askirmas / arg-env

, argPrefix = "--env-file="

, {"length": argPrefixLength} = argPrefix

, packagePrefix = "npm_package_config_env_file"

, envPrefix = "ENV_FILE"

/**

 * @see https://github.com/npm/cli/issues/3775

 * @see https://github.com/npm/run-script/issues/37 */

const npm7delimiter = "\n\n"

export {

  fromArgs,

  fromPackageEnv,

  fromEnv

}

function fromArgs<T extends boolean>(

  argv: typeof process["argv"],

  deleteThem: T

) {

  const {length} = argv

  // CONSIDER `collected: Set<string>`

  , collected: string[] = []

  , indexesToDelete = deleteThem ? [] as number[] : undefined

  for (let i = argStart; i < length; i++) {

    const arg = argv[i]

    if (!arg.startsWith(argPrefix))

      continue

    collected.push(arg.substr(argPrefixLength))

    deleteThem && indexesToDelete!.push(i)

  }

  const lengthToDelete = indexesToDelete?.length

  if (lengthToDelete) {

    let deleteIndex = 0

    , curIndex = indexesToDelete[0]

    for (let preIndex = curIndex; preIndex < length; preIndex++) {

      while (preIndex === indexesToDelete[deleteIndex]) {

        preIndex++

        deleteIndex++

      }

      argv[curIndex] = argv[preIndex]

      curIndex++

    }

    argv.length -= lengthToDelete

  }

  return collected

}

function fromEnv(env: Readonly<Env>) {

  return fromArrayAsAssoc(

    env,

    envPrefix,

    envPrefix in env

    ? [env[envPrefix]!]

    : []

  )

}

// CONSIDER `collected: Set<string>`

function fromArrayAsAssoc(env: Readonly<Env>, prefix: string, collected: string[]) {

  let i = 0

  , key = `${prefix}_${i}`

  while (key in env) {

    collected.push(env[key]!)

    i++

    key = `${prefix}_${i}`

  }

  return collected

}