/**
 * In-memory structured initd journal (NDJSON lines) exposed under /run/bare-os/unit-journal/.
 */

const MAX_LINES_PER_UNIT = 400
const MAX_LINE_UTF8 = 4096

/** @type {Map<string, string[]>} */
const linesByUnit = new Map()

function journalMaxLinesPerUnit() {
  const raw = globalThis.process?.env?.BARE_OS_INITD_JOURNAL_MAX_LINES
  if (raw == null || raw === '') return MAX_LINES_PER_UNIT
  const n = Number.parseInt(String(raw), 10)
  return Number.isFinite(n) && n > 10 ? Math.min(n, 20000) : MAX_LINES_PER_UNIT
}

/**
 * @param {string} unit
 * @param {Record<string, unknown>} rec
 */
export function appendBareInitdJournal(unit, rec) {
  if (!unit || !/^[a-zA-Z0-9._-]+$/.test(unit)) return
  const payload = { ts: Date.now(), unit, ...rec }
  let line
  try {
    line = JSON.stringify(payload) + '\n'
  } catch {
    return
  }
  if (line.length > MAX_LINE_UTF8) return
  let arr = linesByUnit.get(unit)
  if (!arr) {
    arr = []
    linesByUnit.set(unit, arr)
  }
  arr.push(line)
  const cap = journalMaxLinesPerUnit()
  while (arr.length > cap) arr.shift()
}

/**
 * @param {string} unit
 * @returns {string}
 */
export function getBareInitdJournalNdjson(unit) {
  const arr = linesByUnit.get(unit)
  return arr ? arr.join('') : ''
}

/** @returns {string[]} */
export function listBareInitdJournalUnits() {
  return [...linesByUnit.keys()].sort()
}

export function clearBareInitdJournalForTests() {
  linesByUnit.clear()
}