Copilot Chat: support multiple document import (#1675)

### Motivation and Context
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  2. What problem does it solve?
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Copilot Chat currently only supports importing a single document at a
time. Supporting multiple documents will improve user experience.

### Description
<!-- Describe your changes, the overall approach, the underlying design.
These notes will help understanding how your code works. Thanks! -->
1. Add multi-document support in DocumentImportController. Did a little
refactoring too.
2. Create a configurable limit on the number of documents that can be
imported at a time. It's currently set to 10.
3. Enable support in the webapp, both drag&drop and file explorer.
Update the document history item to show multiple files.
4. Update the import document console app to support multi-doc import.

![image](https://github.com/microsoft/semantic-kernel/assets/12570346/64e025fb-de71-4bef-9903-08ad570c5e1e)

Future work:
https://github.com/orgs/microsoft/projects/852/views/1?pane=issue&itemId=31798351

### Contribution Checklist
<!-- Before submitting this PR, please make sure: -->
- [ ] The code builds clean without any errors or warnings
- [ ] The PR follows SK Contribution Guidelines
(https://github.com/microsoft/semantic-kernel/blob/main/CONTRIBUTING.md)
- [ ] The code follows the .NET coding conventions
(https://learn.microsoft.com/dotnet/csharp/fundamentals/coding-style/coding-conventions)
verified with `dotnet format`
- [ ] All unit tests pass, and I have added new tests where possible
- [ ] I didn't break anyone 😄

---------

Co-authored-by: Aman Sachan <51973971+amsacha@users.noreply.github.com>

samples/apps/copilot-chat-app/importdocument/Program.cs

@@ -13,7 +13,7 @@
 namespace ImportDocument;
 
 /// <summary>
-/// This console app imports a file to the CopilotChat WebAPI document memory store.
+/// This console app imports a list of files to the CopilotChat WebAPI document memory store.
 /// </summary>
 public static class Program
 {
@@ -26,30 +26,30 @@ public static void Main(string[] args)
             return;
         }
 
-        var fileOption = new Option<FileInfo>(name: "--file", description: "The file to import to document memory store.")
+        var filesOption = new Option<IEnumerable<FileInfo>>(name: "--files", description: "The files to import to document memory store.")
         {
-            IsRequired = true
+            IsRequired = true,
+            AllowMultipleArgumentsPerToken = true,
         };
 
-        // TODO: UI to retrieve ChatID from the WebApp will be added in the future with multi-user support.
         var chatCollectionOption = new Option<Guid>(
             name: "--chat-id",
             description: "Save the extracted context to an isolated chat collection.",
             getDefaultValue: () => Guid.Empty
         );
 
         var rootCommand = new RootCommand(
-            "This console app imports a file to the CopilotChat WebAPI's document memory store."
+            "This console app imports files to the CopilotChat WebAPI's document memory store."
         )
         {
-            fileOption, chatCollectionOption
+            filesOption, chatCollectionOption
         };
 
-        rootCommand.SetHandler(async (file, chatCollectionId) =>
+        rootCommand.SetHandler(async (files, chatCollectionId) =>
             {
-                await UploadFileAsync(file, config!, chatCollectionId);
+                await ImportFilesAsync(files, config!, chatCollectionId);
             },
-            fileOption, chatCollectionOption
+            filesOption, chatCollectionOption
         );
 
         rootCommand.Invoke(args);
@@ -97,17 +97,20 @@ private static async Task<bool> AcquireUserAccountAsync(
     }
 
     /// <summary>
-    /// Conditionally uploads a file to the Document Store for parsing.
+    /// Conditionally imports a list of files to the Document Store.
     /// </summary>
-    /// <param name="file">The file to upload for injection.</param>
+    /// <param name="files">A list of files to import.</param>
     /// <param name="config">Configuration.</param>
     /// <param name="chatCollectionId">Save the extracted context to an isolated chat collection.</param>
-    private static async Task UploadFileAsync(FileInfo file, Config config, Guid chatCollectionId)
+    private static async Task ImportFilesAsync(IEnumerable<FileInfo> files, Config config, Guid chatCollectionId)
     {
-        if (!file.Exists)
+        foreach (var file in files)
         {
-            Console.WriteLine($"File {file.FullName} does not exist.");
-            return;
+            if (!file.Exists)
+            {
+                Console.WriteLine($"File {file.FullName} does not exist.");
+                return;
+            }
         }
 
         IAccount? userAccount = null;
@@ -120,11 +123,12 @@ private static async Task UploadFileAsync(FileInfo file, Config config, Guid cha
         }
         Console.WriteLine($"Successfully acquired User ID. Continuing...");
 
-        using var fileContent = new StreamContent(file.OpenRead());
-        using var formContent = new MultipartFormDataContent
+        using var formContent = new MultipartFormDataContent();
+        List<StreamContent> filesContent = files.Select(file => new StreamContent(file.OpenRead())).ToList();
+        for (int i = 0; i < filesContent.Count; i++)
         {
-            { fileContent, "formFile", file.Name }
-        };
+            formContent.Add(filesContent[i], "formFiles", files.ElementAt(i).Name);
+        }
 
         var userId = userAccount!.HomeAccountId.Identifier;
         var userName = userAccount.Username;
@@ -153,6 +157,12 @@ private static async Task UploadFileAsync(FileInfo file, Config config, Guid cha
             // Calling UploadAsync here to make sure disposable objects are still in scope.
             await UploadAsync(formContent, accessToken!, config);
         }
+
+        // Dispose of all the file streams.
+        foreach (var fileContent in filesContent)
+        {
+            fileContent.Dispose();
+        }
     }
 
     /// <summary>
@@ -185,7 +195,7 @@ private static async Task UploadAsync(
         try
         {
             using HttpResponseMessage response = await httpClient.PostAsync(
-                new Uri(new Uri(config.ServiceUri), "importDocument"),
+                new Uri(new Uri(config.ServiceUri), "importDocuments"),
                 multipartFormDataContent
             );
 

samples/apps/copilot-chat-app/importdocument/README.md

@@ -32,18 +32,23 @@ Importing documents enables Copilot Chat to have up-to-date knowledge of specifi
 4. **Run** the following command to import a document to the app under the global document collection where
    all users will have access to:
 
-   `dotnet run -- --file .\sample-docs\ms10k.txt`
+   `dotnet run --files .\sample-docs\ms10k.txt`
 
    Or **Run** the following command to import a document to the app under a chat isolated document collection where
    only the chat session will have access to:
 
-   `dotnet run -- --file .\sample-docs\ms10k.txt --chat-id [chatId]`
+   `dotnet run --files .\sample-docs\ms10k.txt --chat-id [chatId]`
 
    > Note that this will open a browser window for you to sign in to retrieve your user id to make sure you have access to the chat session.
 
    > Currently only supports txt and pdf files. A sample file is provided under ./sample-docs.
 
    Importing may take some time to generate embeddings for each piece/chunk of a document.
+
+   To import multiple files, specify multiple files. For example:
+
+   `dotnet run --files .\sample-docs\ms10k.txt .\sample-docs\Microsoft-Responsible-AI-Standard-v2-General-Requirements.pdf`
+
 5. Chat with the bot.
 
    Examples: