package expiry

import (
	"time"

	"gorm.io/gorm"
)

const (
	// 物品分类
	CategoryFood     = "food"
	CategoryMedicine = "medicine"
	CategoryCosmetic = "cosmetic"
	CategoryOther    = "other"
)

const (
	// 物品状态
	StatusNormal    = "normal"
	StatusExpiring  = "expiring"
	StatusExpired   = "expired"
	StatusUsed      = "used"
	StatusDiscarded = "discarded"
)

var defaultRemindDays = []int{7, 3, 1}

// ExpiryItem 表示保质期物品数据模型。
type ExpiryItem struct {
	ID             uint           `json:"id" gorm:"primaryKey;comment:主键ID"`
	UserID         uint           `json:"user_id" gorm:"not null;index:idx_user_expiry,priority:1;index:idx_user_category,priority:1;index:idx_user_status,priority:1;comment:用户ID"`
	MiniProgramID  uint           `json:"mini_program_id" gorm:"not null;comment:小程序ID"`
	Name           string         `json:"name" gorm:"size:100;not null;comment:物品名称"`
	Category       string         `json:"category" gorm:"size:20;not null;index:idx_user_category,priority:2;comment:分类"`
	ProductionDate *time.Time     `json:"production_date" gorm:"type:date;comment:生产日期"`
	ExpiryDate     time.Time      `json:"expiry_date" gorm:"type:date;not null;index:idx_user_expiry,priority:2;comment:过期日期"`
	ShelfLifeDays  *int           `json:"shelf_life_days" gorm:"comment:保质期天数"`
	Quantity       int            `json:"quantity" gorm:"default:1;comment:数量"`
	Location       string         `json:"location" gorm:"size:50;comment:存放位置"`
	Remark         string         `json:"remark" gorm:"size:255;comment:备注"`
	Status         string         `json:"status" gorm:"size:20;default:'normal';index:idx_user_status,priority:2;comment:状态"`
	CreatedAt      time.Time      `json:"created_at" gorm:"comment:创建时间"`
	UpdatedAt      time.Time      `json:"updated_at" gorm:"comment:更新时间"`
	DeletedAt      gorm.DeletedAt `json:"-" gorm:"index:idx_deleted_at;comment:删除时间"`
}

func (ExpiryItem) TableName() string {
	return "expiry_items"
}

// CalculateDaysLeft 计算当前日期与过期日期之间的天数差。
func (item *ExpiryItem) CalculateDaysLeft() int {
	now := dateOnly(time.Now())
	expiry := dateOnly(item.ExpiryDate)
	return int(expiry.Sub(now).Hours() / 24)
}

// CalculateStatus 根据过期日期动态计算状态。
// 若已被业务标记为 used/discarded，则保留该状态。
func (item *ExpiryItem) CalculateStatus() string {
	if item.Status == StatusUsed || item.Status == StatusDiscarded {
		return item.Status
	}

	daysLeft := item.CalculateDaysLeft()
	if daysLeft < 0 {
		return StatusExpired
	}
	if daysLeft <= 7 {
		return StatusExpiring
	}
	return StatusNormal
}

// ExpiryUserSettings 表示用户提醒设置。
type ExpiryUserSettings struct {
	ID         uint      `json:"id" gorm:"primaryKey;comment:主键ID"`
	UserID     uint      `json:"user_id" gorm:"not null;uniqueIndex;comment:用户ID"`
	RemindDays []int     `json:"remind_days" gorm:"type:json;serializer:json;comment:提醒天数"`
	CreatedAt  time.Time `json:"created_at" gorm:"comment:创建时间"`
	UpdatedAt  time.Time `json:"updated_at" gorm:"comment:更新时间"`
}

func (ExpiryUserSettings) TableName() string {
	return "expiry_user_settings"
}

func dateOnly(t time.Time) time.Time {
	year, month, day := t.In(time.Local).Date()
	return time.Date(year, month, day, 0, 0, 0, 0, time.Local)
}