package com.learn.service.mp;

import com.baomidou.mybatisplus.core.conditions.query.LambdaQueryWrapper;
import com.baomidou.mybatisplus.core.metadata.IPage;
import com.baomidou.mybatisplus.extension.plugins.pagination.Page;
import com.learn.entity.Student;
import com.learn.repository.mp.StudentMapper;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;

import java.util.List;
import java.util.Optional;

@Service
public class StudentMpService {

    private final StudentMapper mapper;

    public StudentMpService(StudentMapper mapper) { this.mapper = mapper; }

    @Transactional
    public Student add(Student s) { mapper.insert(s); return s; }

    @Transactional(readOnly = true)
    public List<Student> list() {
        LambdaQueryWrapper<Student> w = new LambdaQueryWrapper<>();
        w.orderByDesc(Student::getScore);
        return mapper.selectList(w);
    }

    @Transactional(readOnly = true)
    public Optional<Student> getById(Long id) {
        return Optional.ofNullable(mapper.selectById(id));
    }

    @Transactional(readOnly = true)
    public List<Student> search(String keyword) {
        LambdaQueryWrapper<Student> w = new LambdaQueryWrapper<>();
        w.like(Student::getName, keyword).or().like(Student::getEmail, keyword);
        w.orderByDesc(Student::getScore);
        return mapper.selectList(w);
    }

    @Transactional
    public Optional<Student> update(Long id, Student updated) {
        Student existing = mapper.selectById(id);
        if (existing == null) return Optional.empty();
        if (updated.getName() != null) existing.setName(updated.getName());
        if (updated.getAge() > 0) existing.setAge(updated.getAge());
        if (updated.getEmail() != null) existing.setEmail(updated.getEmail());
        if (updated.getScore() >= 0) existing.setScore(updated.getScore());
        mapper.updateById(existing);
        return Optional.of(existing);
    }

    @Transactional
    public boolean delete(Long id) { return mapper.deleteById(id) > 0; }

    @Transactional(readOnly = true)
    public IPage<Student> page(int pageNum, int pageSize, String keyword) {
        Page<Student> page = new Page<>(pageNum, pageSize);
        LambdaQueryWrapper<Student> w = new LambdaQueryWrapper<>();
        if (keyword != null && !keyword.trim().isEmpty()) {
            w.like(Student::getName, keyword).or().like(Student::getEmail, keyword);
        }
        w.orderByDesc(Student::getScore);
        return mapper.selectPage(page, w);
    }

    @Transactional(readOnly = true)
    public long count() { return mapper.selectCount(null); }

    @Transactional(readOnly = true)
    public long countExcellent(int minScore) {
        LambdaQueryWrapper<Student> w = new LambdaQueryWrapper<>();
        w.ge(Student::getScore, minScore);
        return mapper.selectCount(w);
    }

    @Transactional
    public Student updateAvatar(Long id, String filename) {
        Student s = mapper.selectById(id);
        if (s == null) throw new RuntimeException("学生不存在");
        s.setAvatar(filename);
        mapper.updateById(s);
        return s;
    }
}