bubbletea_rs/

event.rs

//! This module defines the various message types used in `bubbletea-rs`.
//! Messages are events that trigger updates in your application's model.
//! They are typically sent by commands or the input handler.

use std::any::Any;
use std::sync::atomic::{AtomicU64, Ordering};
use std::sync::OnceLock;
use tokio::sync::mpsc;
use tokio_util::sync::CancellationToken;

/// A message represents any event that can trigger a model update.
///
/// `Msg` is a type alias for `Box<dyn Any + Send>`, allowing it to hold
/// any type that implements `Any` and `Send`. This provides flexibility
/// in defining custom message types for your application.
pub type Msg = Box<dyn Any + Send>;

/// Event sender abstraction that can be either bounded or unbounded.
///
/// `EventSender` provides a unified interface for sending messages through
/// either bounded or unbounded channels. This abstraction allows the framework
/// to switch between different channel types without changing the API.
///
/// # Examples
///
/// ```
/// use bubbletea_rs::event::{EventSender, Msg};
/// use tokio::sync::mpsc;
///
/// // Create from unbounded channel
/// let (tx, _rx) = mpsc::unbounded_channel::<Msg>();
/// let sender = EventSender::from_unbounded(tx);
///
/// // Send a message
/// let msg: Msg = Box::new("Hello");
/// sender.send(msg).unwrap();
/// ```
#[derive(Clone)]
pub enum EventSender {
    /// Unbounded channel sender used for unlimited-capacity message delivery.
    Unbounded(mpsc::UnboundedSender<Msg>),
    /// Bounded channel sender that applies backpressure when full.
    Bounded(mpsc::Sender<Msg>),
}

impl EventSender {
    /// Send a message through the channel.
    ///
    /// Attempts to send a message through the underlying channel. For unbounded
    /// channels, this will only fail if the receiver has been dropped. For bounded
    /// channels, this may also fail due to backpressure (channel full).
    ///
    /// # Arguments
    ///
    /// * `msg` - The message to send
    ///
    /// # Returns
    ///
    /// Returns `Ok(())` if the message was sent successfully, or an error if:
    /// - The channel is closed (`Error::ChannelClosed`)
    /// - The channel is full (`Error::ChannelFull`) for bounded channels
    ///
    /// # Examples
    ///
    /// ```
    /// use bubbletea_rs::event::{EventSender, Msg};
    /// use tokio::sync::mpsc;
    ///
    /// let (tx, _rx) = mpsc::unbounded_channel::<Msg>();
    /// let sender = EventSender::from_unbounded(tx);
    ///
    /// let msg: Msg = Box::new(42);
    /// match sender.send(msg) {
    ///     Ok(()) => println!("Message sent!"),
    ///     Err(e) => eprintln!("Failed to send: {}", e),
    /// }
    /// ```
    pub fn send(&self, msg: Msg) -> Result<(), crate::Error> {
        match self {
            // Unbounded send fails only when the receiver is closed.
            EventSender::Unbounded(tx) => tx.send(msg).map_err(|_| crate::Error::ChannelClosed),
            // Bounded send can fail due to Full (backpressure) or Closed.
            EventSender::Bounded(tx) => tx.try_send(msg).map_err(Into::into),
        }
    }

    /// Check if the sender is closed.
    ///
    /// Returns `true` if the receiver side of the channel has been dropped,
    /// meaning that any future send operations will fail.
    ///
    /// # Returns
    ///
    /// `true` if the channel is closed, `false` otherwise
    ///
    /// # Examples
    ///
    /// ```
    /// use bubbletea_rs::event::{EventSender, Msg};
    /// use tokio::sync::mpsc;
    ///
    /// let (tx, rx) = mpsc::unbounded_channel::<Msg>();
    /// let sender = EventSender::from_unbounded(tx);
    ///
    /// assert!(!sender.is_closed());
    /// drop(rx); // Drop the receiver
    /// assert!(sender.is_closed());
    /// ```
    pub fn is_closed(&self) -> bool {
        match self {
            EventSender::Unbounded(tx) => tx.is_closed(),
            EventSender::Bounded(tx) => tx.is_closed(),
        }
    }

    /// Create an EventSender from an UnboundedSender (for backward compatibility).
    ///
    /// This method creates an `EventSender` wrapping an unbounded channel sender.
    /// Unbounded channels have unlimited capacity and never apply backpressure.
    ///
    /// # Arguments
    ///
    /// * `tx` - The unbounded sender to wrap
    ///
    /// # Returns
    ///
    /// An `EventSender` that uses the provided unbounded channel
    ///
    /// # Examples
    ///
    /// ```
    /// use bubbletea_rs::event::{EventSender, Msg};
    /// use tokio::sync::mpsc;
    ///
    /// let (tx, _rx) = mpsc::unbounded_channel::<Msg>();
    /// let sender = EventSender::from_unbounded(tx);
    /// ```
    pub fn from_unbounded(tx: mpsc::UnboundedSender<Msg>) -> Self {
        EventSender::Unbounded(tx)
    }

    /// Create an EventSender from a bounded Sender (for testing).
    ///
    /// This method creates an `EventSender` wrapping a bounded channel sender.
    /// Bounded channels have limited capacity and will apply backpressure when full.
    /// This is primarily used in testing scenarios to verify behavior under
    /// backpressure conditions.
    ///
    /// # Arguments
    ///
    /// * `tx` - The bounded sender to wrap
    ///
    /// # Returns
    ///
    /// An `EventSender` that uses the provided bounded channel
    ///
    /// # Examples
    ///
    /// ```
    /// use bubbletea_rs::event::{EventSender, Msg};
    /// use tokio::sync::mpsc;
    ///
    /// let (tx, _rx) = mpsc::channel::<Msg>(10); // Capacity of 10
    /// let sender = EventSender::from_bounded(tx);
    /// ```
    pub fn from_bounded(tx: mpsc::Sender<Msg>) -> Self {
        EventSender::Bounded(tx)
    }
}

impl From<mpsc::UnboundedSender<Msg>> for EventSender {
    fn from(tx: mpsc::UnboundedSender<Msg>) -> Self {
        EventSender::Unbounded(tx)
    }
}

impl From<mpsc::Sender<Msg>> for EventSender {
    fn from(tx: mpsc::Sender<Msg>) -> Self {
        EventSender::Bounded(tx)
    }
}

/// Event receiver abstraction that can be either bounded or unbounded.
///
/// `EventReceiver` provides a unified interface for receiving messages from
/// either bounded or unbounded channels. This abstraction allows the framework
/// to switch between different channel types without changing the API.
///
/// # Examples
///
/// ```no_run
/// use bubbletea_rs::event::{EventReceiver, EventSender, Msg};
/// use tokio::sync::mpsc;
///
/// async fn example() {
///     let (tx, rx) = mpsc::unbounded_channel::<Msg>();
/// let mut receiver = EventReceiver::Unbounded(rx);
/// let sender = EventSender::from_unbounded(tx);
///
/// // Send and receive a message
/// sender.send(Box::new(42)).unwrap();
///     if let Some(msg) = receiver.recv().await {
///         // Process the message
///     }
/// }
/// ```
pub enum EventReceiver {
    /// Unbounded channel receiver counterpart for unlimited-capacity channels.
    Unbounded(mpsc::UnboundedReceiver<Msg>),
    /// Bounded channel receiver that may yield `None` when closed and drained.
    Bounded(mpsc::Receiver<Msg>),
}

impl EventReceiver {
    /// Receive the next message from the channel.
    ///
    /// Asynchronously waits for the next message from the channel. Returns `None`
    /// when the sender side has been dropped and all messages have been received.
    ///
    /// # Returns
    ///
    /// - `Some(Msg)` if a message was received
    /// - `None` if the channel is closed and empty
    ///
    /// # Examples
    ///
    /// ```no_run
    /// use bubbletea_rs::event::{EventReceiver, Msg};
    /// use tokio::sync::mpsc;
    ///
    /// async fn example() {
    ///     let (tx, rx) = mpsc::unbounded_channel::<Msg>();
    /// let mut receiver = EventReceiver::Unbounded(rx);
    ///
    /// // Send a message
    /// tx.send(Box::new("Hello")).unwrap();
    ///
    /// // Receive the message
    /// match receiver.recv().await {
    ///     Some(msg) => {
    ///         if let Some(text) = msg.downcast_ref::<&str>() {
    ///             println!("Received: {}", text);
    ///         }
    ///     }
    ///     None => println!("Channel closed"),
    /// }
    /// }
    /// ```
    pub async fn recv(&mut self) -> Option<Msg> {
        match self {
            EventReceiver::Unbounded(rx) => rx.recv().await,
            EventReceiver::Bounded(rx) => rx.recv().await,
        }
    }
}

/// Global event sender set by Program on startup so commands can emit messages
/// back into the event loop from background tasks.
///
/// This global static is initialized once when a `Program` starts running and
/// provides a way for background tasks and commands to send messages back to
/// the main event loop. It uses `OnceLock` to ensure thread-safe one-time
/// initialization.
///
/// # Examples
///
/// ```
/// use bubbletea_rs::event::{EVENT_SENDER, Msg};
///
/// // In a background task or command
/// if let Some(sender) = EVENT_SENDER.get() {
///     let msg: Msg = Box::new("Task completed");
///     sender.send(msg).unwrap();
/// }
/// ```
///
/// # Note
///
/// This is automatically initialized by the framework. User code should only
/// read from it, never write to it.
pub static EVENT_SENDER: OnceLock<EventSender> = OnceLock::new();

/// Global timer ID generator for unique timer identification.
///
/// This atomic counter ensures that each timer created in the application
/// receives a unique identifier. The counter starts at 1 and increments
/// atomically to avoid race conditions in multi-threaded environments.
static TIMER_ID_COUNTER: AtomicU64 = AtomicU64::new(1);

/// Generates a unique timer ID.
///
/// This function atomically increments and returns a unique identifier
/// for timers. Each call is guaranteed to return a different value,
/// even when called from multiple threads simultaneously.
///
/// # Returns
///
/// A unique `u64` identifier for a timer
///
/// # Examples
///
/// ```
/// use bubbletea_rs::event::next_timer_id;
///
/// let id1 = next_timer_id();
/// let id2 = next_timer_id();
/// assert_ne!(id1, id2);
/// ```
pub fn next_timer_id() -> u64 {
    TIMER_ID_COUNTER.fetch_add(1, Ordering::Relaxed)
}

/// A message indicating a keyboard input event.
#[derive(Debug, Clone)]
pub struct KeyMsg {
    /// The `crossterm::event::KeyCode` representing the key pressed.
    pub key: crossterm::event::KeyCode,
    /// The `crossterm::event::KeyModifiers` active during the key press.
    pub modifiers: crossterm::event::KeyModifiers,
}

/// A message indicating a mouse input event.
#[derive(Debug, Clone)]
pub struct MouseMsg {
    /// The column coordinate of the mouse event.
    pub x: u16,
    /// The row coordinate of the mouse event.
    pub y: u16,
    /// The `crossterm::event::MouseEventKind` representing the type of mouse event.
    pub button: crossterm::event::MouseEventKind,
    /// The `crossterm::event::KeyModifiers` active during the mouse event.
    pub modifiers: crossterm::event::KeyModifiers,
}

/// A message indicating that text was pasted into the terminal (bracketed paste).
///
/// This message is generated when bracketed paste mode is enabled and the user
/// pastes text into the terminal. The pasted content is captured as a single
/// string, preserving newlines and special characters.
///
/// # Examples
///
/// ```
/// use bubbletea_rs::event::PasteMsg;
///
/// // Handling a paste event in your model's update method
/// let paste_msg = PasteMsg("Hello\nWorld".to_string());
/// // The text contains the exact pasted content
/// assert_eq!(paste_msg.0, "Hello\nWorld");
/// ```
///
/// # Note
///
/// Bracketed paste mode must be enabled with `EnableBracketedPasteMsg` for
/// these messages to be generated.
#[derive(Debug, Clone)]
pub struct PasteMsg(pub String);

/// A message indicating a change in the terminal window size.
#[derive(Debug, Clone)]
pub struct WindowSizeMsg {
    /// The new width of the terminal window.
    pub width: u16,
    /// The new height of the terminal window.
    pub height: u16,
}

/// A message to signal the application to quit.
///
/// Sending this message to the `Program` will initiate a graceful shutdown.
#[derive(Debug, Clone)]
pub struct QuitMsg;

/// A message to forcefully kill the application immediately.
///
/// Sending this message to the `Program` will cause it to terminate as soon as
/// possible. The event loop will stop without invoking the model's `update` and
/// will return an `Error::ProgramKilled`.
#[derive(Debug, Clone)]
pub struct KillMsg;

/// A message to signal an application interruption.
///
/// This is typically sent when an interrupt signal (e.g., Ctrl+C) is received.
#[derive(Debug, Clone)]
pub struct InterruptMsg;

/// A message to signal the application to suspend.
///
/// This can be used to temporarily pause the application, for example, when
/// another process needs control of the terminal.
#[derive(Debug, Clone)]
pub struct SuspendMsg;

/// A message to signal the application to resume after suspension.
#[derive(Debug, Clone)]
pub struct ResumeMsg;

/// A message indicating that the terminal gained focus.
#[derive(Debug, Clone)]
pub struct FocusMsg;

/// A message indicating that the terminal lost focus.
#[derive(Debug, Clone)]
pub struct BlurMsg;

/// An internal message type used to batch multiple messages together.
/// This is not exposed as a public API.
#[derive(Debug)]
pub struct BatchMsgInternal {
    /// Aggregated messages to dispatch as a single batch.
    pub messages: Vec<Msg>,
}

/// A message to signal the terminal to enter the alternate screen buffer.
#[derive(Debug, Clone)]
pub struct EnterAltScreenMsg;

/// A message to signal the terminal to exit the alternate screen buffer.
#[derive(Debug, Clone)]
pub struct ExitAltScreenMsg;

/// A message to signal the terminal to enable mouse cell motion reporting.
#[derive(Debug, Clone)]
pub struct EnableMouseCellMotionMsg;

/// A message to signal the terminal to enable all mouse motion reporting.
#[derive(Debug, Clone)]
pub struct EnableMouseAllMotionMsg;

/// A message to signal the terminal to disable mouse reporting.
#[derive(Debug, Clone)]
pub struct DisableMouseMsg;

/// A message to signal the terminal to enable bracketed paste mode.
#[derive(Debug, Clone)]
pub struct EnableBracketedPasteMsg;

/// A message to signal the terminal to disable bracketed paste mode.
#[derive(Debug, Clone)]
pub struct DisableBracketedPasteMsg;

/// A message to signal the terminal to enable focus reporting.
#[derive(Debug, Clone)]
pub struct EnableReportFocusMsg;

/// A message to signal the terminal to disable focus reporting.
#[derive(Debug, Clone)]
pub struct DisableReportFocusMsg;

/// A message to signal the terminal to show the cursor.
#[derive(Debug, Clone)]
pub struct ShowCursorMsg;

/// A message to signal the terminal to hide the cursor.
#[derive(Debug, Clone)]
pub struct HideCursorMsg;

/// A message to signal the terminal to clear the screen.
#[derive(Debug, Clone)]
pub struct ClearScreenMsg;

/// A message to signal the terminal to request its current window size.
///
/// The terminal will respond with a `WindowSizeMsg` containing its dimensions.
#[derive(Debug, Clone)]
pub struct RequestWindowSizeMsg;

/// A message to print a line to the terminal.
///
/// This message causes the program to print text to the terminal output.
/// The text will be printed as-is with a newline appended.
///
/// # Examples
///
/// ```
/// use bubbletea_rs::event::PrintMsg;
///
/// // Print a simple message
/// let msg = PrintMsg("Hello, Terminal!".to_string());
/// ```
///
/// # Note
///
/// This bypasses the normal view rendering and directly outputs to the terminal.
/// Use sparingly as it can interfere with the TUI display.
#[derive(Debug, Clone)]
pub struct PrintMsg(pub String);

/// A message to print formatted text to the terminal.
///
/// Similar to `PrintMsg`, but the text is treated as pre-formatted and
/// printed exactly as provided without adding a newline.
///
/// # Examples
///
/// ```
/// use bubbletea_rs::event::PrintfMsg;
///
/// // Print formatted text without automatic newline
/// let msg = PrintfMsg("Progress: 50%\r".to_string());
/// ```
///
/// # Note
///
/// This bypasses the normal view rendering and directly outputs to the terminal.
/// Useful for progress indicators or custom formatting that requires precise
/// control over newlines and carriage returns.
#[derive(Debug, Clone)]
pub struct PrintfMsg(pub String);

/// A message to set the terminal window title.
///
/// This message updates the terminal window's title bar with the provided string.
/// Not all terminals support this feature.
///
/// # Examples
///
/// ```
/// use bubbletea_rs::event::SetWindowTitleMsg;
///
/// // Set a custom window title
/// let msg = SetWindowTitleMsg("My App - Document.txt".to_string());
/// ```
///
/// # Platform Support
///
/// - **Unix/Linux**: Generally supported in most terminal emulators
/// - **macOS**: Supported in Terminal.app and iTerm2
/// - **Windows**: Supported in Windows Terminal and newer console hosts
#[derive(Debug, Clone)]
pub struct SetWindowTitleMsg(pub String);

/// An internal message used to start a recurring timer.
///
/// This structure is used internally by the framework to manage recurring
/// timers created with the `every()` command. It contains the timer's
/// configuration and a cancellation token for stopping the timer.
///
/// # Note
///
/// This is not exposed as a public API and should not be used directly
/// by application code. Use the `every()` command function instead.
pub struct EveryMsgInternal {
    /// Interval between timer ticks.
    pub duration: std::time::Duration,
    /// Function invoked on each tick producing a message.
    pub func: Box<dyn Fn(std::time::Duration) -> Msg + Send>,
    /// Token used to cancel the running timer.
    pub cancellation_token: CancellationToken,
    /// Unique identifier for this timer instance.
    pub timer_id: u64,
}

impl std::fmt::Debug for EveryMsgInternal {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        f.debug_struct("EveryMsgInternal")
            .field("duration", &self.duration)
            .field("timer_id", &self.timer_id)
            .field("func", &"<closure>")
            .finish()
    }
}

/// A message to cancel a specific timer.
///
/// This message stops a running timer identified by its unique ID.
/// If the timer has already completed or been cancelled, this message
/// has no effect.
///
/// # Fields
///
/// * `timer_id` - The unique identifier of the timer to cancel
///
/// # Examples
///
/// ```
/// use bubbletea_rs::event::{CancelTimerMsg, next_timer_id};
///
/// // Cancel a specific timer
/// let timer_id = next_timer_id();
/// let cancel_msg = CancelTimerMsg { timer_id };
/// ```
#[derive(Debug, Clone)]
pub struct CancelTimerMsg {
    /// The unique identifier of the timer to cancel.
    pub timer_id: u64,
}

/// A message to cancel all active timers.
///
/// This message stops all currently running timers in the program.
/// This is useful during cleanup or when transitioning between different
/// application states.
///
/// # Examples
///
/// ```
/// use bubbletea_rs::event::CancelAllTimersMsg;
///
/// // Cancel all timers
/// let cancel_all = CancelAllTimersMsg;
/// ```
///
/// # Use Cases
///
/// - Application shutdown
/// - State transitions that invalidate existing timers
/// - Error recovery scenarios
#[derive(Debug, Clone)]
pub struct CancelAllTimersMsg;