/**Walks the directory tree received from */
const walkTree = tree => {
  if (!tree.children) {
    let unit = 0
    let subject = ''
    let { path } = tree
    if (path.includes('unit1')) {
      unit = 1
    } else {
      unit = 2
    }
    /**
     * Takes the path eg. public/June2011Paper1.pdf
     * Splits and take last element June2011Paper1.pdf
     * Then takes that and drops the .pdf to create the title
     *   */
    let title = path
      .split('/')
      .slice(-1)[0]
      .split('.')[0]
    let [month, year, paper] = title.split('_')

    if (path.includes('physics')) subject = 'physics'
    else if (path.includes('economics')) subject = 'economics'
    else if (path.includes('communication_studies'))
      subject = 'communication_studies'
    else if (path.includes('chemistry')) subject = 'chemistry'
    else if (path.includes('biology')) subject = 'biology'
    else if (path.includes('pure_math')) subject = 'pure_math'

    //Removes public/ from path
    let newPath = path.replace('public/', '')

    return { unit, title, month, year, paper, path: newPath, subject }
  } else {
    let { children } = tree
    return children.map(child => walkTree(child))
  }
}

const flatten = (arr, result = []) => {
  arr.map(child => {
    if (Array.isArray(child)) {
      flatten(child, result)
    } else {
      result.push(child)
    }
  })
  return result
}

module.exports = { flatten, walkTree }