Add chatbot feature

docs/ENDPOINTS.md

@@ -2,6 +2,7 @@
 
 * [Endpoints](#endpoints)
   * [Upload](#upload)
+  * [Chat](#chat)
   * [Get Metadata](#get-metadata)
   * [Search](#search)
   * [Summarize](#summarize)
@@ -55,6 +56,31 @@ You will need to adjust startup arguments, e.g., you could add the following to
 -Dspring.servlet.multipart.max-file-size=250MB
 ```
 
+### Chat
+
+Converse with an AI chatbot who is aware of all uploaded content.  Ask a question, get a response.
+
+```python
+GET /chat
+```
+
+**Sample interaction**
+
+```bash
+❯ http :8080/api/files/chat q=="Tell me something about the character Hermia from A Midsummer Night's Dream"
+HTTP/1.1 200
+Connection: keep-alive
+Content-Length: 795
+Content-Type: text/plain;charset=UTF-8
+Date: Tue, 22 Oct 2024 12:24:58 GMT
+Keep-Alive: timeout=60
+
+Hermia is a key character in "A Midsummer Night's Dream," portrayed as the daughter of Egeus. She is in love with Lysander, but her father wishes her to marry Demetrius, which creates conflict in the story. Hermia is depicted as strong-willed and defiant; she boldly asserts her feelings and desires, expressing her wish that her father could see things from her perspective (Act I).
+
+She passionately defends her love for Lysander and is determined to be with him despite the obstacles posed by her father and societal expectations. Hermia's character embodies themes of love, rebellion, and the struggle for autonomy within the constraints of Athenian law. Her determination to follow her heart leads her to plan an escape with Lysander, showcasing her bravery and commitment to love (Act I).
+```
+
+
 ### Get Metadata
 
 Retrieve metadata for all files in an S3-compliant object store's bucket

src/main/java/org/cftoolsuite/controller/DocumentController.java

@@ -4,6 +4,7 @@
 
 import org.apache.commons.lang3.StringUtils;
 import org.cftoolsuite.domain.FileMetadata;
+import org.cftoolsuite.service.ChatService;
 import org.cftoolsuite.service.DocumentIngestionService;
 import org.cftoolsuite.service.DocumentSearchService;
 import org.cftoolsuite.service.DocumentSummarizationService;
@@ -24,14 +25,17 @@
 @RequestMapping("/api/files")
 public class DocumentController {
 
+    private final ChatService chatService;
     private final FileService fileService;
     private final DocumentIngestionService documentIngestionService;
     private final DocumentSearchService documentSearchService;
     private final DocumentSummarizationService documentSummarizationService;
 
     public DocumentController(
+        ChatService chatService,
         FileService fileService, DocumentIngestionService documentIngestionService,
         DocumentSearchService documentSearchService, DocumentSummarizationService documentSummarizationService) {
+        this.chatService = chatService;
         this.fileService = fileService;
         this.documentIngestionService = documentIngestionService;
         this.documentSearchService = documentSearchService;
@@ -45,6 +49,12 @@ public ResponseEntity<FileMetadata> uploadFile(@RequestParam("fileName") Multipa
         return ResponseEntity.ok(fileMetadata);
     }
 
+    @GetMapping("/chat")
+    public ResponseEntity<String> chat(@RequestParam("q") String message) {
+        String response = chatService.askQuestion(message);
+        return ResponseEntity.ok(response);
+    }
+
     @GetMapping
     public ResponseEntity<List<FileMetadata>> getFileMetadata(@RequestParam(value = "fileName", required = false) String fileName) {
         if (StringUtils.isBlank(fileName)) {

src/main/java/org/cftoolsuite/service/ChatService.java

@@ -0,0 +1,46 @@
+package org.cftoolsuite.service;
+
+import org.springframework.ai.chat.client.ChatClient;
+import org.springframework.ai.chat.client.advisor.MessageChatMemoryAdvisor;
+import org.springframework.ai.chat.client.advisor.QuestionAnswerAdvisor;
+import org.springframework.ai.chat.client.advisor.SimpleLoggerAdvisor;
+import org.springframework.ai.chat.memory.ChatMemory;
+import org.springframework.ai.chat.memory.InMemoryChatMemory;
+import org.springframework.ai.chat.model.ChatModel;
+import org.springframework.ai.vectorstore.SearchRequest;
+import org.springframework.ai.vectorstore.VectorStore;
+import org.springframework.stereotype.Service;
+
+@Service
+public class ChatService {
+
+    private final ChatClient chatClient;
+
+    public ChatService(ChatModel model, VectorStore vectorStore) {
+        ChatMemory chatMemory = new InMemoryChatMemory();
+        this.chatClient = ChatClient.builder(model)
+                .defaultSystem("""
+                    You are an AI assistant with access to a specific knowledge base
+                    Follow these guidelines:
+                        Only use information from the provided context.
+                        If the answer is not in the context, state that you don't have sufficient information.
+                        Do not use any external knowledge or make assumptions beyond the given data.
+                        Cite the relevant parts of the context in your responses including the source and origin.
+                        Respond in a clear, concise manner without editorializing.
+                    """
+                )
+        		.defaultAdvisors(
+                        new MessageChatMemoryAdvisor(chatMemory),
+        				new QuestionAnswerAdvisor(vectorStore, SearchRequest.defaults()),
+        				new SimpleLoggerAdvisor())
+        		.build();
+    }
+
+    public String askQuestion(String question) {
+        return chatClient
+                .prompt()
+                .user(question)
+                .call()
+                .content();
+    }
+}