package repository

import (
	"errors"
	"time"

	"github.com/2930134478/AI-CS/backend/models"
	"gorm.io/gorm"
)

// MessageRepository 封装与消息相关的数据库操作。
type MessageRepository struct {
	db *gorm.DB
}

// NewMessageRepository 创建消息仓库实例。
func NewMessageRepository(db *gorm.DB) *MessageRepository {
	return &MessageRepository{db: db}
}

// Create 新建一条消息记录。
func (r *MessageRepository) Create(message *models.Message) error {
	return r.db.Create(message).Error
}

// ListByConversationID 按时间顺序查询会话中的全部消息。
func (r *MessageRepository) ListByConversationID(conversationID uint) ([]models.Message, error) {
	var messages []models.Message
	if err := r.db.Where("conversation_id = ?", conversationID).Order("created_at asc").Find(&messages).Error; err != nil {
		return nil, err
	}
	return messages, nil
}

// LatestByConversationID 查询会话中最新的一条消息。
func (r *MessageRepository) LatestByConversationID(conversationID uint) (*models.Message, error) {
	var message models.Message
	if err := r.db.Where("conversation_id = ?", conversationID).
		Order("created_at desc").
		First(&message).Error; err != nil {
		if errors.Is(err, gorm.ErrRecordNotFound) {
			return nil, nil
		}
		return nil, err
	}
	return &message, nil
}

// CountUnreadBySender 统计指定发送方的未读消息数量。
func (r *MessageRepository) CountUnreadBySender(conversationID uint, senderIsAgent bool) (int64, error) {
	var count int64
	if err := r.db.Model(&models.Message{}).
		Where("conversation_id = ? AND sender_is_agent = ? AND is_read = ?", conversationID, senderIsAgent, false).
		Count(&count).Error; err != nil {
		return 0, err
	}
	return count, nil
}

// FindConversationIDsByContent 根据关键字查询包含该内容的会话 ID。
func (r *MessageRepository) FindConversationIDsByContent(keyword string) ([]uint, error) {
	var ids []uint
	if err := r.db.Model(&models.Message{}).
		Where("content LIKE ?", keyword).
		Pluck("conversation_id", &ids).Error; err != nil {
		return nil, err
	}
	return ids, nil
}

// MarkMessagesRead 将指定发送方的未读消息标记为已读，并返回受影响的消息 ID 及时间。
func (r *MessageRepository) MarkMessagesRead(conversationID uint, senderIsAgent bool) ([]uint, int64, time.Time, error) {
	var messageIDs []uint
	if err := r.db.Model(&models.Message{}).
		Where("conversation_id = ? AND sender_is_agent = ? AND is_read = ?", conversationID, senderIsAgent, false).
		Pluck("id", &messageIDs).Error; err != nil {
		return nil, 0, time.Time{}, err
	}
	if len(messageIDs) == 0 {
		return []uint{}, 0, time.Time{}, nil
	}
	now := time.Now()
	if err := r.db.Model(&models.Message{}).
		Where("id IN ?", messageIDs).
		Updates(map[string]interface{}{
			"is_read": true,
			"read_at": now,
		}).Error; err != nil {
		return nil, 0, time.Time{}, err
	}
	remaining, err := r.CountUnreadBySender(conversationID, senderIsAgent)
	if err != nil {
		return nil, 0, time.Time{}, err
	}
	return messageIDs, remaining, now, nil
}