package com.gym.service;

import com.gym.model.Course;
import com.gym.model.User;
import com.gym.repository.CourseRepository;
import com.gym.repository.UserRepository;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
import java.time.LocalDateTime;
import java.util.List;
import java.util.Optional;

@Service
public class CourseService {

    @Autowired
    private CourseRepository courseRepository;

    @Autowired
    private UserRepository userRepository;

    // 创建课程
    public Course createCourse(Course course, Long coachId) {
        // 验证教练是否存在
        User coach = userRepository.findById(coachId)
                .orElseThrow(() -> new RuntimeException("教练不存在"));

        // 验证教练角色
        if (!"COACH".equals(coach.getRole())) {
            throw new RuntimeException("该用户不是教练");
        }

        course.setCoach(coach);
        course.setCurrentParticipants(0);
        course.setIsAvailable(true);
        course.setStatus("UPCOMING");
        course.setCreateTime(LocalDateTime.now());

        return courseRepository.save(course);
    }

    // 获取所有课程
    public List<Course> getAllCourses() {
        return courseRepository.findAll();
    }

    // 获取可用课程
    public List<Course> getAvailableCourses() {
        return courseRepository.findAvailableCourses();
    }

    // 根据ID获取课程
    public Optional<Course> getCourseById(Long id) {
        return courseRepository.findById(id);
    }

    // 更新课程信息
    public Course updateCourse(Long id, Course updatedCourse) {
        return courseRepository.findById(id)
                .map(course -> {
                    if (updatedCourse.getName() != null) {
                        course.setName(updatedCourse.getName());
                    }
                    if (updatedCourse.getType() != null) {
                        course.setType(updatedCourse.getType());
                    }
                    if (updatedCourse.getStartTime() != null) {
                        course.setStartTime(updatedCourse.getStartTime());
                    }
                    if (updatedCourse.getEndTime() != null) {
                        course.setEndTime(updatedCourse.getEndTime());
                    }
                    if (updatedCourse.getDurationMinutes() != null) {
                        course.setDurationMinutes(updatedCourse.getDurationMinutes());
                    }
                    if (updatedCourse.getLocation() != null) {
                        course.setLocation(updatedCourse.getLocation());
                    }
                    if (updatedCourse.getMaxParticipants() != null) {
                        course.setMaxParticipants(updatedCourse.getMaxParticipants());
                    }
                    if (updatedCourse.getPrice() != null) {
                        course.setPrice(updatedCourse.getPrice());
                    }
                    if (updatedCourse.getDescription() != null) {
                        course.setDescription(updatedCourse.getDescription());
                    }
                    if (updatedCourse.getIsAvailable() != null) {
                        course.setIsAvailable(updatedCourse.getIsAvailable());
                    }
                    return courseRepository.save(course);
                })
                .orElseThrow(() -> new RuntimeException("课程不存在"));
    }

    // 删除课程
    public void deleteCourse(Long id) {
        courseRepository.deleteById(id);
    }

    // 预约课程（增加参与人数）
    public Course enrollCourse(Long courseId) {
        return courseRepository.findById(courseId)
                .map(course -> {
                    if (!course.getIsAvailable()) {
                        throw new RuntimeException("该课程不可预约");
                    }
                    if (course.getCurrentParticipants() >= course.getMaxParticipants()) {
                        throw new RuntimeException("课程已满");
                    }
                    if ("COMPLETED".equals(course.getStatus()) || "CANCELLED".equals(course.getStatus())) {
                        throw new RuntimeException("该课程已结束或取消");
                    }

                    course.setCurrentParticipants(course.getCurrentParticipants() + 1);
                    return courseRepository.save(course);
                })
                .orElseThrow(() -> new RuntimeException("课程不存在"));
    }

    // 取消预约（减少参与人数）
    public Course cancelEnrollment(Long courseId) {
        return courseRepository.findById(courseId)
                .map(course -> {
                    if (course.getCurrentParticipants() <= 0) {
                        throw new RuntimeException("没有可取消的预约");
                    }

                    course.setCurrentParticipants(course.getCurrentParticipants() - 1);
                    return courseRepository.save(course);
                })
                .orElseThrow(() -> new RuntimeException("课程不存在"));
    }

    // 设置课程状态
    public Course setCourseStatus(Long id, String status) {
        return courseRepository.findById(id)
                .map(course -> {
                    course.setStatus(status);
                    return courseRepository.save(course);
                })
                .orElseThrow(() -> new RuntimeException("课程不存在"));
    }

    // 搜索课程
    public List<Course> searchCourses(String keyword) {
        return courseRepository.findByNameContaining(keyword);
    }

    // 获取教练的课程
    public List<Course> getCoachCourses(Long coachId) {
        return courseRepository.findByCoachId(coachId);
    }

    // 获取按类型分类的课程
    public List<Course> getCoursesByType(String type) {
        return courseRepository.findByType(type);
    }
}