quick fix user recommendations

app/src/main/java/de/akamu/tudarmstadt/features/dashboard/FriendsListFragment.kt

@@ -117,15 +117,15 @@ class FriendsListFragment : Fragment(),
     }
 
     override fun bindRecommendedUsersAdapter(
-        allUsers: ArrayList<User>,
+        recommendedUsers: ArrayList<User>,
         friends: ArrayList<User>,
         duels: ArrayList<Duel>
     ) {
         nestedScollView_friends.visibility = View.VISIBLE
-        textView_friends_recommended_users.visibility = View.VISIBLE
         textView_your_friends.visibility = View.VISIBLE
+        textView_friends_recommended_users.visibility = View.VISIBLE
         recyclerView_recommended_user_list.visibility = View.VISIBLE
-        recyclerView_recommended_user_list.adapter = RecommendedUsersAdapter(allUsers, duels, presenter, this, requireActivity())
+        recyclerView_recommended_user_list.adapter = RecommendedUsersAdapter(recommendedUsers, duels, presenter, this, requireActivity())
         recyclerView_recommended_user_list.layoutManager = LinearLayoutManager(requireActivity(), RecyclerView.HORIZONTAL, false)
     }
 

app/src/main/java/de/akamu/tudarmstadt/features/dashboard/RecommendedUsersAdapter.kt

@@ -35,7 +35,7 @@ class RecommendedUsersAdapter(
     }
 
     override fun getItemCount(): Int {
-        return Constants.MAX_RECOMMENDATIONS
+        return recommendedUsers.size
     }
 
     override fun onBindViewHolder(holder: RecommendedUsersAdapter.RecommendedUserViewHolder, position: Int) {

app/src/main/java/de/akamu/tudarmstadt/features/friends/FriendsListContract.kt

@@ -14,7 +14,7 @@ interface FriendsListContract {
          */
         fun bindFriendListAdapter(friends: ArrayList<User>, duels: ArrayList<Duel>)
         /** Bind RecommendedUsersAdapter **/
-        fun bindRecommendedUsersAdapter(allUsers: ArrayList<User>, friends: ArrayList<User>, duels: ArrayList<Duel>)
+        fun bindRecommendedUsersAdapter(recommendedUsers: ArrayList<User>, friends: ArrayList<User>, duels: ArrayList<Duel>)
         /** Let the user know that fetching his/her friends has failed due to [reason] **/
         fun showFetchFriendsFailed(reason: String)
         /** Let the user know that sending a challenge request has failed due to [reason] **/

app/src/main/java/de/akamu/tudarmstadt/features/friends/FriendsListPresenter.kt

@@ -20,6 +20,7 @@ class FriendsListPresenter(
     lateinit var allUsers: ArrayList<User>
     lateinit var mFriends: ArrayList<User>
     lateinit var mDuels: ArrayList<Duel>
+    lateinit var mRecommendedUsers: ArrayList<User>
 
     private var userFetched: Boolean = false
     private var friendsFetched: Boolean = false
@@ -33,17 +34,17 @@ class FriendsListPresenter(
 
     override fun fetchAllUsers() {
         friendsInteractor.getAllUsers(object : FriendsDataSource.GetAllUsersCallback {
-        override fun onGetAllUsersSuccess(all: ArrayList<User>) {
-            allUsers = all
-            userFetched = true
-            handleFriendsAndDuelCallback()
-        }
+            override fun onGetAllUsersSuccess(all: ArrayList<User>) {
+                allUsers = all
+                userFetched = true
+                handleFriendsAndDuelCallback()
+            }
 
-        override fun onGetAllUsersFailed(reason: String) {
-            // silent?
-        }
+            override fun onGetAllUsersFailed(reason: String) {
+                // silent?
+            }
 
-    })
+        })
     }
 
     override fun fetchFriends() {
@@ -75,8 +76,9 @@ class FriendsListPresenter(
     }
 
     private fun handleFriendsAndDuelCallback() {
-        if(friendsFetched && duelsFetched && userFetched) {
-            view?.bindRecommendedUsersAdapter(getRecommendedUsers(allUsers), mFriends, mDuels)
+        if (friendsFetched && duelsFetched && userFetched) {
+            mRecommendedUsers = getRecommendedUsers(allUsers)
+            view?.bindRecommendedUsersAdapter(mRecommendedUsers, mFriends, mDuels)
             view?.bindFriendListAdapter(mFriends, mDuels)
         }
     }
@@ -84,66 +86,74 @@ class FriendsListPresenter(
     private fun getRecommendedUsers(allUsers: ArrayList<User>): ArrayList<User> {
         val generatedIndices: ArrayList<Int> = arrayListOf()
         val recommendedUsers: ArrayList<User> = arrayListOf()
-        val allUsersCopy: ArrayList<User> = arrayListOf()
+        var allUsersCopy: ArrayList<User> = arrayListOf()
         allUsersCopy.addAll(allUsers)
-        val allUsersIterator = allUsersCopy.listIterator()
-
-        // Make sure we don't recommend someone who is already a friend
-        while (allUsersIterator.hasNext()) {
-            val user = allUsersIterator.next()
-            // Remove yourself fromm the list
-            if (user.id == ID_ME) {
-                allUsersIterator.remove()
-            }
-            for (friend in mFriends) {
-                if (user.username == friend.username) {
-                    allUsersIterator.remove()
-                }
-            }
-        }
+        allUsersCopy = ArrayList(allUsersCopy.distinct())
+
+        // Make sure we don't recommend someone who is already a friend or ourselves
+        val possibleUsers = ArrayList(allUsersCopy.filter{user ->
+                user.id != ID_ME && !isAlreadyFriend(user)
+        })
+
+        if (possibleUsers.isEmpty()) return possibleUsers
+        val maxShownRecommendations =
+            if (possibleUsers.size < Constants.MAX_RECOMMENDATIONS) possibleUsers.size
+            else Constants.MAX_RECOMMENDATIONS
 
-        for (i in 0 until Constants.MAX_RECOMMENDATIONS) {
-            var index = (0 until allUsersCopy.size).random()
+        for (i in 0 until maxShownRecommendations) {
+            var index = (0 until possibleUsers.size).random()
             // Make sure we do not recommend the same user twice or more
             while (generatedIndices.contains(index)) {
-                index = (0 until allUsersCopy.size).random()
+                index = (0 until possibleUsers.size).random()
             }
             generatedIndices.add(index)
-            recommendedUsers.add(allUsersCopy[index])
+            recommendedUsers.add(possibleUsers[index])
         }
         return recommendedUsers
     }
 
-    override fun sendChallengeRequest(friend: User, callback: ChallengeSentCallback) {
-        friendsInteractor.sendChallengeRequest(friend, object : FriendsDataSource.ChallengeRequestCallback {
-            override fun onChallengeRequestSuccess(friendName: String) {
-                view?.showSendChallengeRequestSuccess(friendName)
-                callback.indicateChallengeSentSuccessfully()
+    private fun isAlreadyFriend(user: User) : Boolean {
+        for (friend in mFriends) {
+            if (user.username == friend.username) {
+                return true
             }
+        }
+        return false
+    }
 
-            override fun onChallengeRequestFailedNoPoolsSelected() {
-                view?.showSendChallengeRequestFailedNoPoolsSelected()
-                callback.indicateChallengeSentFailed()
-            }
+    override fun sendChallengeRequest(friend: User, callback: ChallengeSentCallback) {
+        friendsInteractor.sendChallengeRequest(
+            friend,
+            object : FriendsDataSource.ChallengeRequestCallback {
+                override fun onChallengeRequestSuccess(friendName: String) {
+                    view?.showSendChallengeRequestSuccess(friendName)
+                    callback.indicateChallengeSentSuccessfully()
+                }
 
-            override fun onChallengeRequestFailed(reason: String) {
-                view?.showSendChallengeRequestFailed(reason)
-                callback.indicateChallengeSentFailed()
-            }
+                override fun onChallengeRequestFailedNoPoolsSelected() {
+                    view?.showSendChallengeRequestFailedNoPoolsSelected()
+                    callback.indicateChallengeSentFailed()
+                }
 
-            override fun onChallengeRequestFailedNoPoolsInCommon() {
-                view?.showSendChallengeRequestFailedNoPoolsInCommon()
-                callback.indicateChallengeSentFailed()
-            }
+                override fun onChallengeRequestFailed(reason: String) {
+                    view?.showSendChallengeRequestFailed(reason)
+                    callback.indicateChallengeSentFailed()
+                }
 
-        })
+                override fun onChallengeRequestFailedNoPoolsInCommon() {
+                    view?.showSendChallengeRequestFailedNoPoolsInCommon()
+                    callback.indicateChallengeSentFailed()
+                }
+
+            })
     }
 
     override fun findUsersThatStartWith(startsWith: String) {
         val usersThatStartsWith = ArrayList<User>()
         allUsers.forEach {
             if (it.username.startsWith(startsWith, true)
-                && it.username != me.username) {
+                && it.username != me.username
+            ) {
                 usersThatStartsWith.add(it)
             }
         }