Model for mongodb

chat-model.js

users: [
  {
    nick: String,
    thumb: String
  }
]

messages: [
  {
    sender: String, // users_id
    receiver: [
      { users: [
          String, // users_id
        ]
      }
        group: [
          String, // groups_id
        ]
      }
    ],
    content: String,
    files: String, // files_id  
    sent: Date
  }
]

groups: [
  {
    name: String,
    description: String,
    thumb: String,
    link: String,
    visibility: String,
    admins: [
      String
    ],
    members: [
      String // users_id
    ],
    blocks: [
      String // users_id
    ],
    created_at: Date
  }
]

files: [
  {
    name: String,
    path: String,
    type: String,
    sender: String, // users_is
    uploaded_at: Date
  }
]