a7n-platform 0.18.0

// SPDX-License-Identifier: GPL-3.0-or-later

//! Channels shared by the daemon and future platform input threads.

use std::time::{Duration, Instant};

use a7n_proto::v1::InputEvent;
use tokio::sync::mpsc;

#[cfg(all(unix, not(target_os = "macos")))]
mod accumulate;
#[cfg(all(unix, not(target_os = "macos")))]
mod evdev_keymap;
#[cfg(target_os = "macos")]
pub(crate) mod macos;
#[cfg(all(test, not(target_os = "macos")))]
#[path = "input/macos/keymap.rs"]
mod macos_keymap;
mod scroll;
#[cfg(all(unix, not(target_os = "macos")))]
mod wayland;
#[cfg(windows)]
pub(crate) mod windows;
#[cfg(all(unix, not(target_os = "macos")))]
mod x11;

pub const KEEPALIVE_INTERVAL: Duration = Duration::from_millis(500);
pub const DEADMAN_TIMEOUT: Duration = Duration::from_millis(1500);

/// Raw pointer and key events queued for the daemon.
#[cfg(all(unix, not(target_os = "macos")))]
const CAPTURE_EVENT_CAPACITY: usize = 1024;
#[cfg(all(unix, not(target_os = "macos")))]
const CAPTURE_CONTROL_CAPACITY: usize = 16;
#[cfg(all(unix, not(target_os = "macos")))]
const INJECT_COMMAND_CAPACITY: usize = 1024;
/// Position reports are superseded by the next one, so a short queue is enough.
#[cfg(all(unix, not(target_os = "macos")))]
const INJECT_POINTER_CAPACITY: usize = 64;

#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub struct Bounds {
    pub x: i32,
    pub y: i32,
    pub width: u32,
    pub height: u32,
}

#[derive(Debug)]
pub enum Captured {
    Pointer { x: i32, y: i32, dx: i32, dy: i32 },
    Input(InputEvent),
}

#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub enum CaptureControl {
    Grab(bool),
    Keepalive,
}

/// While grabbed, all events still arrive here but do not reach the local OS.
#[derive(Debug)]
pub struct Capture {
    pub bounds: Bounds,
    pub events: mpsc::Receiver<Captured>,
    pub control: mpsc::Sender<CaptureControl>,
}

#[derive(Debug)]
pub enum Inject {
    Event(InputEvent),
    Motion { dx: i32, dy: i32 },
    Warp { x: i32, y: i32 },
}

#[derive(Debug)]
pub struct Injector {
    pub bounds: Bounds,
    pub commands: mpsc::Sender<Inject>,
    /// Absolute pointer position and raw delta after each motion or warp.
    pub pointer: mpsc::Receiver<Captured>,
}

#[derive(Debug, thiserror::Error)]
pub enum InputError {
    #[error("input capture and injection are not supported on this platform")]
    Unsupported,
    #[error("{0} permission missing")]
    MissingPermission(&'static str),
    #[cfg(all(unix, not(target_os = "macos")))]
    #[error("Wayland portal failed: {0}")]
    Portal(String),
    #[cfg(target_os = "macos")]
    #[error("macOS input failed: {0}")]
    Macos(#[from] std::io::Error),
    #[cfg(all(unix, not(target_os = "macos")))]
    #[error("cannot connect to the X server: {0}")]
    X11Connect(#[from] x11rb::errors::ConnectError),
    #[cfg(all(unix, not(target_os = "macos")))]
    #[error("X connection failed: {0}")]
    X11Connection(#[from] x11rb::errors::ConnectionError),
    #[cfg(all(unix, not(target_os = "macos")))]
    #[error("X request failed: {0}")]
    X11Reply(#[from] x11rb::errors::ReplyError),
    #[cfg(all(unix, not(target_os = "macos")))]
    #[error("the X server lacks the {0} extension")]
    MissingX11Extension(&'static str),
    #[error("cannot start an input thread: {0}")]
    Thread(std::io::Error),
    #[cfg(windows)]
    #[error("Windows input failed: {0}")]
    Windows(#[from] std::io::Error),
}

/// # Errors
/// Returns [`InputError::Unsupported`] when no backend fits the session
/// (no display, other platforms), or the backend's own error when it
/// cannot start.
pub fn start() -> Result<(Capture, Injector), InputError> {
    start_platform()
}

#[cfg(all(unix, not(target_os = "macos")))]
fn start_platform() -> Result<(Capture, Injector), InputError> {
    match detect_backend() {
        Backend::Wayland => wayland::start(),
        Backend::X11 => x11::start(),
        Backend::None => Err(InputError::Unsupported),
    }
}

/// The backend the current session environment calls for.
#[cfg(all(unix, not(target_os = "macos")))]
pub(crate) fn detect_backend() -> Backend {
    let session_type = std::env::var("XDG_SESSION_TYPE").ok();
    select_backend(
        session_type.as_deref(),
        env_set("DISPLAY"),
        env_set("WAYLAND_DISPLAY"),
    )
}

#[cfg(all(unix, not(target_os = "macos")))]
fn env_set(name: &str) -> bool {
    std::env::var_os(name).is_some_and(|value| !value.is_empty())
}

#[cfg(windows)]
fn start_platform() -> Result<(Capture, Injector), InputError> {
    windows::start()
}

#[cfg(target_os = "macos")]
fn start_platform() -> Result<(Capture, Injector), InputError> {
    macos::start()
}

#[cfg(not(any(windows, unix)))]
fn start_platform() -> Result<(Capture, Injector), InputError> {
    Err(InputError::Unsupported)
}

#[cfg(all(unix, not(target_os = "macos")))]
#[derive(Debug, PartialEq, Eq)]
pub(crate) enum Backend {
    Wayland,
    X11,
    None,
}

/// `XWayland` cannot capture global input, so a Wayland session never gets the
/// X11 backend even when `DISPLAY` is set.
#[cfg(all(unix, not(target_os = "macos")))]
pub(crate) fn select_backend(
    session_type: Option<&str>,
    display_set: bool,
    wayland_display_set: bool,
) -> Backend {
    if session_type == Some("wayland") {
        return if wayland_display_set {
            Backend::Wayland
        } else {
            Backend::None
        };
    }
    if display_set {
        Backend::X11
    } else {
        Backend::None
    }
}

/// Backends check this independently so a stalled daemon cannot keep input grabbed.
#[derive(Debug)]
pub struct DeadMan {
    last: Instant,
}

impl DeadMan {
    #[must_use]
    pub fn new(now: Instant) -> Self {
        Self { last: now }
    }

    pub fn keepalive(&mut self, now: Instant) {
        self.last = now;
    }

    #[must_use]
    pub fn expired(&self, now: Instant) -> bool {
        now.saturating_duration_since(self.last) >= DEADMAN_TIMEOUT
    }
}

#[cfg(test)]
mod tests {
    use super::*;

    #[cfg(all(unix, not(target_os = "macos")))]
    #[test]
    fn select_backend_session_type_and_displays_pick_backend() {
        // Arrange
        let cases = [
            (Some("wayland"), true, true, Backend::Wayland),
            (Some("wayland"), false, true, Backend::Wayland),
            (Some("wayland"), true, false, Backend::None),
            (Some("x11"), false, false, Backend::None),
            (Some("x11"), true, false, Backend::X11),
            (Some("x11"), true, true, Backend::X11),
            (None, true, false, Backend::X11),
            (None, false, true, Backend::None),
        ];

        for (session_type, display_set, wayland_display_set, expected) in cases {
            // Act
            let backend = select_backend(session_type, display_set, wayland_display_set);

            // Assert
            assert_eq!(
                backend, expected,
                "{session_type:?} display={display_set} wayland={wayland_display_set}"
            );
        }
    }

    #[test]
    fn expired_keepalive_missing_releases_at_timeout() {
        // Arrange
        let now = Instant::now();
        let mut deadman = DeadMan::new(now);
        deadman.keepalive(now + KEEPALIVE_INTERVAL);

        // Act
        let expired = [
            DEADMAN_TIMEOUT.saturating_sub(Duration::from_nanos(1)),
            DEADMAN_TIMEOUT,
        ]
        .map(|elapsed| deadman.expired(now + KEEPALIVE_INTERVAL + elapsed));

        // Assert
        assert_eq!(expired, [false, true]);
    }
}