package com.example.rxjava

import org.funktionale.either.Either
import rx.Observable

data class ValidationError(val errorMsg: String)

class Requirement(val msg: String, val isSatisfiable: (String) -> Boolean) {

    fun check(password: String): ValidationError? {
        return if (isSatisfiable(password)) null
               else ValidationError(msg)
    }

}

class PasswordValidator(val requirements: List<Requirement>) {

    constructor(vararg requirements: Requirement) : this(requirements.toList())

    fun validate(password: String): List<ValidationError> {
        return requirements
                .map { requirement -> requirement.check(password) }
                .filterNotNull()
    }

}

fun main(args: Array<String>) {

    val passwordValidator = PasswordValidator(
            Requirement("At least 4 characters") { it.length > 3 },
            Requirement("At least one character in lower case") { it.any(Char::isLowerCase) }
    )

    Observable.just("12Q")
            .map { pswd ->
                val errors = passwordValidator.validate(pswd)

                if (errors.isEmpty()) Either.right(pswd)
                else Either.left(errors)
            }
            .subscribe({ either -> either.fold(
                            { errors -> println("Weak password: $errors") },
                            { println("Strong password: $it") })
                       },
                       { it.printStackTrace() })


}