M7: open dropped files that have no file on disk

A home-screen drop that carries only bytes queued file.open with data and name, which file.open rejected because it requires a path. file.open now also takes base64 data with a name and opens it as a new document without a save path.

crates/engine/src/cmd/file.rs

@@ -30,7 +30,7 @@ pub fn specs() -> Vec<CommandSpec> {
         spec!(
             "file.open",
             "Open",
-            "{path, variables? (REST: the local variables JSON as an object, JSON text or a path; default `<name>.variables.json` or `variables.json` next to the file)} (.figcraft, .json: FigCraft or REST API file JSON, .fig (best effort), .svg, .png, .jpg …); REST and .fig imports return `warnings`",
+            "{path | data (base64) + name (tells the format; opens as a new unsaved document), variables? (REST: the local variables JSON as an object, JSON text or a path; default `<name>.variables.json` or `variables.json` next to the file)} (.figcraft, .json: FigCraft or REST API file JSON, .fig (best effort), .svg, .png, .jpg …); REST and .fig imports return `warnings`",
             false,
             open
         ),
@@ -653,8 +653,13 @@ fn open_recent(s: &mut Session, p: &Value) -> Result<Value> {
 }
 
 fn open(s: &mut Session, p: &Value) -> Result<Value> {
-    let path = req_string("file.open", p, "path")?;
     let variables = variables_param("file.open", p)?;
+    if string(p, "path").is_none()
+        && let Some(d) = string(p, "data")
+    {
+        return open_data(s, &d, p, variables.as_ref());
+    }
+    let path = req_string("file.open", p, "path")?;
     // Already open: switch to it.
     if let Some(i) = s.docs.iter().position(|d| d.path.as_deref() == Some(path.as_str())) {
         s.active = i;
@@ -679,6 +684,21 @@ fn open(s: &mut Session, p: &Value) -> Result<Value> {
     Ok(out)
 }
 
+/// [`open`] for a file given as base64 `data` (a file dropped without a path on disk): `name` tells
+/// the format. It opens as a new document with no path, so the first save asks where to put it.
+fn open_data(s: &mut Session, data: &str, p: &Value, variables: Option<&Value>) -> Result<Value> {
+    let name = req_string("file.open", p, "name")?;
+    let data = data.split_once(',').map_or(data, |(_, b)| b);
+    let bytes = base64::engine::general_purpose::STANDARD.decode(data.trim()).map_err(|e| bad("file.open", e.to_string()))?;
+    let (loaded, rest) = load_with(&bytes, &name, variables, &figcraft_format::rest::no_images)?;
+    let warnings = rest || ext(&name) == "svg";
+    s.docs.push(DocState::new(loaded.doc, None).with_versions(loaded.versions).with_branches(loaded.branches));
+    s.active = s.docs.len() - 1;
+    let mut out = json!({"index": s.active});
+    out[if warnings { "warnings" } else { "repairs" }] = json!(loaded.issues);
+    Ok(out)
+}
+
 /// Thumbnail PNG of the first page's content (for file browsers / the home screen).
 pub fn thumbnail(doc: &Document) -> Option<Vec<u8>> {
     let page = doc.first_page()?;
@@ -1351,6 +1371,25 @@ mod rest_import_tests {
         assert!(thumbnail(&doc).is_some());
     }
 
+    #[test]
+    fn open_takes_data_and_a_name_as_a_new_unsaved_document() {
+        let mut saved = Session::new();
+        saved.execute("shape.rectangle", &json!({"x": 0, "y": 0, "width": 10, "height": 10})).unwrap();
+        let bytes = file_bytes(saved.ds().unwrap()).unwrap();
+        let data = base64::engine::general_purpose::STANDARD.encode(&bytes);
+        let mut s = Session::new();
+        let recent = s.prefs.recent_files.clone();
+        let r = s.execute("file.open", &json!({"data": data, "name": "Dropped.figcraft"})).unwrap();
+        let open = s.docs.len();
+        assert_eq!(r["index"], open - 1, "a document of its own, made active");
+        assert_eq!(s.ds().unwrap().path, None, "no path to save over");
+        assert!(s.doc().unwrap().nodes().any(|n| matches!(n.kind, NodeKind::Rectangle)));
+        assert_eq!(s.prefs.recent_files, recent, "nothing on disk to remember");
+        assert!(s.execute("file.open", &json!({"data": data})).is_err(), "the name tells the format");
+        assert!(s.execute("file.open", &json!({"data": "not base64!", "name": "x.svg"})).is_err());
+        assert_eq!(s.docs.len(), open, "a refused open adds nothing");
+    }
+
     #[test]
     fn open_and_import_rest_json() {
         let dir = std::env::temp_dir().join(format!("figcraft-rest-{}", std::process::id()));