import { execFile, spawn } from "node:child_process"
import { Readable } from "node:stream"

const REMOTE_HOST = process.env.BACKUPS_REMOTE_HOST || "malio-b@192.168.0.179"
const REMOTE_ROOT = process.env.BACKUPS_REMOTE_ROOT || "/home/malio-b/backups"
const FOLDER_MAP: Record<string, string> = {
  ferme: "bdd_recette/ferme",
  inventory: "bdd_recette/inventory",
  sirh: "bdd_recette/sirh",
  user: "bdd_recette/user",
  bitwarden: "bitwarden"
}

const isSafeFolder = (value: string) => /^[a-zA-Z0-9._-]+$/.test(value)
const isSafeFile = (value: string) => /^[^/\\]+$/.test(value)
const shellQuote = (value: string) => `'${value.replace(/'/g, `'\\''`)}'`

function runSsh(command: string): Promise<string> {
  return new Promise((resolve, reject) => {
    execFile(
      "ssh",
      ["-o", "BatchMode=yes", "-o", "ConnectTimeout=5", REMOTE_HOST, command],
      { maxBuffer: 5 * 1024 * 1024 },
      (error, stdout, stderr) => {
        if (error) {
          reject(stderr || error.message)
          return
        }
        resolve(stdout)
      }
    )
  })
}

async function remoteDirExists(remoteDir: string): Promise<boolean> {
  const output = await runSsh(`[ -d ${shellQuote(remoteDir)} ] && echo yes || echo no`)
  return output.trim() === "yes"
}

async function resolveFolderRemoteDir(folderName: string): Promise<string | null> {
  const mapped = FOLDER_MAP[folderName]
  if (mapped) {
    return `${REMOTE_ROOT}/${mapped}`
  }

  const direct = `${REMOTE_ROOT}/${folderName}`
  if (await remoteDirExists(direct)) {
    return direct
  }

  const nested = `${REMOTE_ROOT}/bdd_recette/${folderName}`
  if (await remoteDirExists(nested)) {
    return nested
  }

  return null
}

function buildContentDisposition(fileName: string) {
  const asciiName = fileName.replace(/[^\x20-\x7E]/g, "_").replace(/["\\]/g, "_")
  return `attachment; filename="${asciiName}"; filename*=UTF-8''${encodeURIComponent(fileName)}`
}

function speedtestStream(event: any) {
  const size = 128 * 1024 * 1024
  let sent = 0

  const stream = new Readable({
    read(chunkSize) {
      if (sent >= size) {
        this.push(null)
        return
      }

      const remaining = size - sent
      const chunk = Buffer.alloc(Math.min(chunkSize, remaining), "a")
      sent += chunk.length
      this.push(chunk)
    }
  })

  setHeader(event, "Content-Type", "application/octet-stream")
  setHeader(event, "Content-Length", size)
  return stream
}

export default defineEventHandler(async (event) => {
  const { folder, file } = getQuery(event)
  const folderName = typeof folder === "string" ? folder : null
  const fileName = typeof file === "string" ? file : null

  // Compat mode: utilisé par le test de débit.
  if (!folderName || !fileName) {
    return speedtestStream(event)
  }

  if (!isSafeFolder(folderName) || !isSafeFile(fileName)) {
    throw createError({ statusCode: 400, statusMessage: "Paramètres invalides" })
  }

  const remoteDir = await resolveFolderRemoteDir(folderName)
  if (!remoteDir) {
    throw createError({ statusCode: 404, statusMessage: "Dossier introuvable" })
  }

  const remotePath = `${remoteDir}/${fileName}`
  const existsOutput = await runSsh(`[ -f ${shellQuote(remotePath)} ] && echo yes || echo no`)
  if (existsOutput.trim() !== "yes") {
    throw createError({ statusCode: 404, statusMessage: "Fichier introuvable" })
  }

  setHeader(event, "Content-Type", "application/octet-stream")
  setHeader(event, "Content-Disposition", buildContentDisposition(fileName))

  const child = spawn("ssh", [
    "-o",
    "BatchMode=yes",
    "-o",
    "ConnectTimeout=5",
    REMOTE_HOST,
    `cat ${shellQuote(remotePath)}`
  ])

  let stderr = ""
  child.stderr.on("data", (chunk) => {
    stderr += chunk.toString()
  })

  child.on("close", (code) => {
    if (code !== 0) {
      console.error(`Erreur téléchargement SSH (${code}): ${stderr}`)
    }
  })

  return sendStream(event, child.stdout)
})