import type { RewriteTree } from './BlockTree'
import type { ChatState } from './qa'
import { useEffect, useMemo, useReducer, useRef } from 'react'
import { chatReducer, EMPTY_CHAT, newAskId, unfinished } from './qa'
import { toAskImage } from './qaImages'
import { ANSWER_FRAME_MS } from './useQa'
import { onMessage, postMessage } from './vscode'

/**
 * 按注释规范重写：收扩展端的重写记录、当前一轮的进展，给块树用的状态和动作。和问 AI 同一套：
 * 排着队的、进行中的、出错被叫停留着的那一轮记在扩展端，页面重新加载后随 qa 消息的 rewriteCurrent 接上。profile 下拉是自己的，和问 AI 的互不影响。
 */
export function useRewrite(): RewriteTree {
  const [state, dispatch] = useReducer(chatReducer<ChatState>, EMPTY_CHAT)

  useEffect(() => {
    /** 攒着没画的进展：askId → 最新的一份 */
    const pending = new Map<string, { question: string, text: string, activity?: string, queued?: boolean }>()
    let timer: ReturnType<typeof setTimeout> | undefined
    const flush = (): void => {
      timer = undefined
      for (const [askId, progress] of pending)
        dispatch({ type: 'answer', askId, ...progress })
      pending.clear()
    }
    const off = onMessage((msg) => {
      switch (msg.type) {
        case 'qa':
          dispatch({ type: 'sync', available: msg.available, threads: msg.rewrites, current: msg.rewriteCurrent })
          return
        case 'profiles':
          if (msg.kind === 'rewrite')
            dispatch({ type: 'profiles', profiles: { options: msg.options, selected: msg.selected } })
          return
        case 'rewriteProgress':
          pending.set(msg.askId, { question: msg.question, text: msg.text, ...(msg.activity !== undefined && { activity: msg.activity }), ...(msg.queued && { queued: true }) })
          timer ??= setTimeout(flush, ANSWER_FRAME_MS)
          return
        case 'rewriteEnd':
          clearTimeout(timer)
          flush()
          dispatch({ type: 'answerEnd', end: msg })
      }
    })
    return () => {
      clearTimeout(timer)
      off()
    }
  }, [])

  /** 动作里读眼下的状态（这块是不是已经在写或排着队） */
  const current = useRef(state)
  current.current = state

  return useMemo((): RewriteTree => ({
    state,
    onSelectProfile: id => postMessage({ type: 'selectProfile', kind: 'rewrite', id }),
    onRewrite: (anchor) => {
      if (current.current.asks.some(ask => ask.anchor === anchor && unfinished(ask)))
        return
      const askId = newAskId()
      // 那句技能命令由扩展端拼好，开始后随 rewriteProgress 报上来
      dispatch({ type: 'ask', askId, anchor, question: '', images: [] })
      postMessage({ type: 'rewriteComment', askId, anchor, images: [] })
    },
    onAsk: (anchor, request, images) => {
      const askId = newAskId()
      dispatch({ type: 'ask', askId, anchor, question: request, images: images.map(image => image.url) })
      postMessage({ type: 'rewriteComment', askId, anchor, request, images: images.map(toAskImage) })
    },
    onStop: askId => postMessage({ type: 'stopRewrite', askId }),
    onDelete: (anchor, entryId) => postMessage({ type: 'deleteRewrite', anchor, entryId }),
    onOpen: anchor => dispatch({ type: 'open', anchor }),
    onClose: (anchor) => {
      dispatch({ type: 'close', anchor })
      postMessage({ type: 'forgetRound', kind: 'rewrite', anchor })
    },
  }), [state])
}