import { defineStore } from 'pinia'
import { computed, ref } from 'vue'

export type AiRole = 'user' | 'assistant' | 'system'

export interface AiMessage {
  id: string
  role: AiRole
  content: string
  /** 是否仍在流式生成中，用于 UI 展示打字光标 */
  pending?: boolean
  /** 标记本条消息是否出错，UI 显示重试按钮 */
  error?: boolean
  /** 仅 assistant 消息使用：本轮回答结束后由大模型给出的追问建议 */
  recommendQuestions?: string[]
  createdAt: number
}

export const useAiStore = defineStore(
  'ai',
  () => {
    const messages = ref<AiMessage[]>([])
    /** 一组对话共用同一个 thread，跨多轮维持上下文 */
    const threadId = ref('')

    const messageCount = computed(() => messages.value.length)

    function ensureThreadId() {
      if (!threadId.value) {
        threadId.value = `thread_id_${Date.now()}${Math.floor(Math.random() * 10000)}`
      }
      return threadId.value
    }

    function addMessage(message: AiMessage) {
      messages.value.push(message)
    }

    function updateMessage(id: string, patch: Partial<AiMessage>) {
      const target = messages.value.find(m => m.id === id)
      if (!target) {
        return
      }
      Object.assign(target, patch)
    }

    function appendDelta(id: string, delta: string) {
      const target = messages.value.find(m => m.id === id)
      if (!target) {
        return
      }
      target.content += delta
    }

    function removeMessage(id: string) {
      messages.value = messages.value.filter(m => m.id !== id)
    }

    function clear() {
      messages.value = []
      threadId.value = ''
    }

    return {
      messages,
      threadId,
      messageCount,
      ensureThreadId,
      addMessage,
      updateMessage,
      appendDelta,
      removeMessage,
      clear,
    }
  },
  {
    persist: true,
  },
)