fix(ui): Save As saves under the filename typed in the dialog (#689) (#757)

Co-authored-by: Brandon Thomas <echelon@gmail.com>

apps/wordcraft/src/file_dialogs.rs

@@ -51,7 +51,10 @@ impl Launcher {
             let dialog = rfd::AsyncFileDialog::new().set_parent(parent);
             let picking: Picking = match req {
                 FileDialogRequest::Open { purpose } => Box::pin(open_filters(dialog, &purpose).pick_file()),
-                FileDialogRequest::Save { name } => Box::pin(dialog.set_file_name(name).save_file()),
+                FileDialogRequest::Save { name } => {
+                    let exts = save_exts(&name);
+                    Box::pin(dialog.set_file_name(name).add_filter("Documents", &exts).save_file())
+                }
             };
             let ctx = self.ctx.clone();
             let waiting = std::thread::Builder::new().name("file dialog".into()).spawn(move || {
@@ -82,3 +85,43 @@ fn open_filters(d: rfd::AsyncFileDialog, purpose: &str) -> rfd::AsyncFileDialog
             .add_filter("All files", &["*"])
     }
 }
+
+/// The file types Save As offers: every format the engine saves, with the suggested name's own
+/// format first. rfd makes a filter's first extension the dialog's default, which the Windows,
+/// macOS and Linux panels append to a file name the user typed without one; with no filter at
+/// all the name came back bare and the save failed, since the format is chosen by extension
+/// (#689).
+fn save_exts(name: &str) -> Vec<String> {
+    let suggested = std::path::Path::new(name)
+        .extension()
+        .and_then(|e| e.to_str())
+        .map(|e| e.to_ascii_lowercase())
+        .filter(|e| wordcraft_engine::io::SAVE_EXTS.contains(&e.as_str()))
+        .unwrap_or_else(|| "docx".to_string());
+    let mut exts: Vec<String> = Vec::with_capacity(wordcraft_engine::io::SAVE_EXTS.len());
+    exts.push(suggested.clone());
+    exts.extend(wordcraft_engine::io::SAVE_EXTS.iter().filter(|e| **e != suggested).map(|e| (*e).to_string()));
+    exts
+}
+
+#[cfg(test)]
+mod tests {
+    use super::save_exts;
+
+    /// #689: the Save dialog's default extension is the suggested name's own format, so a file
+    /// name the user types without one is saved in the document's format instead of coming back
+    /// bare and failing.
+    #[test]
+    fn save_dialog_defaults_to_the_suggested_format() {
+        assert_eq!(save_exts("novel.docx")[0], "docx");
+        assert_eq!(save_exts("report.odt")[0], "odt");
+        assert_eq!(save_exts("annual report.pdf")[0], "pdf");
+        // A suggested name always has an extension; anything unreadable falls back to Word's.
+        assert_eq!(save_exts("no extension")[0], "docx");
+        assert_eq!(save_exts("mystery.rtf2")[0], "docx");
+        // Every savable format is still offered, once.
+        let exts = save_exts("novel.docx");
+        assert!(wordcraft_engine::io::SAVE_EXTS.iter().all(|e| exts.iter().any(|x| x == e)));
+        assert_eq!(exts.len(), wordcraft_engine::io::SAVE_EXTS.len());
+    }
+}

crates/ui-egui/src/file_dialogs.rs

@@ -321,6 +321,35 @@ mod tests {
         let _ = std::fs::remove_dir_all(&dir);
     }
 
+    /// #689: Save As honours the filename typed in the dialog, not just the folder: a document
+    /// opened as `a/one.docx` and saved as `b/two.docx` is written there and takes that path.
+    #[test]
+    fn save_as_with_a_new_filename_saves_under_it() {
+        let dir = scratch("rename");
+        let opened = dir.join("one.docx");
+        let picked = dir.join("sub").join("two.docx");
+        std::fs::create_dir_all(dir.join("sub")).unwrap();
+        wordcraft_engine::Session::new(wordcraft_doc::Document::from_text("original"))
+            .run("file.save", &json!({"path": opened.to_string_lossy()}))
+            .unwrap();
+        let (mut a, shown) = async_app();
+        a.run("file.open", json!({"path": opened.to_string_lossy()})).unwrap();
+        assert_eq!(a.session.path.as_deref(), Some(opened.as_path()));
+        a.save_as_dialog();
+        answer(&shown, Some(&picked.to_string_lossy()));
+        let r = a.poll_file_dialog().unwrap().unwrap();
+        assert_eq!(r, json!({"saved": true}), "the save-as succeeded");
+        assert_eq!(a.session.path.as_deref(), Some(picked.as_path()), "the picked filename is the document's path");
+        assert!(picked.is_file(), "the file is written under the picked name");
+        assert!(saved_text(&picked).contains("original"));
+        // F12 (file.saveAs without a path) lands in the same dialog, suggesting the new name.
+        let r = a.run("file.saveAs", json!({})).unwrap();
+        assert_eq!(r, json!({"saved": false}));
+        assert!(a.file_dialog_open(), "F12's saveAs request opens the dialog");
+        assert_eq!(shown.borrow()[0].0, FileDialogRequest::Save { name: "two.docx".into() });
+        let _ = std::fs::remove_dir_all(&dir);
+    }
+
     /// While a dialog is open, more Save As / Open / Export / Picture clicks don't open a second one.
     #[test]
     fn a_second_dialog_while_one_is_open_is_ignored() {