// 模拟 OpenAI 兼容接口，用于本地联调和端到端测试（不消耗真实 token）
// 用法：node scripts/mock-llm.mjs [port]
// - 模型 id 含 "trunc" 时，作家第一轮输出会以 finish_reason=length 结束，用于测试自动续写
import { createServer } from 'node:http'

const port = Number(process.argv[2] || process.env.MOCK_PORT || 4010)
const log = (...a) => console.log('[mock]', ...a)

function json(res, status, body) {
  res.writeHead(status, { 'Content-Type': 'application/json' })
  res.end(JSON.stringify(body))
}

function completion(model, message, finish = 'stop') {
  return {
    id: `chatcmpl-${Date.now()}`,
    object: 'chat.completion',
    created: Math.floor(Date.now() / 1000),
    model,
    choices: [{ index: 0, message: { role: 'assistant', content: null, ...message }, finish_reason: finish }],
    usage: { prompt_tokens: 1200, completion_tokens: 300, total_tokens: 1500 }
  }
}

const toolCall = (name, args) => ({
  id: `call_${name}_${Math.random().toString(36).slice(2, 8)}`,
  type: 'function',
  function: { name, arguments: JSON.stringify(args) }
})

const text = m => (typeof m.content === 'string' ? m.content : (m.content || []).map(p => p.text || '').join(''))

function handleTools(body) {
  const names = body.tools.map(t => t.function.name)
  const hasToolResult = body.messages.some(m => m.role === 'tool')
  const prompt = body.messages.filter(m => m.role === 'user').map(text).join('\n')

  if (names.includes('set_chapter_plan')) {
    if (hasToolResult) return completion(body.model, { content: '整体采用三幕结构，前三章完成人物登场与核心冲突的建立。' })
    const m = prompt.match(/从第(\d+)章开始的 (\d+) 个章节/)
    const from = m ? Number(m[1]) : 1
    const count = Math.min(m ? Number(m[2]) : 3, 3)
    const chapters = Array.from({ length: count }, (_, i) => ({
      index: from + i,
      title: ['雨季', '旧城', '回声'][i] ?? `第${from + i}章`,
      synopsis: `第${from + i}章梗概：主角在雨中重逢旧识，埋下关于旧城往事的悬念。`
    }))
    return completion(body.model, { tool_calls: [toolCall('set_chapter_plan', { chapters })] }, 'tool_calls')
  }

  if (names.includes('write_brief')) {
    if (hasToolResult) return completion(body.model, { content: '本章以环境开篇，节奏先慢后快。' })
    const writerId = prompt.match(/id=([a-z0-9]+)｜/)?.[1]
    const calls = [toolCall('write_brief', {
      title: '雨落昆明',
      goal: '让主角与简琳琅在雨中初遇，建立两人之间的张力',
      plotPoints: ['午后雷声，雨季开始', '主角在骑楼下避雨', '简琳琅撑伞经过，两人短暂交谈', '她留下一个意味深长的问题'],
      characters: ['简琳琅：表面强势，内心戒备'],
      setting: '2011 年 5 月底，昆明老街',
      mood: '潮湿、暧昧、略带不安',
      targetWords: 1200,
      endingHook: '她问：你还记得百鸟县吗？'
    })]
    if (writerId && !prompt.includes('用户已为本章指定作家')) calls.push(toolCall('assign_writer', { writerId, reason: '擅长氛围描写' }))
    return completion(body.model, { tool_calls: calls }, 'tool_calls')
  }
  return completion(body.model, { content: '好的。' })
}

function handleText(body) {
  const system = body.messages.filter(m => m.role === 'system').map(text).join('\n')
  if (system.includes('资料员')) {
    return completion(body.model, {
      content: '```json\n' + JSON.stringify({
        summary: '雨季的第一声雷后，主角在骑楼下避雨，与撑伞经过的简琳琅短暂交谈。她看似随意，却在离开前提起了百鸟县。',
        characterStates: [{ name: '简琳琅', state: '刚与主角重逢，情绪克制，似乎有所隐瞒' }],
        newForeshadowing: ['简琳琅提起百鸟县的真正用意'],
        resolvedForeshadowing: [],
        events: ['主角与简琳琅雨中重逢']
      }) + '\n```'
    })
  }
  return completion(body.model, { content: '## 审稿意见\n\n1. 情节点全部完成。\n2. 结尾钩子可以更含蓄。\n\n**总评分：8/10**' })
}

function streamChapter(res, body) {
  const userTurns = body.messages.filter(m => m.role === 'user').length
  const truncate = body.model.includes('trunc') && userTurns === 1
  const paragraphs = truncate
    ? ['午后，一声闷雷从天边滚过来。', '\n\n雨点砸在青石板上，溅起细碎的水花。']
    : userTurns > 1
      ? ['\n\n她收起伞，抬眼看他：“你还记得百鸟县吗？”']
      : ['午后，一声闷雷从天边滚过来。', '\n\n雨来得又急又密，他退到骑楼下。', '\n\n简琳琅撑着一把黑伞从街角走来，高跟鞋踩过积水。', '\n\n“借个地方躲雨。”她说。', '\n\n她收起伞，抬眼看他：“你还记得百鸟县吗？”']
  res.writeHead(200, { 'Content-Type': 'text/event-stream', 'Cache-Control': 'no-cache', 'Connection': 'keep-alive' })
  const base = { id: `chatcmpl-${Date.now()}`, object: 'chat.completion.chunk', created: Math.floor(Date.now() / 1000), model: body.model }
  const send = obj => res.write(`data: ${JSON.stringify({ ...base, ...obj })}\n\n`)
  send({ choices: [{ index: 0, delta: { role: 'assistant', content: '' }, finish_reason: null }] })
  const chunks = paragraphs.flatMap(p => p.match(/.{1,4}/gs))
  let i = 0
  const timer = setInterval(() => {
    if (res.destroyed) return clearInterval(timer)
    if (i < chunks.length) {
      send({ choices: [{ index: 0, delta: { content: chunks[i++] }, finish_reason: null }] })
      return
    }
    clearInterval(timer)
    send({ choices: [{ index: 0, delta: {}, finish_reason: truncate ? 'length' : 'stop' }] })
    send({ choices: [], usage: { prompt_tokens: 2000, completion_tokens: 400, total_tokens: 2400 } })
    res.write('data: [DONE]\n\n')
    res.end()
  }, 15)
}

createServer(async (req, res) => {
  const url = new URL(req.url, `http://localhost:${port}`)
  if (req.method === 'GET' && url.pathname.endsWith('/models')) {
    return json(res, 200, { object: 'list', data: [{ id: 'mock-editor' }, { id: 'mock-writer-trunc' }] })
  }
  if (req.method === 'POST' && url.pathname.endsWith('/chat/completions')) {
    let raw = ''
    for await (const c of req) raw += c
    const body = JSON.parse(raw)
    if (req.headers.authorization !== 'Bearer test-key') return json(res, 401, { error: { message: 'invalid api key' } })
    log(body.model, body.stream ? 'stream' : 'json', body.tools ? `tools=${body.tools.map(t => t.function.name).join(',')}` : '')
    if (body.stream) return streamChapter(res, body)
    return json(res, 200, body.tools?.length ? handleTools(body) : handleText(body))
  }
  json(res, 404, { error: { message: 'not found' } })
}).listen(port, () => log(`listening on http://localhost:${port}/v1`))