Added timer

app/src/main/java/com/example/android/guesstheword/screens/game/GameFragment.kt

@@ -58,13 +58,17 @@ class GameFragment : Fragment() {
         }
 
         viewModel.score.observe(this, Observer {
-            binding.scoreText.text = it.toString()
+            binding.scoreText.text = getString(R.string.score_format, it)
         })
 
         viewModel.word.observe(this, Observer {
             binding.wordText.text = it
         })
 
+        viewModel.gameTimer.observe(this, Observer {
+            binding.timerText.text = getString(R.string.time_format, it)
+        })
+
         viewModel.eventGameFinished.observe(this, Observer {
             if (it) {
                 gameFinished()

app/src/main/java/com/example/android/guesstheword/screens/game/GameViewModel.kt

@@ -1,10 +1,26 @@
 package com.example.android.guesstheword.screens.game
 
+import android.os.CountDownTimer
+import android.text.format.DateUtils
 import androidx.lifecycle.LiveData
 import androidx.lifecycle.MutableLiveData
+import androidx.lifecycle.Transformations
 import androidx.lifecycle.ViewModel
 
 class GameViewModel(): ViewModel() {
+
+    companion object {
+        // These represent different important times
+        // This is when the game is over
+        const val DONE = 0L
+        // This is the number of milliseconds in a second
+        const val ONE_SECOND = 1000L
+        // This is the total time of the game
+        const val COUNTDOWN_TIME = 60000L
+    }
+
+    private val timer: CountDownTimer
+
     // The current word
     private val _word = MutableLiveData<String>()
     val word: LiveData<String>
@@ -15,6 +31,12 @@ class GameViewModel(): ViewModel() {
     val score: LiveData<Int>
         get() = _score
 
+    private val _gameTimer = MutableLiveData<Long>()
+    val gameTimer: LiveData<String>
+        get() = Transformations.map(_gameTimer) {
+            DateUtils.formatElapsedTime(it / ONE_SECOND)
+        };
+
     private val _eventGameFinished = MutableLiveData<Boolean>()
     val eventGameFinished: LiveData<Boolean>
         get() = _eventGameFinished
@@ -28,6 +50,24 @@ class GameViewModel(): ViewModel() {
         _eventGameFinished.value = false
         _word.value = ""
         _score.value = 0
+
+        timer = object : CountDownTimer(COUNTDOWN_TIME, ONE_SECOND) {
+
+            override fun onTick(millisUntilFinished: Long) {
+                _gameTimer.value = millisUntilFinished
+            }
+
+            override fun onFinish() {
+                endGame()
+            }
+        }
+
+        timer.start()
+    }
+
+    override fun onCleared() {
+        super.onCleared()
+        timer.cancel()
     }
 
     /**
@@ -66,7 +106,7 @@ class GameViewModel(): ViewModel() {
     private fun nextWord() {
         //Select and remove a word from the list
         if (wordList.isEmpty()) {
-            _eventGameFinished.value = true
+            endGame()
         } else {
             _word.value = wordList.removeAt(0)
         }
@@ -84,6 +124,13 @@ class GameViewModel(): ViewModel() {
         nextWord()
     }
 
+    fun endGame() {
+        if (_gameTimer.value?.toInt() == 0) {
+            timer.cancel()
+        }
+        _eventGameFinished.value = true
+    }
+
     fun onGameFinishComplete() {
         _eventGameFinished.value = false
     }

app/src/main/res/values/strings.xml

@@ -26,4 +26,5 @@
     <string name="word_is">The word is…</string>
     <string name="quote_format">\"%s\"</string>
     <string name="score_format">Current Score: %d</string>
+    <string name="time_format">Time Left: %s</string>
 </resources>