changed Time increase and decrease functions

app/src/main/java/be/ugent/sel/studeez/data/local/models/timer_functional/FunctionalCustomTimer.kt

@@ -4,7 +4,7 @@ class FunctionalCustomTimer(studyTime: Int) : FunctionalTimer(studyTime) {
 
     override fun tick() {
         if (!hasEnded()) {
-            time.minOne()
+            time++
             totalStudyTime++
         }
     }

app/src/main/java/be/ugent/sel/studeez/data/local/models/timer_functional/FunctionalEndlessTimer.kt

@@ -11,7 +11,7 @@ class FunctionalEndlessTimer : FunctionalTimer(0) {
     }
 
     override fun tick() {
-        time.plusOne()
+        time++
         totalStudyTime++
     }
 

app/src/main/java/be/ugent/sel/studeez/data/local/models/timer_functional/FunctionalPomodoroTimer.kt

@@ -22,7 +22,7 @@ class FunctionalPomodoroTimer(
             }
             isInBreak = !isInBreak
         }
-        time.minOne()
+        time--
 
         if (!isInBreak) {
             totalStudyTime++

app/src/main/java/be/ugent/sel/studeez/data/local/models/timer_functional/FunctionalTimer.kt

@@ -4,7 +4,7 @@ import be.ugent.sel.studeez.data.local.models.SessionReport
 import com.google.firebase.Timestamp
 
 abstract class FunctionalTimer(initialValue: Int) {
-    val time: Time = Time(initialValue)
+    var time: Time = Time(initialValue)
     var totalStudyTime: Int = 0
 
     fun getHoursMinutesSeconds(): HoursMinutesSeconds {

app/src/main/java/be/ugent/sel/studeez/data/local/models/timer_functional/Time.kt

@@ -1,19 +1,13 @@
 package be.ugent.sel.studeez.data.local.models.timer_functional
 
-class Time(initialTime: Int) {
+class Time(var time: Int) {
+    operator fun invoke() = time
 
-    var time = initialTime
+    operator fun inc(): Time = Time(time + 1)
 
-    fun minOne() {
-        time--
-    }
-
-    fun plusOne() {
-        time++
-    }
+    operator fun dec(): Time = Time(time - 1)
 
     fun getAsHMS(): HoursMinutesSeconds {
         return HoursMinutesSeconds(time)
     }
-
-}
+}