/**
 * ConversationService
 * 负责对话的管理
 * 
 * 职责：
 * - 对话的创建、读取、删除
 * - 对话与话题的关联
 * - 对话元数据管理
 */

import type { Conversation } from '../../types/chat'

export interface CreateConversationOptions {
  topicId: string
  model?: string
  temperature?: number
  maxTokens?: number
  systemPrompt?: string
}

export class ConversationService {
  private conversations: Map<string, Conversation>

  constructor(conversations: Map<string, Conversation>) {
    this.conversations = conversations
  }

  /**
   * 创建新对话
   */
  createConversation(options: CreateConversationOptions): Conversation {
    const conversation: Conversation = {
      id: this.generateId(),
      topicId: options.topicId,
      messages: [],
      createdAt: new Date(),
      updatedAt: new Date(),
      metadata: {
        model: options.model,
        temperature: options.temperature,
        maxTokens: options.maxTokens,
        systemPrompt: options.systemPrompt
      }
    }

    this.conversations.set(conversation.id, conversation)
    return conversation
  }

  /**
   * 获取对话
   */
  getConversation(conversationId: string): Conversation | undefined {
    return this.conversations.get(conversationId)
  }

  /**
   * 根据 topicId 获取对话
   */
  getConversationByTopicId(topicId: string): Conversation | undefined {
    for (const conv of this.conversations.values()) {
      if (conv.topicId === topicId) {
        return conv
      }
    }
    return undefined
  }

  /**
   * 获取所有对话
   */
  getAllConversations(): Conversation[] {
    return Array.from(this.conversations.values())
  }

  /**
   * 删除对话
   */
  deleteConversation(conversationId: string): boolean {
    return this.conversations.delete(conversationId)
  }

  /**
   * 删除话题对应的对话
   */
  deleteConversationByTopicId(topicId: string): boolean {
    for (const [id, conv] of this.conversations.entries()) {
      if (conv.topicId === topicId) {
        this.conversations.delete(id)
        return true
      }
    }
    return false
  }

  /**
   * 更新对话元数据
   */
  updateMetadata(
    conversationId: string,
    metadata: Partial<Conversation['metadata']>
  ): boolean {
    const conversation = this.conversations.get(conversationId)
    if (!conversation) return false

    conversation.metadata = {
      ...conversation.metadata,
      ...metadata
    }
    conversation.updatedAt = new Date()
    return true
  }

  /**
   * 清空对话消息
   */
  clearMessages(conversationId: string): boolean {
    const conversation = this.conversations.get(conversationId)
    if (!conversation) return false

    conversation.messages = []
    conversation.updatedAt = new Date()
    return true
  }

  /**
   * 获取对话消息数量
   */
  getMessageCount(conversationId: string): number {
    const conversation = this.conversations.get(conversationId)
    return conversation?.messages.length || 0
  }

  /**
   * 生成唯一 ID
   */
  private generateId(): string {
    return `${Date.now()}_${Math.random().toString(36).substr(2, 9)}`
  }
}