#59 implementation of UserDAO

app/src/main/java/be/ugent/sel/studeez/domain/implementation/FirebaseUserDAO.kt

@@ -1,2 +1,29 @@
 package be.ugent.sel.studeez.domain.implementation
 
+import be.ugent.sel.studeez.domain.AccountDAO
+import be.ugent.sel.studeez.domain.UserDAO
+import com.google.firebase.firestore.DocumentReference
+import com.google.firebase.firestore.FirebaseFirestore
+import kotlinx.coroutines.tasks.await
+import javax.inject.Inject
+
+class FirebaseUserDAO @Inject constructor(
+    private val firestore: FirebaseFirestore,
+    private val auth: AccountDAO
+    ) : UserDAO {
+
+    override suspend fun getUserName(): String? {
+        return currentUserDocument().get().await().getString("username")
+    }
+
+    override suspend fun save(newUsername: String) {
+        currentUserDocument().set(mapOf("username" to newUsername))
+    }
+
+    private fun currentUserDocument(): DocumentReference =
+        firestore.collection(USER_COLLECTION).document(auth.currentUserId)
+
+    companion object {
+        private const val USER_COLLECTION = "users"
+    }
+}