Update: Basic Functions of chat.html 75% maybe

frontend/js/pages/chat/SessionManager.js

@@ -0,0 +1,178 @@
+// Filename: frontend/js/pages/chat/SessionManager.js
+
+import { nanoid } from 'https://cdn.jsdelivr.net/npm/nanoid/nanoid.js';
+
+const LOCAL_STORAGE_KEY = 'gemini_chat_state';
+
+/**
+ * Manages the state and persistence of chat sessions.
+ * This class handles loading from/saving to localStorage,
+ * and all operations like creating, switching, and deleting sessions.
+ */
+export class SessionManager {
+    constructor() {
+        this.state = null;
+    }
+
+    /**
+     * Initializes the manager by loading state from localStorage or creating a default state.
+     */
+    init() {
+        this._loadState();
+    }
+
+    // --- Public API for state access ---
+
+    getSessions() {
+        return this.state.sessions;
+    }
+
+    getCurrentSessionId() {
+        return this.state.currentSessionId;
+    }
+
+    getCurrentSession() {
+        return this.state.sessions.find(s => s.id === this.state.currentSessionId);
+    }
+
+    // --- Public API for state mutation ---
+
+    /**
+     * Creates a new, empty session and sets it as the current one.
+     */
+    createSession() {
+        const newSessionId = nanoid();
+        const newSession = {
+            id: newSessionId,
+            name: '新会话',
+            systemPrompt: '',
+            messages: [],
+            modelConfig: { model: 'gemini-2.0-flash-lite' },
+            params: { temperature: 0.7 }
+        };
+        this.state.sessions.unshift(newSession);
+        this.state.currentSessionId = newSessionId;
+        this._saveState();
+    }
+
+    /**
+     * Switches the current session to the one with the given ID.
+     * @param {string} sessionId The ID of the session to switch to.
+     */
+    switchSession(sessionId) {
+        if (this.state.currentSessionId === sessionId) return;
+        this.state.currentSessionId = sessionId;
+        this._saveState();
+    }
+
+    /**
+     * Deletes a session by its ID.
+     * @param {string} sessionId The ID of the session to delete.
+     */
+    deleteSession(sessionId) {
+        this.state.sessions = this.state.sessions.filter(s => s.id !== sessionId);
+
+        if (this.state.currentSessionId === sessionId) {
+            this.state.currentSessionId = this.state.sessions[0]?.id || null;
+            if (!this.state.currentSessionId) {
+                this._createInitialState(); // Create a new one if all are deleted
+            }
+        }
+        
+        this._saveState();
+    }
+    
+    /**
+     * [NEW] Clears all messages from the currently active session.
+     */
+    clearCurrentSession() {
+        const currentSession = this.getCurrentSession();
+        if (currentSession) {
+            currentSession.messages = [];
+            this._saveState();
+        }
+    }
+    
+    /**
+     * Adds a message to the current session and updates the session name if it's the first message.
+     * @param {object} message The message object to add.
+     * @returns {object} The session that was updated.
+     */
+    addMessage(message) {
+        const currentSession = this.getCurrentSession();
+        if (currentSession) {
+            if (currentSession.messages.length === 0 && message.role === 'user') {
+                currentSession.name = message.content.substring(0, 30);
+            }
+            currentSession.messages.push(message);
+            this._saveState();
+            return currentSession;
+        }
+        return null;
+    }
+
+    deleteMessage(messageId) {
+        const currentSession = this.getCurrentSession();
+        if (currentSession) {
+            const messageIndex = currentSession.messages.findIndex(m => m.id === messageId);
+            if (messageIndex > -1) {
+                currentSession.messages.splice(messageIndex, 1);
+                this._saveState();
+                console.log(`Message ${messageId} deleted.`);
+            }
+        }
+    }
+
+    truncateMessagesAfter(messageId) {
+        const currentSession = this.getCurrentSession();
+        if (currentSession) {
+            const messageIndex = currentSession.messages.findIndex(m => m.id === messageId);
+            // Ensure the message exists and it's not already the last one
+            if (messageIndex > -1 && messageIndex < currentSession.messages.length - 1) {
+                currentSession.messages.splice(messageIndex + 1);
+                this._saveState();
+                console.log(`Truncated messages after ${messageId}.`);
+            }
+        }
+    }
+    // --- Private persistence methods ---
+
+    _saveState() {
+        try {
+            localStorage.setItem(LOCAL_STORAGE_KEY, JSON.stringify(this.state));
+        } catch (error) {
+            console.error("Failed to save session state:", error);
+        }
+    }
+
+    _loadState() {
+        try {
+            const stateString = localStorage.getItem(LOCAL_STORAGE_KEY);
+            if (stateString) {
+                this.state = JSON.parse(stateString);
+            } else {
+                this._createInitialState();
+            }
+        } catch (error) {
+            console.error("Failed to load session state, creating initial state:", error);
+            this._createInitialState();
+        }
+    }
+    
+    _createInitialState() {
+        const initialSessionId = nanoid();
+        this.state = {
+            sessions: [{
+                id: initialSessionId,
+                name: '新会话',
+                systemPrompt: '',
+                messages: [],
+                modelConfig: { model: 'gemini-2.0-flash-lite' },
+                params: { temperature: 0.7 }
+            }],
+            currentSessionId: initialSessionId,
+            settings: {}
+        };
+        this._saveState();
+    }
+}