update the clock time every second

app/src/main/kotlin/com/simplemobiletools/clock/fragments/ClockFragment.kt

@@ -1,14 +1,42 @@
 package com.simplemobiletools.clock.fragments
 
 import android.content.Context
+import android.os.Handler
 import android.util.AttributeSet
 import android.widget.RelativeLayout
 import com.simplemobiletools.commons.extensions.updateTextColors
 import kotlinx.android.synthetic.main.fragment_clock.view.*
+import java.util.*
 
 class ClockFragment(context: Context, attributeSet: AttributeSet) : RelativeLayout(context, attributeSet) {
+    private val ONE_SECOND = 1000L
+    private var passedSeconds = 0
+
+    private val updateHandler = Handler()
+
     override fun onFinishInflate() {
         super.onFinishInflate()
         context.updateTextColors(clock_fragment)
+        val offset = Calendar.getInstance().timeZone.rawOffset
+        passedSeconds = ((Calendar.getInstance().timeInMillis + offset) / 1000).toInt()
+        updateCurrentTime()
+    }
+
+    private fun updateCurrentTime() {
+        val hours = (passedSeconds / 3600) % 24
+        val minutes = (passedSeconds / 60) % 60
+        val seconds = passedSeconds % 60
+        val format = "%02d:%02d:%02d"
+        clock_time.text = String.format(format, hours, minutes, seconds)
+
+        updateHandler.postDelayed({
+            passedSeconds++
+            updateCurrentTime()
+        }, ONE_SECOND)
+    }
+
+    override fun onDetachedFromWindow() {
+        super.onDetachedFromWindow()
+        updateHandler.removeCallbacksAndMessages(null)
     }
 }