package ru.ulstu.students.service;

import org.apache.commons.lang3.StringUtils;
import org.springframework.data.domain.Sort;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;
import ru.ulstu.core.util.DateUtils;
import ru.ulstu.deadline.model.Deadline;
import ru.ulstu.deadline.service.DeadlineService;
import ru.ulstu.students.model.Scheduler;
import ru.ulstu.students.model.Task;
import ru.ulstu.students.model.TaskDto;
import ru.ulstu.students.model.TaskFilterDto;
import ru.ulstu.students.repository.SchedulerRepository;
import ru.ulstu.students.repository.TaskRepository;
import ru.ulstu.tags.model.Tag;
import ru.ulstu.tags.service.TagService;
import ru.ulstu.timeline.service.EventService;

import java.io.IOException;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Calendar;
import java.util.Date;
import java.util.List;
import java.util.Map;
import java.util.Set;
import java.util.TreeMap;
import java.util.stream.Collectors;

import static org.springframework.util.ObjectUtils.isEmpty;
import static ru.ulstu.core.util.StreamApiUtils.convert;
import static ru.ulstu.students.model.Task.TaskStatus.IN_WORK;

@Service
public class TaskService {

    private final static int MAX_DISPLAY_SIZE = 40;

    private final TaskRepository taskRepository;
    private final SchedulerRepository schedulerRepository;
    private final DeadlineService deadlineService;
    private final TagService tagService;
    private final EventService eventService;


    public TaskService(TaskRepository taskRepository,
                       DeadlineService deadlineService, TagService tagService, SchedulerRepository schedulerRepository, EventService eventService) {
        this.taskRepository = taskRepository;
        this.deadlineService = deadlineService;
        this.tagService = tagService;
        this.eventService = eventService;
        this.schedulerRepository = schedulerRepository;
    }

    public List<Task> findAll() {
        return taskRepository.findAll(new Sort(Sort.Direction.DESC, "createDate"));
    }

    public List<TaskDto> findAllDto() {
        List<TaskDto> tasks = convert(findAll(), TaskDto::new);
        tasks.forEach(taskDto -> taskDto.setTitle(StringUtils.abbreviate(taskDto.getTitle(), MAX_DISPLAY_SIZE)));
        return tasks;
    }

    public TaskDto findOneDto(Integer id) {
        return new TaskDto(taskRepository.findOne(id));
    }

    public List<TaskDto> filter(TaskFilterDto filterDto) {
        if (filterDto.getOrder().compareTo("new") == 0) {
            return convert(taskRepository.filterNew(
                    filterDto.getStatus(),
                    filterDto.getTag() == null ? null : tagService.findById(filterDto.getTag())), TaskDto::new);
        } else {
            return convert(taskRepository.filterOld(
                    filterDto.getStatus(),
                    filterDto.getTag() == null ? null : tagService.findById(filterDto.getTag())), TaskDto::new);
        }
    }

    @Transactional
    public Integer create(TaskDto taskDto) throws IOException {
        Task newTask = copyFromDto(new Task(), taskDto);
        newTask = taskRepository.save(newTask);
        eventService.createFromTask(newTask);
        return newTask.getId();
    }

    private Task copyFromDto(Task task, TaskDto taskDto) throws IOException {
        task.setTitle(taskDto.getTitle());
        task.setDescription(taskDto.getDescription());
        task.setStatus(taskDto.getStatus() == null ? IN_WORK : taskDto.getStatus());
        task.setDeadlines(deadlineService.saveOrCreate(taskDto.getDeadlines()));
        task.setCreateDate(task.getCreateDate() == null ? new Date() : task.getCreateDate());
        task.setUpdateDate(new Date());
        task.getTags().clear();
        task.setTags(tagService.saveOrCreate(taskDto.getTags()));
        return task;
    }

    @Transactional
    public Integer update(TaskDto taskDto) throws IOException {
        Task task = taskRepository.findOne(taskDto.getId());
        taskRepository.save(copyFromDto(task, taskDto));
        eventService.updateTaskDeadlines(task);
        return task.getId();
    }

    @Transactional
    public boolean delete(Integer taskId) throws IOException {
        if (taskRepository.exists(taskId)) {
            Task scheduleTask = taskRepository.findOne(taskId);
            Scheduler sch = schedulerRepository.findOneByTask(scheduleTask);
            if (sch != null) {
                schedulerRepository.delete(sch.getId());
            }
            taskRepository.delete(taskId);
            return true;
        }
        return false;

    }

    public void save(TaskDto taskDto) throws IOException {
        if (isEmpty(taskDto.getId())) {
            create(taskDto);
        } else {
            update(taskDto);
        }
    }

    private void copyMainPart(Task newTask, Task task) {
        newTask.setTitle(task.getTitle());
        newTask.setTags(tagService.saveOrCreate(task.getTags()));
        newTask.setCreateDate(new Date());
        newTask.setStatus(Task.TaskStatus.LOADED_FROM_KIAS);
    }

    private Task copyTaskWithNewDates(Task task) {
        Task newTask = new Task();
        copyMainPart(newTask, task);
        Calendar cal1 = DateUtils.getCalendar(newTask.getCreateDate());
        Calendar cal2 = DateUtils.getCalendar(task.getCreateDate());
        Integer interval = cal1.get(Calendar.DAY_OF_YEAR) - cal2.get(Calendar.DAY_OF_YEAR);
        newTask.setDeadlines(newDatesDeadlines(task.getDeadlines(), interval));
        return newTask;
    }

    private List<Deadline> newDatesDeadlines(List<Deadline> deadlines, Integer interval) {
        return deadlines
                .stream()
                .map(deadline -> {
                    Deadline newDeadline = new Deadline();
                    Date newDate = DateUtils.addDays(deadline.getDate(), interval);
                    newDeadline.setDescription(deadline.getDescription());
                    newDeadline.setDate(newDate);
                    return deadlineService.create(newDeadline);
                }).collect(Collectors.toList());
    }

    private Task copyTaskWithNewYear(Task task) {
        Task newTask = new Task();
        copyMainPart(newTask, task);
        newTask.setDeadlines(newYearDeadlines(task.getDeadlines()));
        return newTask;
    }

    private List<Deadline> newYearDeadlines(List<Deadline> deadlines) {
        return deadlines
                .stream()
                .map(deadline -> {
                    Deadline newDeadline = new Deadline();
                    newDeadline.setDescription(deadline.getDescription());
                    newDeadline.setDate(DateUtils.addYears(deadline.getDate(), 1));
                    return deadlineService.create(newDeadline);
                }).collect(Collectors.toList());
    }

    private boolean equalsDate(Task task) {
        Calendar taskDate = DateUtils.getCalendar(task.getCreateDate());
        Calendar nowDate = DateUtils.getCalendar(new Date());
        return (taskDate.get(Calendar.DAY_OF_MONTH) == nowDate.get(Calendar.DAY_OF_MONTH) &&
                taskDate.get(Calendar.MONTH) + 1 == nowDate.get(Calendar.MONTH) + 1 &&
                taskDate.get(Calendar.YEAR) + 1 == nowDate.get(Calendar.YEAR));
    }

    @Transactional
    public List<Task> generateYearTasks() {
        Set<Tag> tags = checkRepeatingTags(false);
        List<Task> tasks = new ArrayList<>();
        tags.forEach(tag -> {
            Task singleTask = findTasksByTag(tag).get(0);
            if (equalsDate(singleTask)) {
                if (!tasks.contains(singleTask)) {
                    tasks.add(singleTask);
                }
            }
        });
        if (tasks != null) {
            tasks.forEach(task -> {
                Task newTask = copyTaskWithNewYear(task);
                taskRepository.save(newTask);
            });
            return tasks;
        }
        return null;
    }


    @Transactional
    public Set<Tag> checkRepeatingTags(Boolean createPeriodTask) { //param: false = year task; true = period task
        Map<Tag, Long> tagsCount = new TreeMap<>();
        List<Tag> tags = tagService.getTags();
        List<Task> tasks = taskRepository.findAllYear(DateUtils.clearTime(DateUtils.addYears(new Date(), -1)));
        tags.forEach(tag ->
                tagsCount.put(tag, tasks
                        .stream()
                        .filter(task -> task.getTags().contains(tag))
                        .count()));
        if (!createPeriodTask) {
            return tagsCount
                    .entrySet()
                    .stream()
                    .filter(tagLongEntry -> tagLongEntry.getValue() == 1)
                    .collect(Collectors.toMap(Map.Entry::getKey, Map.Entry::getValue))
                    .keySet();
        } else {
            return tagsCount
                    .entrySet()
                    .stream()
                    .filter(tagLongEntry -> tagLongEntry.getValue() >= 2)
                    .collect(Collectors.toMap(Map.Entry::getKey, Map.Entry::getValue))
                    .keySet();
        }

    }

    public List<Task.TaskStatus> getTaskStatuses() {
        return Arrays.asList(Task.TaskStatus.values());
    }

    public List<Tag> getTags() {
        return tagService.getTags();
    }

    public List<Task> findTasksByTag(Tag tag) {
        return taskRepository.findByTag(tag);
    }

    @Transactional
    public Task createPeriodTask(Scheduler scheduler) {
        Task newTask = copyTaskWithNewDates(scheduler.getTask());
        taskRepository.save(newTask);
        return newTask;
    }
}