feat: Add support for useDeferredApi

- Port over the functionality of GetPanelApiContext into a hook that can be easily used instead
- Will be necessary to ensure widgets panels are wrapped in the correct API, as they are opened using portal panels and may not be wrapped in the same API

packages/jsapi-bootstrap/src/useApi.test.ts

@@ -0,0 +1,39 @@
+import { renderHook } from '@testing-library/react-hooks';
+import dh from '@deephaven/jsapi-shim';
+import { useContext } from 'react';
+import { TestUtils } from '@deephaven/utils';
+import { useApi } from './useApi';
+
+const { asMock } = TestUtils;
+
+jest.mock('react', () => ({
+  ...jest.requireActual('react'),
+  useContext: jest.fn(),
+}));
+
+beforeEach(() => {
+  jest.clearAllMocks();
+  expect.hasAssertions();
+
+  asMock(useContext).mockName('useContext');
+});
+
+describe('useApi', () => {
+  it('should return API context value', () => {
+    asMock(useContext).mockReturnValue(dh);
+
+    const { result } = renderHook(() => useApi());
+    expect(result.current).toBe(dh);
+  });
+
+  it('should throw if context is null', () => {
+    asMock(useContext).mockReturnValue(null);
+
+    const { result } = renderHook(() => useApi());
+    expect(result.error).toEqual(
+      new Error(
+        'No API available in useApi. Was code wrapped in ApiBootstrap or ApiContext.Provider?'
+      )
+    );
+  });
+});

packages/jsapi-bootstrap/src/useApi.ts

@@ -2,6 +2,10 @@ import type { dh as DhType } from '@deephaven/jsapi-types';
 import { useContextOrThrow } from '@deephaven/react-hooks';
 import { ApiContext } from './ApiBootstrap';
 
+/**
+ * Retrieve the API for the current context.
+ * @returns The API instance from the nearest ApiContext.Provider, or throws if none is set
+ */
 export function useApi(): DhType {
   return useContextOrThrow(
     ApiContext,

packages/jsapi-bootstrap/src/useDeferredApi.test.ts

@@ -0,0 +1,69 @@
+import { act, renderHook } from '@testing-library/react-hooks';
+import type { dh as DhType } from '@deephaven/jsapi-types';
+import { useContext } from 'react';
+import { TestUtils } from '@deephaven/utils';
+import { DeferredApiOptions, useDeferredApi } from './useDeferredApi';
+
+const { asMock, createMockProxy, flushPromises } = TestUtils;
+
+const dh1 = createMockProxy<DhType>();
+const dh2 = createMockProxy<DhType>();
+
+jest.mock('react', () => ({
+  ...jest.requireActual('react'),
+  useContext: jest.fn(),
+}));
+
+beforeEach(() => {
+  jest.clearAllMocks();
+  asMock(useContext).mockName('useContext');
+});
+
+describe('useApi', () => {
+  it('should return API directly if a value is provided from useContext, whatever the options are', () => {
+    asMock(useContext).mockReturnValue(dh1);
+
+    const { result } = renderHook(() => useDeferredApi());
+    expect(result.current).toEqual([dh1, null]);
+
+    const { result: result2 } = renderHook(() =>
+      useDeferredApi({ foo: 'bar' })
+    );
+    expect(result2.current).toEqual([dh1, null]);
+  });
+
+  it('should resolve to the API value when it is provided from the function', async () => {
+    asMock(useContext).mockReturnValue(async (options?: DeferredApiOptions) => {
+      switch (options?.id) {
+        case '1':
+          return dh1;
+        case '2':
+          return dh2;
+        default:
+          throw new Error('Invalid id');
+      }
+    });
+
+    const { rerender, result } = renderHook(
+      (options?: DeferredApiOptions) => useDeferredApi(options),
+      { initialProps: { id: '1' } }
+    );
+    await act(flushPromises);
+    expect(result.current).toEqual([dh1, null]);
+
+    rerender({ id: '2' });
+    await act(flushPromises);
+    expect(result.current).toEqual([dh2, null]);
+
+    rerender({ id: '3' });
+    await act(flushPromises);
+    expect(result.current).toEqual([null, expect.any(Error)]);
+  });
+
+  it('returns an error if the context is null', async () => {
+    asMock(useContext).mockReturnValue(null);
+
+    const { result } = renderHook(() => useDeferredApi());
+    expect(result.current).toEqual([null, expect.any(Error)]);
+  });
+});

packages/jsapi-bootstrap/src/useDeferredApi.ts

@@ -0,0 +1,75 @@
+import { createContext, useContext, useEffect, useState } from 'react';
+import type { dh as DhType } from '@deephaven/jsapi-types';
+import { ApiContext } from './ApiBootstrap';
+
+/** Options for retrieving the deferred */
+export type DeferredApiOptions = Record<string, unknown>;
+
+export type DeferredApiFetcher = (
+  options?: DeferredApiOptions
+) => Promise<DhType>;
+
+export const DeferredApiContext = createContext<
+  DhType | DeferredApiFetcher | null
+>(null);
+
+/**
+ * Retrieve the API for the current context, given the metadata provided.
+ * The API may need to be loaded, and will return `null` until it is ready.
+ * @returns A tuple with the API instance, and an error if one occurred.
+ */
+export function useDeferredApi(
+  options?: Record<string, unknown>
+): [DhType | null, unknown | null] {
+  const [api, setApi] = useState<DhType | null>(null);
+  const [error, setError] = useState<unknown | null>(null);
+  const deferredApi = useContext(DeferredApiContext);
+  const contextApi = useContext(ApiContext);
+
+  useEffect(() => {
+    if (deferredApi == null) {
+      if (contextApi != null) {
+        setApi(contextApi);
+        setError(null);
+        return;
+      }
+      setApi(null);
+      setError(
+        new Error(
+          'No API available in useDeferredApi. Was code wrapped in ApiBootstrap or DeferredApiContext.Provider?'
+        )
+      );
+      return;
+    }
+    let isCancelled = false;
+
+    async function loadApi() {
+      if (typeof deferredApi === 'function') {
+        try {
+          const newApi = await deferredApi(options);
+          if (!isCancelled) {
+            setApi(newApi);
+            setError(null);
+          }
+        } catch (e) {
+          if (!isCancelled) {
+            setApi(null);
+            setError(e);
+          }
+        }
+      } else {
+        setApi(deferredApi);
+      }
+    }
+
+    loadApi();
+
+    return () => {
+      isCancelled = true;
+    };
+  }, [contextApi, deferredApi, options]);
+
+  return [api, error];
+}
+
+export default useDeferredApi;