introduce Contact model

libsession/src/main/java/org/session/libsession/messaging/contacts/Contact.kt

@@ -0,0 +1,72 @@
+package org.session.libsession.messaging.contacts
+
+import org.session.libsession.messaging.threads.recipients.Recipient
+
+class Contact(val sessionID: String) {
+    // The URL from which to fetch the contact's profile picture.
+    var profilePictureURL: String? = null
+    // The file name of the contact's profile picture on local storage.
+    var profilePictureFileName: String? = null
+    // The key with which the profile picture is encrypted.
+    var profilePictureEncryptionKey: ByteArray? = null
+    // The ID of the thread associated with this contact.
+    var threadID: String? = null
+    // This flag is used to determine whether we should auto-download files sent by this contact.
+    var isTrusted = false
+
+    // region: Name
+    // The name of the contact. Use this whenever you need the "real", underlying name of a user (e.g. when sending a message).
+    var name: String? = null
+    // The contact's nickname, if the user set one.
+    var nickname: String? = null
+    // The name to display in the UI. For local use only.
+    fun displayName(context: ContactContext): String? {
+        this.nickname?.let { return it }
+        return when {
+            context == ContactContext.REGULAR -> this.name
+            context == ContactContext.OPEN_GROUP -> {
+                // In open groups, where it's more likely that multiple users have the same name,
+                // we display a bit of the Session ID after a user's display name for added context.
+                this.name?.let {
+                    return "${this.name}${this.sessionID.takeLast(8)}"
+                }
+                return null
+            }
+            else -> throw Exception("Unknown contact context!")
+        }
+    }
+    //end region
+
+    enum class ContactContext {
+        REGULAR, OPEN_GROUP
+    }
+
+    fun isValid(): Boolean {
+        if (profilePictureURL != null) { return profilePictureEncryptionKey != null }
+        if (profilePictureEncryptionKey != null) { return profilePictureURL != null}
+        return true
+    }
+
+    override fun equals(other: Any?): Boolean {
+        return if (other is Contact) {
+            other.sessionID == this.sessionID
+        } else {
+            false
+        }
+    }
+
+    override fun hashCode(): Int {
+        return sessionID.hashCode()
+    }
+
+    override fun toString(): String {
+        return nickname ?: name ?: sessionID
+    }
+
+    companion object {
+        fun contextForRecipient(recipient: Recipient): ContactContext {
+            return if (recipient.isOpenGroupRecipient) { ContactContext.OPEN_GROUP }
+            else { ContactContext.REGULAR }
+        }
+    }
+}