package entities

import (
	"time"

	"github.com/google/uuid"
	"gorm.io/gorm"
)

// AnnouncementStatus 公告状态枚举
type AnnouncementStatus string

const (
	AnnouncementStatusDraft     AnnouncementStatus = "draft"     // 草稿
	AnnouncementStatusPublished AnnouncementStatus = "published" // 已发布
	AnnouncementStatusArchived  AnnouncementStatus = "archived"  // 已归档
)

// Announcement 公告聚合根
// 用于对系统公告进行管理，支持发布、撤回、定时发布等功能
type Announcement struct {
	// 基础标识
	ID          string             `gorm:"primaryKey;type:varchar(36)" json:"id" comment:"公告唯一标识"`
	Title       string             `gorm:"type:varchar(200);not null;index" json:"title" comment:"公告标题"`
	Content     string             `gorm:"type:text;not null" json:"content" comment:"公告内容"`
	Status      AnnouncementStatus `gorm:"type:varchar(20);not null;default:'draft';index" json:"status" comment:"公告状态"`
	ScheduledAt *time.Time         `gorm:"index" json:"scheduled_at" comment:"定时发布时间"`
	CreatedAt   time.Time          `gorm:"autoCreateTime;index" json:"created_at" comment:"创建时间"`
	UpdatedAt   time.Time          `gorm:"autoUpdateTime" json:"updated_at" comment:"更新时间"`
	DeletedAt   gorm.DeletedAt     `gorm:"index" json:"-" comment:"软删除时间"`
}

// TableName 指定表名
func (Announcement) TableName() string {
	return "announcements"
}

// BeforeCreate GORM钩子：创建前自动生成UUID
func (a *Announcement) BeforeCreate(tx *gorm.DB) error {
	if a.ID == "" {
		a.ID = uuid.New().String()
	}
	return nil
}

// 实现 Entity 接口 - 提供统一的实体管理接口
// GetID 获取实体唯一标识
func (a *Announcement) GetID() string {
	return a.ID
}

// GetCreatedAt 获取创建时间
func (a *Announcement) GetCreatedAt() time.Time {
	return a.CreatedAt
}

// GetUpdatedAt 获取更新时间
func (a *Announcement) GetUpdatedAt() time.Time {
	return a.UpdatedAt
}

// 验证公告信息
func (a *Announcement) Validate() error {
	if a.Title == "" {
		return NewValidationError("公告标题不能为空")
	}
	if a.Content == "" {
		return NewValidationError("公告内容不能为空")
	}
	return nil
}

// 发布公告
func (a *Announcement) Publish() error {
	if a.Status == AnnouncementStatusPublished {
		return NewValidationError("公告已经是发布状态")
	}
	a.Status = AnnouncementStatusPublished
	now := time.Now()
	a.CreatedAt = now

	return nil
}

// 撤回公告
func (a *Announcement) Withdraw() error {
	if a.Status == AnnouncementStatusDraft {
		return NewValidationError("公告已经是草稿状态")
	}
	a.Status = AnnouncementStatusDraft
	now := time.Now()
	a.CreatedAt = now

	return nil
}

// 定时发布公告
func (a *Announcement) SchedulePublish(scheduledTime time.Time) error {
	if a.Status == AnnouncementStatusPublished {
		return NewValidationError("公告已经是发布状态")
	}
	a.Status = AnnouncementStatusDraft // 保持草稿状态，等待定时发布
	a.ScheduledAt = &scheduledTime

	return nil
}

// 更新定时发布时间
func (a *Announcement) UpdateSchedulePublish(scheduledTime time.Time) error {
	if a.Status == AnnouncementStatusPublished {
		return NewValidationError("公告已经是发布状态")
	}
	if scheduledTime.Before(time.Now()) {
		return NewValidationError("定时发布时间不能早于当前时间")
	}
	a.ScheduledAt = &scheduledTime
	return nil
}

// CancelSchedulePublish 取消定时发布
func (a *Announcement) CancelSchedulePublish() error {
	if a.Status == AnnouncementStatusPublished {
		return NewValidationError("公告已经是发布状态")
	}
	a.ScheduledAt = nil
	return nil
}

// IsScheduled 判断是否已设置定时发布
func (a *Announcement) IsScheduled() bool {
	return a.ScheduledAt != nil && a.Status == AnnouncementStatusDraft
}

// GetScheduledTime 获取定时发布时间
func (a *Announcement) GetScheduledTime() *time.Time {
	return a.ScheduledAt
}