package fr.univtln.bruno.samples.java101.tp3.functional;
   
   import fr.univtln.bruno.samples.java101.tp3.Person;
   import lombok.extern.slf4j.Slf4j;
   
   import java.util.List;
   import java.util.Map;
   import java.util.stream.Collectors;
   
  /**
   * Applied functional examples that operate on collections using the Stream API.
   *
   * <p>These examples were moved from other TP3 subpackages to centralize all
   * functional idioms in the `functional` package.</p>
   */
  @Slf4j
  public class AppliedFunctionnalExamples {
  
    /**
     * Private constructor to prevent instantiation.
     */
    private AppliedFunctionnalExamples() {
      // utility class
    }
  
    /**
     * Demonstrate mapping and collecting on a list of Person instances.
     */
    public static void listStreamsExample() {
      log.info("=== List stream mapping example ===");
      List<Person> people = List.of(
        Person.of("Charlie", "Brown", 35),
        Person.of("Alice", "Smith", 30),
        Person.of("Bob", "Jones", 25)
      );
      log.info("Original names: {}", people.stream().map(Person::getFullName).toList());
      log.info("Names with ages: {}", people.stream().map(p -> p.getFullName() + "(" + p.age() + ")").toList());
    }
  
    /**
     * Demonstrate streaming over grouped values (e.g. after a grouping operation) to extract names.
     */
    public static void mapStreamGroupingExample() {
      log.info("=== Map grouping stream example ===");
      List<Person> people = List.of(
        Person.of("Alice", "Smith", 30),
        Person.of("Bob", "Jones", 25),
        Person.of("Charlie", "Brown", 35),
        Person.of("David", "Smith", 40)
      );
      Map<String, List<Person>> byLast = people.stream().collect(Collectors.groupingBy(Person::lastName));
      byLast.forEach((ln, ps) -> log.info("{} -> {}", ln, ps.stream().map(Person::getFullName).toList()));
    }
  
    /**
     * Runner for applied functional examples.
     *
     * @param args ignored
     */
    public static void main(String[] args) {
      listStreamsExample();
      mapStreamGroupingExample();
    }
  }