document.addEventListener('DOMContentLoaded', function () {

    let currentRoomId = null;
    let lastMessageId = 0;
    let messagePollInterval = null;
    let roomPollInterval = null;
    let isFetchingMessages = false;

    const UI = {
        roomList: document.getElementById('room-list'),
        noChatSelected: document.getElementById('no-chat-selected'),
        chatHeader: document.getElementById('active-chat-header'),
        chatTitle: document.getElementById('active-chat-title'),
        chatHeaderInfo: document.getElementById('chat-header-info'),
        messages: document.getElementById('chat-messages'),
        inputArea: document.getElementById('chat-input-area'),
        form: document.getElementById('chat-form'),
        input: document.getElementById('chat-input'),
        indicator: document.getElementById('polling-indicator'),

        // 🟢 متغیرهای جدید برای Modal کاربران
        newChatBtn: document.getElementById('new-chat-btn'),
        usersModal: document.getElementById('users-modal'),
        closeModalBtn: document.getElementById('close-users-modal'),
        usersList: document.getElementById('users-list'),
        searchInput: document.getElementById('user-search-input')
    };

    // ── منطق مودال کاربران ──
    if (UI.newChatBtn) {
        UI.newChatBtn.addEventListener('click', () => {
            UI.usersModal.style.transform = 'translateY(0)'; // نمایش مودال (بالا آمدن)
            fetchUsers(''); // لود اولیه لیست کاربران
        });
    }

    if (UI.closeModalBtn) {
        UI.closeModalBtn.addEventListener('click', () => {
            UI.usersModal.style.transform = 'translateY(100%)'; // مخفی کردن مودال (پایین رفتن)
        });
    }

    if (UI.searchInput) {
        let timeout = null;
        UI.searchInput.addEventListener('input', (e) => {
            clearTimeout(timeout);
            // دی‌باونس (Debounce) برای جلوگیری از ریکوئست‌های تکراری
            timeout = setTimeout(() => {
                fetchUsers(e.target.value);
            }, 300);
        });
    }

    async function fetchUsers(query) {
        UI.usersList.innerHTML = '<div class="flex items-center justify-center h-20"><span class="material-symbols-outlined animate-spin text-gray-400">autorenew</span></div>';
        try {
            const res = await fetch(`${window.CHAT_CONFIG.apiUrlUsers}?q=${encodeURIComponent(query)}`);
            const data = await res.json();
            renderUsers(data.users);
        } catch (e) {
            console.error("Failed to fetch users:", e);
            UI.usersList.innerHTML = `<p class="text-center text-red-400 mt-4 text-sm">${window.CHAT_CONFIG.trans.failedToLoadUsers}</p>`;
        }
    }

    function renderUsers(users) {
        if (users.length === 0) {
            UI.usersList.innerHTML = `<p class="text-center text-gray-500 mt-6 text-sm font-medium">${window.CHAT_CONFIG.trans.noUsersFound}</p>`;
            return;
        }

        UI.usersList.innerHTML = users.map(user => {
            const initial = user.name ? user.name.charAt(0).toUpperCase() : 'U';

            // استفاده از کلاس‌های room-item و room-avatar برای هماهنگی 100 درصدی
            return `
                <div onclick="startChatWithUser(${user.id})" class="room-item flex items-center gap-3 p-3 cursor-pointer">
                    
                    <div class="room-avatar" style="background: linear-gradient(135deg, #0A522E, #052B18); box-shadow: 0 2px 8px rgba(10, 82, 46, 0.3); color: #FAF6E9;">
                        ${initial}
                    </div>
                    
                    <div class="flex-1 min-w-0">
                        <div class="mb-1.5">
                            <span class="font-semibold text-[14px] text-gray-900 dark:text-gray-100 truncate block">${user.name}</span>
                        </div>
                        <div class="flex items-center">
                            <span class="text-[10px] font-medium tracking-wide text-gray-500 uppercase bg-gray-200 dark:bg-gray-700 px-2 py-0.5 rounded-full">${user.role}</span>
                        </div>
                    </div>
                    
                </div>
            `;
        }).join('');
    }

    window.startChatWithUser = async function (userId) {
        // بستن مودال بلافاصله بعد از کلیک
        UI.usersModal.style.transform = 'translateY(100%)';

        try {
            const res = await fetch(window.CHAT_CONFIG.apiUrlCreateRoom, {
                method: 'POST',
                headers: {
                    'Content-Type': 'application/json',
                    'X-CSRFToken': window.CHAT_CONFIG.csrfToken
                },
                body: JSON.stringify({ user_id: userId })
            });
            const data = await res.json();

            if (data.success) {
                // اگر با موفقیت ساخته یا پیدا شد، مستقیماً وارد چت می‌شویم
                selectRoom(data.room_id, data.title);
            }
        } catch (e) {
            console.error("Failed to start chat:", e);
        }
    };
    // ── پایان منطق مودال کاربران ──


    // ── بقیه کدهای قبلی (fetchRooms, renderRooms, fetchMessages و...) بدون تغییر در اینجا قرار دارند ──
    async function fetchRooms() {
        try {
            const res = await fetch(window.CHAT_CONFIG.apiUrlRooms);
            const data = await res.json();
            renderRooms(data.rooms);
        } catch (e) { console.error("Failed to fetch rooms:", e); }
    }

    function renderRooms(rooms) {
        if (rooms.length === 0) {
            UI.roomList.innerHTML = `<p class="text-center text-sm text-gray-500 mt-10 px-4">${window.CHAT_CONFIG.trans.noActiveChatsFound}</p>`;
            return;
        }

        UI.roomList.innerHTML = rooms.map(room => {
            const isActive = currentRoomId === room.id;
            const safeTitle = room.title.replace(/'/g, "\\'");
            const initial = room.title ? room.title.charAt(0).toUpperCase() : 'G';

            return `
                <div onclick="selectRoom(${room.id}, '${safeTitle}')" 
                     class="room-item flex items-center gap-3 p-3 cursor-pointer ${isActive ? 'room-item-active' : ''}">
                    
                    <div class="room-avatar">
                        ${initial}
                    </div>

                    <div class="flex-1 min-w-0">
                        <div class="flex justify-between items-center mb-1">
                            <span class="font-semibold text-[14px] text-gray-900 dark:text-gray-100 truncate pr-2">${room.title}</span>
                            <span class="text-[11px] text-gray-400 whitespace-nowrap flex-shrink-0">${room.time}</span>
                        </div>
                        <div class="flex justify-between items-center">
                            <span class="text-[12px] font-medium text-gray-500 truncate">${room.type === 'group' ? '👥 ' + window.CHAT_CONFIG.trans.groupChat : '👤 ' + window.CHAT_CONFIG.trans.privateChat}</span>
                            ${room.unread > 0 ? `<span class="shadow-sm text-[10px] font-bold rounded-full unread-badge">${room.unread}</span>` : ''}
                        </div>
                    </div>
                </div>
            `;
        }).join('');
    }

    window.selectRoom = function (id, title) {
        currentRoomId = id;
        lastMessageId = 0;
        isFetchingMessages = false;

        // 🟢 Optimistic UI: Update active state and remove unread badge immediately
        document.querySelectorAll('.room-item').forEach(el => el.classList.remove('room-item-active'));
        const clickedRoom = document.querySelector(`.room-item[onclick*="selectRoom(${id}"]`);
        if (clickedRoom) {
            clickedRoom.classList.add('room-item-active');
            const badge = clickedRoom.querySelector('.unread-badge');
            if (badge) badge.remove(); // Hide badge instantly
        }

        // 🟢 تغییر invisible به hidden برای کارکرد درست بلوک‌ها
        UI.noChatSelected.classList.add('hidden');
        UI.chatHeaderInfo.classList.remove('hidden'); // 🟢 تغییر یافته
        UI.messages.classList.remove('hidden');
        UI.inputArea.classList.remove('hidden');

        UI.chatTitle.textContent = title;
        UI.messages.innerHTML = '<div class="flex items-center justify-center h-full"><span class="material-symbols-outlined animate-spin text-gray-400 text-3xl">autorenew</span></div>';

        stopPolling();
        fetchMessages().then(() => {
            startPolling();
            scrollToBottom();
            fetchRooms(); // Sync with backend to ensure exact unread counts
        });

        UI.input.focus();
    };

    async function fetchMessages() {
        if (!currentRoomId || isFetchingMessages) return;
        isFetchingMessages = true;

        try {
            UI.indicator.classList.remove('hidden');
            setTimeout(() => UI.indicator.classList.add('hidden'), 500);

            const res = await fetch(`${window.CHAT_CONFIG.apiUrlMessagesBase}${currentRoomId}/?last_id=${lastMessageId}`);
            const data = await res.json();

            if (data.messages && data.messages.length > 0) {
                if (lastMessageId === 0) UI.messages.innerHTML = '';

                renderMessages(data.messages);
                lastMessageId = data.messages[data.messages.length - 1].id;
                scrollToBottom();
            } else if (lastMessageId === 0) {
                UI.messages.innerHTML = `<div class="flex flex-col items-center justify-center h-full text-gray-400 gap-2"><span class="material-symbols-outlined text-5xl opacity-30">chat</span><p class="text-sm font-medium">${window.CHAT_CONFIG.trans.noMessagesYet}</p></div>`;
            }
        } catch (e) {
            console.error("Failed to fetch messages:", e);
        } finally {
            isFetchingMessages = false;
        }
    }

    function renderMessages(messages) {
        const html = messages.map(m => {
            const isMe = m.is_me;
            const alignClass = isMe ? 'message-sent' : 'message-received';
            const bubbleClass = isMe ? 'message-bubble-sent' : 'message-bubble-received';

            const senderName = !isMe ? `<div class="text-[11px] font-bold text-blue-600 dark:text-blue-400 mb-1 opacity-90">${m.sender_name}</div>` : '';
            const safeContent = m.content.replace(/</g, "&lt;").replace(/>/g, "&gt;");
            const timeColor = isMe ? 'text-blue-100' : 'text-gray-400';
            const tickIcon = isMe ? `<span class="material-symbols-outlined text-[13px] ml-1 text-white opacity-80">done_all</span>` : '';

            return `
                <div class="message-bubble ${alignClass} w-full">
                    <div class="${bubbleClass}">
                        <div class="message-content">
                            ${senderName}
                            <p class="m-0">${safeContent}</p>
                            <div class="message-meta ${timeColor} flex items-center justify-end">
                                ${m.sent_at} ${tickIcon}
                            </div>
                        </div>
                    </div>
                </div>
            `;
        }).join('');

        UI.messages.insertAdjacentHTML('beforeend', html);
    }

    function scrollToBottom() {
        UI.messages.scrollTo({ top: UI.messages.scrollHeight, behavior: 'smooth' });
    }

    // ── Textarea Auto-resize & Key Handling ──
    UI.input.addEventListener('input', function () {
        this.style.height = 'auto';
        this.style.height = (this.scrollHeight) + 'px';
    });

    UI.input.addEventListener('keydown', function (e) {
        if (e.key === 'Enter' && !e.shiftKey) {
            e.preventDefault();
            // Trigger form submit
            UI.form.dispatchEvent(new Event('submit', { cancelable: true, bubbles: true }));
        }
    });

    UI.form.addEventListener('submit', async (e) => {
        e.preventDefault();
        const text = UI.input.value.trim();
        if (!text || !currentRoomId) return;

        UI.input.value = '';
        UI.input.style.height = 'auto'; // Reset height

        try {
            await fetch(`${window.CHAT_CONFIG.apiUrlSendBase}${currentRoomId}/`, {
                method: 'POST',
                headers: {
                    'Content-Type': 'application/json',
                    'X-CSRFToken': window.CHAT_CONFIG.csrfToken
                },
                body: JSON.stringify({ content: text })
            });
            await fetchMessages();
            fetchRooms();
        } catch (e) { console.error("Failed to send message:", e); }
    });

    function startPolling() {
        messagePollInterval = setInterval(fetchMessages, 3000);
    }

    function stopPolling() {
        if (messagePollInterval) clearInterval(messagePollInterval);
    }

    fetchRooms();
    roomPollInterval = setInterval(fetchRooms, 10000);
});