/**
 * 会话取证 · schema 探测：解压多帧 zstd → 事件类型直方图 + 每类样本键结构（先摸清格式）
 * 会话 schema 探测（只读）：输出事件类型直方图 + 少量样本键结构
 * 用法：node probe-schema.mjs <session.jsonl.zstd>
 */
import { readFileSync } from 'node:fs'
import { zstdDecompressSync } from 'node:zlib'

const raw = readFileSync(process.argv[2])
const MAGIC = Buffer.from([0x28, 0xb5, 0x2f, 0xfd])
const offs = []
for (let i = 0; i + 4 <= raw.length; i++) if (raw.compare(MAGIC, 0, 4, i, i + 4) === 0) offs.push(i)
let text = ''
const frames = offs.length ? offs : [0]
for (let f = 0; f < frames.length; f++) {
  const s = frames[f], e = f + 1 < frames.length ? frames[f + 1] : raw.length
  try { text += zstdDecompressSync(raw.subarray(s, e)).toString('utf8') } catch {}
}
const lines = text.split('\n').filter((l) => l.trim())
console.log('解压后 %d 行 / %d 字符 / zstd 帧 %d', lines.length, text.length, frames.length)

const types = new Map()
const samples = new Map()
for (const l of lines) {
  let o
  try { o = JSON.parse(l) } catch { continue }
  const t = o.type ?? o.event ?? o.kind ?? '(no-type)'
  types.set(t, (types.get(t) ?? 0) + 1)
  if (!samples.has(t)) samples.set(t, o)
}
console.log('\n=== 事件类型直方图 ===')
for (const [t, n] of [...types].sort((a, b) => b[1] - a[1])) console.log('  %-28s %d', t, n)

console.log('\n=== 每类样本（键 + 截断值） ===')
for (const [t, o] of samples) {
  console.log('--- %s ---', t)
  const dump = (v, depth = 0) => {
    if (v === null) return 'null'
    if (Array.isArray(v)) return `[${v.length} items${v.length ? ': ' + dump(v[0], depth + 1) : ''}]`
    if (typeof v === 'object') {
      if (depth > 1) return '{…}'
      return '{' + Object.entries(v).slice(0, 10).map(([k, x]) => `${k}: ${dump(x, depth + 1)}`).join(', ') + '}'
    }
    const s = String(v)
    return JSON.stringify(s.length > 90 ? s.slice(0, 90) + '…' : s)
  }
  console.log('   ' + dump(o).slice(0, 1200))
}