Merge pull request #223 from zellij-org/isolate-pty

Psuedo Client-Server model

1 files changed, 810 insertions, 4 deletions

diff --git a/src/server/mod.rs b/src/server/mod.rs
index 626b4e6b..6eb2455b 100644
--- a/src/server/mod.rs
+++ b/src/server/mod.rs
@@ -1,5 +1,811 @@
-use super::super::common::{screen};
+use interprocess::local_socket::LocalSocketListener;
+use serde::{Deserialize, Serialize};
+use std::path::PathBuf;
+use std::sync::mpsc::channel;
+use std::thread;
+use std::{collections::HashMap, fs};
+use std::{
+    collections::HashSet,
+    str::FromStr,
+    sync::{Arc, Mutex, RwLock},
+};
+use wasmer::{ChainableNamedResolver, Instance, Module, Store, Value};
+use wasmer_wasi::{Pipe, WasiState};
+use zellij_tile::data::{Event, EventType, InputMode, ModeInfo};
 
-pub fn start_server() {
-  // TODO
-}
\ No newline at end of file
+use crate::cli::CliArgs;
+use crate::client::ClientInstruction;
+use crate::common::{
+    errors::{ContextType, PluginContext, PtyContext, ScreenContext, ServerContext},
+    input::actions::{Action, Direction},
+    input::handler::get_mode_info,
+    os_input_output::{set_permissions, ServerOsApi},
+    pty_bus::{PtyBus, PtyInstruction},
+    screen::{Screen, ScreenInstruction},
+    setup::install::populate_data_dir,
+    utils::consts::{ZELLIJ_IPC_PIPE, ZELLIJ_PROJ_DIR},
+    wasm_vm::{wasi_read_string, wasi_write_object, zellij_exports, PluginEnv, PluginInstruction},
+    ChannelWithContext, SenderType, SenderWithContext,
+};
+use crate::layout::Layout;
+use crate::panes::PaneId;
+use crate::panes::PositionAndSize;
+
+/// Instructions related to server-side application including the
+/// ones sent by client to server
+#[derive(Serialize, Deserialize, Debug, Clone)]
+pub enum ServerInstruction {
+    TerminalResize(PositionAndSize),
+    NewClient(PositionAndSize, CliArgs),
+    Action(Action),
+    Render(Option<String>),
+    UnblockInputThread,
+    ClientExit,
+}
+
+struct SessionMetaData {
+    pub send_pty_instructions: SenderWithContext<PtyInstruction>,
+    pub send_screen_instructions: SenderWithContext<ScreenInstruction>,
+    pub send_plugin_instructions: SenderWithContext<PluginInstruction>,
+    screen_thread: Option<thread::JoinHandle<()>>,
+    pty_thread: Option<thread::JoinHandle<()>>,
+    wasm_thread: Option<thread::JoinHandle<()>>,
+}
+
+impl Drop for SessionMetaData {
+    fn drop(&mut self) {
+        let _ = self.send_pty_instructions.send(PtyInstruction::Exit);
+        let _ = self.send_screen_instructions.send(ScreenInstruction::Exit);
+        let _ = self.send_plugin_instructions.send(PluginInstruction::Exit);
+        let _ = self.screen_thread.take().unwrap().join();
+        let _ = self.pty_thread.take().unwrap().join();
+        let _ = self.wasm_thread.take().unwrap().join();
+    }
+}
+
+pub fn start_server(os_input: Box<dyn ServerOsApi>) -> thread::JoinHandle<()> {
+    let (send_server_instructions, receive_server_instructions): ChannelWithContext<
+        ServerInstruction,
+    > = channel();
+    let send_server_instructions =
+        SenderWithContext::new(SenderType::Sender(send_server_instructions));
+    let sessions: Arc<RwLock<Option<SessionMetaData>>> = Arc::new(RwLock::new(None));
+
+    #[cfg(test)]
+    handle_client(
+        sessions.clone(),
+        os_input.clone(),
+        send_server_instructions.clone(),
+    );
+    #[cfg(not(test))]
+    let _ = thread::Builder::new()
+        .name("server_listener".to_string())
+        .spawn({
+            let os_input = os_input.clone();
+            let sessions = sessions.clone();
+            let send_server_instructions = send_server_instructions.clone();
+            move || {
+                drop(std::fs::remove_file(&*ZELLIJ_IPC_PIPE));
+                let listener = LocalSocketListener::bind(&**ZELLIJ_IPC_PIPE).unwrap();
+                set_permissions(&*ZELLIJ_IPC_PIPE);
+                for stream in listener.incoming() {
+                    match stream {
+                        Ok(stream) => {
+                            let mut os_input = os_input.clone();
+                            os_input.update_receiver(stream);
+                            let sessions = sessions.clone();
+                            let send_server_instructions = send_server_instructions.clone();
+                            handle_client(sessions, os_input, send_server_instructions);
+                        }
+                        Err(err) => {
+                            panic!("err {:?}", err);
+                        }
+                    }
+                }
+            }
+        });
+
+    thread::Builder::new()
+        .name("server_thread".to_string())
+        .spawn({
+            move || loop {
+                let (instruction, mut err_ctx) = receive_server_instructions.recv().unwrap();
+                err_ctx.add_call(ContextType::IPCServer(ServerContext::from(&instruction)));
+                match instruction {
+                    ServerInstruction::NewClient(full_screen_ws, opts) => {
+                        let session_data = init_session(
+                            os_input.clone(),
+                            opts,
+                            send_server_instructions.clone(),
+                            full_screen_ws,
+                        );
+                        *sessions.write().unwrap() = Some(session_data);
+                        sessions
+                            .read()
+                            .unwrap()
+                            .as_ref()
+                            .unwrap()
+                            .send_pty_instructions
+                            .send(PtyInstruction::NewTab)
+                            .unwrap();
+                    }
+                    ServerInstruction::UnblockInputThread => {
+                        os_input.send_to_client(ClientInstruction::UnblockInputThread);
+                    }
+                    ServerInstruction::ClientExit => {
+                        *sessions.write().unwrap() = None;
+                        os_input.send_to_client(ClientInstruction::Exit);
+                        drop(std::fs::remove_file(&*ZELLIJ_IPC_PIPE));
+                        break;
+                    }
+                    ServerInstruction::Render(output) => {
+                        os_input.send_to_client(ClientInstruction::Render(output))
+                    }
+                    _ => panic!("Received unexpected instruction."),
+                }
+            }
+        })
+        .unwrap()
+}
+
+fn handle_client(
+    sessions: Arc<RwLock<Option<SessionMetaData>>>,
+    mut os_input: Box<dyn ServerOsApi>,
+    send_server_instructions: SenderWithContext<ServerInstruction>,
+) {
+    thread::Builder::new()
+        .name("server_router".to_string())
+        .spawn(move || loop {
+            let (instruction, mut err_ctx) = os_input.recv_from_client();
+            err_ctx.add_call(ContextType::IPCServer(ServerContext::from(&instruction)));
+            let rlocked_sessions = sessions.read().unwrap();
+            match instruction {
+                ServerInstruction::ClientExit => {
+                    send_server_instructions.send(instruction).unwrap();
+                    break;
+                }
+                ServerInstruction::Action(action) => {
+                    route_action(action, rlocked_sessions.as_ref().unwrap(), &*os_input);
+                }
+                ServerInstruction::TerminalResize(new_size) => {
+                    rlocked_sessions
+                        .as_ref()
+                        .unwrap()
+                        .send_screen_instructions
+                        .send(ScreenInstruction::TerminalResize(new_size))
+                        .unwrap();
+                }
+                ServerInstruction::NewClient(..) => {
+                    os_input.add_client_sender();
+                    send_server_instructions.send(instruction).unwrap();
+                }
+                _ => {
+                    send_server_instructions.send(instruction).unwrap();
+                }
+            }
+        })
+        .unwrap();
+}
+
+fn init_session(
+    os_input: Box<dyn ServerOsApi>,
+    opts: CliArgs,
+    send_server_instructions: SenderWithContext<ServerInstruction>,
+    full_screen_ws: PositionAndSize,
+) -> SessionMetaData {
+    let (send_screen_instructions, receive_screen_instructions): ChannelWithContext<
+        ScreenInstruction,
+    > = channel();
+    let send_screen_instructions =
+        SenderWithContext::new(SenderType::Sender(send_screen_instructions));
+
+    let (send_plugin_instructions, receive_plugin_instructions): ChannelWithContext<
+        PluginInstruction,
+    > = channel();
+    let send_plugin_instructions =
+        SenderWithContext::new(SenderType::Sender(send_plugin_instructions));
+    let (send_pty_instructions, receive_pty_instructions): ChannelWithContext<PtyInstruction> =
+        channel();
+    let send_pty_instructions = SenderWithContext::new(SenderType::Sender(send_pty_instructions));
+
+    // Determine and initialize the data directory
+    let data_dir = opts
+        .data_dir
+        .unwrap_or_else(|| ZELLIJ_PROJ_DIR.data_dir().to_path_buf());
+    populate_data_dir(&data_dir);
+
+    // Don't use default layouts in tests, but do everywhere else
+    #[cfg(not(test))]
+    let default_layout = Some(PathBuf::from("default"));
+    #[cfg(test)]
+    let default_layout = None;
+    let maybe_layout = opts
+        .layout
+        .map(|p| Layout::new(&p, &data_dir))
+        .or_else(|| default_layout.map(|p| Layout::from_defaults(&p, &data_dir)));
+
+    let mut pty_bus = PtyBus::new(
+        receive_pty_instructions,
+        send_screen_instructions.clone(),
+        send_plugin_instructions.clone(),
+        os_input.clone(),
+        opts.debug,
+    );
+
+    let pty_thread = thread::Builder::new()
+        .name("pty".to_string())
+        .spawn({
+            let send_server_instructions = send_server_instructions.clone();
+            move || loop {
+                let (event, mut err_ctx) = pty_bus
+                    .receive_pty_instructions
+                    .recv()
+                    .expect("failed to receive event on channel");
+                err_ctx.add_call(ContextType::Pty(PtyContext::from(&event)));
+                match event {
+                    PtyInstruction::SpawnTerminal(file_to_open) => {
+                        let pid = pty_bus.spawn_terminal(file_to_open);
+                        pty_bus
+                            .send_screen_instructions
+                            .send(ScreenInstruction::NewPane(PaneId::Terminal(pid)))
+                            .unwrap();
+                    }
+                    PtyInstruction::SpawnTerminalVertically(file_to_open) => {
+                        let pid = pty_bus.spawn_terminal(file_to_open);
+                        pty_bus
+                            .send_screen_instructions
+                            .send(ScreenInstruction::VerticalSplit(PaneId::Terminal(pid)))
+                            .unwrap();
+                    }
+                    PtyInstruction::SpawnTerminalHorizontally(file_to_open) => {
+                        let pid = pty_bus.spawn_terminal(file_to_open);
+                        pty_bus
+                            .send_screen_instructions
+                            .send(ScreenInstruction::HorizontalSplit(PaneId::Terminal(pid)))
+                            .unwrap();
+                    }
+                    PtyInstruction::NewTab => {
+                        if let Some(layout) = maybe_layout.clone() {
+                            pty_bus.spawn_terminals_for_layout(layout);
+                        } else {
+                            let pid = pty_bus.spawn_terminal(None);
+                            pty_bus
+                                .send_screen_instructions
+                                .send(ScreenInstruction::NewTab(pid))
+                                .unwrap();
+                        }
+                    }
+                    PtyInstruction::ClosePane(id) => {
+                        pty_bus.close_pane(id);
+                        send_server_instructions
+                            .send(ServerInstruction::UnblockInputThread)
+                            .unwrap();
+                    }
+                    PtyInstruction::CloseTab(ids) => {
+                        pty_bus.close_tab(ids);
+                        send_server_instructions
+                            .send(ServerInstruction::UnblockInputThread)
+                            .unwrap();
+                    }
+                    PtyInstruction::Exit => {
+                        break;
+                    }
+                }
+            }
+        })
+        .unwrap();
+
+    let screen_thread = thread::Builder::new()
+        .name("screen".to_string())
+        .spawn({
+            let os_input = os_input.clone();
+            let send_plugin_instructions = send_plugin_instructions.clone();
+            let send_pty_instructions = send_pty_instructions.clone();
+            let send_server_instructions = send_server_instructions;
+            let max_panes = opts.max_panes;
+            let colors = os_input.load_palette();
+
+            move || {
+                let mut screen = Screen::new(
+                    receive_screen_instructions,
+                    send_plugin_instructions,
+                    send_pty_instructions,
+                    send_server_instructions,
+                    &full_screen_ws,
+                    os_input,
+                    max_panes,
+                    ModeInfo {
+                        palette: colors,
+                        ..ModeInfo::default()
+                    },
+                    InputMode::Normal,
+                    colors,
+                );
+                loop {
+                    let (event, mut err_ctx) = screen
+                        .receiver
+                        .recv()
+                        .expect("failed to receive event on channel");
+                    err_ctx.add_call(ContextType::Screen(ScreenContext::from(&event)));
+                    match event {
+                        ScreenInstruction::PtyBytes(pid, vte_bytes) => {
+                            let active_tab = screen.get_active_tab_mut().unwrap();
+                            if active_tab.has_terminal_pid(pid) {
+                                // it's most likely that this event is directed at the active tab
+                                // look there first
+                                active_tab.handle_pty_bytes(pid, vte_bytes);
+                            } else {
+                                // if this event wasn't directed at the active tab, start looking
+                                // in other tabs
+                                let all_tabs = screen.get_tabs_mut();
+                                for tab in all_tabs.values_mut() {
+                                    if tab.has_terminal_pid(pid) {
+                                        tab.handle_pty_bytes(pid, vte_bytes);
+                                        break;
+                                    }
+                                }
+                            }
+                        }
+                        ScreenInstruction::Render => {
+                            screen.render();
+                        }
+                        ScreenInstruction::NewPane(pid) => {
+                            screen.get_active_tab_mut().unwrap().new_pane(pid);
+                            screen
+                                .send_server_instructions
+                                .send(ServerInstruction::UnblockInputThread)
+                                .unwrap();
+                        }
+                        ScreenInstruction::HorizontalSplit(pid) => {
+                            screen.get_active_tab_mut().unwrap().horizontal_split(pid);
+                            screen
+                                .send_server_instructions
+                                .send(ServerInstruction::UnblockInputThread)
+                                .unwrap();
+                        }
+                        ScreenInstruction::VerticalSplit(pid) => {
+                            screen.get_active_tab_mut().unwrap().vertical_split(pid);
+                            screen
+                                .send_server_instructions
+                                .send(ServerInstruction::UnblockInputThread)
+                                .unwrap();
+                        }
+                        ScreenInstruction::WriteCharacter(bytes) => {
+                            let active_tab = screen.get_active_tab_mut().unwrap();
+                            match active_tab.is_sync_panes_active() {
+                                true => active_tab.write_to_terminals_on_current_tab(bytes),
+                                false => active_tab.write_to_active_terminal(bytes),
+                            }
+                        }
+                        ScreenInstruction::ResizeLeft => {
+                            screen.get_active_tab_mut().unwrap().resize_left();
+                        }
+                        ScreenInstruction::ResizeRight => {
+                            screen.get_active_tab_mut().unwrap().resize_right();
+                        }
+                        ScreenInstruction::ResizeDown => {
+                            screen.get_active_tab_mut().unwrap().resize_down();
+                        }
+                        ScreenInstruction::ResizeUp => {
+                            screen.get_active_tab_mut().unwrap().resize_up();
+                        }
+                        ScreenInstruction::SwitchFocus => {
+                            screen.get_active_tab_mut().unwrap().move_focus();
+                        }
+                        ScreenInstruction::FocusNextPane => {
+                            screen.get_active_tab_mut().unwrap().focus_next_pane();
+                        }
+                        ScreenInstruction::FocusPreviousPane => {
+                            screen.get_active_tab_mut().unwrap().focus_previous_pane();
+                        }
+                        ScreenInstruction::MoveFocusLeft => {
+                            screen.get_active_tab_mut().unwrap().move_focus_left();
+                        }
+                        ScreenInstruction::MoveFocusDown => {
+                            screen.get_active_tab_mut().unwrap().move_focus_down();
+                        }
+                        ScreenInstruction::MoveFocusRight => {
+                            screen.get_active_tab_mut().unwrap().move_focus_right();
+                        }
+                        ScreenInstruction::MoveFocusUp => {
+                            screen.get_active_tab_mut().unwrap().move_focus_up();
+                        }
+                        ScreenInstruction::ScrollUp => {
+                            screen
+                                .get_active_tab_mut()
+                                .unwrap()
+                                .scroll_active_terminal_up();
+                        }
+                        ScreenInstruction::ScrollDown => {
+                            screen
+                                .get_active_tab_mut()
+                                .unwrap()
+                                .scroll_active_terminal_down();
+                        }
+                        ScreenInstruction::PageScrollUp => {
+                            screen
+                                .get_active_tab_mut()
+                                .unwrap()
+                                .scroll_active_terminal_up_page();
+                        }
+                        ScreenInstruction::PageScrollDown => {
+                            screen
+                                .get_active_tab_mut()
+                                .unwrap()
+                                .scroll_active_terminal_down_page();
+                        }
+                        ScreenInstruction::ClearScroll => {
+                            screen
+                                .get_active_tab_mut()
+                                .unwrap()
+                                .clear_active_terminal_scroll();
+                        }
+                        ScreenInstruction::CloseFocusedPane => {
+                            screen.get_active_tab_mut().unwrap().close_focused_pane();
+                            screen.render();
+                        }
+                        ScreenInstruction::SetSelectable(id, selectable) => {
+                            screen
+                                .get_active_tab_mut()
+                                .unwrap()
+                                .set_pane_selectable(id, selectable);
+                        }
+                        ScreenInstruction::SetMaxHeight(id, max_height) => {
+                            screen
+                                .get_active_tab_mut()
+                                .unwrap()
+                                .set_pane_max_height(id, max_height);
+                        }
+                        ScreenInstruction::SetInvisibleBorders(id, invisible_borders) => {
+                            screen
+                                .get_active_tab_mut()
+                                .unwrap()
+                                .set_pane_invisible_borders(id, invisible_borders);
+                            screen.render();
+                        }
+                        ScreenInstruction::ClosePane(id) => {
+                            screen.get_active_tab_mut().unwrap().close_pane(id);
+                            screen.render();
+                        }
+                        ScreenInstruction::ToggleActiveTerminalFullscreen => {
+                            screen
+                                .get_active_tab_mut()
+                                .unwrap()
+                                .toggle_active_pane_fullscreen();
+                        }
+                        ScreenInstruction::NewTab(pane_id) => {
+                            screen.new_tab(pane_id);
+                            screen
+                                .send_server_instructions
+                                .send(ServerInstruction::UnblockInputThread)
+                                .unwrap();
+                        }
+                        ScreenInstruction::SwitchTabNext => {
+                            screen.switch_tab_next();
+                            screen
+                                .send_server_instructions
+                                .send(ServerInstruction::UnblockInputThread)
+                                .unwrap();
+                        }
+                        ScreenInstruction::SwitchTabPrev => {
+                            screen.switch_tab_prev();
+                            screen
+                                .send_server_instructions
+                                .send(ServerInstruction::UnblockInputThread)
+                                .unwrap();
+                        }
+                        ScreenInstruction::CloseTab => {
+                            screen.close_tab();
+                            screen
+                                .send_server_instructions
+                                .send(ServerInstruction::UnblockInputThread)
+                                .unwrap();
+                        }
+                        ScreenInstruction::ApplyLayout(layout, new_pane_pids) => {
+                            screen.apply_layout(layout, new_pane_pids);
+                            screen
+                                .send_server_instructions
+                                .send(ServerInstruction::UnblockInputThread)
+                                .unwrap();
+                        }
+                        ScreenInstruction::GoToTab(tab_index) => {
+                            screen.go_to_tab(tab_index as usize);
+                            screen
+                                .send_server_instructions
+                                .send(ServerInstruction::UnblockInputThread)
+                                .unwrap();
+                        }
+                        ScreenInstruction::UpdateTabName(c) => {
+                            screen.update_active_tab_name(c);
+                            screen
+                                .send_server_instructions
+                                .send(ServerInstruction::UnblockInputThread)
+                                .unwrap();
+                        }
+                        ScreenInstruction::TerminalResize(new_size) => {
+                            screen.resize_to_screen(new_size);
+                        }
+                        ScreenInstruction::ChangeMode(mode_info) => {
+                            screen.change_mode(mode_info);
+                        }
+                        ScreenInstruction::ToggleActiveSyncPanes => {
+                            screen
+                                .get_active_tab_mut()
+                                .unwrap()
+                                .toggle_sync_panes_is_active();
+                            screen.update_tabs();
+                        }
+                        ScreenInstruction::Exit => {
+                            break;
+                        }
+                    }
+                }
+            }
+        })
+        .unwrap();
+
+    let wasm_thread = thread::Builder::new()
+        .name("wasm".to_string())
+        .spawn({
+            let send_screen_instructions = send_screen_instructions.clone();
+            let send_pty_instructions = send_pty_instructions.clone();
+            let send_plugin_instructions = send_plugin_instructions.clone();
+
+            let store = Store::default();
+            let mut plugin_id = 0;
+            let mut plugin_map = HashMap::new();
+            move || loop {
+                let (event, mut err_ctx) = receive_plugin_instructions
+                    .recv()
+                    .expect("failed to receive event on channel");
+                err_ctx.add_call(ContextType::Plugin(PluginContext::from(&event)));
+                match event {
+                    PluginInstruction::Load(pid_tx, path) => {
+                        let plugin_dir = data_dir.join("plugins/");
+                        let wasm_bytes = fs::read(&path)
+                            .or_else(|_| fs::read(&path.with_extension("wasm")))
+                            .or_else(|_| fs::read(&plugin_dir.join(&path).with_extension("wasm")))
+                            .unwrap_or_else(|_| panic!("cannot find plugin {}", &path.display()));
+
+                        // FIXME: Cache this compiled module on disk. I could use `(de)serialize_to_file()` for that
+                        let module = Module::new(&store, &wasm_bytes).unwrap();
+
+                        let output = Pipe::new();
+                        let input = Pipe::new();
+                        let mut wasi_env = WasiState::new("Zellij")
+                            .env("CLICOLOR_FORCE", "1")
+                            .preopen(|p| {
+                                p.directory(".") // FIXME: Change this to a more meaningful dir
+                                    .alias(".")
+                                    .read(true)
+                                    .write(true)
+                                    .create(true)
+                            })
+                            .unwrap()
+                            .stdin(Box::new(input))
+                            .stdout(Box::new(output))
+                            .finalize()
+                            .unwrap();
+
+                        let wasi = wasi_env.import_object(&module).unwrap();
+
+                        let plugin_env = PluginEnv {
+                            plugin_id,
+                            send_screen_instructions: send_screen_instructions.clone(),
+                            send_pty_instructions: send_pty_instructions.clone(),
+                            send_plugin_instructions: send_plugin_instructions.clone(),
+                            wasi_env,
+                            subscriptions: Arc::new(Mutex::new(HashSet::new())),
+                        };
+
+                        let zellij = zellij_exports(&store, &plugin_env);
+                        let instance = Instance::new(&module, &zellij.chain_back(wasi)).unwrap();
+
+                        let start = instance.exports.get_function("_start").unwrap();
+
+                        // This eventually calls the `.init()` method
+                        start.call(&[]).unwrap();
+
+                        plugin_map.insert(plugin_id, (instance, plugin_env));
+                        pid_tx.send(plugin_id).unwrap();
+                        plugin_id += 1;
+                    }
+                    PluginInstruction::Update(pid, event) => {
+                        for (&i, (instance, plugin_env)) in &plugin_map {
+                            let subs = plugin_env.subscriptions.lock().unwrap();
+                            // FIXME: This is very janky... Maybe I should write my own macro for Event -> EventType?
+                            let event_type = EventType::from_str(&event.to_string()).unwrap();
+                            if (pid.is_none() || pid == Some(i)) && subs.contains(&event_type) {
+                                let update = instance.exports.get_function("update").unwrap();
+                                wasi_write_object(&plugin_env.wasi_env, &event);
+                                update.call(&[]).unwrap();
+                            }
+                        }
+                        drop(send_screen_instructions.send(ScreenInstruction::Render));
+                    }
+                    PluginInstruction::Render(buf_tx, pid, rows, cols) => {
+                        let (instance, plugin_env) = plugin_map.get(&pid).unwrap();
+
+                        let render = instance.exports.get_function("render").unwrap();
+
+                        render
+                            .call(&[Value::I32(rows as i32), Value::I32(cols as i32)])
+                            .unwrap();
+
+                        buf_tx.send(wasi_read_string(&plugin_env.wasi_env)).unwrap();
+                    }
+                    PluginInstruction::Unload(pid) => drop(plugin_map.remove(&pid)),
+                    PluginInstruction::Exit => break,
+                }
+            }
+        })
+        .unwrap();
+    SessionMetaData {
+        send_plugin_instructions,
+        send_screen_instructions,
+        send_pty_instructions,
+        screen_thread: Some(screen_thread),
+        pty_thread: Some(pty_thread),
+        wasm_thread: Some(wasm_thread),
+    }
+}
+
+fn route_action(action: Action, session: &SessionMetaData, os_input: &dyn ServerOsApi) {
+    match action {
+        Action::Write(val) => {
+            session
+                .send_screen_instructions
+                .send(ScreenInstruction::ClearScroll)
+                .unwrap();
+            session
+                .send_screen_instructions
+                .send(ScreenInstruction::WriteCharacter(val))
+                .unwrap();
+        }
+        Action::SwitchToMode(mode) => {
+            let palette = os_input.load_palette();
+            session
+                .send_plugin_instructions
+                .send(PluginInstruction::Update(
+                    None,
+                    Event::ModeUpdate(get_mode_info(mode, palette)),
+                ))
+                .unwrap();
+            session
+                .send_screen_instructions
+                .send(ScreenInstruction::ChangeMode(get_mode_info(mode, palette)))
+                .unwrap();
+            session
+                .send_screen_instructions
+                .send(ScreenInstruction::Render)
+                .unwrap();
+        }
+        Action::Resize(direction) => {
+            let screen_instr = match direction {
+                Direction::Left => ScreenInstruction::ResizeLeft,
+                Direction::Right => ScreenInstruction::ResizeRight,
+                Direction::Up => ScreenInstruction::ResizeUp,
+                Direction::Down => ScreenInstruction::ResizeDown,
+            };
+            session.send_screen_instructions.send(screen_instr).unwrap();
+        }
+        Action::SwitchFocus => {
+            session
+                .send_screen_instructions
+                .send(ScreenInstruction::SwitchFocus)
+                .unwrap();
+        }
+        Action::FocusNextPane => {
+            session
+                .send_screen_instructions
+                .send(ScreenInstruction::FocusNextPane)
+                .unwrap();
+        }
+        Action::FocusPreviousPane => {
+            session
+                .send_screen_instructions
+                .send(ScreenInstruction::FocusPreviousPane)
+                .unwrap();
+        }
+        Action::MoveFocus(direction) => {
+            let screen_instr = match direction {
+                Direction::Left => ScreenInstruction::MoveFocusLeft,
+                Direction::Right => ScreenInstruction::MoveFocusRight,
+                Direction::Up => ScreenInstruction::MoveFocusUp,
+                Direction::Down => ScreenInstruction::MoveFocusDown,
+            };
+            session.send_screen_instructions.send(screen_instr).unwrap();
+        }
+        Action::ScrollUp => {
+            session
+                .send_screen_instructions
+                .send(ScreenInstruction::ScrollUp)
+                .unwrap();
+        }
+        Action::ScrollDown => {
+            session
+                .send_screen_instructions
+                .send(ScreenInstruction::ScrollDown)
+                .unwrap();
+        }
+        Action::PageScrollUp => {
+            session
+                .send_screen_instructions
+                .send(ScreenInstruction::PageScrollUp)
+                .unwrap();
+        }
+        Action::PageScrollDown => {
+            session
+                .send_screen_instructions
+                .send(ScreenInstruction::PageScrollDown)
+                .unwrap();
+        }
+        Action::ToggleFocusFullscreen => {
+            session
+                .send_screen_instructions
+                .send(ScreenInstruction::ToggleActiveTerminalFullscreen)
+                .unwrap();
+        }
+        Action::NewPane(direction) => {
+            let pty_instr = match direction {
+                Some(Direction::Left) => PtyInstruction::SpawnTerminalVertically(None),
+                Some(Direction::Right) => PtyInstruction::SpawnTerminalVertically(None),
+                Some(Direction::Up) => PtyInstruction::SpawnTerminalHorizontally(None),
+                Some(Direction::Down) => PtyInstruction::SpawnTerminalHorizontally(None),
+                // No direction specified - try to put it in the biggest available spot
+                None => PtyInstruction::SpawnTerminal(None),
+            };
+            session.send_pty_instructions.send(pty_instr).unwrap();
+        }
+        Action::CloseFocus => {
+            session
+                .send_screen_instructions
+                .send(ScreenInstruction::CloseFocusedPane)
+                .unwrap();
+        }
+        Action::NewTab => {
+            session
+                .send_pty_instructions
+                .send(PtyInstruction::NewTab)
+                .unwrap();
+        }
+        Action::GoToNextTab => {
+            session
+                .send_screen_instructions
+                .send(ScreenInstruction::SwitchTabNext)
+                .unwrap();
+        }
+        Action::GoToPreviousTab => {
+            session
+                .send_screen_instructions
+                .send(ScreenInstruction::SwitchTabPrev)
+                .unwrap();
+        }
+        Action::ToggleActiveSyncPanes => {
+            session
+                .send_screen_instructions
+                .send(ScreenInstruction::ToggleActiveSyncPanes)
+                .unwrap();
+        }
+        Action::CloseTab => {
+            session
+                .send_screen_instructions
+                .send(ScreenInstruction::CloseTab)
+                .unwrap();
+        }
+        Action::GoToTab(i) => {
+            session
+                .send_screen_instructions
+                .send(ScreenInstruction::GoToTab(i))
+                .unwrap();
+        }
+        Action::TabNameInput(c) => {
+            session
+                .send_screen_instructions
+                .send(ScreenInstruction::UpdateTabName(c))
+                .unwrap();
+        }
+        Action::NoOp => {}
+        Action::Quit => panic!("Received unexpected action"),
+    }
+}