use std::borrow::Cow;
use std::ffi::{CStr, CString};

use bitflags::bitflags;
use ecs::actions::Actions;
use ecs::extension::Collector as ExtensionCollector;
use ecs::sole::Single;
use ecs::Sole;
use glfw::window::{Hint as WindowCreationHint, HintValue as WindowCreationHintValue};
use glfw::WindowSize;
use util_macros::VariantArr;

use crate::data_types::dimens::Dimens;
use crate::event::{Conclude as ConcludeEvent, Start as StartEvent};
use crate::vector::Vec2;

#[derive(Debug, Sole)]
/// Has to be dropped last since it holds the OpenGL context.
#[sole(drop_last)]
pub struct Window
{
    inner: glfw::Window,
}

impl Window
{
    /// Returns a new Window builder.
    #[must_use]
    pub fn builder() -> Builder
    {
        Builder::default()
    }

    /// Sets the value of a input mode.
    ///
    /// # Errors
    /// Returns `Err` if the input mode is unsupported on the current system.
    pub fn set_input_mode(
        &self,
        input_mode: InputMode,
        enabled: bool,
    ) -> Result<(), Error>
    {
        Ok(self
            .inner
            .set_input_mode(input_mode.to_glfw_input_mode(), enabled)?)
    }

    /// Sets the cursor mode.
    ///
    /// # Errors
    /// If a platform error occurs.
    pub fn set_cursor_mode(&self, cursor_mode: CursorMode) -> Result<(), Error>
    {
        Ok(self
            .inner
            .set_cursor_mode(cursor_mode.to_glfw_cursor_mode())?)
    }

    /// Returns whether or not the window should close. Will return true when the user has
    /// attempted to close the window.
    #[must_use]
    pub fn should_close(&self) -> bool
    {
        self.inner.should_close()
    }

    /// Processes all pending events.
    ///
    /// # Errors
    /// If a platform error occurs.
    pub fn poll_events(&self) -> Result<(), Error>
    {
        Ok(self.inner.poll_events()?)
    }

    /// Swaps the front and back buffers of the window.
    ///
    /// # Errors
    /// Will return `Err` if a platform error occurs or if no OpenGL window context
    /// is present.
    pub fn swap_buffers(&self) -> Result<(), Error>
    {
        Ok(self.inner.swap_buffers()?)
    }

    /// Returns the size of the window.
    ///
    /// # Errors
    /// Will return `Err` if a platform error occurs.
    pub fn size(&self) -> Result<Dimens<u32>, Error>
    {
        let size = self.inner.size()?;

        Ok(Dimens {
            width: size.width,
            height: size.height,
        })
    }

    /// Returns the address of the specified OpenGL function, if it is supported by the
    /// current OpenGL context.
    ///
    /// # Errors
    /// Will return `Err` if a platform error occurs or if no current context has
    /// been set.
    ///
    /// # Panics
    /// Will panic if the `proc_name` argument contains a nul byte.
    pub fn get_proc_address(
        &self,
        proc_name: &str,
    ) -> Result<unsafe extern "C" fn(), Error>
    {
        let proc_name_c: Cow<CStr> = CStr::from_bytes_with_nul(proc_name.as_bytes())
            .map(Cow::Borrowed)
            .or_else(|_| CString::new(proc_name).map(Cow::Owned))
            .expect("OpenGL function name contains a nul byte");

        Ok(self.inner.get_proc_address(&proc_name_c)?)
    }

    /// Makes the OpenGL context of the window current for the calling thread.
    ///
    /// # Errors
    /// Will return `Err` if a platform error occurs or if no OpenGL context is
    /// present.
    pub fn make_context_current(&self) -> Result<(), Error>
    {
        Ok(self.inner.make_context_current()?)
    }

    /// Sets the window's framebuffer size callback.
    pub fn set_framebuffer_size_callback(&self, callback: impl Fn(Dimens<u32>) + 'static)
    {
        self.inner.set_framebuffer_size_callback(move |size| {
            callback(Dimens {
                width: size.width,
                height: size.height,
            });
        });
    }

    /// Sets the window's key size callback.
    pub fn set_key_callback(
        &self,
        callback: impl Fn(Key, i32, KeyState, KeyModifiers) + 'static,
    )
    {
        self.inner
            .set_key_callback(move |key, scancode, key_state, key_modifiers| {
                let Some(key_state) = KeyState::from_glfw_key_state(key_state) else {
                    return;
                };

                callback(
                    Key::from_glfw_key(key),
                    scancode,
                    key_state,
                    KeyModifiers::from_bits_truncate(key_modifiers.bits()),
                )
            });
    }

    /// Sets the window's cursor position callback.
    pub fn set_cursor_pos_callback(&self, callback: impl Fn(Vec2<f64>) + 'static)
    {
        self.inner
            .set_cursor_pos_callback(move |pos| callback(Vec2 { x: pos.x, y: pos.y }));
    }

    /// Sets the window's mouse button callback. The given function is called when a mouse
    /// button enters a new state.
    pub fn set_mouse_button_callback(
        &self,
        callback: impl Fn(MouseButton, MouseButtonState, KeyModifiers) + 'static,
    )
    {
        self.inner.set_mouse_button_callback(
            move |mouse_button, mouse_button_state, key_modifiers| {
                callback(
                    MouseButton::from_glfw_mouse_button(mouse_button),
                    MouseButtonState::from_glfw_mouse_button_state(mouse_button_state),
                    KeyModifiers::from_bits_truncate(key_modifiers.bits()),
                )
            },
        );
    }

    /// Sets the window's close callback.
    pub fn set_close_callback(&self, callback: impl Fn() + 'static)
    {
        self.inner.set_close_callback(callback);
    }

    /// Sets the window's focus callback. The callback is called when the window loses or
    /// gains input focus.
    pub fn set_focus_callback(&self, callback: impl Fn(bool) + 'static)
    {
        self.inner.set_focus_callback(callback);
    }
}

/// [`Window`] builder.
#[derive(Debug, Clone, Default)]
pub struct Builder
{
    inner: glfw::WindowBuilder,
}

impl Builder
{
    /// Sets whether the OpenGL context should be created in debug mode, which may
    /// provide additional error and diagnostic reporting functionality.
    pub fn opengl_debug_context(mut self, enabled: bool) -> Self
    {
        self.inner = self.inner.hint(
            WindowCreationHint::OpenGLDebugContext,
            WindowCreationHintValue::Bool(enabled),
        );

        self
    }

    /// Set the desired number of samples to use for multisampling. Zero disables
    /// multisampling.
    pub fn multisampling_sample_count(mut self, sample_count: u16) -> Self
    {
        self.inner = self.inner.hint(
            WindowCreationHint::Samples,
            WindowCreationHintValue::Number(sample_count as i32),
        );

        self
    }

    /// Creates a new window.
    ///
    /// # Errors
    /// Will return `Err` if the title contains a internal nul byte or if a platform error
    /// occurs.
    pub fn create(&self, size: Dimens<u32>, title: &str) -> Result<Window, Error>
    {
        let builder = self.inner.clone().hint(
            WindowCreationHint::OpenGLDebugContext,
            WindowCreationHintValue::Bool(true),
        );

        let window = builder.create(
            &WindowSize {
                width: size.width,
                height: size.height,
            },
            title,
        )?;

        Ok(Window { inner: window })
    }
}

#[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, VariantArr)]
#[variant_arr(name = KEYS)]
pub enum Key
{
    Space,
    Apostrophe,
    Comma,
    Minus,
    Period,
    Slash,
    Digit0,
    Digit1,
    Digit2,
    Digit3,
    Digit4,
    Digit5,
    Digit6,
    Digit7,
    Digit8,
    Digit9,
    Semicolon,
    Equal,
    A,
    B,
    C,
    D,
    E,
    F,
    G,
    H,
    I,
    J,
    K,
    L,
    M,
    N,
    O,
    P,
    Q,
    R,
    S,
    T,
    U,
    V,
    W,
    X,
    Y,
    Z,
    LeftBracket,
    Backslash,
    RightBracket,
    GraveAccent,
    World1,
    World2,
    Escape,
    Enter,
    Tab,
    Backspace,
    Insert,
    Delete,
    Right,
    Left,
    Down,
    Up,
    PageUp,
    PageDown,
    Home,
    End,
    CapsLock,
    ScrollLock,
    NumLock,
    PrintScreen,
    Pause,
    F1,
    F2,
    F3,
    F4,
    F5,
    F6,
    F7,
    F8,
    F9,
    F10,
    F11,
    F12,
    F13,
    F14,
    F15,
    F16,
    F17,
    F18,
    F19,
    F20,
    F21,
    F22,
    F23,
    F24,
    F25,
    Kp0,
    Kp1,
    Kp2,
    Kp3,
    Kp4,
    Kp5,
    Kp6,
    Kp7,
    Kp8,
    Kp9,
    KpDecimal,
    KpDivide,
    KpMultiply,
    KpSubtract,
    KpAdd,
    KpEnter,
    KpEqual,
    LeftShift,
    LeftControl,
    LeftAlt,
    LeftSuper,
    RightShift,
    RightControl,
    RightAlt,
    RightSuper,
    Menu,
}

impl Key
{
    fn from_glfw_key(glfw_key: glfw::window::Key) -> Self
    {
        match glfw_key {
            glfw::window::Key::Space => Self::Space,
            glfw::window::Key::Apostrophe => Self::Apostrophe,
            glfw::window::Key::Comma => Self::Comma,
            glfw::window::Key::Minus => Self::Minus,
            glfw::window::Key::Period => Self::Period,
            glfw::window::Key::Slash => Self::Slash,
            glfw::window::Key::Digit0 => Self::Digit0,
            glfw::window::Key::Digit1 => Self::Digit1,
            glfw::window::Key::Digit2 => Self::Digit2,
            glfw::window::Key::Digit3 => Self::Digit3,
            glfw::window::Key::Digit4 => Self::Digit4,
            glfw::window::Key::Digit5 => Self::Digit5,
            glfw::window::Key::Digit6 => Self::Digit6,
            glfw::window::Key::Digit7 => Self::Digit7,
            glfw::window::Key::Digit8 => Self::Digit8,
            glfw::window::Key::Digit9 => Self::Digit9,
            glfw::window::Key::Semicolon => Self::Semicolon,
            glfw::window::Key::Equal => Self::Equal,
            glfw::window::Key::A => Self::A,
            glfw::window::Key::B => Self::B,
            glfw::window::Key::C => Self::C,
            glfw::window::Key::D => Self::D,
            glfw::window::Key::E => Self::E,
            glfw::window::Key::F => Self::F,
            glfw::window::Key::G => Self::G,
            glfw::window::Key::H => Self::H,
            glfw::window::Key::I => Self::I,
            glfw::window::Key::J => Self::J,
            glfw::window::Key::K => Self::K,
            glfw::window::Key::L => Self::L,
            glfw::window::Key::M => Self::M,
            glfw::window::Key::N => Self::N,
            glfw::window::Key::O => Self::O,
            glfw::window::Key::P => Self::P,
            glfw::window::Key::Q => Self::Q,
            glfw::window::Key::R => Self::R,
            glfw::window::Key::S => Self::S,
            glfw::window::Key::T => Self::T,
            glfw::window::Key::U => Self::U,
            glfw::window::Key::V => Self::V,
            glfw::window::Key::W => Self::W,
            glfw::window::Key::X => Self::X,
            glfw::window::Key::Y => Self::Y,
            glfw::window::Key::Z => Self::Z,
            glfw::window::Key::LeftBracket => Self::LeftBracket,
            glfw::window::Key::Backslash => Self::Backslash,
            glfw::window::Key::RightBracket => Self::RightBracket,
            glfw::window::Key::GraveAccent => Self::GraveAccent,
            glfw::window::Key::World1 => Self::World1,
            glfw::window::Key::World2 => Self::World2,
            glfw::window::Key::Escape => Self::Escape,
            glfw::window::Key::Enter => Self::Enter,
            glfw::window::Key::Tab => Self::Tab,
            glfw::window::Key::Backspace => Self::Backspace,
            glfw::window::Key::Insert => Self::Insert,
            glfw::window::Key::Delete => Self::Delete,
            glfw::window::Key::Right => Self::Right,
            glfw::window::Key::Left => Self::Left,
            glfw::window::Key::Down => Self::Down,
            glfw::window::Key::Up => Self::Up,
            glfw::window::Key::PageUp => Self::PageUp,
            glfw::window::Key::PageDown => Self::PageDown,
            glfw::window::Key::Home => Self::Home,
            glfw::window::Key::End => Self::End,
            glfw::window::Key::CapsLock => Self::CapsLock,
            glfw::window::Key::ScrollLock => Self::ScrollLock,
            glfw::window::Key::NumLock => Self::NumLock,
            glfw::window::Key::PrintScreen => Self::PrintScreen,
            glfw::window::Key::Pause => Self::Pause,
            glfw::window::Key::F1 => Self::F1,
            glfw::window::Key::F2 => Self::F2,
            glfw::window::Key::F3 => Self::F3,
            glfw::window::Key::F4 => Self::F4,
            glfw::window::Key::F5 => Self::F5,
            glfw::window::Key::F6 => Self::F6,
            glfw::window::Key::F7 => Self::F7,
            glfw::window::Key::F8 => Self::F8,
            glfw::window::Key::F9 => Self::F9,
            glfw::window::Key::F10 => Self::F10,
            glfw::window::Key::F11 => Self::F11,
            glfw::window::Key::F12 => Self::F12,
            glfw::window::Key::F13 => Self::F13,
            glfw::window::Key::F14 => Self::F14,
            glfw::window::Key::F15 => Self::F15,
            glfw::window::Key::F16 => Self::F16,
            glfw::window::Key::F17 => Self::F17,
            glfw::window::Key::F18 => Self::F18,
            glfw::window::Key::F19 => Self::F19,
            glfw::window::Key::F20 => Self::F20,
            glfw::window::Key::F21 => Self::F21,
            glfw::window::Key::F22 => Self::F22,
            glfw::window::Key::F23 => Self::F23,
            glfw::window::Key::F24 => Self::F24,
            glfw::window::Key::F25 => Self::F25,
            glfw::window::Key::Kp0 => Self::Kp0,
            glfw::window::Key::Kp1 => Self::Kp1,
            glfw::window::Key::Kp2 => Self::Kp2,
            glfw::window::Key::Kp3 => Self::Kp3,
            glfw::window::Key::Kp4 => Self::Kp4,
            glfw::window::Key::Kp5 => Self::Kp5,
            glfw::window::Key::Kp6 => Self::Kp6,
            glfw::window::Key::Kp7 => Self::Kp7,
            glfw::window::Key::Kp8 => Self::Kp8,
            glfw::window::Key::Kp9 => Self::Kp9,
            glfw::window::Key::KpDecimal => Self::KpDecimal,
            glfw::window::Key::KpDivide => Self::KpDivide,
            glfw::window::Key::KpMultiply => Self::KpMultiply,
            glfw::window::Key::KpSubtract => Self::KpSubtract,
            glfw::window::Key::KpAdd => Self::KpAdd,
            glfw::window::Key::KpEnter => Self::KpEnter,
            glfw::window::Key::KpEqual => Self::KpEqual,
            glfw::window::Key::LeftShift => Self::LeftShift,
            glfw::window::Key::LeftControl => Self::LeftControl,
            glfw::window::Key::LeftAlt => Self::LeftAlt,
            glfw::window::Key::LeftSuper => Self::LeftSuper,
            glfw::window::Key::RightShift => Self::RightShift,
            glfw::window::Key::RightControl => Self::RightControl,
            glfw::window::Key::RightAlt => Self::RightAlt,
            glfw::window::Key::RightSuper => Self::RightSuper,
            glfw::window::Key::Menu => Self::Menu,
        }
    }
}

#[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)]
pub enum KeyState
{
    Pressed,
    Released,
}

impl KeyState
{
    fn from_glfw_key_state(glfw_key_state: glfw::window::KeyState) -> Option<Self>
    {
        match glfw_key_state {
            glfw::window::KeyState::Pressed => Some(Self::Pressed),
            glfw::window::KeyState::Released => Some(Self::Released),
            glfw::window::KeyState::Repeat => None,
        }
    }
}

#[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)]
pub enum MouseButton
{
    One,
    Two,
    Three,
    Four,
    Five,
    Six,
    Seven,
    Eight,
}

impl MouseButton
{
    pub const LEFT: Self = Self::One;
    pub const MIDDLE: Self = Self::Three;
    pub const RIGHT: Self = Self::Two;

    fn from_glfw_mouse_button(mouse_button: glfw::window::MouseButton) -> Self
    {
        match mouse_button {
            glfw::window::MouseButton::One => Self::One,
            glfw::window::MouseButton::Two => Self::Two,
            glfw::window::MouseButton::Three => Self::Three,
            glfw::window::MouseButton::Four => Self::Four,
            glfw::window::MouseButton::Five => Self::Five,
            glfw::window::MouseButton::Six => Self::Six,
            glfw::window::MouseButton::Seven => Self::Seven,
            glfw::window::MouseButton::Eight => Self::Eight,
        }
    }
}

#[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)]
pub enum MouseButtonState
{
    Pressed,
    Released,
}

impl MouseButtonState
{
    fn from_glfw_mouse_button_state(
        mouse_button_state: glfw::window::MouseButtonState,
    ) -> Self
    {
        match mouse_button_state {
            glfw::window::MouseButtonState::Pressed => Self::Pressed,
            glfw::window::MouseButtonState::Released => Self::Released,
        }
    }
}

bitflags! {
    #[derive(Debug, Clone, Copy)]
    pub struct KeyModifiers: i32 {
        const SHIFT = glfw::window::KeyModifiers::SHIFT.bits();
        const CONTROL = glfw::window::KeyModifiers::CONTROL.bits();
        const ALT = glfw::window::KeyModifiers::ALT.bits();
        const SUPER = glfw::window::KeyModifiers::SUPER.bits();
        const CAPS_LOCK = glfw::window::KeyModifiers::CAPS_LOCK.bits();
        const NUM_LOCK = glfw::window::KeyModifiers::NUM_LOCK.bits();
    }
}

#[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)]
pub enum CursorMode
{
    /// Hides and grabs the cursor, providing virtual and unlimited cursor movement.
    Disabled,

    /// Makes the cursor invisible when it is over the content area of the window but
    /// does not restrict the cursor from leaving.
    Hidden,

    /// Makes the cursor visible and behaving normally.
    Normal,
}

impl CursorMode
{
    fn to_glfw_cursor_mode(self) -> glfw::window::CursorMode
    {
        match self {
            Self::Disabled => glfw::window::CursorMode::Disabled,
            Self::Hidden => glfw::window::CursorMode::Hidden,
            Self::Normal => glfw::window::CursorMode::Normal,
        }
    }
}

#[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)]
pub enum InputMode
{
    /// When the cursor is disabled, raw (unscaled and unaccelerated) mouse motion can be
    /// enabled if available.
    ///
    /// Raw mouse motion is closer to the actual motion of the mouse across a surface. It
    /// is not affected by the scaling and acceleration applied to the motion of the
    /// desktop cursor. That processing is suitable for a cursor while raw motion is
    /// better for controlling for example a 3D camera. Because of this, raw mouse motion
    /// is only provided when the cursor is disabled.
    RawMouseMotion,
}

impl InputMode
{
    fn to_glfw_input_mode(self) -> glfw::window::InputMode
    {
        match self {
            Self::RawMouseMotion => glfw::window::InputMode::RawMouseMotion,
        }
    }
}

#[derive(Debug)]
pub struct Extension
{
    window_builder: Builder,
    window_size: Dimens<u32>,
    window_title: String,
}

impl Extension
{
    #[must_use]
    pub fn new(window_builder: Builder) -> Self
    {
        Self { window_builder, ..Default::default() }
    }

    #[must_use]
    pub fn window_size(mut self, window_size: Dimens<u32>) -> Self
    {
        self.window_size = window_size;

        self
    }

    #[must_use]
    pub fn window_title(mut self, window_title: impl Into<String>) -> Self
    {
        self.window_title = window_title.into();

        self
    }
}

impl ecs::extension::Extension for Extension
{
    fn collect(self, mut collector: ExtensionCollector<'_>)
    {
        collector.add_system(StartEvent, initialize);
        collector.add_system(ConcludeEvent, update);

        let window = self
            .window_builder
            .create(self.window_size, &self.window_title)
            .unwrap();

        window.set_cursor_mode(CursorMode::Normal).unwrap();

        collector.add_sole(window).ok();
    }
}

impl Default for Extension
{
    fn default() -> Self
    {
        Self {
            window_builder: Builder::default(),
            window_size: Dimens { width: 1920, height: 1080 },
            window_title: String::new(),
        }
    }
}

#[derive(Debug, thiserror::Error)]
#[error(transparent)]
pub struct Error(glfw::Error);

impl From<glfw::Error> for Error
{
    fn from(err: glfw::Error) -> Self
    {
        Self(err)
    }
}

fn initialize(window: Single<Window>, actions: Actions)
{
    let actions_weak_ref = actions.to_weak_ref();

    window.set_close_callback(move || {
        let actions_weak_ref = actions_weak_ref.clone();

        let actions_ref = actions_weak_ref.access().expect("No world");

        actions_ref.to_actions().stop();
    });
}

fn update(window: Single<Window>)
{
    window
        .swap_buffers()
        .expect("Failed to swap window buffers");

    window.poll_events().expect("Failed to poll window events");
}