/**
 * Extract embedded native helpers next to the agent storage dir
 * (or PEARDATA_HELPER_DIR) so they can be exec'd from Bare/Node.
 */
import fs from 'fs'
import path from 'path'
import os from 'os'
import { EMBEDDED_HELPERS } from './embedded-helpers.js'

function helperDir() {
  if (process.env.PEARDATA_HELPER_DIR) return process.env.PEARDATA_HELPER_DIR
  if (process.env.PEARDATA_HOME) return path.join(process.env.PEARDATA_HOME, 'helpers')
  if (process.env.PEARDATA_DATA_DIR) return path.join(process.env.PEARDATA_DATA_DIR, 'helpers')
  return path.join(os.tmpdir(), 'peardata-helpers')
}

function hostKey() {
  return `${process.platform}-${process.arch}`
}

/**
 * @param {string} name e.g. peardata-ebpf
 * @returns {string|null} absolute path to executable
 */
export function extractHelper(name) {
  const keyed = `${name}-${hostKey()}`
  const b64 = EMBEDDED_HELPERS[keyed] || EMBEDDED_HELPERS[name]
  if (!b64) {
    // Fall back to sibling of process.execPath / PATH
    const siblings = [
      path.join(path.dirname(process.execPath || ''), name),
      path.join(process.cwd(), 'native', 'prebuilds', `${name}-${hostKey()}`),
      path.join(process.cwd(), 'native', 'prebuilds', name),
      `/usr/local/lib/peardata/${name}`,
    ]
    for (const p of siblings) {
      try {
        if (fs.existsSync(p)) {
          fs.accessSync(p, fs.constants.X_OK)
          return p
        }
      } catch {
        // continue
      }
    }
    return null
  }

  const dir = helperDir()
  fs.mkdirSync(dir, { recursive: true })
  const dest = path.join(dir, name)
  const buf = Buffer.from(b64, 'base64')
  let needWrite = true
  try {
    const st = fs.statSync(dest)
    if (st.size === buf.length) needWrite = false
  } catch {
    needWrite = true
  }
  if (needWrite) {
    fs.writeFileSync(dest, buf, { mode: 0o755 })
    try {
      fs.chmodSync(dest, 0o755)
    } catch {
      // ignore
    }
  }
  return dest
}

export function hasEmbeddedHelper(name) {
  const keyed = `${name}-${hostKey()}`
  return Boolean(EMBEDDED_HELPERS[keyed] || EMBEDDED_HELPERS[name])
}