feishu-integration/
├── src/
│   ├── config/
│   │   ├── feishu.ts              # Feishu app configuration
│   │   └── env.ts                 # Environment variable management
│   ├── auth/
│   │   ├── token-manager.ts       # Token retrieval and caching
│   │   └── event-verify.ts        # Event subscription verification
│   ├── bot/
│   │   ├── command-handler.ts     # Bot command handler
│   │   ├── message-sender.ts      # Message sending wrapper
│   │   └── card-builder.ts        # Message card builder
│   ├── approval/
│   │   ├── approval-define.ts     # Approval definition management
│   │   ├── approval-instance.ts   # Approval instance operations
│   │   └── approval-callback.ts   # Approval event callbacks
│   ├── bitable/
│   │   ├── table-client.ts        # Bitable CRUD operations
│   │   └── sync-service.ts        # Data synchronization service
│   ├── sso/
│   │   ├── oauth-handler.ts       # OAuth authorization flow
│   │   └── user-sync.ts           # User info synchronization
│   ├── webhook/
│   │   ├── event-dispatcher.ts    # Event dispatcher
│   │   └── handlers/              # Event handlers by type
│   └── utils/
│       ├── http-client.ts         # HTTP request wrapper
│       ├── logger.ts              # Logging utility
│       └── retry.ts               # Retry mechanism
├── tests/
├── docker-compose.yml
└── package.json

// src/auth/token-manager.ts
import * as lark from '@larksuiteoapi/node-sdk';

const client = new lark.Client({
  appId: process.env.FEISHU_APP_ID!,
  appSecret: process.env.FEISHU_APP_SECRET!,
  disableTokenCache: false, // SDK built-in caching
});

export { client };

// Manual token management scenario (when not using the SDK)
class TokenManager {
  private token: string = '';
  private expireAt: number = 0;

  async getTenantAccessToken(): Promise<string> {
    if (this.token && Date.now() < this.expireAt) {
      return this.token;
    }

    const resp = await fetch(
      'https://open.feishu.cn/open-apis/auth/v3/tenant_access_token/internal',
      {
        method: 'POST',
        headers: { 'Content-Type': 'application/json' },
        body: JSON.stringify({
          app_id: process.env.FEISHU_APP_ID,
          app_secret: process.env.FEISHU_APP_SECRET,
        }),
      }
    );

    const data = await resp.json();
    if (data.code !== 0) {
      throw new Error(`Failed to obtain token: ${data.msg}`);
    }

    this.token = data.tenant_access_token;
    // Expire 5 minutes early to avoid boundary issues
    this.expireAt = Date.now() + (data.expire - 300) * 1000;
    return this.token;
  }
}

export const tokenManager = new TokenManager();

// src/bot/card-builder.ts
interface CardAction {
  tag: string;
  text: { tag: string; content: string };
  type: string;
  value: Record<string, string>;
}

// Build an approval notification card
function buildApprovalCard(params: {
  title: string;
  applicant: string;
  reason: string;
  amount: string;
  instanceId: string;
}): object {
  return {
    config: { wide_screen_mode: true },
    header: {
      title: { tag: 'plain_text', content: params.title },
      template: 'orange',
    },
    elements: [
      {
        tag: 'div',
        fields: [
          {
            is_short: true,
            text: { tag: 'lark_md', content: `**Applicant**\n${params.applicant}` },
          },
          {
            is_short: true,
            text: { tag: 'lark_md', content: `**Amount**\n¥${params.amount}` },
          },
        ],
      },
      {
        tag: 'div',
        text: { tag: 'lark_md', content: `**Reason**\n${params.reason}` },
      },
      { tag: 'hr' },
      {
        tag: 'action',
        actions: [
          {
            tag: 'button',
            text: { tag: 'plain_text', content: 'Approve' },
            type: 'primary',
            value: { action: 'approve', instance_id: params.instanceId },
          },
          {
            tag: 'button',
            text: { tag: 'plain_text', content: 'Reject' },
            type: 'danger',
            value: { action: 'reject', instance_id: params.instanceId },
          },
          {
            tag: 'button',
            text: { tag: 'plain_text', content: 'View Details' },
            type: 'default',
            url: `https://your-domain.com/approval/${params.instanceId}`,
          },
        ],
      },
    ],
  };
}

// Send a message card
async function sendCardMessage(
  client: any,
  receiveId: string,
  receiveIdType: 'open_id' | 'chat_id' | 'user_id',
  card: object
): Promise<string> {
  const resp = await client.im.message.create({
    params: { receive_id_type: receiveIdType },
    data: {
      receive_id: receiveId,
      msg_type: 'interactive',
      content: JSON.stringify(card),
    },
  });

  if (resp.code !== 0) {
    throw new Error(`Failed to send card: ${resp.msg}`);
  }
  return resp.data!.message_id;
}

// src/webhook/event-dispatcher.ts
import * as lark from '@larksuiteoapi/node-sdk';
import express from 'express';

const app = express();

const eventDispatcher = new lark.EventDispatcher({
  encryptKey: process.env.FEISHU_ENCRYPT_KEY || '',
  verificationToken: process.env.FEISHU_VERIFICATION_TOKEN || '',
});

// Listen for bot message received events
eventDispatcher.register({
  'im.message.receive_v1': async (data) => {
    const message = data.message;
    const chatId = message.chat_id;
    const content = JSON.parse(message.content);

    // Handle plain text messages
    if (message.message_type === 'text') {
      const text = content.text as string;
      await handleBotCommand(chatId, text);
    }
  },
});

// Listen for approval status changes
eventDispatcher.register({
  'approval.approval.updated_v4': async (data) => {
    const instanceId = data.approval_code;
    const status = data.status;

    if (status === 'APPROVED') {
      await onApprovalApproved(instanceId);
    } else if (status === 'REJECTED') {
      await onApprovalRejected(instanceId);
    }
  },
});

// Card action callback handler
const cardActionHandler = new lark.CardActionHandler({
  encryptKey: process.env.FEISHU_ENCRYPT_KEY || '',
  verificationToken: process.env.FEISHU_VERIFICATION_TOKEN || '',
}, async (data) => {
  const action = data.action.value;

  if (action.action === 'approve') {
    await processApproval(action.instance_id, true);
    // Return the updated card
    return {
      toast: { type: 'success', content: 'Approval granted' },
    };
  }
  return {};
});

app.use('/webhook/event', lark.adaptExpress(eventDispatcher));
app.use('/webhook/card', lark.adaptExpress(cardActionHandler));

app.listen(3000, () => console.log('Feishu event service started'));

// src/bitable/table-client.ts
class BitableClient {
  constructor(private client: any) {}

  // Query table records (with filtering and pagination)
  async listRecords(
    appToken: string,
    tableId: string,
    options?: {
      filter?: string;
      sort?: string[];
      pageSize?: number;
      pageToken?: string;
    }
  ) {
    const resp = await this.client.bitable.appTableRecord.list({
      path: { app_token: appToken, table_id: tableId },
      params: {
        filter: options?.filter,
        sort: options?.sort ? JSON.stringify(options.sort) : undefined,
        page_size: options?.pageSize || 100,
        page_token: options?.pageToken,
      },
    });

    if (resp.code !== 0) {
      throw new Error(`Failed to query records: ${resp.msg}`);
    }
    return resp.data;
  }

  // Batch create records
  async batchCreateRecords(
    appToken: string,
    tableId: string,
    records: Array<{ fields: Record<string, any> }>
  ) {
    const resp = await this.client.bitable.appTableRecord.batchCreate({
      path: { app_token: appToken, table_id: tableId },
      data: { records },
    });

    if (resp.code !== 0) {
      throw new Error(`Failed to batch create records: ${resp.msg}`);
    }
    return resp.data;
  }

  // Update a single record
  async updateRecord(
    appToken: string,
    tableId: string,
    recordId: string,
    fields: Record<string, any>
  ) {
    const resp = await this.client.bitable.appTableRecord.update({
      path: {
        app_token: appToken,
        table_id: tableId,
        record_id: recordId,
      },
      data: { fields },
    });

    if (resp.code !== 0) {
      throw new Error(`Failed to update record: ${resp.msg}`);
    }
    return resp.data;
  }
}

// Example: Sync external order data to a Bitable spreadsheet
async function syncOrdersToBitable(orders: any[]) {
  const bitable = new BitableClient(client);
  const appToken = process.env.BITABLE_APP_TOKEN!;
  const tableId = process.env.BITABLE_TABLE_ID!;

  const records = orders.map((order) => ({
    fields: {
      'Order ID': order.orderId,
      'Customer Name': order.customerName,
      'Order Amount': order.amount,
      'Status': order.status,
      'Created At': order.createdAt,
    },
  }));

  // Maximum 500 records per batch
  for (let i = 0; i < records.length; i += 500) {
    const batch = records.slice(i, i + 500);
    await bitable.batchCreateRecords(appToken, tableId, batch);
  }
}

// src/approval/approval-instance.ts

// Create an approval instance via API
async function createApprovalInstance(params: {
  approvalCode: string;
  userId: string;
  formValues: Record<string, any>;
  approvers?: string[];
}) {
  const resp = await client.approval.instance.create({
    data: {
      approval_code: params.approvalCode,
      user_id: params.userId,
      form: JSON.stringify(
        Object.entries(params.formValues).map(([name, value]) => ({
          id: name,
          type: 'input',
          value: String(value),
        }))
      ),
      node_approver_user_id_list: params.approvers
        ? [{ key: 'node_1', value: params.approvers }]
        : undefined,
    },
  });

  if (resp.code !== 0) {
    throw new Error(`Failed to create approval: ${resp.msg}`);
  }
  return resp.data!.instance_code;
}

// Query approval instance details
async function getApprovalInstance(instanceCode: string) {
  const resp = await client.approval.instance.get({
    params: { instance_id: instanceCode },
  });

  if (resp.code !== 0) {
    throw new Error(`Failed to query approval instance: ${resp.msg}`);
  }
  return resp.data;
}

// src/sso/oauth-handler.ts
import { Router } from 'express';

const router = Router();

// Step 1: Redirect to Feishu authorization page
router.get('/login/feishu', (req, res) => {
  const redirectUri = encodeURIComponent(
    `${process.env.BASE_URL}/callback/feishu`
  );
  const state = generateRandomState();
  req.session!.oauthState = state;

  res.redirect(
    `https://open.feishu.cn/open-apis/authen/v1/authorize` +
    `?app_id=${process.env.FEISHU_APP_ID}` +
    `&redirect_uri=${redirectUri}` +
    `&state=${state}`
  );
});

// Step 2: Feishu callback — exchange code for user_access_token
router.get('/callback/feishu', async (req, res) => {
  const { code, state } = req.query;

  if (state !== req.session!.oauthState) {
    return res.status(403).json({ error: 'State mismatch — possible CSRF attack' });
  }

  const tokenResp = await client.authen.oidcAccessToken.create({
    data: {
      grant_type: 'authorization_code',
      code: code as string,
    },
  });

  if (tokenResp.code !== 0) {
    return res.status(401).json({ error: 'Authorization failed' });
  }

  const userToken = tokenResp.data!.access_token;

  // Step 3: Retrieve user info
  const userResp = await client.authen.userInfo.get({
    headers: { Authorization: `Bearer ${userToken}` },
  });

  const feishuUser = userResp.data;
  // Bind or create a local user linked to the Feishu user
  const localUser = await bindOrCreateUser({
    openId: feishuUser!.open_id!,
    unionId: feishuUser!.union_id!,
    name: feishuUser!.name!,
    email: feishuUser!.email!,
    avatar: feishuUser!.avatar_url!,
  });

  const jwt = signJwt({ userId: localUser.id });
  res.redirect(`${process.env.FRONTEND_URL}/auth?token=${jwt}`);
});

export default router;