package service

import (
	"errors"
	"photowall/internal/model"

	"gorm.io/gorm"
)

type SchoolService struct {
	db *gorm.DB
}

func NewSchoolService(db *gorm.DB) *SchoolService {
	return &SchoolService{db: db}
}

type SchoolQuery struct {
	RegionID   uint             `form:"region_id"`
	SchoolType model.SchoolType `form:"school_type"`
	Keyword    string           `form:"keyword"`
	Page       int              `form:"page"`
	PageSize   int              `form:"page_size"`
}

// PageResp 通用分页响应
type PageResp struct {
	List  interface{} `json:"list"`
	Total int64       `json:"total"`
	Page  int         `json:"page"`
}

type SchoolListResp = PageResp // 别名兼容

func (s *SchoolService) List(q *SchoolQuery) (*SchoolListResp, error) {
	if q.Page <= 0 {
		q.Page = 1
	}
	if q.PageSize <= 0 || q.PageSize > 100 {
		q.PageSize = 20
	}
	db := s.db.Model(&model.School{})
	if q.RegionID > 0 {
		db = db.Where("region_id = ?", q.RegionID)
	}
	if q.SchoolType != "" {
		db = db.Where("school_type = ?", q.SchoolType)
	}
	if q.Keyword != "" {
		db = db.Where("name LIKE ? OR name_en LIKE ?", "%"+q.Keyword+"%", "%"+q.Keyword+"%")
	}
	var total int64
	db.Count(&total)
	var list []model.School
	err := db.Order("id desc").Offset((q.Page - 1) * q.PageSize).Limit(q.PageSize).Find(&list).Error
	if err != nil {
		return nil, err
	}
	return &SchoolListResp{List: list, Total: total, Page: q.Page}, nil
}

// Create 创建学校（必须挂在 county 级地区下）
func (s *SchoolService) Create(school *model.School) error {
	// 校验 region 必须是 county 级
	var region model.Region
	if err := s.db.First(&region, school.RegionID).Error; err != nil {
		return errors.New("所属地区不存在")
	}
	if region.Level != model.LevelCounty {
		return errors.New("学校必须挂载在区/县级地区下")
	}
	if school.Name == "" {
		return errors.New("学校名称不能为空")
	}
	if school.SchoolType == "" {
		return errors.New("请选择学校类型")
	}
	return s.db.Create(school).Error
}

func (s *SchoolService) GetByID(id uint) (*model.School, error) {
	var school model.School
	if err := s.db.First(&school, id).Error; err != nil {
		return nil, errors.New("学校不存在")
	}
	return &school, nil
}

func (s *SchoolService) Update(id uint, updates map[string]interface{}) error {
	res := s.db.Model(&model.School{}).Where("id = ?", id).Updates(updates)
	if res.Error != nil {
		return res.Error
	}
	if res.RowsAffected == 0 {
		return errors.New("学校不存在")
	}
	return nil
}

func (s *SchoolService) Delete(id uint) error {
	// 检查是否有班级引用
	var count int64
	s.db.Model(&model.Class{}).Where("school_id = ?", id).Count(&count)
	if count > 0 {
		return errors.New("该学校下已有班级，无法删除")
	}
	return s.db.Delete(&model.School{}, id).Error
}

// ---- 学院 ----

func (s *SchoolService) ListColleges(schoolID uint) ([]model.College, error) {
	var list []model.College
	err := s.db.Where("school_id = ?", schoolID).Order("name").Find(&list).Error
	return list, err
}

func (s *SchoolService) CreateCollege(schoolID uint, name string) (*model.College, error) {
	if name == "" {
		return nil, errors.New("学院名称不能为空")
	}
	// 校验学校是否支持学院
	var school model.School
	if err := s.db.First(&school, schoolID).Error; err != nil {
		return nil, errors.New("学校不存在")
	}
	if !school.SchoolType.HasCollege() {
		return nil, errors.New("该学校类型不支持学院层级")
	}
	c := &model.College{SchoolID: schoolID, Name: name}
	if err := s.db.Create(c).Error; err != nil {
		return nil, err
	}
	return c, nil
}

func (s *SchoolService) UpdateCollege(id uint, name string) error {
	res := s.db.Model(&model.College{}).Where("id = ?", id).Update("name", name)
	if res.Error != nil {
		return res.Error
	}
	if res.RowsAffected == 0 {
		return errors.New("学院不存在")
	}
	return nil
}

func (s *SchoolService) DeleteCollege(id uint) error {
	var count int64
	s.db.Model(&model.Class{}).Where("college_id = ?", id).Count(&count)
	if count > 0 {
		return errors.New("该学院下已有班级，无法删除")
	}
	return s.db.Delete(&model.College{}, id).Error
}