package service

import (
	"errors"

	"git.huangwc.com/pig/pig-farm-controller/internal/infra/logs"
	"git.huangwc.com/pig/pig-farm-controller/internal/infra/models"
	"git.huangwc.com/pig/pig-farm-controller/internal/infra/repository"

	"gorm.io/gorm"
)

var (
	ErrHouseContainsPens = errors.New("无法删除包含猪栏的猪舍")
	ErrHouseNotFound     = errors.New("指定的猪舍不存在")
	ErrPenInUse          = errors.New("猪栏正在被活跃批次使用，无法删除")
)

// PigFarmService 提供了猪场资产管理的业务逻辑
type PigFarmService interface {
	// PigHouse methods
	CreatePigHouse(name, description string) (*models.PigHouse, error)
	GetPigHouseByID(id uint) (*models.PigHouse, error)
	ListPigHouses() ([]models.PigHouse, error)
	UpdatePigHouse(id uint, name, description string) (*models.PigHouse, error)
	DeletePigHouse(id uint) error

	// Pen methods
	CreatePen(penNumber string, houseID uint, capacity int) (*models.Pen, error)
	GetPenByID(id uint) (*models.Pen, error)
	ListPens() ([]models.Pen, error)
	UpdatePen(id uint, penNumber string, houseID uint, capacity int, status models.PenStatus) (*models.Pen, error)
	DeletePen(id uint) error
}

type pigFarmService struct {
	logger *logs.Logger
	repo   repository.PigFarmRepository
}

// NewPigFarmService 创建一个新的 PigFarmService 实例
func NewPigFarmService(repo repository.PigFarmRepository, logger *logs.Logger) PigFarmService {
	return &pigFarmService{
		logger: logger,
		repo:   repo,
	}
}

// --- PigHouse Implementation ---

func (s *pigFarmService) CreatePigHouse(name, description string) (*models.PigHouse, error) {
	house := &models.PigHouse{
		Name:        name,
		Description: description,
	}
	err := s.repo.CreatePigHouse(house)
	return house, err
}

func (s *pigFarmService) GetPigHouseByID(id uint) (*models.PigHouse, error) {
	return s.repo.GetPigHouseByID(id)
}

func (s *pigFarmService) ListPigHouses() ([]models.PigHouse, error) {
	return s.repo.ListPigHouses()
}

func (s *pigFarmService) UpdatePigHouse(id uint, name, description string) (*models.PigHouse, error) {
	house := &models.PigHouse{
		Model:       gorm.Model{ID: id},
		Name:        name,
		Description: description,
	}
	err := s.repo.UpdatePigHouse(house)
	if err != nil {
		return nil, err
	}
	// 返回更新后的完整信息
	return s.repo.GetPigHouseByID(id)
}

func (s *pigFarmService) DeletePigHouse(id uint) error {
	// 业务逻辑：检查猪舍是否包含猪栏
	penCount, err := s.repo.CountPensInHouse(id)
	if err != nil {
		return err
	}
	if penCount > 0 {
		return ErrHouseContainsPens
	}

	// 调用仓库层进行删除
	err = s.repo.DeletePigHouse(id)
	if errors.Is(err, gorm.ErrRecordNotFound) {
		return ErrHouseNotFound // 或者直接返回 gorm.ErrRecordNotFound，取决于业务需求
	}
	return err
}

// --- Pen Implementation ---

func (s *pigFarmService) CreatePen(penNumber string, houseID uint, capacity int) (*models.Pen, error) {
	// 业务逻辑：验证所属猪舍是否存在
	_, err := s.repo.GetPigHouseByID(houseID)
	if err != nil {
		if errors.Is(err, gorm.ErrRecordNotFound) {
			return nil, ErrHouseNotFound
		}
		return nil, err
	}

	pen := &models.Pen{
		PenNumber: penNumber,
		HouseID:   houseID,
		Capacity:  capacity,
		Status:    models.PenStatusEmpty,
	}
	err = s.repo.CreatePen(pen)
	return pen, err
}

func (s *pigFarmService) GetPenByID(id uint) (*models.Pen, error) {
	return s.repo.GetPenByID(id)
}

func (s *pigFarmService) ListPens() ([]models.Pen, error) {
	return s.repo.ListPens()
}

func (s *pigFarmService) UpdatePen(id uint, penNumber string, houseID uint, capacity int, status models.PenStatus) (*models.Pen, error) {
	// 业务逻辑：验证所属猪舍是否存在
	_, err := s.repo.GetPigHouseByID(houseID)
	if err != nil {
		if errors.Is(err, gorm.ErrRecordNotFound) {
			return nil, ErrHouseNotFound
		}
		return nil, err
	}

	pen := &models.Pen{
		Model:     gorm.Model{ID: id},
		PenNumber: penNumber,
		HouseID:   houseID,
		Capacity:  capacity,
		Status:    status,
	}
	err = s.repo.UpdatePen(pen)
	if err != nil {
		return nil, err
	}
	// 返回更新后的完整信息
	return s.repo.GetPenByID(id)
}

func (s *pigFarmService) DeletePen(id uint) error {
	// 业务逻辑：检查猪栏是否被活跃批次使用
	pen, err := s.repo.GetPenByID(id)
	if err != nil {
		if errors.Is(err, gorm.ErrRecordNotFound) {
			return gorm.ErrRecordNotFound // 猪栏不存在
		}
		return err
	}

	// 检查猪栏是否关联了活跃批次
	if *pen.PigBatchID != 0 {
		pigBatch, err := s.repo.GetPigBatchByID(*pen.PigBatchID)
		if err != nil && !errors.Is(err, gorm.ErrRecordNotFound) {
			return err
		}
		// 如果批次活跃，则不能删除猪栏
		if pigBatch.IsActive() {
			return ErrPenInUse
		}
	}

	// 调用仓库层进行删除
	err = s.repo.DeletePen(id)
	if errors.Is(err, gorm.ErrRecordNotFound) {
		return gorm.ErrRecordNotFound // 猪栏不存在
	}
	return err
}