message.kt

data class Message(
    @PrimaryKey
    val id: String,
    var chatUsers: ArrayList<String>,
    @ServerTimestamp
    var createdAt: Date?=Date(),
    var type: String="text",//0=text,1=audio,2=image,3=video,4=file
    var status: Int=0,//0=sending,1=sent,2=delivered,3=seen,4=failed
    var textMessage: TextMessage=TextMessage("hello chat"),
    @ServerTimestamp
    var deliveryTime: Date?=null,
    @ServerTimestamp
    var seenTime: Date?=null,
    @set:Exclude @get:Exclude
    var chatUserId: String?=null)

data class TextMessage(val text: String)