import { prisma } from '@/lib/prisma'
import type { MessageParam } from '@anthropic-ai/sdk/resources'

export interface ConversationData {
  id: string
  title: string | null
  messages: MessageParam[]
  createdAt: Date
  updatedAt: Date
}

export class ConversationService {
  /**
   * 创建新对话
   */
  static async createConversation(userId: string, initialMessage: string): Promise<string> {
    // 生成对话标题（取用户消息的前30个字符）
    const title = initialMessage.length > 30 
      ? initialMessage.substring(0, 30) + '...' 
      : initialMessage

    const systemMessage: MessageParam = {
      role: "user",
      content: `你是PC DIY商店的专业AI助手。你的主要职责是：
                
                1. 帮助用户查找和推荐PC配件
                2. 提供配件的价格、性能和兼容性信息
                3. 根据用户预算和需求推荐最适合的配件
                4. 解答关于PC装机的技术问题`
    }

    const assistantGreeting: MessageParam = {
      role: "assistant",
      content: "您好！我是PC DIY商店的AI助手，很高兴为您服务。请告诉我您需要什么帮助？"
    }

    const userMessage: MessageParam = {
      role: "user",
      content: initialMessage
    }

    const initialMessages = [systemMessage, assistantGreeting, userMessage]

    const conversation = await prisma.conversation.create({
      data: {
        userId,
        title,
        messages: JSON.stringify(initialMessages)
      }
    })

    return conversation.id
  }

  /**
   * 获取对话
   */
  static async getConversation(conversationId: string, userId: string): Promise<ConversationData | null> {
    const conversation = await prisma.conversation.findFirst({
      where: {
        id: conversationId,
        userId
      }
    })

    if (!conversation) {
      return null
    }

    return {
      id: conversation.id,
      title: conversation.title,
      messages: JSON.parse(conversation.messages) as MessageParam[],
      createdAt: conversation.createdAt,
      updatedAt: conversation.updatedAt
    }
  }

  /**
   * 更新对话消息
   */
  static async updateConversationMessages(
    conversationId: string, 
    userId: string, 
    messages: MessageParam[]
  ): Promise<void> {
    await prisma.conversation.updateMany({
      where: {
        id: conversationId,
        userId
      },
      data: {
        messages: JSON.stringify(messages),
        updatedAt: new Date()
      }
    })
  }

  /**
   * 获取用户的对话列表
   */
  static async getUserConversations(userId: string, page = 1, limit = 20) {
    const skip = (page - 1) * limit

    const [conversations, total] = await Promise.all([
      prisma.conversation.findMany({
        where: { userId },
        select: {
          id: true,
          title: true,
          createdAt: true,
          updatedAt: true
        },
        orderBy: { updatedAt: 'desc' },
        skip,
        take: limit
      }),
      prisma.conversation.count({
        where: { userId }
      })
    ])

    return {
      conversations,
      total,
      page,
      totalPages: Math.ceil(total / limit)
    }
  }

  /**
   * 删除对话
   */
  static async deleteConversation(conversationId: string, userId: string): Promise<boolean> {
    const result = await prisma.conversation.deleteMany({
      where: {
        id: conversationId,
        userId
      }
    })

    return result.count > 0
  }

  /**
   * 更新对话标题
   */
  static async updateConversationTitle(
    conversationId: string, 
    userId: string, 
    title: string
  ): Promise<boolean> {
    const result = await prisma.conversation.updateMany({
      where: {
        id: conversationId,
        userId
      },
      data: { title }
    })

    return result.count > 0
  }
}