diff --git a/app/src/main/java/be/ugent/sel/studeez/domain/SubjectDAO.kt b/app/src/main/java/be/ugent/sel/studeez/domain/SubjectDAO.kt
index da6abbe..bad8106 100644
--- a/app/src/main/java/be/ugent/sel/studeez/domain/SubjectDAO.kt
+++ b/app/src/main/java/be/ugent/sel/studeez/domain/SubjectDAO.kt
@@ -12,5 +12,10 @@ interface SubjectDAO {
     fun deleteSubject(oldSubject: Subject)
 
     fun updateSubject(newSubject: Subject)
+
+    suspend fun getTaskCount(subject: Subject): Int
+    suspend fun getCompletedTaskCount(subject: Subject): Int
+    fun getStudyTime(subject: Subject): Flow<Int>
+
     suspend fun getSubject(subjectId: String): Subject?
 }
\ No newline at end of file
diff --git a/app/src/main/java/be/ugent/sel/studeez/domain/TaskDAO.kt b/app/src/main/java/be/ugent/sel/studeez/domain/TaskDAO.kt
index 4c7ee44..8a2dd41 100644
--- a/app/src/main/java/be/ugent/sel/studeez/domain/TaskDAO.kt
+++ b/app/src/main/java/be/ugent/sel/studeez/domain/TaskDAO.kt
@@ -14,11 +14,5 @@ interface TaskDAO {
 
     fun deleteTask(oldTask: Task)
 
-    fun toggleTaskCompleted(task: Task, completed: Boolean)
-
     suspend fun getTask(subjectId: String, taskId: String): Task
-
-    suspend fun getTaskCount(subject: Subject): Int
-
-    suspend fun getCompletedTaskCount(subject: Subject): Int
 }
\ No newline at end of file
diff --git a/app/src/main/java/be/ugent/sel/studeez/domain/implementation/FireBaseSubjectDAO.kt b/app/src/main/java/be/ugent/sel/studeez/domain/implementation/FireBaseSubjectDAO.kt
index 9156771..3e9ae13 100644
--- a/app/src/main/java/be/ugent/sel/studeez/domain/implementation/FireBaseSubjectDAO.kt
+++ b/app/src/main/java/be/ugent/sel/studeez/domain/implementation/FireBaseSubjectDAO.kt
@@ -4,6 +4,7 @@ import be.ugent.sel.studeez.data.local.models.task.Subject
 import be.ugent.sel.studeez.domain.AccountDAO
 import be.ugent.sel.studeez.domain.SubjectDAO
 import be.ugent.sel.studeez.domain.TaskDAO
+import com.google.firebase.firestore.AggregateSource
 import com.google.firebase.firestore.CollectionReference
 import com.google.firebase.firestore.FirebaseFirestore
 import com.google.firebase.firestore.ktx.snapshots
@@ -24,8 +25,8 @@ class FireBaseSubjectDAO @Inject constructor(
             .map { it.toObjects(Subject::class.java) }
             .map { subjects ->
                 subjects.map { subject ->
-                    subject.taskCount = taskDAO.getTaskCount(subject)
-                    subject.taskCompletedCount = taskDAO.getCompletedTaskCount(subject)
+                    subject.taskCount = getTaskCount(subject)
+                    subject.taskCompletedCount = getCompletedTaskCount(subject)
                     subject
                 }
             }
@@ -47,8 +48,39 @@ class FireBaseSubjectDAO @Inject constructor(
         currentUserSubjectsCollection().document(newSubject.id).set(newSubject)
     }
 
+    override suspend fun getTaskCount(subject: Subject): Int {
+        return subjectTasksCollection(subject)
+            .nonArchived()
+            .count()
+            .get(AggregateSource.SERVER)
+            .await()
+            .count.toInt()
+    }
+
+    override suspend fun getCompletedTaskCount(subject: Subject): Int {
+        return subjectTasksCollection(subject)
+            .nonArchived()
+            .completed()
+            .count()
+            .get(AggregateSource.SERVER)
+            .await()
+            .count.toInt()
+    }
+
+    override fun getStudyTime(subject: Subject): Flow<Int> {
+        return taskDAO.getTasks(subject)
+            .map { tasks -> tasks.sumOf { it.time } }
+    }
+
     private fun currentUserSubjectsCollection(): CollectionReference =
         firestore.collection(FireBaseCollections.USER_COLLECTION)
             .document(auth.currentUserId)
             .collection(FireBaseCollections.SUBJECT_COLLECTION)
+
+    private fun subjectTasksCollection(subject: Subject): CollectionReference =
+        firestore.collection(FireBaseCollections.USER_COLLECTION)
+            .document(auth.currentUserId)
+            .collection(FireBaseCollections.SUBJECT_COLLECTION)
+            .document(subject.id)
+            .collection(FireBaseCollections.TASK_COLLECTION)
 }
\ No newline at end of file
diff --git a/app/src/main/java/be/ugent/sel/studeez/domain/implementation/FireBaseTaskDAO.kt b/app/src/main/java/be/ugent/sel/studeez/domain/implementation/FireBaseTaskDAO.kt
index 049bb54..bde5c6f 100644
--- a/app/src/main/java/be/ugent/sel/studeez/domain/implementation/FireBaseTaskDAO.kt
+++ b/app/src/main/java/be/ugent/sel/studeez/domain/implementation/FireBaseTaskDAO.kt
@@ -5,7 +5,6 @@ import be.ugent.sel.studeez.data.local.models.task.Task
 import be.ugent.sel.studeez.data.local.models.task.TaskDocument
 import be.ugent.sel.studeez.domain.AccountDAO
 import be.ugent.sel.studeez.domain.TaskDAO
-import com.google.firebase.firestore.AggregateSource
 import com.google.firebase.firestore.CollectionReference
 import com.google.firebase.firestore.FirebaseFirestore
 import com.google.firebase.firestore.Query
@@ -31,44 +30,20 @@ class FireBaseTaskDAO @Inject constructor(
         return selectedSubjectTasksCollection(subjectId).document(taskId).get().await().toObject()!!
     }
 
-    override suspend fun getTaskCount(subject: Subject): Int {
-        return selectedSubjectTasksCollection(subject.id)
-            .nonArchived()
-            .count()
-            .get(AggregateSource.SERVER)
-            .await()
-            .count.toInt()
-    }
-
-    override suspend fun getCompletedTaskCount(subject: Subject): Int {
-        return selectedSubjectTasksCollection(subject.id)
-            .completed()
-            .nonArchived()
-            .count()
-            .get(AggregateSource.SERVER)
-            .await()
-            .count.toInt()
-    }
-
     override fun saveTask(newTask: Task) {
         selectedSubjectTasksCollection(newTask.subjectId).add(newTask)
     }
 
     override fun updateTask(newTask: Task) {
-        selectedSubjectTasksCollection(newTask.subjectId).document(newTask.id).set(newTask)
+        selectedSubjectTasksCollection(newTask.subjectId)
+            .document(newTask.id)
+            .set(newTask)
     }
 
     override fun deleteTask(oldTask: Task) {
         selectedSubjectTasksCollection(oldTask.subjectId).document(oldTask.id).delete()
     }
 
-    override fun toggleTaskCompleted(task: Task, completed: Boolean) {
-        selectedSubjectTasksCollection(task.subjectId)
-            .document(task.id)
-//            .update(TaskDocument.completed, completed)
-            .set(task.copy(completed = completed))
-    }
-
     private fun selectedSubjectTasksCollection(subjectId: String): CollectionReference =
         firestore.collection(FireBaseCollections.USER_COLLECTION)
             .document(auth.currentUserId)
@@ -76,18 +51,18 @@ class FireBaseTaskDAO @Inject constructor(
             .document(subjectId)
             .collection(FireBaseCollections.TASK_COLLECTION)
 
-    // Extend CollectionReference and Query with some filters
+}
 
-    private fun CollectionReference.nonArchived(): Query =
-        this.whereEqualTo(TaskDocument.archived, false)
+// Extend CollectionReference and Query with some filters
 
-    private fun Query.nonArchived(): Query =
-        this.whereEqualTo(TaskDocument.archived, false)
+fun CollectionReference.nonArchived(): Query =
+    this.whereEqualTo(TaskDocument.archived, false)
 
-    private fun CollectionReference.completed(): Query =
-        this.whereEqualTo(TaskDocument.completed, true)
+fun Query.nonArchived(): Query =
+    this.whereEqualTo(TaskDocument.archived, false)
 
-    private fun Query.completed(): Query =
-        this.whereEqualTo(TaskDocument.completed, true)
+fun CollectionReference.completed(): Query =
+    this.whereEqualTo(TaskDocument.completed, true)
 
-}
\ No newline at end of file
+fun Query.completed(): Query =
+    this.whereEqualTo(TaskDocument.completed, true)