const EMPTY_CONNECTION_IDS_HTML = '<p class="text-gray-500 text-sm">\u6682\u65e0\u53ef\u7528\u7684\u8fde\u63a5ID</p>';
const EMPTY_USERS_HTML = '<p class="text-gray-500 text-sm">\u6682\u65e0\u5728\u7ebf\u7528\u6237</p>';
const HALL_LABEL = '\u5927\u5385\uff08\u672a\u52a0\u5165\u623f\u95f4\uff09';
const HOST_LABEL = '\u623f\u4e3b';
const PARTICIPANT_LABEL = '\u6210\u5458';
const UNKNOWN_USER_LABEL = '\u533f\u540d\u7528\u6237';
const UNSET_USER_ID_LABEL = '\u672a\u8bbe\u7f6eID';
const SELF_LABEL = '\u81ea\u5df1';
const SELECT_LABEL = '\u9009\u62e9';
const USER_COUNT_SUFFIX = '\u4eba';
const ONLINE_USERS_SUMMARY_SUFFIX = ' \u4e2aWebSocket\u7528\u6237\u5728\u7ebf';

function escapeHtml(value) {
    return String(value || '')
        .replace(/&/g, '&amp;')
        .replace(/</g, '&lt;')
        .replace(/>/g, '&gt;')
        .replace(/"/g, '&quot;')
        .replace(/'/g, '&#39;');
}

export async function fetchOnlineUsers() {
    const response = await fetch('/signaling/users');
    if (!response.ok) {
        throw new Error('Failed to fetch online users');
    }

    const data = await response.json();
    return Array.isArray(data.users) ? data.users : [];
}

export async function fetchConnectionDirectory() {
    const [connectionResponse, usersResponse] = await Promise.all([
        fetch('/signaling/connection-ids'),
        fetch('/signaling/users')
    ]);

    if (!connectionResponse.ok) {
        throw new Error('Failed to fetch connection IDs');
    }
    if (!usersResponse.ok) {
        throw new Error('Failed to fetch online users');
    }

    const connectionData = await connectionResponse.json();
    const usersData = await usersResponse.json();

    return {
        connectionIds: connectionData.connectionIds || [],
        users: Array.isArray(usersData.users) ? usersData.users : []
    };
}

export function renderConnectionIds({ connectionIds, idsContainer, connectionIdsList, onSelectConnectionId }) {
    if (!idsContainer) {
        return;
    }

    idsContainer.innerHTML = '';

    if (connectionIds.length === 0) {
        idsContainer.innerHTML = EMPTY_CONNECTION_IDS_HTML;
    } else {
        connectionIds.forEach((connectionId) => {
            const item = document.createElement('div');
            item.className = 'flex items-center justify-between p-2 bg-white/5 rounded-lg hover:bg-white/10 cursor-pointer transition-colors';

            const label = document.createElement('span');
            label.className = 'text-sm';
            label.textContent = connectionId;

            const button = document.createElement('button');
            button.className = 'text-xs bg-indigo-600 hover:bg-indigo-700 px-2 py-1 rounded';
            button.type = 'button';
            button.textContent = SELECT_LABEL;
            button.addEventListener('click', () => onSelectConnectionId(connectionId));

            item.appendChild(label);
            item.appendChild(button);
            idsContainer.appendChild(item);
        });
    }

    if (connectionIdsList) {
        connectionIdsList.classList.remove('hidden');
    }
}

export function renderOnlineUsers({ users, currentUserId, onlineUsersList, usersContainer, onlineUsersSummary }) {
    if (!onlineUsersList || !usersContainer || !onlineUsersSummary) {
        return;
    }

    onlineUsersSummary.textContent = `${users.length}${ONLINE_USERS_SUMMARY_SUFFIX}`;
    usersContainer.innerHTML = '';

    if (users.length === 0) {
        usersContainer.innerHTML = EMPTY_USERS_HTML;
        onlineUsersList.classList.remove('hidden');
        return;
    }

    const groupedUsers = users.reduce((groups, user) => {
        const groupName = user.connectionId ? `\u623f\u95f4 ${user.connectionId}` : HALL_LABEL;
        if (!groups[groupName]) {
            groups[groupName] = [];
        }
        groups[groupName].push(user);
        return groups;
    }, {});

    Object.entries(groupedUsers).forEach(([groupName, roomUsers]) => {
        const section = document.createElement('div');
        section.className = 'rounded-lg border border-white/10 bg-white/5 p-3';

        const roomTitle = document.createElement('div');
        roomTitle.className = 'flex items-center justify-between mb-2';
        roomTitle.innerHTML = `
            <span class="text-sm font-medium text-white">${escapeHtml(groupName)}</span>
            <span class="text-xs text-gray-400">${roomUsers.length} ${USER_COUNT_SUFFIX}</span>
        `;
        section.appendChild(roomTitle);

        const roomList = document.createElement('div');
        roomList.className = 'space-y-2';

        roomUsers.forEach((user) => {
            const userName = user.name || user.userId || UNKNOWN_USER_LABEL;
            const avatar = user.avatar || '/images/p2.png';
            const roleLabel = user.role === 'host'
                ? HOST_LABEL
                : (user.role === 'participant' ? PARTICIPANT_LABEL : HALL_LABEL);
            const isSelf = Boolean(user.userId) && user.userId === currentUserId;
            const identity = user.userId || user.socketId || user.participantId || UNSET_USER_ID_LABEL;

            const userItem = document.createElement('div');
            userItem.className = 'flex items-center justify-between rounded-lg bg-black/20 px-3 py-2';
            userItem.innerHTML = `
                <div class="flex items-center gap-3 min-w-0">
                    <img src="${escapeHtml(avatar)}" alt="${escapeHtml(userName)}" class="w-8 h-8 rounded-full object-cover">
                    <div class="min-w-0">
                        <div class="text-sm text-white truncate">${escapeHtml(userName)}</div>
                        <div class="text-xs text-gray-400 truncate">${escapeHtml(identity)}</div>
                    </div>
                </div>
                <div class="flex items-center gap-2">
                    <span class="text-xs px-2 py-1 rounded-full ${user.role === 'host' ? 'bg-indigo-500/20 text-indigo-300' : (user.role === 'participant' ? 'bg-white/10 text-gray-300' : 'bg-emerald-500/20 text-emerald-300')}">${roleLabel}</span>
                    ${isSelf ? `<span class="text-xs text-gray-500">${SELF_LABEL}</span>` : ''}
                </div>
            `;
            roomList.appendChild(userItem);
        });

        section.appendChild(roomList);
        usersContainer.appendChild(section);
    });

    onlineUsersList.classList.remove('hidden');
}