Add NostrContext to manage connection to Nostr relay

src/contexts/nostr-context.tsx

@@ -0,0 +1,48 @@
+import { NRelay, NRelay1, NostrSigner } from '@soapbox/nspec';
+import React, { createContext, useContext, useState, useEffect } from 'react';
+
+import { signer } from 'soapbox/features/nostr/sign';
+import { useInstance } from 'soapbox/hooks/useInstance';
+
+interface NostrContextType {
+  relay?: NRelay;
+  pubkey?: string;
+  signer?: NostrSigner;
+}
+
+const NostrContext = createContext<NostrContextType | undefined>(undefined);
+
+interface NostrProviderProps {
+  children: React.ReactNode;
+}
+
+export const NostrProvider: React.FC<NostrProviderProps> = ({ children }) => {
+  const instance = useInstance();
+  const [relay, setRelay] = useState<NRelay1>();
+
+  const url = instance.nostr?.relay;
+  const pubkey = instance.nostr?.pubkey;
+
+  useEffect(() => {
+    if (url) {
+      setRelay(new NRelay1(url));
+    }
+    return () => {
+      relay?.close();
+    };
+  }, [url]);
+
+  return (
+    <NostrContext.Provider value={{ relay, pubkey, signer }}>
+      {children}
+    </NostrContext.Provider>
+  );
+};
+
+export const useNostr = () => {
+  const context = useContext(NostrContext);
+  if (context === undefined) {
+    throw new Error('useNostr must be used within a NostrProvider');
+  }
+  return context;
+};