mod core;
mod display;
mod dmabuf;
mod mesa_drm;
mod presentation;
mod registry;
mod util;
mod vulkano_data;
mod xdg;

use crate::core::registry::OwnedRegistry;
use crate::nodes::drawable::model::ModelNodeSystemSet;
use crate::wayland::core::seat::SeatMessage;
use crate::wayland::core::surface::Surface;
use crate::wayland::presentation::MonotonicTimestamp;
use crate::{
	BevyMaterial,
	core::{
		error::{Result, ServerError},
		task,
	},
};
use bevy::app::{App, Plugin, Update};
use bevy::ecs::schedule::IntoScheduleConfigs;
use bevy::ecs::system::{Local, Res, ResMut};
use bevy::prelude::{Deref, DerefMut};
use bevy::render::renderer::RenderDevice;
use bevy::render::{Render, RenderApp};
use bevy::{asset::Assets, ecs::resource::Resource, image::Image};
use bevy_dmabuf::import::ImportedDmatexs;
use bevy_mod_openxr::render::end_frame;
use bevy_mod_xr::session::XrRenderSet;
use cluFlock::{FlockLock, ToFlock};
use core::buffer::BufferUsage;
use core::{buffer::Buffer, callback::Callback, surface::WL_SURFACE_REGISTRY};
use display::Display;
use mint::Vector2;
use std::fs::File;
use std::time::Duration;
use std::{
	fs::{self, OpenOptions},
	io::{self, ErrorKind},
	os::unix::fs::OpenOptionsExt,
	path::PathBuf,
	sync::{Arc, OnceLock},
};
use tokio::{net::UnixStream, sync::mpsc, task::AbortHandle};
use tokio_stream::StreamExt;
use tracing::{debug_span, instrument};
use vulkano_data::setup_vulkano_context;
use waynest::{
	server::{
		self,
		protocol::{
			core::wayland::{wl_buffer::WlBuffer, wl_callback::WlCallback, wl_display::WlDisplay},
			stable::xdg_shell::xdg_toplevel::XdgToplevel,
		},
	},
	wire::{DecodeError, ObjectId},
};
use xdg::toplevel::Toplevel;

pub static WAYLAND_DISPLAY: OnceLock<PathBuf> = OnceLock::new();

impl From<waynest::server::Error> for ServerError {
	fn from(err: waynest::server::Error) -> Self {
		ServerError::WaylandError(err)
	}
}

pub fn get_free_wayland_socket_path() -> Option<(PathBuf, FlockLock<File>)> {
	// Use XDG runtime directory for secure, user-specific sockets
	let base_dirs = directories::BaseDirs::new()?;
	let runtime_dir = base_dirs.runtime_dir()?;

	// Iterate through conventional display numbers (matches X11 behavior)
	for display in 0..=32 {
		let socket_path = runtime_dir.join(format!("wayland-{display}"));
		let socket_lock_path = runtime_dir.join(format!("wayland-{display}.lock"));

		// Open lock file without truncation to preserve existing locks
		let Ok(lock) = OpenOptions::new()
			.create(true)
			.truncate(false) // Prevent destroying other processes' locks
			.read(true)
			.write(true)
			.mode(0o660) // Match Wayland-compositor permissions
			.open(&socket_lock_path)
		else {
			continue;
		};

		// Atomic mutual exclusion: fail if another process holds the lock\
		let Ok(lock) = lock.try_exclusive_lock() else {
			continue; // Lock held by active compositor
		};

		// Check for zombie sockets (file exists but nothing listening)
		if socket_path.exists() {
			match std::os::unix::net::UnixStream::connect(&socket_path) {
				Ok(_) => continue, // Active compositor found - skip
				Err(e) if e.kind() == ErrorKind::ConnectionRefused => {
					// Stale socket - safe to remove since we hold the lock
					let _ = fs::remove_file(&socket_path);
				}
				Err(_) => continue, // Transient error - conservative skip
			}
		}

		// Found viable candidate: lock held, socket cleared/available
		return Some((socket_path, lock));
	}

	None // Exhausted all conventional display numbers
}

pub enum Message {
	Disconnect,
	Frame(Arc<Callback>),
	ReleaseBuffer(Arc<Buffer>),
	CloseToplevel(Arc<Toplevel>),
	ResizeToplevel {
		toplevel: Arc<Toplevel>,
		size: Option<Vector2<u32>>,
	},
	SetToplevelVisualActive {
		toplevel: Arc<Toplevel>,
		active: bool,
	},
	Seat(SeatMessage),
	SendPresentationFeedback {
		surface: Arc<Surface>,
		display_timestamp: MonotonicTimestamp,
		refresh_cycle: u64,
	},
}

pub type MessageSink = mpsc::UnboundedSender<Message>;

#[derive(Debug)]
struct WaylandClient {
	abort_handle: AbortHandle,
}
impl WaylandClient {
	pub fn from_stream(socket: UnixStream) -> Result<Self> {
		let pid = socket.peer_cred().ok().and_then(|c| c.pid());
		let mut client = server::Client::new(socket)?;
		let (message_sink, message_source) = mpsc::unbounded_channel();

		client.insert(ObjectId::DISPLAY, Display::new(message_sink, pid));
		let abort_handle = task::new(
			|| "wayland client",
			Self::handle_client_messages(client, message_source),
		)?
		.abort_handle();

		Ok(WaylandClient { abort_handle })
	}
	async fn handle_client_messages(
		mut client: server::Client,
		mut render_message_rx: mpsc::UnboundedReceiver<Message>,
	) -> Result<()> {
		loop {
			tokio::select! {
				// send all queued up messages
				msg = render_message_rx.recv() => {
					if let Some(msg) = msg {
						Self::handle_render_message(&mut client, msg).await?;
					}
				}
				// handle the next message
				msg = client.next_message() => {
					match msg {
						Ok(Some(mut msg)) => {
							if let Err(e) = client.handle_message(&mut msg).await {
								tracing::error!("Wayland: Error handling message: {:?}", e);
								break;
							}
						}
						Err(e) => {
							// wayland clients really aren't nice when disconnecting properly, are they? :p
							if let server::Error::Decode(DecodeError::IoError(e)) = &e && e.kind() == io::ErrorKind::ConnectionReset {
									if let Some(pid) = client.get::<Display>(ObjectId::DISPLAY).and_then(|d| d.pid) {
										tracing::info!("Wayland: Client with pid: {pid} disconnected from server");
									} else {
										tracing::info!("Wayland: Unknown client disconnected from server");
									}
									break;
							}
							tracing::error!("Wayland: Error reading message: {:?}", e);
							break;
						}
						Ok(None) => {
							if let Some(pid) = client.get::<Display>(ObjectId::DISPLAY).and_then(|d| d.pid) {
								tracing::info!("Wayland: Client with pid: {pid} disconnected from server");
							} else {
								tracing::info!("Wayland: Unknown client disconnected from server");
							}
							// Message stream ended
							break;
						}
					}
				}
			}
		}
		Ok(())
	}

	async fn handle_render_message(
		client: &mut server::Client,
		message: Message,
	) -> Result<bool, waynest::server::Error> {
		match message {
			Message::Disconnect => return Ok(true),
			Message::Frame(callback) => {
				let now = rustix::time::clock_gettime(rustix::time::ClockId::Monotonic);
				let now = Duration::new(now.tv_sec as u64, now.tv_nsec as u32);
				let ms = (now.as_millis() % (u32::MAX as u128)) as u32;
				callback.done(client, callback.0, ms).await?;
				client
					.get::<Display>(ObjectId::DISPLAY)
					.unwrap()
					.delete_id(client, ObjectId::DISPLAY, callback.0.as_raw())
					.await?;
				client.remove(callback.0);
			}
			Message::ReleaseBuffer(buffer) => {
				buffer.release(client, buffer.id).await?;
			}
			Message::CloseToplevel(toplevel) => {
				toplevel.close(client, toplevel.id).await?;
			}
			Message::ResizeToplevel { toplevel, size } => {
				toplevel.set_size(size);
				toplevel.reconfigure(client).await?;
			}
			Message::SetToplevelVisualActive { toplevel, active } => {
				toplevel.set_activated(active);
				toplevel.reconfigure(client).await?;
			}
			Message::Seat(seat_message) => {
				if let Some(seat) = client.get::<Display>(ObjectId::DISPLAY).unwrap().seat.get() {
					seat.handle_message(client, seat_message).await?;
				}
			}
			Message::SendPresentationFeedback {
				surface,
				display_timestamp,
				refresh_cycle,
			} => {
				surface
					.send_presentation_feedback(client, display_timestamp, refresh_cycle)
					.await?;
			}
		}
		Ok(false)
	}
}
impl Drop for WaylandClient {
	fn drop(&mut self) {
		self.abort_handle.abort();
	}
}

#[derive(Debug, Resource)]
pub struct Wayland {
	_lockfile: FlockLock<File>,
	abort_handle: AbortHandle,
}
impl Wayland {
	pub fn new() -> Result<Self> {
		let (socket_path, _lockfile) =
			get_free_wayland_socket_path().ok_or(ServerError::WaylandError(
				waynest::server::Error::IoError(std::io::ErrorKind::AddrNotAvailable.into()),
			))?;

		let _ = WAYLAND_DISPLAY.set(socket_path.clone());

		let listener =
			server::Listener::new_with_path(&socket_path).map_err(ServerError::WaylandError)?;

		let abort_handle =
			task::new(|| "wayland loop", Self::handle_wayland_loop(listener))?.abort_handle();

		Ok(Self {
			_lockfile,
			abort_handle,
		})
	}
	async fn handle_wayland_loop(mut listener: server::Listener) -> Result<()> {
		let mut clients = Vec::new();
		loop {
			if let Ok(Some(stream)) = listener.try_next().await {
				debug_span!("Accept wayland client").in_scope(|| {
					if let Ok(client) = WaylandClient::from_stream(stream) {
						clients.push(client);
					}
				});
			}
			clients.retain(|client| !client.abort_handle.is_finished());
		}

		#[allow(unreachable_code)]
		Ok(())
	}
}
impl Drop for Wayland {
	fn drop(&mut self) {
		self.abort_handle.abort();
	}
}

static RENDER_DEVICE: OnceLock<RenderDevice> = OnceLock::new();

pub struct WaylandPlugin;
impl Plugin for WaylandPlugin {
	fn build(&self, app: &mut App) {
		app.add_systems(Update, update_graphics.before(ModelNodeSystemSet));
		app.init_resource::<UsedBuffers>();
		app.sub_app_mut(RenderApp)
			.init_resource::<UsedBuffers>()
			.add_systems(
				Render,
				init_render_device.run_if(|| RENDER_DEVICE.get().is_none()),
			);
	}
	fn finish(&self, app: &mut App) {
		app.sub_app_mut(RenderApp)
			.add_systems(Render, setup_vulkano_context)
			.add_systems(Render, before_render.in_set(XrRenderSet::PreRender))
			.add_systems(Render, after_render.in_set(XrRenderSet::PostRender))
			.add_systems(
				Render,
				submit_frame_timings
					.in_set(XrRenderSet::PostRender)
					.after(end_frame),
			);
	}
}

fn init_render_device(dev: Res<RenderDevice>) {
	_ = RENDER_DEVICE.set(dev.clone());
}

#[derive(Resource, Deref, DerefMut)]
struct UsedBuffers(OwnedRegistry<BufferUsage>);
impl Default for UsedBuffers {
	fn default() -> Self {
		Self(OwnedRegistry::new())
	}
}

fn before_render(buffers: Res<UsedBuffers>) {
	for buf in WL_SURFACE_REGISTRY
		.get_valid_contents()
		.into_iter()
		.filter_map(|surface| surface.current_state().buffer)
		.filter_map(|buffer| buffer.usage)
	{
		buffers.add_raw(buf);
	}
	for surface in WL_SURFACE_REGISTRY.get_valid_contents() {
		surface.frame_event();
	}
}

fn after_render(buffers: Res<UsedBuffers>) {
	buffers.clear();
}

#[instrument(level = "debug", name = "Wayland frame", skip_all)]
fn update_graphics(
	dmatexes: Res<ImportedDmatexs>,
	mut materials: ResMut<Assets<BevyMaterial>>,
	mut images: ResMut<Assets<Image>>,
) {
	for surface in WL_SURFACE_REGISTRY.get_valid_contents() {
		surface.update_graphics(&dmatexes, &mut materials, &mut images);
	}
}

#[instrument(level = "debug", name = "Wayland frame", skip_all)]
fn submit_frame_timings(mut frame_count: Local<u64>) {
	*frame_count += 1;
	for surface in WL_SURFACE_REGISTRY.get_valid_contents() {
		let display_timestamp =
			rustix::time::clock_gettime(rustix::time::ClockId::Monotonic).into();
		surface.submit_presentation_feedback(display_timestamp, *frame_count);
	}
}