How can I integrate OneDrive storage with Firebase authentication in my PWA using Microsoft Graph API?

Below is an overview of the recommended approach using the Microsoft Graph API, which is designed exactly for these kinds of integrations.

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Use Microsoft Graph API for OneDrive Storage

Microsoft Graph provides REST endpoints (and corresponding SDKs) that let you create folders, upload files, and manage content in OneDrive. With this API you can programmatically create a folder (for example, named with the user’s email) and then upload or update files inside that folder.

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Key Steps

1. Register the Application in Azure AD:
   • Create an app registration in the Azure portal so your PWA can obtain an access token for Microsoft Graph.
   • Configure required permissions (for example, Files.ReadWrite.All if you need full access to create and manage folders/files).
   • Use either delegated permissions (if users sign in with their Microsoft accounts) or application permissions (if you are using a service account with a client credentials flow).

2. Implement Secure Authentication:
   • Your PWA should use OAuth 2.0 and OpenID Connect (over HTTPS) to sign in and obtain a token to call Graph securely.
   • The access tokens will be used to call the Microsoft Graph endpoints to create folders and upload the files.

3. Make Graph API Calls:
   • To create a folder, call the appropriate endpoint (for example, POST to /me/drive/root/children with the folder metadata).
   • To upload files, you can perform a PUT to the file upload endpoint (for instance, /me/drive/root:/<foldername>/<filename>:/content).

4. Handle File Uploads:
   • When a user uploads a file to your PWA, first check if a folder with their email exists.
   • If not, use Graph to create a new folder and then upload the file; otherwise, append or update files as needed.

5. Ensure Security and Data Protection:
   • Since you’re handling sensitive files (proof of residence, ID documents, etc.), ensure that all communications use HTTPS.
   • Secure your tokens in transit and at rest, and follow best practices for OAuth token storage and renewal.
   • Use scopes that grant only the necessary permissions.

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Sample Code (C# using Microsoft Graph SDK)

Below is a simplified example of how you might create a folder and then upload a file to a user’s OneDrive using the Microsoft Graph SDK for .NET:

CSHARPCopied
using Microsoft.Graph;
using Microsoft.Identity.Client;
using System.Net.Http.Headers;
using System.Threading.Tasks;

public class GraphHelper
{
    // These values come from your Azure app registration.
    private readonly string clientId = "YOUR_CLIENT_ID";
    private readonly string tenantId = "YOUR_TENANT_ID";
    private readonly string clientSecret = "YOUR_CLIENT_SECRET";
    private readonly string[] scopes = new string[] { "https://graph.microsoft.com/.default" };

    private GraphServiceClient _graphClient;

    public async Task InitializeGraphClientAsync()
    {
        var confidentialClient = ConfidentialClientApplicationBuilder
            .Create(clientId)
            .WithTenantId(tenantId)
            .WithClientSecret(clientSecret)
            .Build();

        var authResult = await confidentialClient.AcquireTokenForClient(scopes).ExecuteAsync();

        _graphClient = new GraphServiceClient(new DelegateAuthenticationProvider(requestMessage =>
        {
            // Append the access token to each outgoing request
            requestMessage.Headers.Authorization =
                new AuthenticationHeaderValue("Bearer", authResult.AccessToken);
            return Task.CompletedTask;
        }));
    }

    // Create (or get) a folder by name in the root of OneDrive
    public async Task<DriveItem> GetOrCreateFolderAsync(string folderName)
    {
        // Try to get the folder (by filtering items in root)
        var items = await _graphClient.Me.Drive.Root.Children
            .Request()
            .Filter($"name eq '{folderName}' and folder ne null")
            .GetAsync();

        DriveItem folder;
        if (items.CurrentPage.Count == 0)
        {
            // Create the folder if it doesn't exist.
            var folderToCreate = new DriveItem
            {
                Name = folderName,
                Folder = new Folder(),
                AdditionalData = new Dictionary<string, object>
                {
                    {"@microsoft.graph.conflictBehavior", "rename"}
                }
            };

            folder = await _graphClient.Me.Drive.Root.Children
                .Request()
                .AddAsync(folderToCreate);
        }
        else
        {
            folder = items.CurrentPage[0];
        }

        return folder;
    }

    // Upload a file to a specific folder
    public async Task<DriveItem> UploadFileAsync(string folderId, string fileName, byte[] fileContent)
    {
        // Upload session for small files can use PutAsync.
        using (var stream = new MemoryStream(fileContent))
        {
            var driveItem = await _graphClient.Me.Drive.Items[folderId].ItemWithPath(fileName)
                .Content
                .Request()
                .PutAsync<DriveItem>(stream);
            return driveItem;
        }
    }
}

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Bringing It Together in Your PWA

1. When a user logs in (using Firebase Auth for your PWA), obtain their email.
2. Call your backend (or a secure API endpoint) that uses the GraphHelper code to initialize the GraphServiceClient.
3. Call GetOrCreateFolderAsync(userEmail) to ensure a folder exists.
4. When the user uploads a file, call UploadFileAsync(folder.Id, fileName, fileContent).
5. Ensure your backend endpoint is secured (e.g., using HTTPS with proper authentication and authorization).

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Final Considerations

• OneDrive Personal vs. Business:
  Depending on whether the OneDrive account is a personal Microsoft account or part of a business subscription, the permissions and API endpoints may differ slightly.

• Seamless Integration:
  To achieve a seamless experience, you might want to incorporate silent token acquisition or session management so that users never have to reauthenticate unnecessarily.

• Testing and Error Handling:
  Ensure robust error handling and logging, especially since you are handling sensitive information.

By following these steps and leveraging the Microsoft Graph API, you will be able to create a secure and seamless file upload system that integrates your PWA with OneDrive.

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For more in-depth details, see the official Microsoft Graph documentation:
OneDrive API overview
Upload small files using Microsoft Graph

This approach meets your requirements for secure file storage and automated folder management tied to each user's email.