import * as fs from 'fs'
import * as path from 'path'

import { RecursiveTravelDirectoriesInput } from '@types'

import { isObjectADirectory } from './isObjectADirectory'

/**
 * recursive travel all directory
 * Params:
 * directory: absolute path
 * travelCallback: call with each directory that have been travled
 * completeCallback: call when finish travel
 *
 * Just like travel a tree using DFS algorithm
 */
export const recursiveTravelDirectory = ({
  rootDirectory,
  currentTravelDirectory = rootDirectory,
  travelCallBack,
}: RecursiveTravelDirectoriesInput) => {
  return new Promise(resolve => {
    fs.readdir(currentTravelDirectory, (err, objs) => {
      if (err) {
        throw err
      }

      // get child branches of current branch
      const childDirectories = objs.filter(obj => isObjectADirectory({ directory: currentTravelDirectory, obj }))

      const childFiles = objs.filter(obj => !isObjectADirectory({ directory: currentTravelDirectory, obj }))

      // travel the the deepst of node of the branch
      if (childDirectories.length === 0) {
        travelCallBack({
          directory: currentTravelDirectory,
          childFiles,
          childDirectories,
        })
        resolve()
        return
      }

      // for each branch in child branch, continue travel deep down
      const promises = []
      for (let directory of childDirectories) {
        promises.push(
          recursiveTravelDirectory({
            travelCallBack,
            currentTravelDirectory: path.join(currentTravelDirectory, directory),
            rootDirectory,
          }),
        )
      }

      /**
       * wait until all child directory have been travlled
       * use for testing purpuse...
       */
      Promise.all(promises).then(() => {
        travelCallBack({
          directory: currentTravelDirectory,
          childFiles,
          childDirectories,
        })
        resolve()
      })
    })
  })
}