi::GLFW_KEY_PRINT_SCREEN,
    Pause = crate::ffi::GLFW_KEY_PAUSE,
    F1 = crate::ffi::GLFW_KEY_F1,
    F2 = crate::ffi::GLFW_KEY_F2,
    F3 = crate::ffi::GLFW_KEY_F3,
    F4 = crate::ffi::GLFW_KEY_F4,
    F5 = crate::ffi::GLFW_KEY_F5,
    F6 = crate::ffi::GLFW_KEY_F6,
    F7 = crate::ffi::GLFW_KEY_F7,
    F8 = crate::ffi::GLFW_KEY_F8,
    F9 = crate::ffi::GLFW_KEY_F9,
    F10 = crate::ffi::GLFW_KEY_F10,
    F11 = crate::ffi::GLFW_KEY_F11,
    F12 = crate::ffi::GLFW_KEY_F12,
    F13 = crate::ffi::GLFW_KEY_F13,
    F14 = crate::ffi::GLFW_KEY_F14,
    F15 = crate::ffi::GLFW_KEY_F15,
    F16 = crate::ffi::GLFW_KEY_F16,
    F17 = crate::ffi::GLFW_KEY_F17,
    F18 = crate::ffi::GLFW_KEY_F18,
    F19 = crate::ffi::GLFW_KEY_F19,
    F20 = crate::ffi::GLFW_KEY_F20,
    F21 = crate::ffi::GLFW_KEY_F21,
    F22 = crate::ffi::GLFW_KEY_F22,
    F23 = crate::ffi::GLFW_KEY_F23,
    F24 = crate::ffi::GLFW_KEY_F24,
    F25 = crate::ffi::GLFW_KEY_F25,
    Kp0 = crate::ffi::GLFW_KEY_KP_0,
    Kp1 = crate::ffi::GLFW_KEY_KP_1,
    Kp2 = crate::ffi::GLFW_KEY_KP_2,
    Kp3 = crate::ffi::GLFW_KEY_KP_3,
    Kp4 = crate::ffi::GLFW_KEY_KP_4,
    Kp5 = crate::ffi::GLFW_KEY_KP_5,
    Kp6 = crate::ffi::GLFW_KEY_KP_6,
    Kp7 = crate::ffi::GLFW_KEY_KP_7,
    Kp8 = crate::ffi::GLFW_KEY_KP_8,
    Kp9 = crate::ffi::GLFW_KEY_KP_9,
    KpDecimal = crate::ffi::GLFW_KEY_KP_DECIMAL,
    KpDivide = crate::ffi::GLFW_KEY_KP_DIVIDE,
    KpMultiply = crate::ffi::GLFW_KEY_KP_MULTIPLY,
    KpSubtract = crate::ffi::GLFW_KEY_KP_SUBTRACT,
    KpAdd = crate::ffi::GLFW_KEY_KP_ADD,
    KpEnter = crate::ffi::GLFW_KEY_KP_ENTER,
    KpEqual = crate::ffi::GLFW_KEY_KP_EQUAL,
    LeftShift = crate::ffi::GLFW_KEY_LEFT_SHIFT,
    LeftControl = crate::ffi::GLFW_KEY_LEFT_CONTROL,
    LeftAlt = crate::ffi::GLFW_KEY_LEFT_ALT,
    LeftSuper = crate::ffi::GLFW_KEY_LEFT_SUPER,
    RightShift = crate::ffi::GLFW_KEY_RIGHT_SHIFT,
    RightControl = crate::ffi::GLFW_KEY_RIGHT_CONTROL,
    RightAlt = crate::ffi::GLFW_KEY_RIGHT_ALT,
    RightSuper = crate::ffi::GLFW_KEY_RIGHT_SUPER,
    Menu = crate::ffi::GLFW_KEY_MENU,
}

#[derive(Debug, Clone, Copy)]
pub enum KeyState
{
    Pressed,
    Released,
}

type FramebufferSizeCb = Box<dyn Fn(Size)>;

thread_local! {
static FRAMEBUFFER_SIZE_CB: RefCell<Option<FramebufferSizeCb>> = RefCell::new(None);
}

extern "C" fn framebuffer_size_callback(
    _window: *mut crate::ffi::GLFWwindow,
    c_width: c_int,
    c_height: c_int,
)
{
    // Width and height can't possibly have their sign bit set
    let width = u32::from_le_bytes(c_width.to_le_bytes());
    let height = u32::from_le_bytes(c_height.to_le_bytes());

    // Unwinds are catched because unwinding from Rust code into foreign code is UB.
    let res = catch_unwind(|| {
        FRAMEBUFFER_SIZE_CB
            .try_with(|framebuffer_size_cb| {
                if let Some(cb) = framebuffer_size_cb.borrow().as_deref() {
                    cb(Size { width, height });
                }
            })
            .ok();
    });

    if res.is_err() {
        println!("ERROR: Panic in framebuffer size callback");
    }
}