let conversations = JSON.parse(localStorage.getItem('gemini_history')) || {};
let currentChatId = null;

function toggleSidebar() {
    const sidebar = document.getElementById('sidebar');
    sidebar.classList.toggle('closed');
}

function renderHistory() {
    const list = document.getElementById('historyList');
    list.innerHTML = '';
    Object.keys(conversations).sort((a,b) => b-a).forEach(id => {
        const item = document.createElement('div');
        item.className = 'history-item';
        if(id === currentChatId) item.style.backgroundColor = "#282a2c";
        item.innerHTML = `
            <span onclick="loadChat('${id}')" style="flex:1; overflow:hidden; text-overflow:ellipsis; white-space:nowrap;">${conversations[id].title}</span>
            <button class="delete-chat-btn" onclick="deleteChat('${id}', event)">✕</button>
        `;
        list.appendChild(item);
    });
}

function startNewChat() {
    currentChatId = 'chat_' + Date.now();
    conversations[currentChatId] = { title: "New Chat", messages: [] };
    saveToLocalStorage();
    renderHistory();
    
    document.getElementById('welcomeScreen').style.display = 'block';
    document.getElementById('chatMessages').style.display = 'none';
    document.getElementById('chatMessages').innerHTML = '';
    
    if(window.innerWidth <= 768) toggleSidebar();
}

function loadChat(id) {
    currentChatId = id;
    renderHistory();
    
    document.getElementById('welcomeScreen').style.display = 'none';
    const msgDiv = document.getElementById('chatMessages');
    msgDiv.style.display = 'flex';
    msgDiv.innerHTML = '';
    
    conversations[id].messages.forEach(msg => {
        appendBubble(msg.role, msg.text);
    });
    
    if(window.innerWidth <= 768) toggleSidebar();
}

function deleteChat(id, event) {
    event.stopPropagation();
    delete conversations[id];
    saveToLocalStorage();
    renderHistory();
    if (currentChatId === id) {
        currentChatId = null;
        document.getElementById('welcomeScreen').style.display = 'block';
        document.getElementById('chatMessages').style.display = 'none';
    }
}

function appendBubble(role, text) {
    const container = document.getElementById('chatMessages');
    const bubble = document.createElement('div');
    bubble.className = `chat-bubble ${role}`;
    
    const avatar = role === 'user' ? '👤' : '✨';
    bubble.innerHTML = `
        <div class="bubble-avatar">${avatar}</div>
        <div class="bubble-text">${text}</div>
    `;
    container.appendChild(bubble);
    const chatContainer = document.getElementById('chatContainer');
    chatContainer.scrollTop = chatContainer.scrollHeight;
}

function useSuggestion(text) {
    document.getElementById('userInput').value = text;
    sendMessage();
}

// এই ফাংশনটি FastAPI-র সাথে কানেক্ট করার জন্য আপডেট করা হলো
async function sendMessage() {
    const input = document.getElementById('userInput');
    const text = input.value.trim();
    if (!text) return;

    if (!currentChatId) {
        currentChatId = 'chat_' + Date.now();
        conversations[currentChatId] = { title: text.substring(0, 24), messages: [] };
    }

    document.getElementById('welcomeScreen').style.display = 'none';
    document.getElementById('chatMessages').style.display = 'flex';

    appendBubble('user', text);
    conversations[currentChatId].messages.push({ role: 'user', text: text });
    
    if(conversations[currentChatId].title === "New Chat") {
        conversations[currentChatId].title = text.substring(0, 24);
    }
    
    input.value = '';
    saveToLocalStorage();
    renderHistory();

    appendBubble('bot', 'Thinking...');
    const lastBubble = document.getElementById('chatMessages').lastChild.querySelector('.bubble-text');

    try {
        // নতুন FastAPI এন্ডপয়েন্ট কল করা হচ্ছে
        const response = await fetch("/api/chat", {
            method: "POST",
            headers: { "Content-Type": "application/json" },
            body: JSON.stringify({ message: text })
        });
        const resJson = await response.json();
        const reply = resJson.reply;

        lastBubble.innerText = reply;
        conversations[currentChatId].messages.push({ role: 'bot', text: reply });
        saveToLocalStorage();
    } catch (e) {
        lastBubble.innerText = "Error: Could not connect to Gemini backend.";
    }
}

function handleKeyPress(e) {
    if (e.key === 'Enter') sendMessage();
}

function saveToLocalStorage() {
    localStorage.setItem('gemini_history', JSON.stringify(conversations));
}

setTimeout(() => {
    renderHistory();
    if(window.innerWidth <= 768) document.getElementById('sidebar').classList.add('closed');
}, 300);