require_relative '../student'
require_relative '../student_short'
require_relative '../data_list_student_short'
require_relative '../data_table'

class StudentsList
  attr_reader :students

  def initialize(filename, persistence_strategy)
    @filename = filename
    @persistence_strategy = persistence_strategy
    @students = []
  end

  # Загрузка студентов через выбранную стратегию
  def load
    @students = @persistence_strategy.load(@filename)
    self
  end

  # Сохранение студентов через выбранную стратегию
  def save
    @persistence_strategy.save(@filename, @students)
    self
  end

  def get_student_by_id(id)
    @students.find { |s| s.id.to_s == id.to_s }
  end

  # Получить список из k студентов (страница n) в виде объекта DataList
  def get_k_n_student_short_list(k, n, data_list = nil)
    start_index = (n - 1) * k
    sorted_students = @students.sort_by { |s| s.surname_initials }
    selected_students = sorted_students[start_index, k] || []
    short_objects = selected_students.map { |s| StudentShort.from_student(s) }

    if data_list && data_list.is_a?(DataList)
      if data_list.respond_to?(:items=)
        data_list.items = short_objects
      else
        data_list = DataListStudentShort.new(short_objects)
      end
      data_list
    else
      DataListStudentShort.new(short_objects)
    end
  end

  # Сортировка студентов по фамилии и инициалам
  def sort_students!
    @students.sort_by! { |s| s.surname_initials }
  end

  def add_student(student)
    new_id = if @students.empty?
               1
             else
               max_id = @students.map { |s| s.id.to_i }.max
               max_id + 1
             end
    student.id = new_id.to_s
    @students << student
    student
  end

  def update_student_by_id(id, new_student)
    index = @students.find_index { |s| s.id.to_s == id.to_s }
    if index
      new_student.id = @students[index].id
      @students[index] = new_student
      true
    else
      false
    end
  end

  def delete_student_by_id(id)
    initial_count = @students.size
    @students.reject! { |s| s.id.to_s == id.to_s }
    initial_count != @students.size
  end

  def get_student_short_count
    @students.size
  end
end