import type { Client } from 'ssh2'
import { execCommand, toFixedNum } from './common.js'

function parseDfLine(output: string): string[] | null {
  const lines = output.split('\n').map((l) => l.trim()).filter(Boolean)
  if (lines.length < 2) return null
  return lines[1].split(/\s+/)
}

export async function collectDiskMetrics(
  client: Client,
): Promise<{ percent: number | null; usedHuman: string | null; totalHuman: string | null; availableHuman: string | null }> {
  let percent: number | null = null
  let usedHuman: string | null = null
  let totalHuman: string | null = null
  let availableHuman: string | null = null

  try {
    const [human, bytes] = await Promise.all([
      execCommand(client, "df -h -P / 2>/dev/null"),
      execCommand(client, "df -B1 -P / 2>/dev/null"),
    ])

    const humanParts = parseDfLine(human.stdout)
    if (humanParts && humanParts.length >= 4) {
      totalHuman = humanParts[1]
      usedHuman = humanParts[2]
      availableHuman = humanParts[3]
    }

    const byteParts = parseDfLine(bytes.stdout)
    if (byteParts && byteParts.length >= 3) {
      const total = Number(byteParts[1])
      const used = Number(byteParts[2])
      if (Number.isFinite(total) && total > 0 && Number.isFinite(used)) {
        percent = toFixedNum((used / total) * 100)
      }
    }
  } catch {
    // best-effort
  }

  return { percent, usedHuman, totalHuman, availableHuman }
}