import Foundation

enum RutError: ErrorType{

  case InvalidRut(message : String)

}
class FormValidator: NSObject {
    static func validateRut(value : String) throws ->String {
    //clean rut
    var rut = value.stringByReplacingOccurrencesOfString(".", withString: "", options: NSStringCompareOptions.LiteralSearch, range: nil)
    rut = rut.stringByReplacingOccurrencesOfString("-", withString: "", options: NSStringCompareOptions.LiteralSearch, range: nil)
    rut =  rut.uppercaseString
    //check length
    if (rut.characters.count < 8 || rut.characters.count > 9  ) {
      throw RutError.InvalidRut(message: "Rut ingresado no válido")
    }
    let rutRegEx = "^(\\d{1,3}(\\.?\\d{3}){2})\\-?([\\dkK])$"

    let rutTest = NSPredicate(format:"SELF MATCHES %@", rutRegEx)

    if (!rutTest.evaluateWithObject(rut)) {

      throw RutError.InvalidRut(message: "Rut ingresado no válido")
    }

    let rutToValidate = getRutAndDv(rut)

    let rutWithoutVerifier = rutToValidate.0
    let verifiedDigit = rutToValidate.1

    let calculatedVerifiedDigit = getVerifiedDigit(rutWithoutVerifier)

    if (verifiedDigit != calculatedVerifiedDigit) {

      throw RutError.InvalidRut(message: "Rut ingresado no válido")
    }

    return rut
  }
  static func getRutAndDv (value : String) -> (String, String) {

    if (value.isEmpty || value.characters.count < 2) {
      return ("","")
    }

    var rut = value.stringByReplacingOccurrencesOfString(".", withString: "", options: NSStringCompareOptions.LiteralSearch, range: nil)
    rut = rut.stringByReplacingOccurrencesOfString("-", withString: "", options: NSStringCompareOptions.LiteralSearch, range: nil)

    let verifiedDigit = Array(rut.characters)[rut.characters.count-1]
    let range : Range<String.Index> = rut.startIndex..<rut.endIndex.advancedBy(-1)
    let rutWithoutVerifiedDigit = rut.substringWithRange(range)

    return (rutWithoutVerifiedDigit, String(verifiedDigit))
  }

  static func getVerifiedDigit (rut : String) -> String {

    var acumulado : Int = 0
    var ti : Int = 2

    for index in (rut.characters.count-1).stride(through: 0, by: -1) {
      let n = Array(rut.characters)[index]
      let nl = String(n)
      guard let vl = Int(nl) else {
        return ""
      }

      acumulado += vl * ti

      if (ti == 7) {
        ti = 1
      }
      ti += 1
    }

    let resto : Int = acumulado % 11
    let numericDigit : Int = 11 - resto
    var digito : String = ""

    if (numericDigit <= 9){
      digito = String(numericDigit);
    }else if (numericDigit == 10){
      digito = "K"
    }else{
      digito = "0"
    }

    return digito
  }


}


//para invocar


do{
      let validator = try FormValidator.validateRut("16242343-5") //cambiar por string de rut a validar

    }catch RutError.InvalidRut(let message) {

      showMessage("Error", message: message, action: nil)
    }catch{
      DDLogError("an error ocurred during rut validation")
    }