From 049c48bbd05caa897655f9bfadde8862a55c420d Mon Sep 17 00:00:00 2001
From: Caroline Nordbrandt <caroline_nordbradt@hotmail.com>
Date: Fri, 8 May 2026 13:46:36 +0200
Subject: [PATCH] Implement session persistence and chat history retrieval

- Refactored `ChatMessage` class to include `senderName`.
- Updated `ChatService` to store sender names when adding user and assistant messages.
- Added logic to persist and retrieve sessions via `sessionId` in the frontend.
- Prefetched session chat history on page load and rendered stored messages in the chat window.
---
 .../projectbifrost/domain/ChatMessage.java    |  4 +-
 .../projectbifrost/service/ChatService.java   |  4 +-
 src/main/resources/static/app.js              | 40 +++++++++++++++++--
 3 files changed, 42 insertions(+), 6 deletions(-)

diff --git a/src/main/java/org/example/projectbifrost/domain/ChatMessage.java b/src/main/java/org/example/projectbifrost/domain/ChatMessage.java
index 47edcfa..1a72518 100644
--- a/src/main/java/org/example/projectbifrost/domain/ChatMessage.java
+++ b/src/main/java/org/example/projectbifrost/domain/ChatMessage.java
@@ -19,11 +19,13 @@
 public class ChatMessage {
     private String role;
     private String content;
+    private String senderName; //For chat
     private LocalDateTime timeStamp;
 
-     public ChatMessage(String role, String message) {
+     public ChatMessage(String role, String message, String senderName) {
         this.role = role;
         this.content = message;
+        this.senderName = senderName;
         this.timeStamp = LocalDateTime.now();//Adds the current time to each message
     }
 }
diff --git a/src/main/java/org/example/projectbifrost/service/ChatService.java b/src/main/java/org/example/projectbifrost/service/ChatService.java
index 953c956..313c199 100644
--- a/src/main/java/org/example/projectbifrost/service/ChatService.java
+++ b/src/main/java/org/example/projectbifrost/service/ChatService.java
@@ -60,8 +60,8 @@ public String chatWithLLM(ChatRequestDTO dto) {
         try {
             String content = fetchResponseFromLLM(apiMessages);
             // Only store in history if we got a real LLM response (not a circuit breaker fallback)
-            chatSession.addMessage(new ChatMessage("user", dto.message()));
-            chatSession.addMessage(new ChatMessage("assistant", content));
+            chatSession.addMessage(new ChatMessage("user", dto.message(), "You"));
+            chatSession.addMessage(new ChatMessage("assistant", content, dto.personality().toString()));
             return content;
         } catch (RetryableHttpException e) {
             // Circuit breaker is open or service unavailable - don't pollute history
diff --git a/src/main/resources/static/app.js b/src/main/resources/static/app.js
index 71fb9b4..cbbaf5a 100644
--- a/src/main/resources/static/app.js
+++ b/src/main/resources/static/app.js
@@ -1,6 +1,15 @@
+const getSessionId = () => {
+    let id = localStorage.getItem('bifrost_session_id'); //Try to find the old sessionID or create a new one
+    if (!id) {
+        id = crypto.randomUUID();
+        localStorage.setItem('bifrost_session_id', id);
+    }
+    return id;
+};
+
 const chatState = {
-    sessionId: crypto.randomUUID(),
-    isWaiting: false //Flag for waiting for response, to prevent multiple sends
+    sessionId: getSessionId(),
+    isWaiting: false
 };
 
 //Save all HTML-elements to reduce boilerplate
@@ -135,4 +144,29 @@ dom.input.addEventListener('keydown', (e) => {
         sendMessage().then(r => {
         }).catch(err => console.error(err));
     }
-});
\ No newline at end of file
+});
+
+// Körs automatiskt när sidan laddas om
+window.addEventListener('DOMContentLoaded', async () => {
+    try {
+        // Vi anropar din befintliga GetMapping: /api/v1/chat/{sessionId}
+        const response = await fetch(`/api/v1/chat/${chatState.sessionId}`);
+
+        if (response.ok) {
+            const sessionData = await response.json(); // Detta matchar din ChatSession-klass
+
+            // if there is sessionData.chatHistory saved, we loop through it and display the messages in the chat window
+            if (sessionData && sessionData.chatHistory && sessionData.chatHistory.length > 0) {
+                sessionData.chatHistory.forEach(msg => {
+                    const role = msg.role === 'assistant' ? 'assistant' : 'user';
+                    // Name saved from backend
+                    const name = role === 'assistant' ? getGodName(msg.senderName) : null;
+
+                    appendMessage(role, name, msg.content);
+                });
+            }
+        }
+    } catch (err) {
+        console.error("Could not fetch chat history:", err);
+    }
+});