package service

import (
	"errors"
	"log"
	"sort"
	"strconv"
	"strings"

	"github.com/sundynix/pets-be/internal/model"
)

// BreedGroup 同一首字母下的品种。小程序端的 A-Z 索引直接照这个渲染
type BreedGroup struct {
	Initial string        `json:"initial"`
	Items   []model.Breed `json:"items"`
}

// ListBreeds 某个物种的品种，按首字母分组。只返回启用的
func (s *Service) ListBreeds(species string) []BreedGroup {
	if species != model.SpeciesCat && species != model.SpeciesDog {
		return []BreedGroup{}
	}
	var all []model.Breed
	s.db.Where("species = ? AND enabled = ?", species, true).
		Order("initial asc, sort asc, id asc").Find(&all)
	if len(all) == 0 {
		// 不硬编码兜底一份：那等于把「后台可配」又变回代码常量，
		// 改了配置的人会发现改了没用。宁可让选择器明显是空的
		log.Printf("[warn] %s 没有任何启用的品种，建档第二步会选不了品种", species)
		return []BreedGroup{}
	}
	byInitial := map[string][]model.Breed{}
	for _, b := range all {
		k := strings.ToUpper(b.Initial)
		if k == "" {
			k = "#" // 没填首字母的兜到最后，别让它凭空消失
		}
		byInitial[k] = append(byInitial[k], b)
	}
	keys := make([]string, 0, len(byInitial))
	for k := range byInitial {
		keys = append(keys, k)
	}
	sort.Strings(keys)
	out := make([]BreedGroup, 0, len(keys))
	for _, k := range keys {
		out = append(out, BreedGroup{Initial: k, Items: byInitial[k]})
	}
	return out
}

// AdminListBreeds 后台用：连停用的一起返回
func (s *Service) AdminListBreeds(species string) []model.Breed {
	q := s.db.Order("species asc, initial asc, sort asc, id asc")
	if species == model.SpeciesCat || species == model.SpeciesDog {
		q = q.Where("species = ?", species)
	}
	var all []model.Breed
	q.Find(&all)
	if all == nil {
		return []model.Breed{}
	}
	return all
}

// SaveBreed 新增或更新
func (s *Service) SaveBreed(in *model.Breed) error {
	in.Name = strings.TrimSpace(in.Name)
	in.Initial = strings.ToUpper(strings.TrimSpace(in.Initial))
	if in.Name == "" {
		return ErrInvalidParam
	}
	if in.Species != model.SpeciesCat && in.Species != model.SpeciesDog {
		return errors.New("物种只能是 cat 或 dog")
	}
	if len(in.Initial) != 1 || in.Initial[0] < 'A' || in.Initial[0] > 'Z' {
		return errors.New("首字母要填一个 A-Z 的字母（用来做侧边索引）")
	}
	// 同物种下不允许同名：品种是拿来做统计口径的，重名会把同一种猫劈成两半
	var n int64
	q := s.db.Model(&model.Breed{}).Where("species = ? AND name = ?", in.Species, in.Name)
	if in.ID != "" {
		q = q.Where("id <> ?", in.ID)
	}
	q.Count(&n)
	if n > 0 {
		return errors.New("这个物种下已经有「" + in.Name + "」了")
	}

	if in.ID == "" {
		return s.db.Create(in).Error
	}
	return s.db.Model(&model.Breed{}).Where("id = ?", in.ID).Updates(map[string]any{
		"species": in.Species, "name": in.Name, "initial": in.Initial,
		"sort": in.Sort, "enabled": in.Enabled,
	}).Error
}

// DeleteBreed 已经有宠物在用的品种不许删——删了那些档案的品种就变成一个
// 查不到的字符串。想让它不再被选到应该用 enabled=false
func (s *Service) DeleteBreed(id string) error {
	var b model.Breed
	if err := s.db.First(&b, "id = ?", id).Error; err != nil {
		return ErrNotFound
	}
	var used int64
	s.db.Model(&model.Pet{}).Where("breed = ?", b.Name).Count(&used)
	if used > 0 {
		return errors.New("已经有 " + strconv.FormatInt(used, 10) + " 个档案填了「" +
			b.Name + "」，删了它们的品种就查不到了。想隐藏请改成停用")
	}
	return s.db.Delete(&model.Breed{}, "id = ?", id).Error
}