Save As suggests a new document's first words as its name (#5795)

Saving a document for the first time suggested Document1.docx whatever
it held. As in Word, a document that was never saved and has no title
of its own is now offered the first words of its first paragraph with
text: up to the first sentence or clause end, without the characters a
file name can't hold, white space collapsed, at most 50 characters cut
at a word's end (Minutes of the board meeting.docx). A path, a file
name or a Title property still name it, and the window title stays
Document1.

Fixes #5793

crates/ui-egui/src/app.rs

@@ -13,6 +13,8 @@ use super::{
 mod commands;
 mod control;
 mod files;
+#[cfg(test)]
+pub(crate) use files::suggested_stem;
 mod fonts;
 mod frame;
 mod input;

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

@@ -298,12 +298,16 @@ impl WordApp {
     }
 
     /// The name Save suggests: the open file's own Word format (so a .docm keeps its macros),
-    /// otherwise .docx.
+    /// otherwise .docx. A document never saved and without a title of its own is named after its
+    /// first words, as Word suggests them (#5793), instead of `Document1`.
     pub(crate) fn default_save_name(&self) -> String {
         let ext = self.session.path.as_ref().and_then(|p| p.extension()).map(|e| e.to_string_lossy().to_string());
+        let unnamed = self.session.path.is_none() && self.session.file_name.is_none() && self.session.doc.core.title.trim().is_empty();
+        let first = || self.session.doc.body.iter().filter_map(|b| b.as_para()).map(|p| p.plain_text()).find_map(|t| suggested_stem(&t));
+        let stem = unnamed.then(first).flatten().unwrap_or_else(|| self.title_stem());
         match ext {
-            Some(e) if wordcraft_engine::io::is_word_package(&e) => format!("{}.{e}", self.title_stem()),
-            _ => format!("{}.docx", self.title_stem()),
+            Some(e) if wordcraft_engine::io::is_word_package(&e) => format!("{stem}.{e}"),
+            _ => format!("{stem}.docx"),
         }
     }
 
@@ -463,3 +467,33 @@ impl WordApp {
         }
     }
 }
+
+/// The most characters a name taken from the text keeps ([`suggested_stem`]).
+const SUGGESTED_MAX: usize = 50;
+
+/// A file name from a paragraph's text (#5793): up to its first sentence or clause end
+/// (`.`, `!`, `?`, `;`, `:` and their full-width forms) or line break, without the characters a
+/// file name can't hold (`\ / : * ? " < > |` and controls), white space collapsed, at most
+/// [`SUGGESTED_MAX`] characters cut at a word's end, and no dot or space at either end (Windows
+/// drops them). `None` when nothing is left, so the next paragraph, or `Document1`, is used.
+pub(crate) fn suggested_stem(text: &str) -> Option<String> {
+    let end = |c: char| matches!(c, '.' | '!' | '?' | ';' | ':' | '\n' | '\r' | '\u{0B}' | '\u{2029}' | '。' | '！' | '？' | '；' | '：');
+    let head = text.split(end).next().unwrap_or("");
+    let kept: String = head.chars().map(|c| if c.is_control() || matches!(c, '\\' | '/' | '*' | '"' | '<' | '>' | '|') { ' ' } else { c }).collect();
+    let mut words = String::new();
+    for w in kept.split_whitespace() {
+        let next = if words.is_empty() { w.chars().count() } else { words.chars().count() + 1 + w.chars().count() };
+        if next > SUGGESTED_MAX {
+            if words.is_empty() {
+                words = w.chars().take(SUGGESTED_MAX).collect();
+            }
+            break;
+        }
+        if !words.is_empty() {
+            words.push(' ');
+        }
+        words.push_str(w);
+    }
+    let words = words.trim_matches(|c: char| c == '.' || c.is_whitespace()).to_string();
+    (!words.is_empty()).then_some(words)
+}

crates/ui-egui/src/file_dialogs/tests.rs

@@ -315,7 +315,8 @@ fn save_as_answer_arriving_later_is_saved() {
     typed(&mut a);
     a.save_as_dialog();
     assert!(a.file_dialog_open());
-    assert_eq!(shown.borrow()[0].0, FileDialogRequest::Save { name: "Document1.docx".into(), dir: None });
+    // A new document is offered its first words as its name, as in Word (#5793).
+    assert_eq!(shown.borrow()[0].0, FileDialogRequest::Save { name: format!("{UNSAVED}.docx"), dir: None });
     let ctx = egui::Context::default();
     let frame = |a: &mut WordApp| ctx.run_ui(egui::RawInput::default(), |ui| a.logic(ui.ctx())).drop_without_applying_deltas();
     frame(&mut a);

crates/ui-egui/src/tests.rs

@@ -96,6 +96,55 @@ fn title_stem_omits_nul_from_each_title_source() {
     }
 }
 
+/// #5793: a name from a paragraph's first words, as Word suggests one: up to the first sentence or
+/// clause end, without what a file name can't hold, at most 50 characters at a word's end.
+#[test]
+fn a_suggested_name_is_the_first_words_of_the_text() {
+    use crate::app::suggested_stem as stem;
+    assert_eq!(stem("Quarterly report for the board. More follows here.").as_deref(), Some("Quarterly report for the board"));
+    assert_eq!(stem("Minutes of the meeting, 6 November").as_deref(), Some("Minutes of the meeting, 6 November"));
+    assert_eq!(stem("What happened? Nobody knows").as_deref(), Some("What happened"));
+    assert_eq!(stem("Plan: phase one").as_deref(), Some("Plan"));
+    assert_eq!(stem("Q3 / Q4 \"draft\" <final> *v2* | a\\b").as_deref(), Some("Q3 Q4 draft final v2 a b"));
+    assert_eq!(stem("  Leading   and   inner   spaces  ").as_deref(), Some("Leading and inner spaces"));
+    assert_eq!(stem("日本語の文書。続きの文").as_deref(), Some("日本語の文書"));
+    let long = "Annual report of the regional committee on transport and infrastructure planning";
+    let got = stem(long).unwrap();
+    assert!(got.chars().count() <= 50 && long.starts_with(&got) && long[got.len()..].starts_with(' '), "{got:?}");
+    assert_eq!(stem(&"x".repeat(80)).map(|s| s.chars().count()), Some(50), "one long word is cut at 50");
+    for nothing in ["", "   ", "...", "?", "/ * |", "\u{1}"] {
+        assert_eq!(stem(nothing), None, "{nothing:?}");
+    }
+}
+
+/// #5793: Save As suggests the first words for a document that was never saved and has no title
+/// of its own (the first paragraph with text, past empty ones); a title, a file name or a path
+/// still name it.
+#[test]
+fn save_as_suggests_the_first_words_of_a_new_document() {
+    let mut app = app();
+    assert_eq!(app.default_save_name(), format!("{}.docx", app.title_stem()), "an empty document");
+    for c in [
+        json!(["text.newParagraph", {}]),
+        json!(["text.insert", {"text": "Minutes of the board meeting. Present: all"}]),
+        json!(["text.newParagraph", {}]),
+        json!(["text.insert", {"text": "Second paragraph"}]),
+    ] {
+        app.session.run(c[0].as_str().unwrap(), &c[1]).unwrap();
+    }
+    assert_eq!(app.default_save_name(), "Minutes of the board meeting.docx");
+    assert_eq!(
+        app.title_stem(),
+        crate::documents::untitled_title(&app.session.resolved_filenames().0).unwrap_or_else(|| "Document1".into()),
+        "the window title stays Document1"
+    );
+    app.session.doc.core.title = "Board minutes".into();
+    assert_eq!(app.default_save_name(), "Board minutes.docx", "a title wins");
+    app.session.doc.core.title.clear();
+    app.session.path = Some(std::path::PathBuf::from("/tmp/kept.docm"));
+    assert_eq!(app.default_save_name(), "kept.docm", "a saved file keeps its name and format");
+}
+
 /// #1678: Focus and Full Screen View put the window in full screen, asked of the system once
 /// per change (switching between the two keeps it), and the usual window comes back after.
 #[test]