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https://github.com/storytold/craft-libs.git
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FredAppsandCursor
50256ca665
A page host can report a new dirty state while post_dirty's event is still dispatching. Remember the state first so that later report wins, and restore the previous state only when the send fails and nothing else recorded one. Co-authored-by: Cursor <cursoragent@cursor.com>
356 lines
16 KiB
Rust
356 lines
16 KiB
Rust
//! The bridge an app's web shell calls: find the host, hear its messages, post the app's.
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//!
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//! ```ignore
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//! if let Some(host) = craft_web_host::web::Host::connect("pdfcraft", &canvas) {
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//! host.listen(move |message| inbox.push(message));
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//! host.post_ready(env!("CARGO_PKG_VERSION"), false);
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//! }
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//! ```
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use std::cell::Cell;
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use std::rc::Rc;
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use wasm_bindgen::closure::Closure;
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use wasm_bindgen::{JsCast as _, JsValue};
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use web_sys::js_sys;
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use crate::{Inbox, Incoming, Mode, Outgoing, VERSION, file_name, message_type};
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/// A file the host passes in, not yet copied into the app's memory: check its size first.
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pub enum FileData {
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/// `bytes`: an `ArrayBuffer` or `Uint8Array`, viewed in place.
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Bytes(js_sys::Uint8Array),
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/// `file`: a `File` or `Blob`, for the app to read in slices.
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Blob(web_sys::Blob),
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}
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impl FileData {
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/// The file's length in bytes, from the data itself (a host's `size` field is not trusted).
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pub fn size(&self) -> f64 {
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match self {
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Self::Bytes(array) => f64::from(array.length()),
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Self::Blob(blob) => blob.size(),
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}
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}
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}
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/// A message from the host.
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pub enum Message {
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/// What the host supports; `handoff`: it routes files the app hands off.
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Host { version: String, handoff: bool },
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/// Open a document as File › Open would. `name` is already cleaned ([`crate::file_name`]).
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Open { name: String, data: FileData },
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/// The save with this `id` is stored.
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Saved { id: String },
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/// The host gave a handed-off file to the app that edits it.
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HandoffDone { name: String, app: String },
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}
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enum Transport {
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/// The same-origin parent window; only it is heard and answered.
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Parent { window: web_sys::Window, parent: web_sys::Window, origin: String },
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/// The app's canvas; messages are `CustomEvent`s on it.
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Page { canvas: web_sys::EventTarget },
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}
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/// The connection to the page hosting the app.
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pub struct Host {
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app: &'static str,
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transport: Transport,
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dirty: Cell<Option<bool>>,
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}
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impl Host {
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/// The host for `app` (its id, as in `<app>:ready`) running on `canvas`, or `None` when the
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/// app is not hosted: no `?host=parent` and no `data-host="page"`, no framing parent, or a
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/// parent on another origin (messages only go to this origin, so the browser would drop them).
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pub fn connect(app: &'static str, canvas: &web_sys::Element) -> Option<Self> {
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let window = web_sys::window()?;
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let query = window.location().search().unwrap_or_default();
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let transport = match Mode::detect(&query, canvas.get_attribute("data-host").as_deref())? {
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Mode::Parent => {
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let parent = window.parent().ok().flatten()?;
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if js_sys::Object::is(&parent, &window) {
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return None;
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}
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let origin = window.location().origin().ok()?;
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// Reading another origin's location throws, which is `None` too.
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if parent.location().origin().ok()? != origin {
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return None;
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}
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Transport::Parent { window, parent, origin }
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}
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Mode::Page => Transport::Page { canvas: canvas.clone().into() },
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};
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Some(Self { app, transport, dirty: Cell::new(None) })
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}
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pub fn mode(&self) -> Mode {
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match self.transport {
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Transport::Parent { .. } => Mode::Parent,
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Transport::Page { .. } => Mode::Page,
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}
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}
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/// Hear the host's messages for this app. The listener lives as long as the page. The
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/// listeners are `Fn`: a page host can dispatch an event while one is still running (a
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/// `saved` for the `save` the handler just posted), and wasm-bindgen refuses to re-enter an
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/// `FnMut` closure before its body runs, so the message would never reach the queue.
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pub fn listen(&self, handler: impl FnMut(Message) + 'static) {
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let app = self.app;
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let inbox = Rc::new(Inbox::new(handler));
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match &self.transport {
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Transport::Parent { window, parent, origin } => {
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let (parent, origin, inbox) = (parent.clone(), origin.clone(), inbox.clone());
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let on_message = Closure::<dyn Fn(web_sys::MessageEvent)>::new(move |event: web_sys::MessageEvent| {
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if event.origin() != origin || !event.source().is_some_and(|s| js_sys::Object::is(&s, &parent)) {
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return;
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}
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let data = event.data();
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let Some(kind) = string(&data, "type").and_then(|t| Incoming::parse(app, &t)) else { return };
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if let Some(message) = read(kind, &data) {
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inbox.deliver(message);
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}
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});
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if window.add_event_listener_with_callback("message", on_message.as_ref().unchecked_ref()).is_ok() {
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on_message.forget();
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}
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}
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Transport::Page { canvas } => {
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for kind in Incoming::ALL {
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let inbox = inbox.clone();
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let on_event = Closure::<dyn Fn(web_sys::CustomEvent)>::new(move |event: web_sys::CustomEvent| {
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if let Some(message) = read(kind, &event.detail()) {
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inbox.deliver(message);
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}
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});
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let name = message_type(app, kind.kind());
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if canvas.add_event_listener_with_callback(&name, on_event.as_ref().unchecked_ref()).is_ok() {
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on_event.forget();
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}
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}
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}
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}
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}
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/// The app is listening: send a document now. `app_version` is the app's own release;
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/// `reads_files`: it takes a `File`/`Blob` and reads it in slices.
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pub fn post_ready(&self, app_version: &str, reads_files: bool) -> Result<(), String> {
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self.post(Outgoing::Ready, &[("version", VERSION.into()), ("appVersion", app_version.into()), ("file", reads_files.into())], None)
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}
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/// Unsaved changes appeared or went away. Repeats of the last state reported are not sent.
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/// The new state is recorded before the send: a page host can report another state while the
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/// event is still dispatching, and that later report wins. A failed send is forgotten.
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pub fn post_dirty(&self, dirty: bool) {
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crate::note_dirty(&self.dirty, dirty, || self.post(Outgoing::Dirty, &[("dirty", dirty.into())], None).is_ok());
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}
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/// Hand the host a file the app would otherwise download: Save, Save As, Export. With an
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/// `id`, the host answers [`Message::Saved`] once it is stored; without one the save is done
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/// once it is posted. The bytes go as a transferred `ArrayBuffer`.
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pub fn post_save(&self, name: &str, bytes: &[u8], id: Option<&str>, save_as: bool) -> Result<(), String> {
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let buffer = js_sys::Uint8Array::from(bytes).buffer();
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let mut fields =
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vec![("name", JsValue::from(file_name(Some(name), "document"))), ("bytes", buffer.clone().into()), ("saveAs", save_as.into())];
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if let Some(id) = id {
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fields.push(("id", id.into()));
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}
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self.post(Outgoing::Save, &fields, Some(&buffer))
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}
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/// The app couldn't start, couldn't take a document, or a save went unconfirmed (`id`).
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pub fn post_failed(&self, error: &str, id: Option<&str>) -> Result<(), String> {
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let mut fields = vec![("error", JsValue::from(error))];
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if let Some(id) = id {
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fields.push(("id", id.into()));
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}
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self.post(Outgoing::Failed, &fields, None)
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}
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/// Pass the host a file another app edits; it answers [`Message::HandoffDone`] or, when no
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/// app it hosts takes the type, `failed`. Without a host, tell the user which app the file
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/// needs instead.
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pub fn post_handoff(&self, name: &str, bytes: &[u8]) -> Result<(), String> {
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let buffer = js_sys::Uint8Array::from(bytes).buffer();
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self.post(Outgoing::Handoff, &[("name", file_name(Some(name), "document").into()), ("bytes", buffer.clone().into())], Some(&buffer))
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}
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fn post(&self, kind: Outgoing, fields: &[(&str, JsValue)], transfer: Option<&js_sys::ArrayBuffer>) -> Result<(), String> {
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let message_type = message_type(self.app, kind.kind());
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let error = |e: JsValue| e.as_string().unwrap_or_else(|| format!("{e:?}"));
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match &self.transport {
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Transport::Parent { parent, origin, .. } => {
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let message = object(&[("type", message_type.as_str().into())], fields)?;
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match transfer {
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Some(buffer) => parent.post_message_with_transfer(&message, origin, &js_sys::Array::of1(buffer)),
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None => parent.post_message(&message, origin),
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}
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.map_err(error)
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}
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Transport::Page { canvas } => {
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let init = web_sys::CustomEventInit::new();
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init.set_detail(&object(&[], fields)?.into());
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let event = web_sys::CustomEvent::new_with_event_init_dict(&message_type, &init).map_err(error)?;
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canvas.dispatch_event(&event).map(|_| ()).map_err(error)
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}
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}
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}
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}
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/// The message a host's object describes, or `None` when a required field is missing.
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fn read(kind: Incoming, data: &JsValue) -> Option<Message> {
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Some(match kind {
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Incoming::Host => Message::Host {
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version: string(data, "version").unwrap_or_else(|| VERSION.to_string()),
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handoff: get(data, "handoff").as_bool() == Some(true),
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},
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Incoming::Open => {
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let name = file_name(string(data, "name").as_deref(), "document");
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Message::Open { name, data: file_data(data)? }
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}
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Incoming::Saved => Message::Saved { id: string(data, "id")? },
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Incoming::HandoffDone => {
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Message::HandoffDone { name: string(data, "name").unwrap_or_default(), app: string(data, "app").unwrap_or_default() }
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}
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})
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}
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/// `file` (a `Blob`; its `size` field is ignored for the Blob's own) or `bytes` (an `ArrayBuffer` or `Uint8Array`), not copied.
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fn file_data(data: &JsValue) -> Option<FileData> {
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let file = get(data, "file");
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if let Some(blob) = file.dyn_ref::<web_sys::Blob>() {
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return Some(FileData::Blob(blob.clone()));
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}
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let bytes = get(data, "bytes");
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if let Some(array) = bytes.dyn_ref::<js_sys::Uint8Array>() {
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Some(FileData::Bytes(array.clone()))
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} else if bytes.is_instance_of::<js_sys::ArrayBuffer>() {
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Some(FileData::Bytes(js_sys::Uint8Array::new(&bytes)))
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} else {
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None
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}
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}
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fn object(head: &[(&str, JsValue)], fields: &[(&str, JsValue)]) -> Result<js_sys::Object, String> {
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let m = js_sys::Object::new();
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for (key, value) in head.iter().chain(fields) {
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js_sys::Reflect::set(&m, &JsValue::from_str(key), value).map_err(|_| "couldn't build the message".to_string())?;
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}
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Ok(m)
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}
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fn get(data: &JsValue, key: &str) -> JsValue {
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js_sys::Reflect::get(data, &JsValue::from_str(key)).unwrap_or(JsValue::UNDEFINED)
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}
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fn string(data: &JsValue, key: &str) -> Option<String> {
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get(data, key).as_string()
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}
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/// Node tests for the parsing of a host's objects: wrong shapes, missing fields, and sizes the
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/// host states against the data it sends. No browser; run with `wasm-bindgen-test-runner`.
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#[cfg(test)]
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mod tests {
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use super::*;
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use wasm_bindgen_test::wasm_bindgen_test;
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fn obj(fields: &[(&str, JsValue)]) -> JsValue {
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object(&[], fields).expect("an object").into()
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}
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fn buffer(len: u32) -> js_sys::ArrayBuffer {
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js_sys::ArrayBuffer::new(len)
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}
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#[wasm_bindgen_test]
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fn an_open_without_bytes_or_a_blob_is_dropped() {
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for data in [
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obj(&[("name", "a.pdf".into())]),
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obj(&[("name", "a.pdf".into()), ("bytes", "text".into())]),
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obj(&[("name", "a.pdf".into()), ("bytes", 42.into())]),
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obj(&[("name", "a.pdf".into()), ("file", "not a blob".into())]),
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JsValue::NULL,
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JsValue::UNDEFINED,
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JsValue::from_str("a string"),
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JsValue::from_f64(7.0),
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] {
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assert!(read(Incoming::Open, &data).is_none());
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}
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}
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#[wasm_bindgen_test]
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fn an_open_takes_bytes_as_an_array_buffer_or_a_uint8_array() {
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let ab = buffer(3);
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let array = js_sys::Uint8Array::new_with_length(5);
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for (bytes, len) in [(JsValue::from(ab), 3.0), (JsValue::from(array), 5.0)] {
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let Some(Message::Open { data, .. }) = read(Incoming::Open, &obj(&[("name", "a.pdf".into()), ("bytes", bytes)])) else {
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panic!("an open with bytes is read");
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};
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assert_eq!(data.size(), len);
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}
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}
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#[wasm_bindgen_test]
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fn an_open_without_a_name_or_with_a_hostile_one_gets_a_clean_name() {
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let named = |name: Option<&str>| {
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let mut fields = vec![("bytes", JsValue::from(buffer(1)))];
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if let Some(n) = name {
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fields.push(("name", n.into()));
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}
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match read(Incoming::Open, &obj(&fields)) {
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Some(Message::Open { name, .. }) => name,
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_ => panic!("an open with bytes is read"),
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}
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};
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assert_eq!(named(None), "document");
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assert_eq!(named(Some("../../etc/passwd")), "passwd");
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assert_eq!(named(Some("a\u{0}b.txt")), "ab.txt");
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assert_eq!(named(Some(&"x".repeat(300))).chars().count(), crate::MAX_NAME_CHARS);
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}
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#[wasm_bindgen_test]
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fn the_size_is_the_data_s_own_not_the_hosts_claim() {
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// An ArrayBuffer of 64 MiB with a `size` field of 1: the bytes are viewed in place, not
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// copied, and the app sees their real length before it decides to read them.
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let ab = buffer(64 << 20);
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let Some(Message::Open { data, .. }) = read(Incoming::Open, &obj(&[("bytes", ab.clone().into()), ("size", 1.into())])) else {
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panic!("an open with bytes is read");
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};
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assert_eq!(data.size(), f64::from(64u32 << 20));
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let FileData::Bytes(view) = &data else { panic!("bytes stay bytes") };
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assert!(js_sys::Object::is(&view.buffer(), &ab), "a view of the host's buffer, not a copy");
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// A Blob of 5 bytes with a `size` field of a terabyte.
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let blob = web_sys::Blob::new_with_str_sequence(&js_sys::Array::of1(&"hello".into())).expect("a Blob");
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let Some(Message::Open { data, .. }) = read(Incoming::Open, &obj(&[("file", blob.into()), ("size", 1e12.into())])) else {
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panic!("an open with a Blob is read");
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};
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assert_eq!(data.size(), 5.0);
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}
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#[wasm_bindgen_test]
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fn a_saved_needs_a_string_id() {
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assert!(matches!(read(Incoming::Saved, &obj(&[("id", "s1".into())])), Some(Message::Saved { id }) if id == "s1"));
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for data in [obj(&[]), obj(&[("id", 3.into())]), JsValue::NULL, JsValue::from_str("s1")] {
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assert!(read(Incoming::Saved, &data).is_none());
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}
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}
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#[wasm_bindgen_test]
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fn a_host_message_and_a_handoff_done_read_whatever_fields_exist() {
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// Nothing required: a missing version is the contract's, `handoff` is true only for `true`.
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for data in [JsValue::NULL, obj(&[]), obj(&[("handoff", "yes".into())]), obj(&[("handoff", 1.into())])] {
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let Some(Message::Host { version, handoff }) = read(Incoming::Host, &data) else { panic!("a host message is read") };
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assert_eq!(version, crate::VERSION);
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assert!(!handoff);
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}
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assert!(matches!(read(Incoming::Host, &obj(&[("handoff", true.into())])), Some(Message::Host { handoff: true, .. })));
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assert!(matches!(
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read(Incoming::HandoffDone, &obj(&[("name", "a.pdf".into()), ("app", "pdfcraft".into())])),
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Some(Message::HandoffDone { name, app }) if name == "a.pdf" && app == "pdfcraft"
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));
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assert!(matches!(read(Incoming::HandoffDone, &JsValue::NULL), Some(Message::HandoffDone { name, app }) if name.is_empty() && app.is_empty()));
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}
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}
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