findByAge.scala

import FindByAgeCmd.*

type Age = Int

case class Person(name: String, age: Age)

val people = List(
  Person("alice", 65),
  Person("bob", 25),
  Person("chien", 15),
  Person("daniel", 35),
  Person("elisa", 45)
)

enum FindByAgeCmd:
  case EqualTo(value: Age)
  case GreaterThan(value: Age)
  case LessThan(value: Age)
  case OrCond(a: FindByAgeCmd, b: FindByAgeCmd)
  case AndCond(a: FindByAgeCmd, b: FindByAgeCmd)

def filterByAge(cmd: FindByAgeCmd, person: Person): Boolean = {  
  cmd match {
    case EqualTo(value) => person.age == value
    case GreaterThan(value) => person.age > value
    case LessThan(value) => person.age < value
    case OrCond(cmdA, cmdB) => filterByAge(cmdA, person) || filterByAge(cmdB, person)
    case AndCond(cmdA, cmdB) => filterByAge(cmdA, person) && filterByAge(cmdB, person)
  }
}

def show(cmd: FindByAgeCmd): String = {
  cmd match {
    case EqualTo(value) => s"Igual a $value"
    case GreaterThan(value) => s"Maior que $value"
    case LessThan(value) => s"Menor que $value"
    case OrCond(cmdA, cmdB) => s"(${show(cmdA)}) OU (${show(cmdB)})"
    case AndCond(cmdA, cmdB) => s"(${show(cmdA)}) E (${show(cmdB)})"
  }
}

/*
-- Busque todas as pessoas com idades
--  - q1. maior que 30                 -> GreaterThan 30
--  - q2. igual a 25                   -> EqualTo 25
--  - q3. menor ou igual a 45          -> OrCond (LessThan 45) (EqualTo 45)
--  - q4. maior que 20 e menor que 60  -> AndCond (GreaterThan 20) (LessThan 60)
*/
def query(cmd: FindByAgeCmd) = {
  val result = people.filter(p => filterByAge(cmd, p))
  println(s"${show(cmd)}: $result")
}

query(GreaterThan(30))
query(EqualTo(25))
query(OrCond(LessThan(45), EqualTo(45)))
query(AndCond(GreaterThan(20), LessThan(60)))