1 files changed, 74 insertions, 0 deletions
diff --git a/frontend/src/components/DeckyGlobalComponentsState.tsx b/frontend/src/components/DeckyGlobalComponentsState.tsx
new file mode 100644
index 00000000..fe45588b
--- /dev/null
+++ b/frontend/src/components/DeckyGlobalComponentsState.tsx
@@ -0,0 +1,74 @@
+import { FC, createContext, useContext, useEffect, useState } from 'react';
+
+interface PublicDeckyGlobalComponentsState {
+  components: Map<string, FC>;
+}
+
+export class DeckyGlobalComponentsState {
+  // TODO a set would be better
+  private _components = new Map<string, FC>();
+
+  public eventBus = new EventTarget();
+
+  publicState(): PublicDeckyGlobalComponentsState {
+    return { components: this._components };
+  }
+
+  addComponent(path: string, component: FC) {
+    this._components.set(path, component);
+    this.notifyUpdate();
+  }
+
+  removeComponent(path: string) {
+    this._components.delete(path);
+    this.notifyUpdate();
+  }
+
+  private notifyUpdate() {
+    this.eventBus.dispatchEvent(new Event('update'));
+  }
+}
+
+interface DeckyGlobalComponentsContext extends PublicDeckyGlobalComponentsState {
+  addComponent(path: string, component: FC): void;
+  removeComponent(path: string): void;
+}
+
+const DeckyGlobalComponentsContext = createContext<DeckyGlobalComponentsContext>(null as any);
+
+export const useDeckyGlobalComponentsState = () => useContext(DeckyGlobalComponentsContext);
+
+interface Props {
+  deckyGlobalComponentsState: DeckyGlobalComponentsState;
+}
+
+export const DeckyGlobalComponentsStateContextProvider: FC<Props> = ({
+  children,
+  deckyGlobalComponentsState: deckyGlobalComponentsState,
+}) => {
+  const [publicDeckyGlobalComponentsState, setPublicDeckyGlobalComponentsState] =
+    useState<PublicDeckyGlobalComponentsState>({
+      ...deckyGlobalComponentsState.publicState(),
+    });
+
+  useEffect(() => {
+    function onUpdate() {
+      setPublicDeckyGlobalComponentsState({ ...deckyGlobalComponentsState.publicState() });
+    }
+
+    deckyGlobalComponentsState.eventBus.addEventListener('update', onUpdate);
+
+    return () => deckyGlobalComponentsState.eventBus.removeEventListener('update', onUpdate);
+  }, []);
+
+  const addComponent = deckyGlobalComponentsState.addComponent.bind(deckyGlobalComponentsState);
+  const removeComponent = deckyGlobalComponentsState.removeComponent.bind(deckyGlobalComponentsState);
+
+  return (
+    <DeckyGlobalComponentsContext.Provider
+      value={{ ...publicDeckyGlobalComponentsState, addComponent, removeComponent }}
+    >
+      {children}
+    </DeckyGlobalComponentsContext.Provider>
+  );
+};