package repository

import (
	"context"
	"strconv"

	"carrot_bbs/internal/model"
	"carrot_bbs/internal/pkg/cursor"

	"gorm.io/gorm"
)

// SystemNotificationRepository 系统通知仓储接口
type SystemNotificationRepository interface {
	Create(notification *model.SystemNotification) error
	GetByID(id int64) (*model.SystemNotification, error)
	GetByReceiverID(receiverID string, page, pageSize int) ([]*model.SystemNotification, int64, error)
	GetUnreadByReceiverID(receiverID string, limit int) ([]*model.SystemNotification, error)
	GetUnreadCount(receiverID string) (int64, error)
	MarkAsRead(id int64, receiverID string) error
	MarkAllAsRead(receiverID string) error
	Delete(id int64, receiverID string) error
	GetByType(receiverID string, notifyType model.SystemNotificationType, page, pageSize int) ([]*model.SystemNotification, int64, error)
	GetByReceiverIDCursor(ctx context.Context, receiverID string, req *cursor.PageRequest) (*cursor.CursorPageResult[*model.SystemNotification], error)
	GetByReceiverIDCursorLegacy(receiverID string, cursorStr string, pageSize int) ([]*model.SystemNotification, string, bool, error)
}

// systemNotificationRepository 系统通知仓储实现
type systemNotificationRepository struct {
	db *gorm.DB
}

// NewSystemNotificationRepository 创建系统通知仓储
func NewSystemNotificationRepository(db *gorm.DB) SystemNotificationRepository {
	return &systemNotificationRepository{db: db}
}

// Create 创建系统通知
func (r *systemNotificationRepository) Create(notification *model.SystemNotification) error {
	return r.db.Create(notification).Error
}

// GetByID 根据ID获取通知
func (r *systemNotificationRepository) GetByID(id int64) (*model.SystemNotification, error) {
	var notification model.SystemNotification
	err := r.db.First(&notification, "id = ?", id).Error
	if err != nil {
		return nil, err
	}
	return &notification, nil
}

// GetByReceiverID 获取用户的通知列表
func (r *systemNotificationRepository) GetByReceiverID(receiverID string, page, pageSize int) ([]*model.SystemNotification, int64, error) {
	var notifications []*model.SystemNotification
	var total int64

	query := r.db.Model(&model.SystemNotification{}).Where("receiver_id = ?", receiverID)
	query.Count(&total)

	offset := (page - 1) * pageSize
	err := query.Offset(offset).
		Limit(pageSize).
		Order("created_at DESC").
		Find(&notifications).Error

	return notifications, total, err
}

// GetUnreadByReceiverID 获取用户的未读通知列表
func (r *systemNotificationRepository) GetUnreadByReceiverID(receiverID string, limit int) ([]*model.SystemNotification, error) {
	var notifications []*model.SystemNotification
	err := r.db.Where("receiver_id = ? AND is_read = ?", receiverID, false).
		Order("created_at DESC").
		Limit(limit).
		Find(&notifications).Error
	return notifications, err
}

// GetUnreadCount 获取用户未读通知数量
func (r *systemNotificationRepository) GetUnreadCount(receiverID string) (int64, error) {
	var count int64
	err := r.db.Model(&model.SystemNotification{}).
		Where("receiver_id = ? AND is_read = ?", receiverID, false).
		Count(&count).Error
	return count, err
}

// MarkAsRead 标记单条通知为已读
func (r *systemNotificationRepository) MarkAsRead(id int64, receiverID string) error {
	now := model.SystemNotification{}.UpdatedAt
	return r.db.Model(&model.SystemNotification{}).
		Where("id = ? AND receiver_id = ?", id, receiverID).
		Updates(map[string]any{
			"is_read": true,
			"read_at": now,
		}).Error
}

// MarkAllAsRead 标记用户所有通知为已读
func (r *systemNotificationRepository) MarkAllAsRead(receiverID string) error {
	now := model.SystemNotification{}.UpdatedAt
	return r.db.Model(&model.SystemNotification{}).
		Where("receiver_id = ? AND is_read = ?", receiverID, false).
		Updates(map[string]any{
			"is_read": true,
			"read_at": now,
		}).Error
}

// Delete 删除通知（软删除）
func (r *systemNotificationRepository) Delete(id int64, receiverID string) error {
	return r.db.Where("id = ? AND receiver_id = ?", id, receiverID).
		Delete(&model.SystemNotification{}).Error
}

// GetByType 获取用户指定类型的通知
func (r *systemNotificationRepository) GetByType(receiverID string, notifyType model.SystemNotificationType, page, pageSize int) ([]*model.SystemNotification, int64, error) {
	var notifications []*model.SystemNotification
	var total int64

	query := r.db.Model(&model.SystemNotification{}).
		Where("receiver_id = ? AND type = ?", receiverID, notifyType)
	query.Count(&total)

	offset := (page - 1) * pageSize
	err := query.Offset(offset).
		Limit(pageSize).
		Order("created_at DESC").
		Find(&notifications).Error

	return notifications, total, err
}

// GetByReceiverIDCursor 游标分页获取用户的通知列表
// 使用统一的 cursor 包进行游标分页
func (r *systemNotificationRepository) GetByReceiverIDCursor(ctx context.Context, receiverID string, req *cursor.PageRequest) (*cursor.CursorPageResult[*model.SystemNotification], error) {
	// 构建基础查询
	query := r.db.WithContext(ctx).Model(&model.SystemNotification{}).Where("receiver_id = ?", receiverID)

	// 使用 CursorBuilder 构建游标查询
	builder := cursor.NewBuilder(query, cursor.SortByCreatedAtDesc).
		WithCursor(req.Cursor, cursor.Direction(req.Direction)).
		WithPageSize(req.PageSize)

	if builder.Error() != nil {
		return nil, builder.Error()
	}

	// 执行查询
	var notifications []*model.SystemNotification
	if err := builder.Build().Find(&notifications).Error; err != nil {
		return nil, err
	}

	// 构建响应
	pageSize := builder.GetPageSize()
	hasMore := cursor.HasMore(len(notifications), pageSize)
	if hasMore {
		notifications = notifications[:pageSize]
	}

	// 生成下一页游标
	var nextCursor string
	if hasMore && len(notifications) > 0 {
		lastNotification := notifications[len(notifications)-1]
		nextCursor = cursor.NewCursor(
			cursor.FormatTime(lastNotification.CreatedAt),
			strconv.FormatInt(lastNotification.ID, 10),
			cursor.SortByCreatedAtDesc,
		).Encode()
	}

	return &cursor.CursorPageResult[*model.SystemNotification]{
		Items:      notifications,
		NextCursor: nextCursor,
		HasMore:    hasMore,
	}, nil
}

// GetByReceiverIDCursorLegacy 游标分页获取用户的通知列表（旧版兼容接口）
// 已废弃：请使用 GetByReceiverIDCursor
func (r *systemNotificationRepository) GetByReceiverIDCursorLegacy(receiverID string, cursorStr string, pageSize int) ([]*model.SystemNotification, string, bool, error) {
	// 构建基础查询
	query := r.db.Model(&model.SystemNotification{}).Where("receiver_id = ?", receiverID)

	// 如果有游标，解析游标并添加条件
	if cursorStr != "" {
		decodedCursor, err := cursor.DecodeCursor(cursorStr)
		if err != nil {
			// 游标格式无效，返回空结果
			return []*model.SystemNotification{}, "", false, nil
		}
		// 使用元组比较进行分页
		condition := "(created_at, id) < (?, ?)"
		query = query.Where(condition, decodedCursor.SortValue, decodedCursor.ID)
	}

	// 多取一条用于判断是否还有下一页
	var notifications []*model.SystemNotification
	err := query.Order("created_at DESC, id DESC").
		Limit(pageSize + 1).
		Find(&notifications).Error

	if err != nil {
		return nil, "", false, err
	}

	hasMore := len(notifications) > pageSize
	if hasMore {
		notifications = notifications[:pageSize]
	}

	// 生成下一页游标
	var nextCursor string
	if hasMore && len(notifications) > 0 {
		lastNotification := notifications[len(notifications)-1]
		nextCursor = cursor.NewCursor(
			cursor.FormatTime(lastNotification.CreatedAt),
			strconv.FormatInt(lastNotification.ID, 10),
			cursor.SortByCreatedAtDesc,
		).Encode()
	}

	return notifications, nextCursor, hasMore, nil
}