Chat client-server using html5 + nodejs +mobile friendly

Chat client-server where: - There are several chat rooms to connect to. - The chat client can show a list of rooms available or go directly to a specific room using a different url - anyone who joins a room can see a list of other users connected - Anyone can talk privately to anyone else or talk to the group - after a specific limit to the number of people who can be chatted with (5) it should not be able to chat until the next day. Users may have a premium account to chat with unlimited people - if someone joins, and people are already talking in a room, people can see the previous messages (up to a limit). - users can join and chat anonymously after signing up Non-functional reqs: - The code should be simple to modify as there will be enhancements to be done in the future. - nodejs - html5 - scalability is desired - It should work on most mobile devices (specially iPhone and Android).