Fix #1685: a save or export that fails is reported in a dialog that stays

A save that couldn't write its file (a read-only folder, a file another
program holds open, a full disk) was only reported in the status bar, a line
the next message replaces; a background save's failure arrived there some
time after the user had moved on. Save, Save As, Save a Copy, Save as
Template, Export As and the commands that write one file now also say it in a
dialog naming the file and the reason, which stays until it is closed. The
document stays modified and keeps the file it had. A message that arrives
while another dialog is open waits for it to close instead of replacing it.
An agent's request gets the error as its reply, without a dialog; a failed
recovery write stays in the status bar.

crates/ui-egui/src/dialogs/confirm.rs

@@ -41,10 +41,27 @@ pub const MESSAGE: &str = "message";
 
 pub(super) const MESSAGE_SPEC: DialogSpec = DialogSpec { ok: None, ..SPEC };
 
+/// Most messages kept for later while a dialog is open ([`tell`]).
+const MAX_WAITING: usize = 16;
+
 /// Tell the user `message` (with an optional `detail` line), both in the UI language, in a dialog
-/// they close.
+/// they close. While another dialog is open (the message comes from work in the background) it
+/// waits its turn instead of replacing it: neither what the user was doing there nor the message
+/// is lost.
 pub fn tell(app: &mut VectorcraftApp, message: &str, detail: &str) {
-    app.ui.dialog = Some(Dialog::new(MESSAGE, json!({"message": message, "detail": detail})));
+    let d = Dialog::new(MESSAGE, json!({"message": message, "detail": detail}));
+    if app.ui.dialog.is_none() {
+        app.ui.dialog = Some(d);
+    } else if app.ui.told.len() < MAX_WAITING && !app.ui.dialog.iter().chain(&app.ui.told).any(|t| t.kind == MESSAGE && t.fields == d.fields) {
+        app.ui.told.push(d);
+    }
+}
+
+/// Show the next message that waited for a dialog to close (each frame).
+pub(super) fn show_waiting(app: &mut VectorcraftApp) {
+    if app.ui.dialog.is_none() && !app.ui.told.is_empty() {
+        app.ui.dialog = Some(app.ui.told.remove(0));
+    }
 }
 
 /// Closes before running, so a dialog the command opens stays open.

crates/ui-egui/src/dialogs/mod.rs

@@ -366,6 +366,7 @@ pub(crate) fn settle(app: &mut VectorcraftApp) {
 pub fn show(app: &mut VectorcraftApp, ctx: &egui::Context) {
     about::show(app, ctx);
     settle(app);
+    confirm::show_waiting(app);
     // The kind of dialog shown last frame: a different one (or none) means this one just opened, and
     // its first field is to take the keyboard focus (`focus_id`, until a field takes it).
     let (shown_id, focus_id) = (egui::Id::new("dialog-shown"), egui::Id::new("dialog-focus-pending"));

crates/ui-egui/src/i18n/cs.tsv

@@ -3508,6 +3508,8 @@ effect	Regular	Pravidelný
 	Serif / Mincho	Patkové / mincho
 	Changes made since it was last saved will be lost.	Změny provedené od posledního uložení budou ztraceny.
 	Can't open “{name}”.	„{name}“ nelze otevřít.
+	Can't save “{name}”.	„{name}“ nelze uložit.
+	Can't export “{name}”.	„{name}“ nelze exportovat.
 	Downloaded {what}	Staženo: {what}
 	Exported {count} file(s) to {folder}	Exportováno souborů: {count} do {folder}
 	Exported {what}	Exportováno: {what}

crates/ui-egui/src/i18n/de.tsv

@@ -754,6 +754,8 @@
 	Do Not Move	Nicht verschieben
 	Do you want to save the changes you made to “{name}”?	Möchten Sie die Änderungen an „{name}“ speichern?
 	Can't open “{name}”.	„{name}“ kann nicht geöffnet werden.
+	Can't save “{name}”.	„{name}“ kann nicht gespeichert werden.
+	Can't export “{name}”.	„{name}“ kann nicht exportiert werden.
 	Document	Dokument
 	Document Color Mode	Dokumentfarbmodus
 	Document Info	Dokumentinformationen

crates/ui-egui/src/i18n/es.tsv

@@ -768,6 +768,8 @@
 	Do Not Move	No mover
 	Do you want to save the changes you made to “{name}”?	¿Quieres guardar los cambios hechos en “{name}”?
 	Can't open “{name}”.	No se puede abrir «{name}».
+	Can't save “{name}”.	No se puede guardar «{name}».
+	Can't export “{name}”.	No se puede exportar «{name}».
 	Document	Documento
 	Document Color Mode	Modo de color del documento
 	Document Info	Información del documento

crates/ui-egui/src/i18n/fr.tsv

@@ -770,6 +770,8 @@
 	Do Not Move	Ne pas déplacer
 	Do you want to save the changes you made to “{name}”?	Voulez-vous enregistrer les modifications apportées à « {name} » ?
 	Can't open “{name}”.	Impossible d’ouvrir « {name} ».
+	Can't save “{name}”.	Impossible d’enregistrer « {name} ».
+	Can't export “{name}”.	Impossible d’exporter « {name} ».
 	Document	Document
 	Document Color Mode	Mode colorimétrique du document
 	Document Info	Informations sur le document

crates/ui-egui/src/i18n/hu.tsv

@@ -485,6 +485,8 @@
 	Calligraphic	Kalligrafikus
 	Calligraphic Brush Options	Kalligrafikus ecset beállításai
 	Can't open “{name}”.	Nem nyitható meg: „{name}”.
+	Can't save “{name}”.	Nem menthető: „{name}”.
+	Can't export “{name}”.	Nem exportálható: „{name}”.
 	Can't print these settings: see the Summary	Ezekkel a beállításokkal nem lehet nyomtatni: lásd az Összegzést
 	Cancel	Mégse
 	Cancel Key Object	Kulcsobjektum megszüntetése

crates/ui-egui/src/i18n/it.tsv

@@ -768,6 +768,8 @@
 	Do Not Move	Non spostare
 	Do you want to save the changes you made to “{name}”?	Vuoi salvare le modifiche apportate a “{name}”?
 	Can't open “{name}”.	Impossibile aprire «{name}».
+	Can't save “{name}”.	Impossibile salvare «{name}».
+	Can't export “{name}”.	Impossibile esportare «{name}».
 	Document	Documento
 	Document Color Mode	Metodo colore documento
 	Document Info	Informazioni documento

crates/ui-egui/src/i18n/ja.tsv

@@ -1223,6 +1223,8 @@
 	Divide Vertically Into	垂直方向に分割
 	Do you want to save the changes you made to “{name}”?	「{name}」への変更を保存しますか？
 	Can't open “{name}”.	「{name}」を開けません。
+	Can't save “{name}”.	「{name}」を保存できません。
+	Can't export “{name}”.	「{name}」を書き出せません。
 	Document	ドキュメント
 	Document Ink Options	ドキュメントのインキオプション
 	Document JSON	ドキュメント JSON

crates/ui-egui/src/i18n/ko.tsv

@@ -1218,6 +1218,8 @@
 	Divide Vertically Into	세로로 나누기
 	Do you want to save the changes you made to “{name}”?	“{name}”의 변경 내용을 저장하시겠습니까?
 	Can't open “{name}”.	“{name}”을(를) 열 수 없습니다.
+	Can't save “{name}”.	“{name}”을(를) 저장할 수 없습니다.
+	Can't export “{name}”.	“{name}”을(를) 내보낼 수 없습니다.
 	Document	문서
 	Document Ink Options	문서 잉크 옵션
 	Document JSON	문서 JSON

crates/ui-egui/src/i18n/pl.tsv

@@ -3391,6 +3391,8 @@ effect	Regular	Normalny
 	Serif / Mincho	Szeryfowe / mincho
 	Changes made since it was last saved will be lost.	Zmiany wprowadzone od ostatniego zapisu zostaną utracone.
 	Can't open “{name}”.	Nie można otworzyć „{name}”.
+	Can't save “{name}”.	Nie można zapisać „{name}”.
+	Can't export “{name}”.	Nie można wyeksportować „{name}”.
 	Downloaded {what}	Pobrano {what}
 	Exported {count} file(s) to {folder}	Wyeksportowane pliki do {folder}: {count}
 	Exported {what}	Wyeksportowano {what}

crates/ui-egui/src/i18n/pt-br.tsv

@@ -692,6 +692,8 @@
 	Divide Vertically Into	Dividir Verticalmente Em
 	Do you want to save the changes you made to “{name}”?	Deseja salvar as alterações feitas em “{name}”?
 	Can't open “{name}”.	Não é possível abrir “{name}”.
+	Can't save “{name}”.	Não é possível salvar “{name}”.
+	Can't export “{name}”.	Não é possível exportar “{name}”.
 	Document	Documento
 	Document Color Mode	Modo de Cor do Documento
 	Document Info	Informações do Documento

crates/ui-egui/src/i18n/ru.tsv

@@ -766,6 +766,8 @@
 	Do Not Move	Не перемещать
 	Do you want to save the changes you made to “{name}”?	Сохранить изменения, внесённые в «{name}»?
 	Can't open “{name}”.	Не удаётся открыть «{name}».
+	Can't save “{name}”.	Не удаётся сохранить «{name}».
+	Can't export “{name}”.	Не удаётся экспортировать «{name}».
 	Document	Документ
 	Document Color Mode	Цветовой режим документа
 	Document Info	Сведения о документе

crates/ui-egui/src/i18n/uk.tsv

@@ -762,6 +762,8 @@
 	Do Not Move	Не переміщати
 	Do you want to save the changes you made to “{name}”?	Зберегти зміни, внесені до «{name}»?
 	Can't open “{name}”.	Не вдається відкрити «{name}».
+	Can't save “{name}”.	Не вдається зберегти «{name}».
+	Can't export “{name}”.	Не вдається експортувати «{name}».
 	Document	Документ
 	Document Color Mode	Колірний режим документа
 	Document Info	Відомості про документ

crates/ui-egui/src/i18n/vi.tsv

@@ -401,6 +401,8 @@
 	Calligraphic	Thư pháp
 	Calligraphic Brush Options	Tùy chọn cọ thư pháp
 	Can't open “{name}”.	Không thể mở “{name}”.
+	Can't save “{name}”.	Không thể lưu “{name}”.
+	Can't export “{name}”.	Không thể xuất “{name}”.
 	Can't print these settings: see the Summary	Không thể in các cài đặt này: xem Tóm tắt
 	Cancel	Hủy
 	Cancel Key Object	Hủy đối tượng chính

crates/ui-egui/src/i18n/zh-hans.tsv

@@ -723,6 +723,8 @@
 	Do Not Move	不移动
 	Do you want to save the changes you made to “{name}”?	要存储对“{name}”所做的更改吗？
 	Can't open “{name}”.	无法打开“{name}”。
+	Can't save “{name}”.	无法保存“{name}”。
+	Can't export “{name}”.	无法导出“{name}”。
 	Document	文档
 	Document Color Mode	文档颜色模式
 	Document Info	文档信息

crates/ui-egui/src/i18n/zh-hant.tsv

@@ -741,6 +741,8 @@
 	Do Not Move	不移動
 	Do you want to save the changes you made to “{name}”?	要儲存對「{name}」所做的變更嗎？
 	Can't open “{name}”.	無法開啟「{name}」。
+	Can't save “{name}”.	無法儲存「{name}」。
+	Can't export “{name}”.	無法匯出「{name}」。
 	Document	文件
 	Document Color Mode	文件色彩模式
 	Document Info	文件資訊

crates/ui-egui/src/io.rs

@@ -167,6 +167,29 @@ pub fn report_open_error(app: &mut VectorcraftApp, name: &str, e: &str) {
     dialogs::confirm::tell(app, &message, &crate::i18n::message(crate::i18n::current(), e));
 }
 
+/// A save or an export that didn't write `path`: say so in a dialog that names the file and the
+/// reason and stays until it is closed, as an editor does (#1685). The status bar's line, which
+/// the caller's error becomes, is replaced by the next message, and a document that wasn't saved
+/// must not look saved: it stays modified, and what was at `path` is as it was. Not for a request
+/// an agent sent and waits on: the error is its reply.
+pub(crate) fn report_write_error(app: &mut VectorcraftApp, export: bool, path: &str, e: &str) {
+    if app.ui.answering_control {
+        return;
+    }
+    let name = fileio::file_name(path);
+    let message = if export { tl!("Can't export “{name}”.") } else { tl!("Can't save “{name}”.") };
+    dialogs::confirm::tell(app, &crate::i18n::fmt(message, &[("name", &name)]), &crate::i18n::message(crate::i18n::current(), e));
+}
+
+/// [`write_to`], a failure reported ([`report_write_error`]).
+pub(crate) fn write_reporting(app: &mut VectorcraftApp, path: &str, bytes: &[u8]) -> Result<(), String> {
+    let r = write_to(&mut app.services, path, bytes);
+    if let Err(e) = &r {
+        report_write_error(app, false, path, e);
+    }
+    r
+}
+
 /// [`open_path`] for a file the user asked for, a failure reported ([`report_open_error`]). On
 /// the desktop a document is decoded off the UI thread ([`crate::opening`]): the result is then
 /// `{background: true, status}`, and the document opens in its tab (or the failure is reported)
@@ -259,7 +282,7 @@ pub(crate) fn write_named(app: &mut VectorcraftApp, path: Option<String>, name:
             pick_path(app, &FilePick { name: name.to_string(), folder, ..Default::default() })?
         }
     };
-    write_to(&mut app.services, &path, bytes)?;
+    write_reporting(app, &path, bytes)?;
     Ok(path)
 }
 
@@ -515,8 +538,10 @@ fn write_plan(app: &mut VectorcraftApp, plan: SavePlan) -> Result<Value, String>
         }
         .map_err(|e| e.to_string())
     };
+    let failed = target.clone().unwrap_or_default();
     let then = move |app: &mut VectorcraftApp, r: Result<Value, String>| {
-        let r = r?;
+        // Not written: the document keeps its file, format and modified state, and the user is told.
+        let r = r.inspect_err(|e| report_write_error(app, false, &failed, e))?;
         // The document may have closed meanwhile: the file is written all the same.
         done.complete(&mut app.session, uid);
         let path = r["path"].as_str().unwrap_or_default().to_string();
@@ -601,8 +626,9 @@ pub fn export(app: &mut VectorcraftApp, format: Option<&str>, path: Option<Strin
         Ok(out)
     };
     let enabled = app.session.prefs.background_export;
-    let mut r = background::run(app, enabled, label, None, work, |app, r| {
-        let r = r?;
+    let failed = target.clone();
+    let mut r = background::run(app, enabled, label, None, work, move |app, r| {
+        let r = r.inspect_err(|e| report_write_error(app, true, &failed, e))?;
         let what = match r["files"].as_array() {
             Some(files) => format!("{} files", files.len()),
             None => r["path"].as_str().unwrap_or_default().to_string(),
@@ -672,7 +698,7 @@ pub(crate) fn run_to_file(app: &mut VectorcraftApp, id: &str, ext: &str, mut par
         Some(p) => p,
         None => target_path(app, None, ext)?,
     };
-    write_to(&mut app.services, &path, &bytes)?;
+    write_reporting(app, &path, &bytes)?;
     Ok((path, v))
 }
 
@@ -829,13 +855,69 @@ mod tests {
         assert!(app.ui.dialog.is_none());
     }
 
+    /// #1685: a save or an export that can't write its file says so in a dialog that names the
+    /// file and the reason and stays until it is closed; the document stays modified and keeps
+    /// the file it had. An agent's request only gets the error, and a message that arrives while
+    /// another dialog is open waits for it to close.
+    #[test]
+    fn a_save_that_cannot_write_is_reported_in_a_dialog_that_stays() {
+        let refuse: crate::WriteFn = Box::new(|p: &str, _: &[u8]| Err(format!("{p}: Access is denied. (os error 5)")));
+        let mut app = VectorcraftApp::new(Session::new(), Services { write: Some(refuse), ..Default::default() });
+        app.run("file.new", json!({"width": 100, "height": 80})).unwrap();
+        app.run("shape.rectangle", json!({"x": 10, "y": 10, "width": 30, "height": 20})).unwrap();
+        let unsaved = |app: &VectorcraftApp| {
+            let st = app.session.doc().unwrap();
+            (st.is_dirty(), st.path.clone())
+        };
+        for (command, path, message) in [
+            ("file.save", "/docs/Poster.vectorcraft", "Can't save “Poster.vectorcraft”."),
+            ("file.saveAs", "/docs/Poster.vectorcraft", "Can't save “Poster.vectorcraft”."),
+            ("file.saveCopy", "/docs/Copy.vectorcraft", "Can't save “Copy.vectorcraft”."),
+            ("file.exportAs", "/docs/Poster.png", "Can't export “Poster.png”."),
+            ("file.export.pdf", "/docs/Poster.pdf", "Can't save “Poster.pdf”."),
+        ] {
+            let e = app.run(command, json!({"path": path})).unwrap_err();
+            assert!(e.contains("Access is denied"), "{command}: {e}");
+            let d = app.ui.dialog.take().unwrap_or_else(|| panic!("{command}: a dialog says so"));
+            assert_eq!((d.kind.as_str(), d.str("message").as_str()), (dialogs::confirm::MESSAGE, message), "{command}");
+            assert_eq!(d.str("detail"), format!("{path}: Access is denied. (os error 5)"), "{command}");
+            assert_eq!(unsaved(&app), (true, None), "{command}");
+        }
+        // An agent waiting on its request gets the error as its reply, and no dialog.
+        app.ui.answering_control = true;
+        assert!(app.run("file.save", json!({"path": "/docs/Poster.vectorcraft"})).is_err());
+        app.ui.answering_control = false;
+        assert!(app.ui.dialog.is_none() && app.ui.told.is_empty());
+        // Under another dialog (a background save that fails later) the message waits its turn,
+        // once, and is drawn when that dialog is closed.
+        dialogs::confirm::ask(&mut app, "Delete the swatch?", "", "edit.undo", json!({}));
+        for _ in 0..2 {
+            report_write_error(&mut app, false, "/docs/Poster.vectorcraft", "the disk is full");
+        }
+        assert_eq!((app.ui.dialog.as_ref().map(|d| d.kind.as_str()), app.ui.told.len()), (Some(dialogs::confirm::KIND), 1));
+        app.ui.dialog = None;
+        for _ in 0..2 {
+            let ctx = egui::Context::default();
+            crate::theme::install_fonts(&ctx);
+            let mut out = ctx.run_ui(egui::RawInput::default(), |ui| dialogs::show(&mut app, ui.ctx()));
+            out.textures_delta.clear();
+        }
+        let d = app.ui.dialog.as_ref().expect("the message is shown, and stays");
+        assert_eq!(
+            (d.kind.as_str(), d.str("message").as_str(), d.str("detail").as_str()),
+            (dialogs::confirm::MESSAGE, "Can't save “Poster.vectorcraft”.", "the disk is full")
+        );
+        assert!(app.ui.told.is_empty());
+    }
+
     /// #1693: a browser download that can't be started is a failed save: the document stays
     /// modified and without a file, and Save Changes doesn't close it.
     #[test]
     fn a_download_that_cannot_start_leaves_the_document_unsaved_and_open() {
         let started = Rc::new(RefCell::new(false));
         let ok = started.clone();
-        let download: crate::DownloadFn = Box::new(move |_: &str, _: &[u8]| if *ok.borrow() { Ok(()) } else { Err("the browser refused the download".into()) });
+        let download: crate::DownloadFn =
+            Box::new(move |_: &str, _: &[u8]| if *ok.borrow() { Ok(()) } else { Err("the browser refused the download".into()) });
         let mut app = VectorcraftApp::new(Session::new(), Services { download: Some(download), ..Default::default() });
         app.run("file.new", json!({"width": 100, "height": 80})).unwrap();
         app.run("shape.rectangle", json!({"x": 10, "y": 10, "width": 30, "height": 20})).unwrap();

crates/ui-egui/src/lib.rs

@@ -780,7 +780,10 @@ impl VectorcraftApp {
             let reply = req.reply.clone();
             // Guarded per request: a panic must not drop the channel (taken out of `self` above).
             let roots = self.automation_roots.clone();
-            let outcome = match file_access::confine(roots.as_ref(), || vectorcraft_engine::guard::catch_panic(|| control::handle(self, ctx, &req))) {
+            self.ui.answering_control = true;
+            let answer = file_access::confine(roots.as_ref(), || vectorcraft_engine::guard::catch_panic(|| control::handle(self, ctx, &req)));
+            self.ui.answering_control = false;
+            let outcome = match answer {
                 Ok(outcome) => outcome,
                 Err(msg) => {
                     self.picks.recover();

crates/ui-egui/src/panels/links.rs

@@ -158,9 +158,9 @@ pub(crate) fn unembed(app: &mut VectorcraftApp, id: u64, name: &str) {
     if app.services.download.is_some() {
         if let Ok(v) = app.session.execute("links.unembed", &json!({ "id": id }))
             && let (Some(name), Some(bytes)) = (v["name"].as_str(), v["dataBase64"].as_str().and_then(vectorcraft_format::base64_decode))
-            && let Err(e) = crate::io::write_to(&mut app.services, name, &bytes)
         {
-            app.status(e);
+            // A download that can't start is said like any file that can't be written.
+            let _ = crate::io::write_reporting(app, name, &bytes);
         }
         return;
     }

crates/ui-egui/src/state.rs

@@ -306,6 +306,14 @@ pub struct UiState {
     pub dock: bool,
     pub view: ViewFlags,
     pub dialog: Option<Dialog>,
+    /// Messages to show in a dialog once the open one is closed (`dialogs::confirm::tell`), in
+    /// the order they came.
+    #[serde(skip)]
+    pub told: Vec<Dialog>,
+    /// A control request is being answered: its caller gets what fails as its reply, so no
+    /// dialog says it too (`io::report_write_error`).
+    #[serde(skip)]
+    pub answering_control: bool,
     /// Toolbar group whose flyout is open.
     pub flyout: Option<usize>,
     /// Last tool shown for each toolbar group (flyout selection sticks).
@@ -681,6 +689,8 @@ impl Default for UiState {
             dock: true,
             view: ViewFlags::default(),
             dialog: None,
+            told: vec![],
+            answering_control: false,
             flyout: None,
             group_tool: vectorcraft_tools::TOOL_GROUPS.iter().map(|g| g[0].id.to_string()).collect(),
             status: String::new(),