package Body;

import java.util.ArrayList;
import java.util.List;

public class Statistics {
    private static final int RETIREMENT_AGE = 70;
    private double averageAge;
    private double averageAgeOfRetiredEmployees;
    private List<Employee> retiredEmployees;
    private List<Employee> retirementAgedButEmployed;

    public Statistics(List<Employee> employees) {
        retiredEmployees = filterRetiredEmployees(employees);
        retirementAgedButEmployed = filterStillWorkingEmployees(employees);

        averageAge = average(employees);
        averageAgeOfRetiredEmployees = average(retiredEmployees);
    }

    private List<Employee> filterStillWorkingEmployees(List<Employee> employees) {

        List<Employee> workingEmployees = new ArrayList<Employee>();
        for (Employee employee : employees) {

            if (isRetiredAndWorking(employee)) {
                workingEmployees.add(employee);
            }
        }
        return workingEmployees;
    }

    private boolean isRetiredAndWorking(Employee employee) {
        return employee.getAge() >= RETIREMENT_AGE && !employee.isRetired();
    }

    private List<Employee> filterRetiredEmployees(List<Employee> employees) {

        List<Employee> retiredEmployees = new ArrayList<Employee>();
        for (Employee employee : employees) {
            if (employee.isRetired()) {
                retiredEmployees.add(employee);
            }
        }
        return retiredEmployees;
    }

    public double average(List<Employee> employees) {
        double average = 0;
        for (Employee employee : employees) {
            average += employee.getAge();
        }
        return average / employees.size();
    }

    public double getAverageAge() {
        return averageAge;
    }

    public List<Employee> getRetiredEmployees() {
        return retiredEmployees;
    }

    public List<Employee> getRetirementAgedButEmployed() {
        return retirementAgedButEmployed;
    }

    public double getAverageAgeOfRetiredEmployees() {
        return averageAgeOfRetiredEmployees;
    }
}