Scoreboard/console/main/log-bus.js

'use strict'

const fs = require('fs')
const path = require('path')

// 日志总线：内存环形缓冲供管理窗口实时查看，同时落一份文件供现场排障。
// 现场没有外网也没有终端，文件日志是事后定位问题的唯一线索。
class LogBus {
  constructor(options = {}) {
    const { maxLines = 2000, file = null, maxFileBytes = 4 * 1024 * 1024 } = options
    this.maxLines = maxLines
    this.maxFileBytes = maxFileBytes
    this.lines = []
    this.listeners = new Set()
    // 子进程的输出是流式分片的，可能把一行拆到两次 data 事件里
    this.pending = new Map()
    this.stream = null
    if (file) this.openFile(file)
  }

  openFile(file) {
    try {
      fs.mkdirSync(path.dirname(file), { recursive: true })
      if (fs.existsSync(file) && fs.statSync(file).size > this.maxFileBytes) {
        fs.renameSync(file, `${file}.1`)
      }
      this.stream = fs.createWriteStream(file, { flags: 'a' })
    } catch (err) {
      this.stream = null
      this.push('console', `日志文件不可写，仅保留内存日志：${err.message}`)
    }
  }

  append(source, chunk) {
    const text = `${this.pending.get(source) || ''}${String(chunk)}`
    const parts = text.split(/\r?\n/)
    // 最后一段是没有换行的残行，留到下一次拼接
    this.pending.set(source, parts.pop() || '')
    for (const part of parts) this.push(source, part)
  }

  push(source, message) {
    const line = `[${new Date().toISOString()}] [${source}] ${message}`
    this.lines.push(line)
    if (this.lines.length > this.maxLines) {
      this.lines.splice(0, this.lines.length - this.maxLines)
    }
    if (this.stream) this.stream.write(`${line}\n`)
    for (const listener of this.listeners) {
      try {
        listener(line)
      } catch {
        // 单个订阅者出错不能拖垮日志链路
      }
    }
  }

  tail() {
    return this.lines.slice()
  }

  clear() {
    this.lines = []
  }

  onLine(listener) {
    this.listeners.add(listener)
    return () => this.listeners.delete(listener)
  }

  close() {
    if (this.stream) {
      this.stream.end()
      this.stream = null
    }
  }
}

module.exports = { LogBus }