allow displaying older messages

app/src/main/kotlin/com/simplemobiletools/smsmessenger/activities/ThreadActivity.kt

@@ -40,6 +40,8 @@ import com.simplemobiletools.commons.extensions.*
 import com.simplemobiletools.commons.helpers.*
 import com.simplemobiletools.commons.models.PhoneNumber
 import com.simplemobiletools.commons.models.SimpleContact
+import com.simplemobiletools.commons.views.MyLinearLayoutManager
+import com.simplemobiletools.commons.views.MyRecyclerView
 import com.simplemobiletools.smsmessenger.R
 import com.simplemobiletools.smsmessenger.adapters.AutoCompleteTextViewAdapter
 import com.simplemobiletools.smsmessenger.adapters.ThreadAdapter
@@ -75,6 +77,9 @@ class ThreadActivity : SimpleActivity() {
     private var attachmentSelections = mutableMapOf<String, AttachmentSelection>()
     private val imageCompressor by lazy { ImageCompressor(this) }
     private var lastAttachmentUri: String? = null
+    private var loadingOlderMessages = false
+    private var allMessagesFetched = false
+    private var nextMessageId = -1L
 
     override fun onCreate(savedInstanceState: Bundle?) {
         super.onCreate(savedInstanceState)
@@ -320,6 +325,14 @@ class ThreadActivity : SimpleActivity() {
                 }.apply {
                     thread_messages_list.adapter = this
                 }
+
+                thread_messages_list.endlessScrollListener = object : MyRecyclerView.EndlessScrollListener {
+                    override fun updateBottom() {}
+
+                    override fun updateTop() {
+                        fetchNextMessages()
+                    }
+                }
             } else {
                 (currAdapter as ThreadAdapter).updateMessages(threadItems)
             }
@@ -351,6 +364,38 @@ class ThreadActivity : SimpleActivity() {
         }
     }
 
+    private fun fetchNextMessages() {
+        if (messages.isEmpty() || allMessagesFetched || loadingOlderMessages) return
+
+        toast("fetchNextMessages")
+
+        val messageId = messages.first().date.toLong()*1000 /*- 1*/
+        if (nextMessageId == messageId /*|| messageId < 1*/) {
+            allMessagesFetched = true
+            return
+        }
+
+        nextMessageId = messageId
+        loadingOlderMessages = true
+
+        ensureBackgroundThread {
+            val olderMessages = getMessages(threadId, true, nextMessageId)
+            messages.addAll(0, olderMessages)
+
+            allMessagesFetched = olderMessages.size < MESSAGES_LIMIT || olderMessages.size == 0
+
+            val lastPosition = (thread_messages_list.layoutManager as MyLinearLayoutManager).findLastVisibleItemPosition()
+            val adapter = thread_messages_list.adapter as ThreadAdapter
+            val topItemAtRefresh = adapter.messages[lastPosition]
+
+            runOnUiThread {
+                loadingOlderMessages = false
+                val itemAtRefreshIndex = messages.indexOfFirst { it == topItemAtRefresh }
+                adapter.updateMessages(getThreadItems(), itemAtRefreshIndex)
+            }
+        }
+    }
+
     private fun setupButtons() {
         updateTextColors(thread_holder)
         val textColor = getProperTextColor()

app/src/main/kotlin/com/simplemobiletools/smsmessenger/adapters/ThreadAdapter.kt

@@ -231,14 +231,14 @@ class ThreadAdapter(
 
     private fun isThreadDateTime(position: Int) = messages.getOrNull(position) is ThreadDateTime
 
-    fun updateMessages(newMessages: ArrayList<ThreadItem>) {
+    fun updateMessages(newMessages: ArrayList<ThreadItem>, scrollPosition: Int = messages.size - 1) {
         val latestMessages = newMessages.clone() as ArrayList<ThreadItem>
         val oldHashCode = messages.hashCode()
         val newHashCode = latestMessages.hashCode()
         if (newHashCode != oldHashCode) {
             messages = latestMessages
             notifyDataSetChanged()
-            recyclerView.scrollToPosition(messages.size - 1)
+            recyclerView.scrollToPosition(scrollPosition)
         }
     }
 

app/src/main/kotlin/com/simplemobiletools/smsmessenger/extensions/Context.kt

@@ -56,7 +56,7 @@ val Context.messageAttachmentsDB: MessageAttachmentsDao get() = getMessagessDB()
 
 val Context.messagesDB: MessagesDao get() = getMessagessDB().MessagesDao()
 
-fun Context.getMessages(threadId: Long, getImageResolutions: Boolean): ArrayList<Message> {
+fun Context.getMessages(threadId: Long, getImageResolutions: Boolean, index: Long = -1): ArrayList<Message> {
     val uri = Sms.CONTENT_URI
     val projection = arrayOf(
         Sms._ID,
@@ -70,9 +70,10 @@ fun Context.getMessages(threadId: Long, getImageResolutions: Boolean): ArrayList
         Sms.STATUS
     )
 
-    val selection = "${Sms.THREAD_ID} = ?"
+    val rangeQuery = if (index == -1L) "" else "AND ${Sms.DATE} <= $index"
+    val selection = "${Sms.THREAD_ID} = ? $rangeQuery"
     val selectionArgs = arrayOf(threadId.toString())
-    val sortOrder = "${Sms._ID} DESC LIMIT 100"
+    val sortOrder = "${Sms._ID} DESC LIMIT $MESSAGES_LIMIT"
 
     val blockStatus = HashMap<String, Boolean>()
     val blockedNumbers = getBlockedNumbers()

app/src/main/kotlin/com/simplemobiletools/smsmessenger/helpers/Constants.kt

@@ -54,6 +54,8 @@ const val FILE_SIZE_600_KB = 614_400L
 const val FILE_SIZE_1_MB = 1_048_576L
 const val FILE_SIZE_2_MB = 2_097_152L
 
+const val MESSAGES_LIMIT = 10
+
 fun refreshMessages() {
     EventBus.getDefault().post(Events.RefreshMessages())
 }