godkimchi-read-line/index.js

kimchi style's read line module

const util = require('util')
const csv = require('csv')
const iconv = require('iconv-lite')
const ReadLines = require('n-readlines')

const DEFAULT_OPTION = { skipHeader: false, encoding: 'utf8', type: 'text', quote: '', delimiter: ',', escape: '"' }

function setupOption (option = {}, yourOption = {}) {
  Object.keys(yourOption).forEach(key => {
    if (option.hasOwnProperty(key)) {
      option[key] = yourOption[key]
    }
  })
}

module.exports = async function (filePath = String, yourOption = DEFAULT_OPTION, cb = undefined) {
  if (typeof arguments[1] === 'function') {
    yourOption = DEFAULT_OPTION
    cb = arguments[1]
  }

  const option = Object.assign({}, DEFAULT_OPTION)
  setupOption(option, yourOption)

  const { quote, delimiter, escape } = option

  const lineReader = new ReadLines(filePath)
  let skipCallback = false, error, data, line, lineCount = 0

  while ((line = lineReader.next()) !== false) {
    skipCallback = false
    error = data = undefined

    try {
      if (++lineCount === 1 && option.skipHeader === true) {
        skipCallback = true
        continue
      } else {
        line = iconv.decode(line, option.encoding)
        data = { line, lineCount }
      }

      if (option.type === 'csv') {
        const [fields] = await util.promisify(csv.parse)(line, { quote, delimiter, escape })
        data.fields = fields
      }
    } catch (e) {
      error = e
    } finally {
      let continueOrNot

      if (skipCallback === true || typeof cb !== 'function') {
        continueOrNot = true
      } else if (cb instanceof (async () => {}).constructor) {
        continueOrNot = await cb(error, data)
      } else {
        continueOrNot = cb(error, data)
      }

      if (continueOrNot === false) {
        break
      }
    }
  }

  return { filePath, option, lineCount }
}