Add a dummy backend

src/backend/consumer.rs

@@ -15,3 +15,6 @@ pub mod libei;
 
 #[cfg(target_os = "macos")]
 pub mod macos;
+
+/// fallback consumer
+pub mod dummy;

src/backend/consumer/dummy.rs

@@ -0,0 +1,21 @@
+use async_trait::async_trait;
+use crate::{consumer::EventConsumer, event::Event, client::{ClientHandle, ClientEvent}};
+
+pub struct DummyConsumer;
+
+impl DummyConsumer {
+    pub fn new() -> Self {
+        Self {}
+    }
+}
+
+#[async_trait]
+impl EventConsumer for DummyConsumer {
+    async fn consume(&mut self, event: Event, client_handle: ClientHandle) {
+        log::info!("received event: ({client_handle}) {event}");
+    }
+    async fn notify(&mut self, client_event: ClientEvent) {
+        log::info!("{client_event:?}");
+    }
+    async fn destroy(&mut self) {}
+}

src/backend/consumer/x11.rs

@@ -1,3 +1,4 @@
+use anyhow::{anyhow, Result};
 use async_trait::async_trait;
 use std::ptr;
 use x11::{xlib::{self, XCloseDisplay}, xtest};
@@ -11,15 +12,16 @@ pub struct X11Consumer {
 unsafe impl Send for X11Consumer {}
 
 impl X11Consumer {
-    pub fn new() -> Self {
+    pub fn new() -> Result<Self> {
         let display = unsafe {
             match xlib::XOpenDisplay(ptr::null()) {
-                d if d == ptr::null::<xlib::Display>() as *mut xlib::Display => None,
-                display => Some(display),
+                d if d == ptr::null::<xlib::Display>() as *mut xlib::Display => {
+                    Err(anyhow!("could not open display"))
+                }
+                display => Ok(display),
             }
-        };
-        let display = display.expect("could not open display");
-        Self { display }
+        }?;
+        Ok(Self { display })
     }
 
     fn relative_motion(&self, dx: i32, dy: i32) {
@@ -68,12 +70,6 @@ impl X11Consumer {
     }
 }
 
-impl Default for X11Consumer {
-    fn default() -> Self {
-        Self::new()
-    }
-}
-
 impl Drop for X11Consumer {
     fn drop(&mut self) {
         unsafe {

src/backend/producer.rs

@@ -1,10 +1,17 @@
 #[cfg(all(unix, feature = "libei", not(target_os = "macos")))]
 pub mod libei;
+
 #[cfg(target_os = "macos")]
 pub mod macos;
+
 #[cfg(all(unix, feature = "wayland", not(target_os = "macos")))]
 pub mod wayland;
+
 #[cfg(windows)]
 pub mod windows;
+
 #[cfg(all(unix, feature = "x11", not(target_os = "macos")))]
 pub mod x11;
+
+/// fallback event producer
+pub mod dummy;

src/backend/producer/dummy.rs

@@ -0,0 +1,41 @@
+use std::io;
+use std::pin::Pin;
+use std::task::{Poll, Context};
+
+use futures_core::Stream;
+
+use crate::event::Event;
+use crate::producer::EventProducer;
+
+use crate::client::{ClientEvent, ClientHandle};
+
+pub struct DummyProducer {}
+
+impl DummyProducer {
+    pub fn new() -> Self {
+        Self {}
+    }
+}
+
+impl Default for DummyProducer {
+    fn default() -> Self {
+        Self::new()
+    }
+}
+
+impl EventProducer for DummyProducer {
+    fn notify(&mut self, _: ClientEvent) {}
+
+    fn release(&mut self) {}
+}
+
+impl Stream for DummyProducer {
+    type Item = io::Result<(ClientHandle, Event)>;
+
+    fn poll_next(
+        self: Pin<&mut Self>,
+        _cx: &mut Context<'_>,
+    ) -> Poll<Option<Self::Item>> {
+        Poll::Pending
+    }
+}

src/backend/producer/libei.rs

@@ -1,4 +1,4 @@
-use anyhow::Result;
+use anyhow::{anyhow, Result};
 use std::{io, task::Poll};
 
 use futures_core::Stream;
@@ -9,7 +9,7 @@ pub struct LibeiProducer {}
 
 impl LibeiProducer {
     pub fn new() -> Result<Self> {
-        Ok(Self {})
+        Err(anyhow!("not implemented"))
     }
 }
 

src/backend/producer/x11.rs

@@ -1,3 +1,4 @@
+use anyhow::{anyhow, Result};
 use std::io;
 use std::task::Poll;
 
@@ -11,14 +12,8 @@ use crate::client::{ClientEvent, ClientHandle};
 pub struct X11Producer {}
 
 impl X11Producer {
-    pub fn new() -> Self {
-        Self {}
-    }
-}
-
-impl Default for X11Producer {
-    fn default() -> Self {
-        Self::new()
+    pub fn new() -> Result<Self> {
+        return Err(anyhow!("not implemented"));
     }
 }
 

src/client.rs

@@ -69,6 +69,7 @@ pub struct Client {
     pub pos: Position,
 }
 
+#[derive(Debug)]
 pub enum ClientEvent {
     Create(ClientHandle, Position),
     Destroy(ClientHandle),

src/consumer.rs

@@ -1,25 +1,13 @@
 use async_trait::async_trait;
 use std::future;
 
-#[cfg(all(unix, not(target_os = "macos")))]
-use std::env;
-
 use crate::{
     backend::consumer,
     client::{ClientEvent, ClientHandle},
     event::Event,
 };
 use anyhow::Result;
 
-#[cfg(all(unix, not(target_os = "macos")))]
-#[derive(Debug)]
-enum Backend {
-    Wlroots,
-    X11,
-    RemoteDesktopPortal,
-    Libei,
-}
-
 #[async_trait]
 pub trait EventConsumer: Send {
     async fn consume(&mut self, event: Event, client_handle: ClientHandle);
@@ -33,90 +21,55 @@ pub trait EventConsumer: Send {
     async fn destroy(&mut self);
 }
 
-pub async fn create() -> Result<Box<dyn EventConsumer>> {
+pub async fn create() -> Box<dyn EventConsumer> {
     #[cfg(windows)]
-    return Ok(Box::new(consumer::windows::WindowsConsumer::new()));
+    return Box::new(consumer::windows::WindowsConsumer::new());
 
     #[cfg(target_os = "macos")]
-    return Ok(Box::new(consumer::macos::MacOSConsumer::new()?));
-
-    #[cfg(all(unix, not(target_os = "macos")))]
-    let backend = match env::var("XDG_SESSION_TYPE") {
-        Ok(session_type) => match session_type.as_str() {
-            "x11" => {
-                log::info!("XDG_SESSION_TYPE = x11 -> using x11 event consumer");
-                Backend::X11
-            }
-            "wayland" => {
-                log::info!("XDG_SESSION_TYPE = wayland -> using wayland event consumer");
-                match env::var("XDG_CURRENT_DESKTOP") {
-                    Ok(current_desktop) => match current_desktop.as_str() {
-                        "GNOME" => {
-                            log::info!("XDG_CURRENT_DESKTOP = GNOME -> using libei backend");
-                            Backend::Libei
-                        }
-                        "KDE" => {
-                            log::info!(
-                                "XDG_CURRENT_DESKTOP = KDE -> using xdg_desktop_portal backend"
-                            );
-                            Backend::RemoteDesktopPortal
-                        }
-                        "sway" => {
-                            log::info!("XDG_CURRENT_DESKTOP = sway -> using wlroots backend");
-                            Backend::Wlroots
-                        }
-                        "Hyprland" => {
-                            log::info!("XDG_CURRENT_DESKTOP = Hyprland -> using wlroots backend");
-                            Backend::Wlroots
-                        }
-                        _ => {
-                            log::warn!(
-                                "unknown XDG_CURRENT_DESKTOP -> defaulting to wlroots backend"
-                            );
-                            Backend::Wlroots
-                        }
-                    },
-                    // default to wlroots backend for now
-                    _ => {
-                        log::warn!("unknown XDG_CURRENT_DESKTOP -> defaulting to wlroots backend");
-                        Backend::Wlroots
-                    }
-                }
-            }
-            _ => panic!("unknown XDG_SESSION_TYPE"),
-        },
-        Err(_) => {
-            panic!("could not detect session type: XDG_SESSION_TYPE environment variable not set!")
+    match consumer::macos::MacOSConsumer::new() {
+        Ok(c) => {
+            log::info!("using macos event consumer");
+            return Box::new(c);
         }
-    };
+        Err(e) => log::error!("macos consumer not available: {e}"),
+    }
 
-    #[cfg(all(unix, not(target_os = "macos")))]
-    match backend {
-        Backend::Libei => {
-            #[cfg(not(feature = "libei"))]
-            panic!("feature libei not enabled");
-            #[cfg(feature = "libei")]
-            Ok(Box::new(consumer::libei::LibeiConsumer::new().await?))
+    #[cfg(all(unix, feature = "wayland", not(target_os = "macos")))]
+    match consumer::wlroots::WlrootsConsumer::new() {
+        Ok(c) => {
+            log::info!("using wlroots event consumer");
+            return Box::new(c);
         }
-        Backend::RemoteDesktopPortal => {
-            #[cfg(not(feature = "xdg_desktop_portal"))]
-            panic!("feature xdg_desktop_portal not enabled");
-            #[cfg(feature = "xdg_desktop_portal")]
-            Ok(Box::new(
-                consumer::xdg_desktop_portal::DesktopPortalConsumer::new().await?,
-            ))
+        Err(e) => log::info!("wayland backend not available: {e}"),
+    }
+
+    #[cfg(all(unix, feature = "libei", not(target_os = "macos")))]
+    match consumer::libei::LibeiConsumer::new().await {
+        Ok(c) => {
+            log::info!("using libei event consumer");
+            return Box::new(c);
         }
-        Backend::Wlroots => {
-            #[cfg(not(feature = "wayland"))]
-            panic!("feature wayland not enabled");
-            #[cfg(feature = "wayland")]
-            Ok(Box::new(consumer::wlroots::WlrootsConsumer::new()?))
+        Err(e) => log::info!("libei not available: {e}"),
+    }
+
+    #[cfg(all(unix, feature = "xdg_desktop_portal", not(target_os = "macos")))]
+    match consumer::xdg_desktop_portal::DesktopPortalConsumer::new().await {
+        Ok(c) => {
+            log::info!("using xdg-remote-desktop-portal event consumer");
+            return Box::new(c);
         }
-        Backend::X11 => {
-            #[cfg(not(feature = "x11"))]
-            panic!("feature x11 not enabled");
-            #[cfg(feature = "x11")]
-            Ok(Box::new(consumer::x11::X11Consumer::new()))
+        Err(e) => log::info!("remote desktop portal not available: {e}"),
+    }
+
+    #[cfg(all(unix, feature = "x11", not(target_os = "macos")))]
+    match consumer::x11::X11Consumer::new() {
+        Ok(c) => {
+            log::info!("using x11 event consumer");
+            return Box::new(c);
         }
+        Err(e) => log::info!("x11 consumer not available: {e}"),
     }
+
+    log::error!("falling back to dummy event consumer");
+    Box::new(consumer::dummy::DummyConsumer::new())
 }

src/main.rs

@@ -70,8 +70,7 @@ fn run_service(config: &Config) -> Result<()> {
         };
 
         // create event producer and consumer
-        let (producer, consumer) = join!(producer::create(), consumer::create(),);
-        let (producer, consumer) = (producer?, consumer?);
+        let (producer, consumer) = join!(producer::create(), consumer::create());
 
         // create server
         let mut event_server = Server::new(config, frontend_adapter, consumer, producer).await?;