event.rs

//! # Event
//!
//! The `event` module provides the functionality to read keyboard, mouse and terminal resize events.
//!
//! * The [`read`](fn.read.html) function returns an [`Event`](enum.Event.html) immediately
//! (if available) or blocks until an [`Event`](enum.Event.html) is available.
//!
//! * The [`poll`](fn.poll.html) function allows you to check if there is or isn't an [`Event`](enum.Event.html) available
//! within the given period of time. In other words - if subsequent call to the [`read`](fn.read.html)
//! function will block or not.
//!
//! It's **not allowed** to call these functions from different threads or combine them with the
//! [`EventStream`](struct.EventStream.html). You're allowed to either:
//!
//! * use the [`read`](fn.read.html) & [`poll`](fn.poll.html) functions on any, but same, thread
//! * or the [`EventStream`](struct.EventStream.html).
//!
//! **Make sure to enable [raw mode](../terminal/index.html#raw-mode) in order for keyboard events to work properly**
//!
//! ## Mouse Events
//!
//! Mouse events are not enabled by default. You have to enable them with the
//! [`EnableMouseCapture`](struct.EnableMouseCapture.html) command. See [Command API](../index.html#command-api)
//! for more information.
//!
//! ## Examples
//!
//! Blocking read:
//!
//! ```no_run
//! use crossterm::event::{read, Event};
//!
//! fn print_events() -> crossterm::Result<()> {
//!     loop {
//!         // `read()` blocks until an `Event` is available
//!         match read()? {
//!             Event::FocusGained => println!("FocusGained"),
//!             Event::FocusLost => println!("FocusLost"),
//!             Event::Key(event) => println!("{:?}", event),
//!             Event::Mouse(event) => println!("{:?}", event),
//!             Event::Resize(width, height) => println!("New size {}x{}", width, height),
//!         }
//!     }
//!     Ok(())
//! }
//! ```
//!
//! Non-blocking read:
//!
//! ```no_run
//! use std::time::Duration;
//!
//! use crossterm::event::{poll, read, Event};
//!
//! fn print_events() -> crossterm::Result<()> {
//!     loop {
//!         // `poll()` waits for an `Event` for a given time period
//!         if poll(Duration::from_millis(500))? {
//!             // It's guaranteed that the `read()` won't block when the `poll()`
//!             // function returns `true`
//!             match read()? {
//!                 Event::FocusGained => println!("FocusGained"),
//!                 Event::FocusLost => println!("FocusLost"),
//!                 Event::Key(event) => println!("{:?}", event),
//!                 Event::Mouse(event) => println!("{:?}", event),
//!                 Event::Resize(width, height) => println!("New size {}x{}", width, height),
//!             }
//!         } else {
//!             // Timeout expired and no `Event` is available
//!         }
//!     }
//!     Ok(())
//! }
//! ```
//!
//! Check the [examples](https://github.com/crossterm-rs/crossterm/tree/master/examples) folder for more of
//! them (`event-*`).

use std::fmt;
use std::hash::{Hash, Hasher};
#[cfg(windows)]
use std::io;
use std::time::Duration;

use bitflags::bitflags;
use parking_lot::{MappedMutexGuard, Mutex, MutexGuard};
#[cfg(feature = "serde")]
use serde::{Deserialize, Serialize};

use crate::{csi, Command, Result};
use filter::{EventFilter, Filter};
use read::InternalEventReader;
#[cfg(feature = "event-stream")]
pub use stream::EventStream;
use timeout::PollTimeout;

pub(crate) mod filter;
mod read;
mod source;
#[cfg(feature = "event-stream")]
mod stream;
pub(crate) mod sys;
mod timeout;

/// Static instance of `InternalEventReader`.
/// This needs to be static because there can be one event reader.
static INTERNAL_EVENT_READER: Mutex<Option<InternalEventReader>> = parking_lot::const_mutex(None);

fn lock_internal_event_reader() -> MappedMutexGuard<'static, InternalEventReader> {
    MutexGuard::map(INTERNAL_EVENT_READER.lock(), |reader| {
        reader.get_or_insert_with(InternalEventReader::default)
    })
}
fn try_lock_internal_event_reader_for(
    duration: Duration,
) -> Option<MappedMutexGuard<'static, InternalEventReader>> {
    Some(MutexGuard::map(
        INTERNAL_EVENT_READER.try_lock_for(duration)?,
        |reader| reader.get_or_insert_with(InternalEventReader::default),
    ))
}

/// Checks if there is an [`Event`](enum.Event.html) available.
///
/// Returns `Ok(true)` if an [`Event`](enum.Event.html) is available otherwise it returns `Ok(false)`.
///
/// `Ok(true)` guarantees that subsequent call to the [`read`](fn.read.html) function
/// won't block.
///
/// # Arguments
///
/// * `timeout` - maximum waiting time for event availability
///
/// # Examples
///
/// Return immediately:
///
/// ```no_run
/// use std::time::Duration;
///
/// use crossterm::{event::poll, Result};
///
/// fn is_event_available() -> Result<bool> {
///     // Zero duration says that the `poll` function must return immediately
///     // with an `Event` availability information
///     poll(Duration::from_secs(0))
/// }
/// ```
///
/// Wait up to 100ms:
///
/// ```no_run
/// use std::time::Duration;
///
/// use crossterm::{event::poll, Result};
///
/// fn is_event_available() -> Result<bool> {
///     // Wait for an `Event` availability for 100ms. It returns immediately
///     // if an `Event` is/becomes available.
///     poll(Duration::from_millis(100))
/// }
/// ```
pub fn poll(timeout: Duration) -> Result<bool> {
    poll_internal(Some(timeout), &EventFilter)
}

/// Reads a single [`Event`](enum.Event.html).
///
/// This function blocks until an [`Event`](enum.Event.html) is available. Combine it with the
/// [`poll`](fn.poll.html) function to get non-blocking reads.
///
/// # Examples
///
/// Blocking read:
///
/// ```no_run
/// use crossterm::{event::read, Result};
///
/// fn print_events() -> Result<bool> {
///     loop {
///         // Blocks until an `Event` is available
///         println!("{:?}", read()?);
///     }
/// }
/// ```
///
/// Non-blocking read:
///
/// ```no_run
/// use std::time::Duration;
///
/// use crossterm::{event::{read, poll}, Result};
///
/// fn print_events() -> Result<bool> {
///     loop {
///         if poll(Duration::from_millis(100))? {
///             // It's guaranteed that `read` won't block, because `poll` returned
///             // `Ok(true)`.
///             println!("{:?}", read()?);
///         } else {
///             // Timeout expired, no `Event` is available
///         }
///     }
/// }
/// ```
pub fn read() -> Result<Event> {
    match read_internal(&EventFilter)? {
        InternalEvent::Event(event) => Ok(event),
        #[cfg(unix)]
        _ => unreachable!(),
    }
}

/// Polls to check if there are any `InternalEvent`s that can be read within the given duration.
pub(crate) fn poll_internal<F>(timeout: Option<Duration>, filter: &F) -> Result<bool>
where
    F: Filter,
{
    let (mut reader, timeout) = if let Some(timeout) = timeout {
        let poll_timeout = PollTimeout::new(Some(timeout));
        if let Some(reader) = try_lock_internal_event_reader_for(timeout) {
            (reader, poll_timeout.leftover())
        } else {
            return Ok(false);
        }
    } else {
        (lock_internal_event_reader(), None)
    };
    reader.poll(timeout, filter)
}

/// Reads a single `InternalEvent`.
pub(crate) fn read_internal<F>(filter: &F) -> Result<InternalEvent>
where
    F: Filter,
{
    let mut reader = lock_internal_event_reader();
    reader.read(filter)
}

/// A command that enables mouse event capturing.
///
/// Mouse events can be captured with [read](./fn.read.html)/[poll](./fn.poll.html).
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub struct EnableMouseCapture;

impl Command for EnableMouseCapture {
    fn write_ansi(&self, f: &mut impl fmt::Write) -> fmt::Result {
        f.write_str(concat!(
            // Normal tracking: Send mouse X & Y on button press and release
            csi!("?1000h"),
            // Button-event tracking: Report button motion events (dragging)
            csi!("?1002h"),
            // Any-event tracking: Report all motion events
            csi!("?1003h"),
            // RXVT mouse mode: Allows mouse coordinates of >223
            csi!("?1015h"),
            // SGR mouse mode: Allows mouse coordinates of >223, preferred over RXVT mode
            csi!("?1006h"),
        ))
    }

    #[cfg(windows)]
    fn execute_winapi(&self) -> Result<()> {
        sys::windows::enable_mouse_capture()
    }

    #[cfg(windows)]
    fn is_ansi_code_supported(&self) -> bool {
        false
    }
}

/// A command that disables mouse event capturing.
///
/// Mouse events can be captured with [read](./fn.read.html)/[poll](./fn.poll.html).
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub struct DisableMouseCapture;

impl Command for DisableMouseCapture {
    fn write_ansi(&self, f: &mut impl fmt::Write) -> fmt::Result {
        f.write_str(concat!(
            // The inverse commands of EnableMouseCapture, in reverse order.
            csi!("?1006l"),
            csi!("?1015l"),
            csi!("?1003l"),
            csi!("?1002l"),
            csi!("?1000l"),
        ))
    }

    #[cfg(windows)]
    fn execute_winapi(&self) -> Result<()> {
        sys::windows::disable_mouse_capture()
    }

    #[cfg(windows)]
    fn is_ansi_code_supported(&self) -> bool {
        false
    }
}

bitflags! {
    /// Represents special flags that tell compatible terminals to add extra information to keyboard events.
    ///
    /// See <https://sw.kovidgoyal.net/kitty/keyboard-protocol/#progressive-enhancement> for more information.
    ///
    /// Alternate keys and Unicode codepoints are not yet supported by crossterm.
    #[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
    pub struct KeyboardEnhancementFlags: u8 {
        /// Represent Escape and modified keys using CSI-u sequences, so they can be unambiguously
        /// read.
        const DISAMBIGUATE_ESCAPE_CODES = 0b0000_0001;
        /// Add extra events with [`KeyEvent.kind`] set to [`KeyEventKind::Repeat`] or
        /// [`KeyEventKind::Release`] when keys are autorepeated or released.
        const REPORT_EVENT_TYPES = 0b0000_0010;
        // Send [alternate keycodes](https://sw.kovidgoyal.net/kitty/keyboard-protocol/#key-codes)
        // in addition to the base keycode.
        //
        // *Note*: these are not yet supported by crossterm.
        // const REPORT_ALTERNATE_KEYS = 0b0000_0100;
        /// Represent all keyboard events as CSI-u sequences. This is required to get repeat/release
        /// events for plain-text keys.
        const REPORT_ALL_KEYS_AS_ESCAPE_CODES = 0b0000_1000;
        // Send the Unicode codepoint as well as the keycode.
        //
        // *Note*: this is not yet supported by crossterm.
        // const REPORT_ASSOCIATED_TEXT = 0b0001_0000;
    }
}

/// A command that enables the [kitty keyboard protocol](https://sw.kovidgoyal.net/kitty/keyboard-protocol/), which adds extra information to keyboard events and removes ambiguity for modifier keys.
///
/// It should be paired with [`PopKeyboardEnhancementFlags`] at the end of execution.
///
/// Example usage:
/// ```no_run
/// use std::io::{Write, stdout};
/// use crossterm::execute;
/// use crossterm::event::{
///     KeyboardEnhancementFlags,
///     PushKeyboardEnhancementFlags,
///     PopKeyboardEnhancementFlags
/// };
///
/// let mut stdout = stdout();
///
/// execute!(
///     stdout,
///     PushKeyboardEnhancementFlags(
///         KeyboardEnhancementFlags::DISAMBIGUATE_ESCAPE_CODES
///     )
/// );
///
/// // ...
///
/// execute!(stdout, PopKeyboardEnhancementFlags);
/// ```
///
/// Note that, currently, only the following support this protocol:
/// * [kitty terminal](https://sw.kovidgoyal.net/kitty/)
/// * [foot terminal](https://codeberg.org/dnkl/foot/issues/319)
/// * [WezTerm terminal](https://wezfurlong.org/wezterm/config/lua/config/enable_kitty_keyboard.html)
/// * [notcurses library](https://github.com/dankamongmen/notcurses/issues/2131)
/// * [neovim text editor](https://github.com/neovim/neovim/pull/18181)
/// * [kakoune text editor](https://github.com/mawww/kakoune/issues/4103)
/// * [dte text editor](https://gitlab.com/craigbarnes/dte/-/issues/138)
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub struct PushKeyboardEnhancementFlags(pub KeyboardEnhancementFlags);

impl Command for PushKeyboardEnhancementFlags {
    fn write_ansi(&self, f: &mut impl fmt::Write) -> fmt::Result {
        write!(f, "{}{}u", csi!(">"), self.0.bits())
    }

    #[cfg(windows)]
    fn execute_winapi(&self) -> Result<()> {
        Err(io::Error::new(
            io::ErrorKind::Unsupported,
            "Keyboard progressive enhancement not implemented for the legacy Windows API.",
        ))
    }

    #[cfg(windows)]
    fn is_ansi_code_supported(&self) -> bool {
        false
    }
}

/// A command that disables extra kinds of keyboard events.
///
/// Specifically, it pops one level of keyboard enhancement flags.
///
/// See [`PushKeyboardEnhancementFlags`] and <https://sw.kovidgoyal.net/kitty/keyboard-protocol/> for more information.
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub struct PopKeyboardEnhancementFlags;

impl Command for PopKeyboardEnhancementFlags {
    fn write_ansi(&self, f: &mut impl fmt::Write) -> fmt::Result {
        f.write_str(csi!("<1u"))
    }

    #[cfg(windows)]
    fn execute_winapi(&self) -> Result<()> {
        Err(io::Error::new(
            io::ErrorKind::Unsupported,
            "Keyboard progressive enhancement not implemented for the legacy Windows API.",
        ))
    }

    #[cfg(windows)]
    fn is_ansi_code_supported(&self) -> bool {
        false
    }
}

/// A command that enables focus event emission.
///
/// Focus events can be captured with [read](./fn.read.html)/[poll](./fn.poll.html).
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub struct EnableFocusChange;

impl Command for EnableFocusChange {
    fn write_ansi(&self, f: &mut impl fmt::Write) -> fmt::Result {
        f.write_str(csi!("?1004h"))
    }

    #[cfg(windows)]
    fn execute_winapi(&self) -> Result<()> {
        // Focus events are always enabled on Windows
        Ok(())
    }
}

/// A command that disables focus event emission.
///
/// Focus events can be captured with [read](./fn.read.html)/[poll](./fn.poll.html).
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub struct DisableFocusChange;

impl Command for DisableFocusChange {
    fn write_ansi(&self, f: &mut impl fmt::Write) -> fmt::Result {
        f.write_str(csi!("?1004l"))
    }

    #[cfg(windows)]
    fn execute_winapi(&self) -> Result<()> {
        // Focus events can't be disabled on Windows
        Ok(())
    }
}

/// Represents an event.
#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
#[derive(Debug, PartialOrd, PartialEq, Eq, Clone, Copy, Hash)]
pub enum Event {
    /// The terminal gained focus
    FocusGained,
    /// The terminal lost focus
    FocusLost,
    /// A single key event with additional pressed modifiers.
    Key(KeyEvent),
    /// A single mouse event with additional pressed modifiers.
    Mouse(MouseEvent),
    /// An resize event with new dimensions after resize (columns, rows).
    /// **Note** that resize events can be occur in batches.
    Resize(u16, u16),
}

/// Represents a mouse event.
///
/// # Platform-specific Notes
///
/// ## Mouse Buttons
///
/// Some platforms/terminals do not report mouse button for the
/// `MouseEventKind::Up` and `MouseEventKind::Drag` events. `MouseButton::Left`
/// is returned if we don't know which button was used.
///
/// ## Key Modifiers
///
/// Some platforms/terminals does not report all key modifiers
/// combinations for all mouse event types. For example - macOS reports
/// `Ctrl` + left mouse button click as a right mouse button click.
#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
#[derive(Debug, PartialOrd, PartialEq, Eq, Clone, Copy, Hash)]
pub struct MouseEvent {
    /// The kind of mouse event that was caused.
    pub kind: MouseEventKind,
    /// The column that the event occurred on.
    pub column: u16,
    /// The row that the event occurred on.
    pub row: u16,
    /// The key modifiers active when the event occurred.
    pub modifiers: KeyModifiers,
}

/// A mouse event kind.
///
/// # Platform-specific Notes
///
/// ## Mouse Buttons
///
/// Some platforms/terminals do not report mouse button for the
/// `MouseEventKind::Up` and `MouseEventKind::Drag` events. `MouseButton::Left`
/// is returned if we don't know which button was used.
#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
#[derive(Debug, PartialOrd, PartialEq, Eq, Clone, Copy, Hash)]
pub enum MouseEventKind {
    /// Pressed mouse button. Contains the button that was pressed.
    Down(MouseButton),
    /// Released mouse button. Contains the button that was released.
    Up(MouseButton),
    /// Moved the mouse cursor while pressing the contained mouse button.
    Drag(MouseButton),
    /// Moved the mouse cursor while not pressing a mouse button.
    Moved,
    /// Scrolled mouse wheel downwards (towards the user).
    ScrollDown,
    /// Scrolled mouse wheel upwards (away from the user).
    ScrollUp,
}

/// Represents a mouse button.
#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
#[derive(Debug, PartialOrd, PartialEq, Eq, Clone, Copy, Hash)]
pub enum MouseButton {
    /// Left mouse button.
    Left,
    /// Right mouse button.
    Right,
    /// Middle mouse button.
    Middle,
}

bitflags! {
    /// Represents key modifiers (shift, control, alt).
    #[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
    pub struct KeyModifiers: u8 {
        const SHIFT = 0b0000_0001;
        const CONTROL = 0b0000_0010;
        const ALT = 0b0000_0100;
        const NONE = 0b0000_0000;
    }
}

/// Represents a keyboard event kind.
#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
#[derive(Debug, PartialOrd, PartialEq, Eq, Clone, Copy, Hash)]
pub enum KeyEventKind {
    Press,
    Repeat,
    Release,
}

bitflags! {
    /// Represents extra state about the key event.
    #[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
    pub struct KeyEventState: u8 {
        /// The key event origins from the keypad.
        const KEYPAD = 0b0000_0001;
    }
}

/// Represents a key event.
#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
#[derive(Debug, PartialOrd, Clone, Copy)]
pub struct KeyEvent {
    /// The key itself.
    pub code: KeyCode,
    /// Additional key modifiers.
    pub modifiers: KeyModifiers,
    /// Kind of event.
    pub kind: KeyEventKind,
    /// Keyboard state.
    ///
    /// Only set if [`KeyboardEnhancementFlags::DISAMBIGUATE_ESCAPE_CODES`] has been enabled with
    /// [`PushKeyboardEnhancementFlags`].
    pub state: KeyEventState,
}

impl KeyEvent {
    pub const fn new(code: KeyCode, modifiers: KeyModifiers) -> KeyEvent {
        KeyEvent {
            code,
            modifiers,
            kind: KeyEventKind::Press,
            state: KeyEventState::empty(),
        }
    }

    pub const fn new_with_kind(
        code: KeyCode,
        modifiers: KeyModifiers,
        kind: KeyEventKind,
    ) -> KeyEvent {
        KeyEvent {
            code,
            modifiers,
            kind,
            state: KeyEventState::empty(),
        }
    }

    pub const fn new_with_kind_and_state(
        code: KeyCode,
        modifiers: KeyModifiers,
        kind: KeyEventKind,
        state: KeyEventState,
    ) -> KeyEvent {
        KeyEvent {
            code,
            modifiers,
            kind,
            state,
        }
    }

    // modifies the KeyEvent,
    // so that KeyModifiers::SHIFT is present iff
    // an uppercase char is present.
    fn normalize_case(mut self) -> KeyEvent {
        let c = match self.code {
            KeyCode::Char(c) => c,
            _ => return self,
        };

        if c.is_ascii_uppercase() {
            self.modifiers.insert(KeyModifiers::SHIFT);
        } else if self.modifiers.contains(KeyModifiers::SHIFT) {
            self.code = KeyCode::Char(c.to_ascii_uppercase())
        }
        self
    }
}

impl From<KeyCode> for KeyEvent {
    fn from(code: KeyCode) -> Self {
        KeyEvent {
            code,
            modifiers: KeyModifiers::empty(),
            kind: KeyEventKind::Press,
            state: KeyEventState::empty(),
        }
    }
}

impl PartialEq for KeyEvent {
    fn eq(&self, other: &KeyEvent) -> bool {
        let KeyEvent {
            code: lhs_code,
            modifiers: lhs_modifiers,
            kind: lhs_kind,
            state: lhs_state,
        } = self.normalize_case();
        let KeyEvent {
            code: rhs_code,
            modifiers: rhs_modifiers,
            kind: rhs_kind,
            state: rhs_state,
        } = other.normalize_case();
        (lhs_code == rhs_code)
            && (lhs_modifiers == rhs_modifiers)
            && (lhs_kind == rhs_kind)
            && (lhs_state == rhs_state)
    }
}

impl Eq for KeyEvent {}

impl Hash for KeyEvent {
    fn hash<H: Hasher>(&self, hash_state: &mut H) {
        let KeyEvent {
            code,
            modifiers,
            kind,
            state,
        } = self.normalize_case();
        code.hash(hash_state);
        modifiers.hash(hash_state);
        kind.hash(hash_state);
        state.hash(hash_state);
    }
}

/// Represents a media key (as part of [`KeyCode::Media`]).
#[derive(Debug, PartialOrd, PartialEq, Eq, Clone, Copy, Hash)]
#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
pub enum MediaKeyCode {
    /// Play media key.
    Play,
    /// Pause media key.
    Pause,
    /// Play/Pause media key.
    PlayPause,
    /// Reverse media key.
    Reverse,
    /// Stop media key.
    Stop,
    /// Fast-forward media key.
    FastForward,
    /// Rewind media key.
    Rewind,
    /// Next-track media key.
    TrackNext,
    /// Previous-track media key.
    TrackPrevious,
    /// Record media key.
    Record,
    /// Lower-volume media key.
    LowerVolume,
    /// Raise-volume media key.
    RaiseVolume,
    /// Mute media key.
    MuteVolume,
}

/// Represents a modifier key (as part of [`KeyCode::Modifier`]).
#[derive(Debug, PartialOrd, PartialEq, Eq, Clone, Copy, Hash)]
#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
pub enum ModifierKeyCode {
    /// Left Shift key.
    LeftShift,
    /// Left Control key.
    LeftControl,
    /// Left Alt key.
    LeftAlt,
    /// Left Super key.
    LeftSuper,
    /// Left Hyper key.
    LeftHyper,
    /// Left Meta key.
    LeftMeta,
    /// Right Shift key.
    RightShift,
    /// Right Control key.
    RightControl,
    /// Right Alt key.
    RightAlt,
    /// Right Super key.
    RightSuper,
    /// Right Hyper key.
    RightHyper,
    /// Right Meta key.
    RightMeta,
    /// Iso Level3 Shift key.
    IsoLevel3Shift,
    /// Iso Level5 Shift key.
    IsoLevel5Shift,
}

/// Represents a key.
#[derive(Debug, PartialOrd, PartialEq, Eq, Clone, Copy, Hash)]
#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
pub enum KeyCode {
    /// Backspace key.
    Backspace,
    /// Enter key.
    Enter,
    /// Left arrow key.
    Left,
    /// Right arrow key.
    Right,
    /// Up arrow key.
    Up,
    /// Down arrow key.
    Down,
    /// Home key.
    Home,
    /// End key.
    End,
    /// Page up key.
    PageUp,
    /// Page down key.
    PageDown,
    /// Tab key.
    Tab,
    /// Shift + Tab key.
    BackTab,
    /// Delete key.
    Delete,
    /// Insert key.
    Insert,
    /// F key.
    ///
    /// `KeyCode::F(1)` represents F1 key, etc.
    F(u8),
    /// A character.
    ///
    /// `KeyCode::Char('c')` represents `c` character, etc.
    Char(char),
    /// Null.
    Null,
    /// Escape key.
    Esc,
    /// Caps Lock key.
    ///
    /// **Note:** this key can only be read if
    /// [`KeyboardEnhancementFlags::DISAMBIGUATE_ESCAPE_CODES`] has been enabled with
    /// [`PushKeyboardEnhancementFlags`].
    CapsLock,
    /// Scroll Lock key.
    ///
    /// **Note:** this key can only be read if
    /// [`KeyboardEnhancementFlags::DISAMBIGUATE_ESCAPE_CODES`] has been enabled with
    /// [`PushKeyboardEnhancementFlags`].
    ScrollLock,
    /// Num Lock key.
    ///
    /// **Note:** this key can only be read if
    /// [`KeyboardEnhancementFlags::DISAMBIGUATE_ESCAPE_CODES`] has been enabled with
    /// [`PushKeyboardEnhancementFlags`].
    NumLock,
    /// Print Screen key.
    ///
    /// **Note:** this key can only be read if
    /// [`KeyboardEnhancementFlags::DISAMBIGUATE_ESCAPE_CODES`] has been enabled with
    /// [`PushKeyboardEnhancementFlags`].
    PrintScreen,
    /// Pause key.
    ///
    /// **Note:** this key can only be read if
    /// [`KeyboardEnhancementFlags::DISAMBIGUATE_ESCAPE_CODES`] has been enabled with
    /// [`PushKeyboardEnhancementFlags`].
    Pause,
    /// Menu key.
    ///
    /// **Note:** this key can only be read if
    /// [`KeyboardEnhancementFlags::DISAMBIGUATE_ESCAPE_CODES`] has been enabled with
    /// [`PushKeyboardEnhancementFlags`].
    Menu,
    /// The "Begin" key (often mapped to the 5 key when Num Lock is turned on).
    ///
    /// **Note:** this key can only be read if
    /// [`KeyboardEnhancementFlags::DISAMBIGUATE_ESCAPE_CODES`] has been enabled with
    /// [`PushKeyboardEnhancementFlags`].
    KeypadBegin,
    /// A media key.
    ///
    /// **Note:** these keys can only be read if
    /// [`KeyboardEnhancementFlags::DISAMBIGUATE_ESCAPE_CODES`] has been enabled with
    /// [`PushKeyboardEnhancementFlags`].
    Media(MediaKeyCode),
    /// A modifier key.
    ///
    /// **Note:** these keys can only be read if **both**
    /// [`KeyboardEnhancementFlags::DISAMBIGUATE_ESCAPE_CODES`] and
    /// [`KeyboardEnhancementFlags::REPORT_ALL_KEYS_AS_ESCAPE_CODES`] have been enabled with
    /// [`PushKeyboardEnhancementFlags`].
    Modifier(ModifierKeyCode),
}

/// An internal event.
///
/// Encapsulates publicly available `Event` with additional internal
/// events that shouldn't be publicly available to the crate users.
#[derive(Debug, PartialOrd, PartialEq, Hash, Clone, Eq)]
pub(crate) enum InternalEvent {
    /// An event.
    Event(Event),
    /// A cursor position (`col`, `row`).
    #[cfg(unix)]
    CursorPosition(u16, u16),
}

#[cfg(test)]
mod tests {
    use std::collections::hash_map::DefaultHasher;
    use std::hash::{Hash, Hasher};

    use super::{KeyCode, KeyEvent, KeyModifiers};

    #[test]
    fn test_equality() {
        let lowercase_d_with_shift = KeyEvent::new(KeyCode::Char('d'), KeyModifiers::SHIFT);
        let uppercase_d_with_shift = KeyEvent::new(KeyCode::Char('D'), KeyModifiers::SHIFT);
        let uppercase_d = KeyEvent::new(KeyCode::Char('D'), KeyModifiers::NONE);
        assert_eq!(lowercase_d_with_shift, uppercase_d_with_shift);
        assert_eq!(uppercase_d, uppercase_d_with_shift);
    }

    #[test]
    fn test_hash() {
        let lowercase_d_with_shift_hash = {
            let mut hasher = DefaultHasher::new();
            KeyEvent::new(KeyCode::Char('d'), KeyModifiers::SHIFT).hash(&mut hasher);
            hasher.finish()
        };
        let uppercase_d_with_shift_hash = {
            let mut hasher = DefaultHasher::new();
            KeyEvent::new(KeyCode::Char('D'), KeyModifiers::SHIFT).hash(&mut hasher);
            hasher.finish()
        };
        let uppercase_d_hash = {
            let mut hasher = DefaultHasher::new();
            KeyEvent::new(KeyCode::Char('D'), KeyModifiers::NONE).hash(&mut hasher);
            hasher.finish()
        };
        assert_eq!(lowercase_d_with_shift_hash, uppercase_d_with_shift_hash);
        assert_eq!(uppercase_d_hash, uppercase_d_with_shift_hash);
    }
}