askirmas / arg-env

import {

  fromArgs,

  fromEnv,

  fromPackageEnv

} from "./cli-utils"

import {

  parse

} from "./parse"

export type Reader = (path: string) => string | Buffer

const {assign: $assign} = Object

export {

  main,

  assigner

}

function main(

  env: Env,

  argv: string[],

  reader: Reader,

  deleteArgs: boolean

) {

  // TODO #13

  const patches = [

    fromEnv(env),

    fromArgs(argv, deleteArgs),

    fromPackageEnv(env)

  ]

  , {length} = patches

  , envPatch: Record<string, unknown> = {}

  for (let i = 0; i < length; i++)

    assigner(

      env, 

      patches[i],

      reader,

      envPatch

    )

  $assign(env, envPatch)

  return envPatch

}

function assigner(

  env: Readonly<Env>,

  files: readonly string[],

  reader: Reader,

  envPatch: Record<string, unknown>

) {

  const {length} = files

  for (let i = length; i--; )

    // NB commutative

    $assign(

      envPatch,

      parse(

        reader(files[i]),

        env,

        envPatch

      )

    )

  return envPatch

}