feat: Reuse auth and network settings between legacy and sdk-gen

docs/reuse-auth-and-network-settings-in-sdk-gen.md

@@ -0,0 +1,226 @@
+# Resuse Authentication and Netowrk Settings from Legacy Node SDK in SDK Gen
+
+This guide explains three methods that help you migrate from the legacy Box Node.js SDK to the new SDK-Gen package by reusing your existing authentication and network configuration.
+
+## Quick Start
+
+If you just want to get a working SDK-Gen client from your legacy client:
+
+```javascript
+const BoxSDK = require('box-node-sdk').default;
+
+// Your existing legacy SDK setup
+const sdk = BoxSDK.getPreconfiguredInstance(config);
+const legacyClient = sdk.getAppAuthClient('enterprise');
+
+// Get sdk gen client from legacy client
+const sdkGenClient = legacyClient.getSdkGenClient();
+
+// Use SDK-Gen client
+const user = await sdkGenClient.users.getUserMe();
+console.log(`User , ${user.name}!`);
+```
+
+---
+
+## getSdkGenClient()
+
+The easiest way to get a fully configured SDK-Gen client. Internally calls `getAuthentication()` and `getNetworkSession()`.
+
+### Signature
+
+```typescript
+getSdkGenClient(options?: {
+  authOptions?: { tokenStorage?: TokenStorage };
+  networkOptions?: {
+    networkClient?: NetworkClient;
+    retryStrategy?: RetryStrategy;
+    dataSanitizer?: DataSanitizer;
+    interceptors?: Interceptor[];
+    additionalHeaders?: { [key: string]: string };
+  };
+}): BoxClient
+```
+
+### Basic Usage
+
+```javascript
+const BoxSDK = require('box-node-sdk').default;
+
+// Initialize legacy SDK
+const sdk = BoxSDK.getPreconfiguredInstance(jwtConfig);
+const legacyClient = sdk.getAppAuthClient('enterprise');
+
+// Get SDK-Gen client
+const sdkGenClient = legacyClient.getSdkGenClient();
+
+// Make API calls
+const user = await sdkGenClient.users.getUserMe();
+const folder = await sdkGenClient.folders.getFolderById('0');
+```
+
+### With Custom Authentication and Network Settings
+
+```javascript
+// Custom token storage
+const { InMemoryTokenStorage } = require('box-node-sdk/lib/sdk-gen/box/tokenStorage/inMemoryTokenStorage');
+
+const sdkGenClient = legacyClient.getSdkGenClient({
+  authOptions: {
+    tokenStorage: new InMemoryTokenStorage(),
+  },
+  networkOptions: {
+    additionalHeaders: {
+      'X-Request-ID': 'request-id',
+    },
+  },
+});
+```
+
+### With Custom Retry Strategy
+
+```javascript
+const { BoxRetryStrategy } = require('box-node-sdk/lib/sdk-gen/networking/retries');
+
+const sdkGenClient = legacyClient.getSdkGenClient({
+  networkOptions: {
+    retryStrategy: new BoxRetryStrategy({
+      maxAttempts: 10,
+      retryBaseInterval: 5,
+    }),
+  },
+});
+```
+
+---
+
+## getAuthentication()
+
+Extracts authentication configuration from the legacy client and returns an SDK-Gen `Authentication` object.
+
+### Signature
+
+```typescript
+getAuthentication(options?: { 
+  tokenStorage?: TokenStorage 
+}): Authentication
+```
+
+### Supported Session Types
+
+| Legacy Session | SDK-Gen Auth Type |
+|---------------|-------------------|
+| `BasicAPISession` | `BoxDeveloperTokenAuth` |
+| `PersistentAPISession` | `BoxOAuth` |
+| `AppAuthSession` | `BoxJwtAuth` |
+| `CCGAPISession` | `BoxCcgAuth` |
+
+### Usage
+
+```javascript
+// Get authentication object
+const auth = legacyClient.getAuthentication();
+
+// Use with SDK-Gen BoxClient
+const { BoxClient } = require('box-node-sdk/lib/sdk-gen/client');
+const sdkGenClient = new BoxClient({ auth });
+```
+
+### With Custom Token Storage
+
+```javascript
+const { InMemoryTokenStorage } = require('box-node-sdk/lib/sdk-gen/box/tokenStorage/inMemoryTokenStorage');
+
+const customStorage = new InMemoryTokenStorage();
+const auth = legacyClient.getAuthentication({
+  tokenStorage: customStorage,
+});
+```
+
+---
+
+## getNetworkSession()
+
+Extracts network configuration from the legacy client and returns an SDK-Gen `NetworkSession` object.
+
+### Signature
+
+```typescript
+getNetworkSession(options?: {
+  networkClient?: NetworkClient;
+  retryStrategy?: RetryStrategy;
+  dataSanitizer?: DataSanitizer;
+  interceptors?: Interceptor[];
+  additionalHeaders?: { [key: string]: string };
+}): NetworkSession
+```
+
+### Configuration Mapping
+
+| Legacy Config | SDK-Gen NetworkSession |
+|--------------|------------------------|
+| `apiRootURL` | `baseUrls.baseUrl` |
+| `uploadAPIRootURL` | `baseUrls.uploadUrl` |
+| `authorizeRootURL` | `baseUrls.oauth2Url` |
+| `proxy.url`, `proxy.username`, `proxy.password` | `proxyConfig` |
+| `request.headers` | `additionalHeaders` |
+| `numMaxRetries` | `retryStrategy.maxAttempts` |
+| `retryIntervalMS` | `retryStrategy.retryBaseInterval` (converted to seconds) |
+| `request.agentOptions` | `agentOptions` |
+
+### Usage
+
+```javascript
+// Get network session
+const networkSession = legacyClient.getNetworkSession();
+
+// Use with SDK-Gen BoxClient
+const { BoxClient } = require('box-node-sdk/lib/sdk-gen/client');
+const auth = legacyClient.getAuthentication();
+const sdkGenClient = new BoxClient({ auth, networkSession });
+```
+
+### With Custom Headers
+
+```javascript
+const networkSession = legacyClient.getNetworkSession({
+  additionalHeaders: {
+    'X-Custom-Header': 'custom-value',
+    'X-Request-ID': 'tracking-123',
+  },
+});
+```
+
+### With Custom Retry Strategy
+
+```javascript
+const { BoxRetryStrategy } = require('box-node-sdk/lib/sdk-gen/networking/retries');
+
+const networkSession = legacyClient.getNetworkSession({
+  retryStrategy: new BoxRetryStrategy({
+    maxAttempts: 15,
+    retryBaseInterval: 3,
+  }),
+});
+```
+
+### With Request Interceptors
+
+```javascript
+const networkSession = legacyClient.getNetworkSession({
+  interceptors: [
+    {
+      beforeRequest: (options) => {
+        console.log('Request:', options.url);
+        return options;
+      },
+      afterResponse: (response) => {
+        console.log('Response:', response.status);
+        return response;
+      },
+    },
+  ],
+});
+```
+
+