feat: 로그인 성공 시 토큰 저장 및 홈 스크린 이동

src/store/auth.tsx

@@ -1,24 +1,58 @@
-import React, { createContext, useContext, useMemo, useState } from "react";
+import AsyncStorage from "@react-native-async-storage/async-storage";
+import React, {
+  createContext,
+  useCallback,
+  useContext,
+  useEffect,
+  useMemo,
+  useState,
+} from "react";
+import { loginApi } from "../api/auth";
+
+const ACCESS_TOKEN_KEY = "accessToken";
 
 export type AuthContextValue = {
+  accessToken: string | null;
   isAuthed: boolean;
-  login: () => void;
-  logout: () => void;
+  isHydrating: boolean; // 앱 시작 시 저장소에서 토큰 읽는 중인지
+  signIn: (loginId: string, password: string) => Promise<void>;
+  signOut: () => Promise<void>;
 };
 
 const AuthContext = createContext<AuthContextValue | null>(null);
 
 export function AuthProvider({ children }: { children: React.ReactNode }) {
-  const [isAuthed, setIsAuthed] = useState<boolean>(false);
-  console.log("isAuthed: " + isAuthed);
+  const [accessToken, setAccessToken] = useState<string | null>(null);
+  const [isHydrating, setIsHydrating] = useState(true);
+
+  useEffect(() => {
+    (async () => {
+      const stored = await AsyncStorage.getItem(ACCESS_TOKEN_KEY);
+      setAccessToken(stored);
+      setIsHydrating(false);
+    })();
+  }, []);
+
+  const signIn = useCallback(async (loginId: string, password: string) => {
+    const token = await loginApi({ loginId, password });
+    setAccessToken(token);
+    await AsyncStorage.setItem(ACCESS_TOKEN_KEY, token);
+  }, []);
+
+  const signOut = useCallback(async () => {
+    setAccessToken(null);
+    await AsyncStorage.removeItem(ACCESS_TOKEN_KEY);
+  }, []);
 
   const value = useMemo<AuthContextValue>(
     () => ({
-      isAuthed,
-      login: () => setIsAuthed(true),
-      logout: () => setIsAuthed(false),
+      accessToken,
+      isAuthed: accessToken != null,
+      isHydrating,
+      signIn,
+      signOut,
     }),
-    [isAuthed]
+    [accessToken, isHydrating, signIn, signOut]
   );
 
   return <AuthContext.Provider value={value}>{children}</AuthContext.Provider>;