figcraft-web: a Save of a host-opened document goes out under the host's file name

In page host mode a plain Save of a .figcraft the host opened used the document's internal name, so the host got a different file name with saveAs true instead of an update to the file it opened. Services gains host_file(); Save uses it for a .figcraft host file, Save As keeps the document name, and a missing, .json or .fig host file stays a Save As.

apps/figcraft-web/src/host.rs

@@ -91,6 +91,11 @@ impl Bridge {
         let _ = self.host.post_failed(error, None);
     }
 
+    /// The document file the host opened or the last Save As made, if any.
+    pub fn host_file(&self) -> Option<String> {
+        self.host_file.borrow().clone()
+    }
+
     /// Hand a file the app would otherwise download to the host; `false` when nothing was
     /// delivered. The `saveAs` rule is this module's documentation's.
     pub fn post_save(&self, path: &str, bytes: &[u8]) -> bool {

apps/figcraft-web/src/web.rs

@@ -279,6 +279,9 @@ impl Services for WebServices {
             }
         }
     }
+    fn host_file(&self) -> Option<String> {
+        self.host.as_ref()?.host_file()
+    }
     fn clipboard_set_text(&mut self, s: &str) {
         figcraft_ui_egui::egui_copy_text(&self.ctx, s);
     }

crates/ui-egui/src/app/files.rs

@@ -6,12 +6,7 @@ use super::{
 impl FigApp {
     pub fn save_as_dialog(&mut self) {
         if self.services.downloads() {
-            if let Some(r) = self.run("file.saveAs", json!({"data": true}))
-                && self.download(r["name"].as_str().unwrap_or_default(), &r)
-            {
-                self.run("file.markSaved", json!({}));
-                dialogs::file_saved(self, &r);
-            }
+            self.save_download(None);
             return;
         }
         let Ok(name) = self.session.doc().map(|d| d.name.clone()) else { return };
@@ -43,6 +38,17 @@ impl FigApp {
         });
     }
 
+    /// Save by handing the file over as a download. `keep`: the name a Save of a host-opened
+    /// document keeps; `None` is a Save As, under the document's own name.
+    fn save_download(&mut self, keep: Option<&str>) {
+        if let Some(r) = self.run("file.saveAs", json!({"data": true}))
+            && self.download(keep.unwrap_or_else(|| r["name"].as_str().unwrap_or_default()), &r)
+        {
+            self.run("file.markSaved", json!({}));
+            dialogs::file_saved(self, &r);
+        }
+    }
+
     pub fn save(&mut self) {
         // A branch tab saves its main file.
         let tab = figcraft_engine::branches::file_tab(&self.session);
@@ -57,6 +63,9 @@ impl FigApp {
             if self.run("file.save", json!({})).is_some() {
                 self.toast(i18n::tr("Saved"));
             }
+        } else if let Some(name) = self.services.host_file().filter(|n| is_document_file(n)) {
+            // A host-opened document is saved as the file the host gave: the host updates that file.
+            self.save_download(Some(&name));
         } else {
             self.save_as_dialog();
         }
@@ -299,3 +308,8 @@ impl FigApp {
         failed
     }
 }
+
+/// A `.figcraft` file name: the document format a Save writes (a `.fig` is an export copy).
+fn is_document_file(name: &str) -> bool {
+    Path::new(name).extension().and_then(OsStr::to_str).is_some_and(|e| e.eq_ignore_ascii_case("figcraft"))
+}

crates/ui-egui/src/host_save_tests.rs

@@ -0,0 +1,60 @@
+//! In a page host the browser hands files to the host: a Save of the document the host opened goes
+//! out under the host's file name, a Save As under the document's own name.
+
+use std::sync::{Arc, Mutex};
+
+use figcraft_engine::Session;
+use serde_json::json;
+
+use crate::{FigApp, Services};
+
+type Saved = Arc<Mutex<Vec<String>>>;
+
+/// Services that save by downloads, with a document file the host opened.
+struct Host {
+    got: Saved,
+    file: Option<&'static str>,
+}
+
+impl Services for Host {
+    fn downloads(&self) -> bool {
+        true
+    }
+    fn download(&mut self, name: &str, _bytes: &[u8]) -> bool {
+        self.got.lock().unwrap().push(name.to_string());
+        true
+    }
+    fn host_file(&self) -> Option<String> {
+        self.file.map(str::to_string)
+    }
+}
+
+fn app(file: Option<&'static str>) -> (FigApp, Saved) {
+    let got = Saved::default();
+    let mut app = FigApp::new(Session::empty(), Box::new(Host { got: got.clone(), file }));
+    app.session.execute("file.new", &json!({"name": "Original"})).unwrap();
+    (app, got)
+}
+
+#[test]
+fn save_keeps_the_name_the_host_opened() {
+    let (mut app, got) = app(Some("client.figcraft"));
+    app.save();
+    assert_eq!(got.lock().unwrap().as_slice(), ["client.figcraft"]);
+}
+
+#[test]
+fn save_as_uses_the_document_s_own_name() {
+    let (mut app, got) = app(Some("client.figcraft"));
+    app.save_as_dialog();
+    assert_eq!(got.lock().unwrap().as_slice(), ["Original.figcraft"]);
+}
+
+#[test]
+fn without_a_host_file_or_for_a_copy_format_save_is_a_save_as() {
+    for file in [None, Some("design.json"), Some("export.fig")] {
+        let (mut app, got) = app(file);
+        app.save();
+        assert_eq!(got.lock().unwrap().as_slice(), ["Original.figcraft"], "{file:?}");
+    }
+}

crates/ui-egui/src/lib.rs

@@ -124,6 +124,8 @@ mod home_recents_tests;
 #[cfg(test)]
 mod home_tests;
 #[cfg(test)]
+mod host_save_tests;
+#[cfg(test)]
 mod idle_tests;
 #[cfg(test)]
 mod ime_tests;

crates/ui-egui/src/services.rs

@@ -24,6 +24,11 @@ pub trait Services {
     fn download(&mut self, _name: &str, _bytes: &[u8]) -> bool {
         false
     }
+    /// The document file a host page opened, where the app runs inside one (the browser's host
+    /// mode): a Save of that document keeps this name instead of the document's own.
+    fn host_file(&self) -> Option<String> {
+        None
+    }
     /// A folder to write several files into.
     fn pick_folder(&mut self, _title: &str) -> DialogFuture {
         Box::pin(std::future::ready(None))