import { defineStore } from 'pinia'
import { useNotesStore } from './notes'
import { ref, computed } from 'vue'
import { fetchSessions, fetchMessages, deleteSession, exportSession, importSession, streamChat, type SessionInfo, type Source, type ImportPayload } from '../api/client'

export interface Message {
  role: 'user' | 'assistant'
  content: string
  pending?: boolean
  error?: boolean
  archived?: boolean
  tags?: string[]
  sources?: Source[]
}

export interface Toast {
  id: number
  message: string
}

let toastSeq = 0

export const useChatStore = defineStore('chat', () => {
  const sessions = ref<SessionInfo[]>([])
  const currentSessionId = ref<string | null>(null)
  const messages = ref<Message[]>([])
  const isStreaming = ref(false)
  const selectedModel = ref('bedrock/jp.anthropic.claude-sonnet-4-6')
  const toasts = ref<Toast[]>([])

  const currentSession = computed(() =>
    sessions.value.find((s) => s.id === currentSessionId.value) ?? null,
  )

  function pushToast(message: string, durationMs = 5000) {
    const id = ++toastSeq
    toasts.value.push({ id, message })
    setTimeout(() => {
      toasts.value = toasts.value.filter((t) => t.id !== id)
    }, durationMs)
  }

  function dismissToast(id: number) {
    toasts.value = toasts.value.filter((t) => t.id !== id)
  }

  async function loadSessions() {
    sessions.value = await fetchSessions()
  }

  async function selectSession(sessionId: string | null) {
    currentSessionId.value = sessionId
    messages.value = []
    if (!sessionId) return
    try {
      const records = await fetchMessages(sessionId)
      messages.value = records
        .filter((r) => r.role === 'user' || r.role === 'assistant')
        .map((r) => ({
          role: r.role as 'user' | 'assistant',
          content: r.content,
          tags: r.tags,
          archived: r.archived_at !== null,
        }))
    } catch (e) {
      pushToast(`メッセージ取得失敗: ${e instanceof Error ? e.message : e}`)
    }
  }

  async function removeSession(sessionId: string) {
    await deleteSession(sessionId)
    if (currentSessionId.value === sessionId) {
      currentSessionId.value = null
      messages.value = []
    }
    await loadSessions()
  }

  function downloadSessionLog(sessionId: string): void {
    exportSession(sessionId)
  }

  async function importSessionFromFile(file: File): Promise<void> {
    let payload: ImportPayload
    try {
      const parsed = JSON.parse(await file.text())
      if (!Array.isArray(parsed?.messages)) {
        throw new Error('messages 配列が見つかりません')
      }
      payload = parsed as ImportPayload
    } catch (e) {
      pushToast(`インポート失敗: JSONの読み込みに失敗しました (${e instanceof Error ? e.message : e})`)
      return
    }
    try {
      const session = await importSession(payload)
      await loadSessions()
      await selectSession(session.id)
      pushToast(`「${session.title}」をインポートしました`)
    } catch (e) {
      pushToast(`インポート失敗: ${e instanceof Error ? e.message : e}`)
    }
  }

  function sendMessage(text: string): void {
    if (isStreaming.value || !text.trim()) return

    messages.value.push({ role: 'user', content: text })
    messages.value.push({ role: 'assistant', content: '', pending: true })
    const msgIdx = messages.value.length - 1  // reactive proxy 経由で更新するためインデックスを保持
    isStreaming.value = true

    streamChat(
      text,
      currentSessionId.value,
      selectedModel.value,
      (chunk) => {
        if (chunk.type === 'session_id' && chunk.value) {
          currentSessionId.value = chunk.value as string
          loadSessions().catch((e) => pushToast(`セッション更新失敗: ${e.message}`))
        } else if (chunk.type === 'chunk' && chunk.value) {
          messages.value[msgIdx].content += chunk.value as string
        } else if (chunk.type === 'sources' && chunk.value) {
          messages.value[msgIdx].sources = chunk.value as Source[]
        } else if (chunk.type === 'notes_updated') {
          // AIが共有ノートを書き換えたので、開いているノートパネルに反映する
          useNotesStore().load().catch((e) => pushToast(`ノート更新失敗: ${e.message}`))
        } else if (chunk.type === 'done') {
          messages.value[msgIdx].pending = false
          isStreaming.value = false
          loadSessions().catch((e) => pushToast(`セッション更新失敗: ${e.message}`))
        } else if (chunk.type === 'error') {
          messages.value[msgIdx].content = (chunk.value as string) ?? 'バックエンドでエラーが発生しました。'
          messages.value[msgIdx].pending = false
          messages.value[msgIdx].error = true
          isStreaming.value = false
        }
      },
      (err) => {
        // 途中まで届いていた内容は残しつつ、エラーメッセージを付記する
        const partial = messages.value[msgIdx].content
        messages.value[msgIdx].content = partial ? `${partial}\n\n⚠️ ${err.message}` : err.message
        messages.value[msgIdx].pending = false
        messages.value[msgIdx].error = true
        isStreaming.value = false
      },
    )
  }

  /** エラーになったアシスタント応答のひとつ前にあるユーザーメッセージを再送信する。 */
  function retryMessage(assistantIdx: number): void {
    if (isStreaming.value) return
    const userIdx = assistantIdx - 1
    const userMsg = messages.value[userIdx]
    if (!userMsg || userMsg.role !== 'user') return

    const text = userMsg.content
    // 失敗したユーザーメッセージとエラー応答を取り除いてから送信し直す
    messages.value.splice(userIdx, 2)
    sendMessage(text)
  }

  return {
    sessions,
    currentSessionId,
    messages,
    isStreaming,
    selectedModel,
    toasts,
    currentSession,
    pushToast,
    dismissToast,
    loadSessions,
    selectSession,
    removeSession,
    downloadSessionLog,
    importSessionFromFile,
    sendMessage,
    retryMessage,
  }
})