exports.replaceDollarWithPercentPair = replaceDollarWithPercentPair
exports.convertToSetCommand = convertToSetCommand
exports.convertToSetCommands = convertToSetCommands

function convertToSetCommand (key, value) {
  var line = ''
  key = key || ''
  key = key.trim()
  value = value || ''
  value = value.trim()
  if (key && value && value.length > 0) {
    line = '@SET ' + key + '=' + replaceDollarWithPercentPair(value) + '\r\n'
  }
  return line
}

function extractVariableValuePairs (declarations) {
  var pairs = {}
  declarations.map(function (declaration) {
    var split = declaration.split('=')
    pairs[split[0]] = split[1]
  })
  return pairs
}

function convertToSetCommands (variableString) {
  var variableValuePairs = extractVariableValuePairs(variableString.split(' '))
  var variableDeclarationsAsBatch = ''
  Object.keys(variableValuePairs).forEach(function (key) {
    variableDeclarationsAsBatch += convertToSetCommand(key, variableValuePairs[key])
  })
  return variableDeclarationsAsBatch
}

function replaceDollarWithPercentPair (value) {
  var dollarExpressions = /\$\{?([^$@#?\- \t{}:]+)\}?/g
  var result = ''
  var startIndex = 0
  do {
    var match = dollarExpressions.exec(value)
    if (match) {
      var betweenMatches = value.substring(startIndex, match.index) || ''
      result += betweenMatches + '%' + match[1] + '%'
      startIndex = dollarExpressions.lastIndex
    }
  } while (dollarExpressions.lastIndex > 0)
  result += value.slice(startIndex)
  return result
}