From 46b8998f6ebbfa7fbf6d0ee84345ca808e6155b5 Mon Sep 17 00:00:00 2001
From: Norman Fomferra <norman.fomferra@brockmann-consult.de>
Date: Tue, 10 Dec 2024 08:44:22 +0100
Subject: [PATCH] respecting multiple signal syntax forms

---
 .../vega/hooks/useSignalListeners.test.ts     | 38 ++++++++++++++++---
 .../plugins/vega/hooks/useSignalListeners.ts  | 35 +++++++++++------
 2 files changed, 55 insertions(+), 18 deletions(-)

diff --git a/chartlets.js/packages/lib/src/plugins/vega/hooks/useSignalListeners.test.ts b/chartlets.js/packages/lib/src/plugins/vega/hooks/useSignalListeners.test.ts
index fc2f92ec..b6d38713 100644
--- a/chartlets.js/packages/lib/src/plugins/vega/hooks/useSignalListeners.test.ts
+++ b/chartlets.js/packages/lib/src/plugins/vega/hooks/useSignalListeners.test.ts
@@ -24,14 +24,27 @@ const chartWithSelect: TopLevelSpec = {
   ...chart,
   params: [
     {
-      name: "points",
-      select: { type: "point", fields: ["x", "a"], on: "click" },
+      name: "sel_point",
+      select: "point",
+    },
+    {
+      name: "sel_interval",
+      select: "interval",
+    },
+    {
+      name: "sel_point_a",
+      select: { on: "click", type: "point", fields: ["x", "a"] },
+    },
+    // Event not supported yet
+    {
+      name: "sel_interval_b",
+      select: { on: "wheel", type: "interval", fields: ["x", "b"] },
     },
   ],
 };
 
 describe("useSignalListeners", () => {
-  it("should return a stable record", () => {
+  it("should return a stable record wo signals", () => {
     const { result, rerender } = renderHook(() =>
       useSignalListeners(chart, "VegaChart", "my_chart", () => {}),
     );
@@ -43,6 +56,19 @@ describe("useSignalListeners", () => {
     expect(signalHandlers1).toBe(signalHandlers1);
   });
 
+  it("should support different signal types", () => {
+    const { result } = renderHook(() =>
+      useSignalListeners(chartWithSelect, "VegaChart", "my_chart", () => {}),
+    );
+    const signalHandlers = result.current;
+    expect(signalHandlers).toBeDefined();
+    expect(signalHandlers["sel_point"]).toBeTypeOf("function");
+    expect(signalHandlers["sel_interval"]).toBeTypeOf("function");
+    expect(signalHandlers["sel_point_a"]).toBeTypeOf("function");
+    // "wheel" not supported
+    expect(signalHandlers["sel_point_b"]).toBeUndefined();
+  });
+
   it("should call onChange", () => {
     const { recordedEvents, onChange } = createChangeHandler();
     const { result } = renderHook(() =>
@@ -50,16 +76,16 @@ describe("useSignalListeners", () => {
     );
     const signalHandlers = result.current;
     expect(signalHandlers).toBeDefined();
-    const signalHandler = signalHandlers["points"];
+    const signalHandler = signalHandlers["sel_point_a"];
     expect(signalHandler).toBeTypeOf("function");
     act(() => {
-      signalHandler("points", [1, 2, 3]);
+      signalHandler("sel_point_a", [1, 2, 3]);
     });
     expect(recordedEvents.length).toBe(1);
     expect(recordedEvents[0]).toEqual({
       componentType: "VegaChart",
       id: "my_chart",
-      property: "points",
+      property: "sel_point_a",
       value: [1, 2, 3],
     });
   });
diff --git a/chartlets.js/packages/lib/src/plugins/vega/hooks/useSignalListeners.ts b/chartlets.js/packages/lib/src/plugins/vega/hooks/useSignalListeners.ts
index 4b2b326c..125621f6 100644
--- a/chartlets.js/packages/lib/src/plugins/vega/hooks/useSignalListeners.ts
+++ b/chartlets.js/packages/lib/src/plugins/vega/hooks/useSignalListeners.ts
@@ -13,15 +13,18 @@ type SignalHandler = (signalName: string, signalValue: unknown) => void;
  * only interested in extracting the handlers, the following
  * properties are required.
  */
-type SelectionParameter = { name: string; select: { on: string } };
+type SelectionParameter = {
+  name: string;
+  select: "point" | "interval" | { type: "point" | "interval"; on: string };
+};
 
 const isSelectionParameter = (param: unknown): param is SelectionParameter =>
   isObject(param) &&
-  "name" in param &&
-  "select" in param &&
-  isObject(param.select) &&
-  param.select?.on !== null &&
-  isString(param.select.on);
+  (param.select === "point" ||
+    param.select === "interval" ||
+    (isObject(param.select) &&
+      (param.select.type === "point" || param.select.type === "interval") &&
+      isString(param.select.on)));
 
 export function useSignalListeners(
   chart: TopLevelSpec | null | undefined,
@@ -36,16 +39,23 @@ export function useSignalListeners(
    * have so that we can create those listeners with the `name` specified in
    * the event-listener object.
    */
-  const signalNames = useMemo((): Record<string, string> => {
-    const signalNames: Record<string, string> = {};
+  const signalNames = useMemo(() => {
+    const signalNames: [string, string][] = [];
     if (!chart || !chart.params) {
       return signalNames;
     }
     return chart.params
       .filter(isSelectionParameter)
-      .reduce((paramNames, param) => {
-        paramNames[param.select.on] = param.name;
-        return paramNames;
+      .reduce((signalNames, param) => {
+        // https://vega.github.io/vega-lite/docs/parameter.html#select
+        if (param.select === "point") {
+          signalNames.push(["click", param.name]);
+        } else if (param.select === "interval") {
+          signalNames.push(["drag", param.name]);
+        } else {
+          signalNames.push([param.select.on, param.name]);
+        }
+        return signalNames;
       }, signalNames);
   }, [chart]);
 
@@ -74,10 +84,11 @@ export function useSignalListeners(
      */
     const signalHandlers: Record<string, SignalHandler> = {
       click: handleClickSignal,
+      drag: handleClickSignal,
     };
 
     const signalListeners: Record<string, SignalHandler> = {};
-    Object.entries(signalNames).forEach(([event, signalName]) => {
+    signalNames.forEach(([event, signalName]) => {
       if (signalHandlers[event]) {
         signalListeners[signalName] = signalHandlers[event];
       } else {