> For the complete documentation index, see [llms.txt](https://docs.caf.io/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.caf.io/caf-sdk/react-native/standalone-modules/cafsmartauth/expo-modules/import-expo-module.md).

# Import Expo Modules

## How to Use the CafSmartAuth Native Module in React Native

This detailed guide explains how to integrate the `CafSmartAuth` expo module into your Expo project using TypeScript. It includes creating a module and a custom hook to manage events and methods provided by the native SDK.

### 1. Create the `CafSmartAuthBridgeModule.ts` File

This file imports the expo module.

#### Example Implementation

```ts
import { NativeModule, requireNativeModule } from "expo";

import { CafSmartAuthBridgeModuleEvents } from "./CafSmartAuthBridgeModule.types";

declare class CafSmartAuthBridgeModule extends NativeModule<CafSmartAuthBridgeModuleEvents> {
  startSmartAuth(
    mfaToken: string,
    faceAuthToken: string,
    personId: string,
    policyId: string,
    jsonString: string
  ): Promise<void>;
  requestLocationPermissions(): Promise<void>;
}

// This call loads the native module object from the JSI.
export default requireNativeModule<CafSmartAuthBridgeModule>(
  "CafSmartAuthBridgeModule"
);
```

### 2. Create the `useSmartAuth.ts` Hook

This hook manages the events and state associated with the `CafSmartAuth` module.

#### Key Functions

* **`formattedOptions`**: Formats the settings sent to the native module into JSON format.
* **`useSmartAuth`**: Hook that:
  * Listens to events emitted by the native module.
  * Updates React state based on the events.
* **`startSmartAuth`**: Method to initiate authentication using the native module.
* **`requestLocationPermissions`**: Method to request location permissions from the user.

#### Example Implementation

```ts
import { useState, useEffect } from "react";

import CafSmartAuthBridgeModule, {
  CafSmartAuthSettings,
  CafSmartAuthResponse,
  CafSmartAuthSuccess,
  CafSmartAuthError,
  CafSmartAuthPending,
  CafSmartAuthCancel,
  CafSmartAuthLoading,
  CafSmartAuthLoaded,
} from "../";

let responseFormattedOptions: string = "";

const formattedOptions = (settings: CafSmartAuthSettings): string => {
  const formatToJSON = JSON.stringify({
    ...settings,
  });

  return formatToJSON;
};

const useSmartAuth = (settings?: CafSmartAuthSettings) => {
  const [response, setResponse] = useState<CafSmartAuthResponse>({
    success: {
      isAuthorized: false,
      attemptId: null,
      attestation: null,
    },
    error: null,
    cancelled: false,
    isLoading: false,
    pending: {
      isAuthorized: false,
      attestation: null,
    },
  });

  responseFormattedOptions = formattedOptions(settings!);

  useEffect(() => {
    CafSmartAuthBridgeModule.addListener(
      "CafSmartAuth_Success",
      (event: CafSmartAuthSuccess) => {
        setResponse({
          success: {
            isAuthorized: event.isAuthorized,
            attemptId: event.attemptId,
            attestation: event.attestation,
          },
          error: null,
          cancelled: false,
          isLoading: false,
          pending: {
            isAuthorized: false,
            attestation: null,
          },
        });
      }
    );

    CafSmartAuthBridgeModule.addListener(
      "CafSmartAuth_Error",
      (event: CafSmartAuthError) => {
        setResponse({
          success: {
            isAuthorized: false,
            attemptId: null,
            attestation: null,
          },
          error: event,
          cancelled: false,
          isLoading: false,
          pending: {
            isAuthorized: false,
            attestation: null,
          },
        });
      }
    );

    CafSmartAuthBridgeModule.addListener(
      "CafSmartAuth_Cancel",
      (event: CafSmartAuthCancel) => {
        setResponse({
          success: {
            isAuthorized: false,
            attemptId: null,
            attestation: null,
          },
          error: null,
          cancelled: event.isCancelled,
          isLoading: false,
          pending: {
            isAuthorized: false,
            attestation: null,
          },
        });
      }
    );

    CafSmartAuthBridgeModule.addListener(
      "CafSmartAuth_Pending",
      (event: CafSmartAuthPending) => {
        setResponse({
          success: {
            isAuthorized: false,
            attemptId: null,
            attestation: null,
          },
          error: null,
          cancelled: false,
          isLoading: false,
          pending: {
            isAuthorized: event.isAuthorized,
            attestation: event.attestation,
          },
        });
      }
    );

    CafSmartAuthBridgeModule.addListener(
      "CafSmartAuth_Loading",
      (event: CafSmartAuthLoading) => {
        setResponse({
          success: {
            isAuthorized: false,
            attemptId: null,
            attestation: null,
          },
          error: null,
          cancelled: false,
          isLoading: event.isLoading,
          pending: {
            isAuthorized: false,
            attestation: null,
          },
        });
      }
    );

    CafSmartAuthBridgeModule.addListener(
      "CafSmartAuth_Loaded",
      (event: CafSmartAuthLoaded) => {
        setResponse({
          success: {
            isAuthorized: false,
            attemptId: null,
            attestation: null,
          },
          error: null,
          cancelled: false,
          isLoading: event.isLoaded,
          pending: {
            isAuthorized: false,
            attestation: null,
          },
        });
      }
    );

    return () => {
      CafSmartAuthBridgeModule.removeAllListeners("CafSmartAuth_Success");
      CafSmartAuthBridgeModule.removeAllListeners("CafSmartAuth_Pending");
      CafSmartAuthBridgeModule.removeAllListeners("CafSmartAuth_Error");
      CafSmartAuthBridgeModule.removeAllListeners("CafSmartAuth_Cancel");
      CafSmartAuthBridgeModule.removeAllListeners("CafSmartAuth_Loading");
      CafSmartAuthBridgeModule.removeAllListeners("CafSmartAuth_Loaded");
    };
  }, []);

  return {
    success: response.success,
    error: response.error,
    cancelled: response.cancelled,
    pending: response.pending,
    isLoading: response.isLoading,
  };
};

const startSmartAuth = (
  mfaToken: string,
  faceAuthToken: string,
  policyId: string,
  personId: string
) => {
  CafSmartAuthBridgeModule.startSmartAuth(
    mfaToken,
    faceAuthToken,
    personId,
    policyId,
    responseFormattedOptions
  );
};

const requestLocationPermissions = async () => {
  await CafSmartAuthBridgeModule.requestLocationPermissions();
};

export { startSmartAuth, requestLocationPermissions, useSmartAuth };
```

### 3. Available Methods

* **`useSmartAuth`**: A hook that provides the following states:
  * `success`: Information about successful authentications.
  * `error`: Details about errors that occurred.
  * `cancelled`: Indicates if the operation was cancelled.
  * `pending`: Information about pending authentications.
  * `isLoading`: Indicates if authentication is in progress.
* **`startSmartAuth`**: Method to start the authentication process.
  * **Parameters**:
    * `mfaToken`: Multi-factor authentication token.
    * `faceAuthToken`: Token for facial authentication.
    * `policyId`: ID of the authentication policy.
    * `personId`: ID of the person to authenticate.
* **`requestLocationPermissions`**: Method to request location permissions from the user (Android only).

### 4. Project Integration

Here is how to implement the hook in your project, follow [SourceCode](/caf-sdk/react-native/standalone-modules/cafsmartauth/expo-modules/source-code.md)


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