Parameters: move user parameters up and down (#1323)

Fixes #1187. New parameters.move {name, before|after} reorders user parameters (the design's own params order, so it is saved with no format change, and undoable); the Parameters dialog's user rows get up/down buttons. Label in every catalog. I merged main in. Checked on main + this branch: cargo check --workspace, the engine parameters tests, the UI parameter_order test, and docs/features.md regenerates unchanged.

crates/engine/src/cmd/parameters.rs

@@ -24,6 +24,8 @@ pub static COMMANDS: &[CommandSpec] = &[
         .params("name, new_name (expressions, feature inputs and dimensions that use it follow)"),
     CommandSpec::new("parameters.delete", "Delete Parameter", delete).params("name (refused while something uses it; the error lists the users)"),
     CommandSpec::new("parameters.favorite", "Favourite Parameter", favorite).params("name, favorite?: bool (default true)"),
+    CommandSpec::new("parameters.move", "Move Parameter", move_param)
+        .params("name, before | after: another user parameter; the user parameter is listed just before or after it"),
     CommandSpec::new("parameters.comment", "Comment Parameter", comment).params("name, comment"),
     CommandSpec::new("parameters.users", "Parameter Users", users)
         .noundo()
@@ -179,6 +181,19 @@ fn favorite(s: &mut Session, p: &Value) -> Result<Value> {
     Ok(json!({"name": name, "favorite": on}))
 }
 
+fn move_param(s: &mut Session, p: &Value) -> Result<Value> {
+    let cmd = "parameters.move";
+    let name = param_name(cmd, p)?.to_string();
+    let (target, after) = match (str_(p, "before"), str_(p, "after")) {
+        (Some(t), None) => (t.to_string(), false),
+        (None, Some(t)) => (t.to_string(), true),
+        _ => return Err(bad(cmd, "give one of `before` or `after`: another user parameter")),
+    };
+    s.doc_mut().move_user_param(&name, &target, after)?;
+    let order: Vec<&str> = s.doc.params.iter().filter(|q| !q.model).map(|q| q.name.as_str()).collect();
+    Ok(json!({"name": name, "order": order}))
+}
+
 fn comment(s: &mut Session, p: &Value) -> Result<Value> {
     let cmd = "parameters.comment";
     let name = param_name(cmd, p)?.to_string();

crates/engine/src/cmd/parameters_tests.rs

@@ -544,3 +544,52 @@ fn switching_configurations_back_reuses_the_later_features() {
     assert!(rel(volume(&mut s), 40.0 * 30.0 * 10.0) < 1e-9);
     assert!(hits(&s) > before, "{r}");
 }
+
+/// The user parameters' names in the order the Parameters dialog lists them.
+fn user_order(s: &mut Session) -> Vec<String> {
+    let v = run(s, "parameters.list", json!({"filter": "user"}));
+    v["parameters"].as_array().unwrap().iter().map(|r| r["name"].as_str().unwrap().to_string()).collect()
+}
+
+#[test]
+fn user_parameters_reorder_with_undo() {
+    // #1187: move a user parameter before or after another; nothing else changes.
+    let mut s = Session::default();
+    for (n, e) in [("a", "1 mm"), ("b", "2 mm"), ("c", "a + b")] {
+        run(&mut s, "parameters.add", json!({"name": n, "expression": e}));
+    }
+    assert_eq!(user_order(&mut s), ["a", "b", "c"]);
+    let r = run(&mut s, "parameters.move", json!({"name": "c", "before": "a"}));
+    assert_eq!(r["order"], json!(["c", "a", "b"]));
+    assert_eq!(user_order(&mut s), ["c", "a", "b"]);
+    run(&mut s, "parameters.move", json!({"name": "c", "after": "a"}));
+    assert_eq!(user_order(&mut s), ["a", "c", "b"]);
+    // Values and references are untouched; the order is kept in the design file.
+    let list = run(&mut s, "parameters.list", json!({"filter": "user"}));
+    let c = list["parameters"].as_array().unwrap().iter().find(|r| r["name"] == "c").unwrap().clone();
+    assert_eq!(c["expression"], "a + b");
+    assert!((c["value"].as_f64().unwrap() - 3.0).abs() < 1e-9, "{c}");
+    let back = Session::new(solidcraft_doc::Document::from_json(&s.doc.to_json()).unwrap());
+    let names: Vec<&str> = back.doc.params.iter().filter(|p| !p.model).map(|p| p.name.as_str()).collect();
+    assert_eq!(names, ["a", "c", "b"]);
+    run(&mut s, "edit.undo", json!({}));
+    assert_eq!(user_order(&mut s), ["c", "a", "b"]);
+}
+
+#[test]
+fn moving_a_parameter_refuses_bad_targets() {
+    let mut s = Session::default();
+    run(&mut s, "parameters.add", json!({"name": "a", "expression": "1 mm"}));
+    run(&mut s, "parameters.add", json!({"name": "b", "expression": "2 mm"}));
+    let before = s.doc.to_json();
+    for p in [
+        json!({"name": "a", "before": "a"}),
+        json!({"name": "a", "before": "nope"}),
+        json!({"name": "nope", "before": "a"}),
+        json!({"name": "a"}),
+        json!({"name": "a", "before": "b", "after": "b"}),
+    ] {
+        err(&mut s, "parameters.move", p);
+    }
+    assert_eq!(s.doc.to_json(), before);
+}