Build a messaging platform

Hi, I want to make a messaging program that is similar to slack.com. I plan to release as open source when completed. The messager needs these features: -channels, private messages -Admin center to control accounts - Admin can access all peoples message / login as them - show when people are online - google file uploader - be able to transfer files images, docs, etc -be about to use # and other references similar to slack. -profiles. - good ui -normal messaging features. - all message archive - every users client gets all message and syncs better devices - presences shifting -active directory / ldap. - past image in message box and send - read recipients - Mobile app for both ios and android with notifications - responsive design - in message commands and references - all docs have editing with etherpad - all files are saved and stored in seafile - Channels should have 3 modes open, need approval, invisible invite only. - Requires search box with open source index server to search all chats, channels and groups. . - polls - integrate round cube or other opensource email client as as seamless tab, unified design and same notification as messages style. Additional Project Description: You can us any open source solution to solve any feature even if i didn't say and you can suggest alternatives to the ones i did mention.