package ml.docilealligator.infinityforreddit.asynctasks;

import android.os.Handler;

import androidx.annotation.NonNull;

import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import java.util.concurrent.Executor;

import ml.docilealligator.infinityforreddit.RedditDataRoomDatabase;
import ml.docilealligator.infinityforreddit.account.Account;
import ml.docilealligator.infinityforreddit.subreddit.SubredditDao;
import ml.docilealligator.infinityforreddit.subreddit.SubredditData;
import ml.docilealligator.infinityforreddit.subscribedsubreddit.SubscribedSubredditDao;
import ml.docilealligator.infinityforreddit.subscribedsubreddit.SubscribedSubredditData;
import ml.docilealligator.infinityforreddit.subscribeduser.SubscribedUserDao;
import ml.docilealligator.infinityforreddit.subscribeduser.SubscribedUserData;

public class InsertSubscribedThings {

    public static void insertSubscribedThings(Executor executor, Handler handler,
                                              RedditDataRoomDatabase redditDataRoomDatabase, @NonNull String accountName,
                                              List<SubscribedSubredditData> subscribedSubredditDataList,
                                              List<SubscribedUserData> subscribedUserDataList,
                                              List<SubredditData> subredditDataList,
                                              InsertSubscribedThingListener insertSubscribedThingListener) {
        executor.execute(() -> {
            if (!accountName.equals(Account.ANONYMOUS_ACCOUNT) && redditDataRoomDatabase.accountDao().getAccountData(accountName) == null) {
                handler.post(insertSubscribedThingListener::insertSuccess);
                return;
            }

            SubscribedSubredditDao subscribedSubredditDao = redditDataRoomDatabase.subscribedSubredditDao();
            SubscribedUserDao subscribedUserDao = redditDataRoomDatabase.subscribedUserDao();
            SubredditDao subredditDao = redditDataRoomDatabase.subredditDao();

            if (subscribedSubredditDataList != null) {
                List<SubscribedSubredditData> existingSubscribedSubredditDataList =
                        subscribedSubredditDao.getAllSubscribedSubredditsList(accountName);
                Collections.sort(subscribedSubredditDataList, (subscribedSubredditData, t1) -> subscribedSubredditData.getName().compareToIgnoreCase(t1.getName()));
                List<String> unsubscribedSubreddits = new ArrayList<>();
                compareTwoSubscribedSubredditList(subscribedSubredditDataList, existingSubscribedSubredditDataList,
                        unsubscribedSubreddits);

                for (String unsubscribed : unsubscribedSubreddits) {
                    subscribedSubredditDao.deleteSubscribedSubreddit(unsubscribed, accountName);
                }

                for (SubscribedSubredditData s : subscribedSubredditDataList) {
                    subscribedSubredditDao.insert(s);
                }
            }

            if (subscribedUserDataList != null) {
                List<SubscribedUserData> existingSubscribedUserDataList =
                        subscribedUserDao.getAllSubscribedUsersList(accountName);
                Collections.sort(subscribedUserDataList, (subscribedUserData, t1) -> subscribedUserData.getName().compareToIgnoreCase(t1.getName()));
                List<String> unsubscribedUsers = new ArrayList<>();
                compareTwoSubscribedUserList(subscribedUserDataList, existingSubscribedUserDataList,
                        unsubscribedUsers);

                for (String unsubscribed : unsubscribedUsers) {
                    subscribedUserDao.deleteSubscribedUser(unsubscribed, accountName);
                }

                for (SubscribedUserData s : subscribedUserDataList) {
                    subscribedUserDao.insert(s);
                }
            }

            if (subredditDataList != null) {
                for (SubredditData s : subredditDataList) {
                    subredditDao.insert(s);
                }
            }

            handler.post(insertSubscribedThingListener::insertSuccess);
        });
    }

    public static void insertSubscribedThings(Executor executor, Handler handler, RedditDataRoomDatabase redditDataRoomDatabase,
                                              SubscribedSubredditData singleSubscribedSubredditData,
                                              InsertSubscribedThingListener insertSubscribedThingListener) {
        executor.execute(() -> {
            String accountName = singleSubscribedSubredditData.getUsername();
            if (redditDataRoomDatabase.accountDao().getAccountData(accountName) == null) {
                handler.post(insertSubscribedThingListener::insertSuccess);
                return;
            }

            redditDataRoomDatabase.subscribedSubredditDao().insert(singleSubscribedSubredditData);
            handler.post(insertSubscribedThingListener::insertSuccess);
        });
    }

    public static void insertSubscribedThings(Executor executor, Handler handler, RedditDataRoomDatabase redditDataRoomDatabase,
                                              SubscribedUserData singleSubscribedUserData,
                                              InsertSubscribedThingListener insertSubscribedThingListener) {
        executor.execute(() -> {
            String accountName = singleSubscribedUserData.getUsername();
            if (redditDataRoomDatabase.accountDao().getAccountData(accountName) == null) {
                handler.post(insertSubscribedThingListener::insertSuccess);
                return;
            }

            redditDataRoomDatabase.subscribedUserDao().insert(singleSubscribedUserData);
            handler.post(insertSubscribedThingListener::insertSuccess);
        });
    }

    private static void compareTwoSubscribedSubredditList(List<SubscribedSubredditData> newSubscribedSubreddits,
                                                   List<SubscribedSubredditData> oldSubscribedSubreddits,
                                                   List<String> unsubscribedSubredditNames) {
        int newIndex = 0;
        for (int oldIndex = 0; oldIndex < oldSubscribedSubreddits.size(); oldIndex++) {
            if (newIndex >= newSubscribedSubreddits.size()) {
                for (; oldIndex < oldSubscribedSubreddits.size(); oldIndex++) {
                    unsubscribedSubredditNames.add(oldSubscribedSubreddits.get(oldIndex).getName());
                }
                return;
            }

            SubscribedSubredditData old = oldSubscribedSubreddits.get(oldIndex);
            for (; newIndex < newSubscribedSubreddits.size(); newIndex++) {
                if (newSubscribedSubreddits.get(newIndex).getName().compareToIgnoreCase(old.getName()) == 0) {
                    newIndex++;
                    break;
                }
                if (newSubscribedSubreddits.get(newIndex).getName().compareToIgnoreCase(old.getName()) > 0) {
                    unsubscribedSubredditNames.add(old.getName());
                    break;
                }
            }
        }
    }

    private static void compareTwoSubscribedUserList(List<SubscribedUserData> newSubscribedUsers,
                                              List<SubscribedUserData> oldSubscribedUsers,
                                              List<String> unsubscribedUserNames) {
        int newIndex = 0;
        for (int oldIndex = 0; oldIndex < oldSubscribedUsers.size(); oldIndex++) {
            if (newIndex >= newSubscribedUsers.size()) {
                for (; oldIndex < oldSubscribedUsers.size(); oldIndex++) {
                    unsubscribedUserNames.add(oldSubscribedUsers.get(oldIndex).getName());
                }
                return;
            }

            SubscribedUserData old = oldSubscribedUsers.get(oldIndex);
            for (; newIndex < newSubscribedUsers.size(); newIndex++) {
                if (newSubscribedUsers.get(newIndex).getName().compareToIgnoreCase(old.getName()) == 0) {
                    newIndex++;
                    break;
                }
                if (newSubscribedUsers.get(newIndex).getName().compareToIgnoreCase(old.getName()) > 0) {
                    unsubscribedUserNames.add(old.getName());
                    break;
                }
            }
        }
    }

    public interface InsertSubscribedThingListener {
        void insertSuccess();
    }
}