Although it's not open sourced, you should check out discord (https://discordapp.com/). Although our niche is gamers, lots of people use Discord for tons of other things. We've got all those things except search (but we're working on it!)
Exactly, a bunch of friends tried to move a chatroom from Skype to Discord, and I blew them off, because I didn't want to move my communication to an app from a company just hoping to get bought out by Twitch probably and shut down within a year. A closed source service with no business model isn't something anyone should even try, much less use.
(disclosure: i work there)