import { onMounted, ref } from 'vue';
import { Agent } from '@atproto/api';
import { BrowserOAuthClient } from '@atproto/oauth-client-browser';
import { joinURL } from 'ufo';

let oauthClient: BrowserOAuthClient | null = null;
let initPromise: Promise<void> | null = null;

// 認証状態をComposable間で共有
const agent = ref<Agent | null>(null);
const isAuthenticated = ref(false);
const isInitializing = ref(true);

const createOAuthClient = async () => {
  if (import.meta.server) {
    return null;
  }

  if (oauthClient) {
    return oauthClient;
  }

  const origin = window.location.origin;
  const hostname = window.location.hostname;

  // ローカル開発
  const isLoopback = hostname === 'localhost' || hostname === '127.0.0.1';

  if (isLoopback) {
    oauthClient = new BrowserOAuthClient({
      clientMetadata: undefined,
      handleResolver: 'https://bsky.social'
    });
  } else {
    // 本番
    const metadataUrl = joinURL(origin, 'client-metadata.json');

    oauthClient = await BrowserOAuthClient.load({
      clientId: metadataUrl,
      handleResolver: 'https://bsky.social'
    });
  }

  return oauthClient;
};

const initAuth = async () => {
  if (import.meta.server) {
    isInitializing.value = false;
    return;
  }

  // 既に初期化処理中なら同じPromiseを待つ
  if (initPromise) {
    return initPromise;
  }

  initPromise = (async () => {
    try {
      console.log('[ATP] Initializing OAuth client...');

      const client = await createOAuthClient();

      if (!client) {
        return;
      }

      console.log('[ATP] Restoring OAuth session...');

      // アプリ起動時に1回だけ実行
      const result = await client.init();

      if (result) {
        agent.value = new Agent(result.session);
        isAuthenticated.value = true;

        console.log('[ATP] Session restored:', result.session.did);
      } else {
        agent.value = null;
        isAuthenticated.value = false;

        console.log('[ATP] No active session');
      }
    } catch (error) {
      console.error('[ATP] OAuth initialization failed:', error);

      agent.value = null;
      isAuthenticated.value = false;
    } finally {
      isInitializing.value = false;
    }
  })();

  return initPromise;
};

export const useAtpAuth = () => {
  const login = async (handleOrPds: string) => {
    if (import.meta.server) {
      return;
    }

    // 初期化完了を待つ
    await initAuth();

    const client = await createOAuthClient();

    if (!client) {
      throw new Error('OAuth client is not available.');
    }

    try {
      // ここでOAuth認可画面へリダイレクト
      await client.signIn(handleOrPds);
    } catch (error) {
      console.error('[ATP] Login failed:', error);

      throw error;
    }
  };

  const logout = async () => {
    if (import.meta.server) {
      return;
    }

    const client = await createOAuthClient();

    try {
      if (client && agent.value) {
        const did = agent.value.assertDid;

        await client.revoke(did);
      }
    } catch (error) {
      console.error('[ATP] Logout failed:', error);
    } finally {
      agent.value = null;
      isAuthenticated.value = false;
    }
  };

  // 各コンポーネントからuseAtpAuth()を呼んでも
  // 共有されたinitAuth()を使う
  onMounted(() => {
    void initAuth();
  });

  return {
    agent,
    isAuthenticated,
    isInitializing,
    initAuth,
    login,
    logout
  };
};