patient.rb

class Patient
  attr_accessor :id, :room
  attr_reader :name

  def initialize(attributes = {})
    @id = attributes[:id]
    @name = attributes[:name]
    @cured = attributes[:cured] || false

    attributes[:room].add_patient(self)
  end

  def cured?
    @cured
  end
end

# p Patient.new(name: 'forrest')

patient_repository.rb

require "csv"
require_relative 'patient'
require_relative 'room_repository'

class PatientRepository
  def initialize(csv_file, room_repository)
    @csv_file = csv_file
    @room_repository = room_repository

    @patients = []

    load_csv
  end

  def find(patient_id)
    @patients.find { |patient| patient.id == patient_id }
  end

  def find_all_by_room_id(room_id)
    @patients.select { |patient| patient.room_id == room_id.to_i }
  end

  def add_patient(new_patient)
    new_patient.id = @next_id
    @next_id += 1
    @patients << new_patient
    save_csv
  end

  private

  def save_csv
    csv_options = { col_sep: ',', force_quotes: false }

    CSV.open(@csv_file, 'wb', csv_options) do |csv|
      csv << %w{ id name cured room_id }

      @patients.each do |patient|
        csv << [patient.id, patient.name, patient.cured?, patient.room.id]
      end
    end
  end

  def load_csv
    csv_options = {
      headers: :first_row,
      header_converters: :symbol
    }

    CSV.foreach(@csv_file, csv_options) do |row|
      row[:id]    = row[:id].to_i          # Convert column to Fixnum
      row[:cured] = row[:cured] == "true"  # Convert column to boolean

      row[:room]  = @room_repository.find(row[:room_id])

      @patients << Patient.new(row)
    end

    @next_id = @patients.empty? ? 1 : @patients.last.id + 1
  end
end

# room_repo = RoomRepository.new('rooms.csv')
# patient_repo = PatientRepository.new('patients.csv', room_repo)

# room = room_repo.find(3)

# p1 = Patient.new(name: 'allen', room: room)
# patient_repo.add_patient(p1)
# p2 = Patient.new(name: 'Dan')
# repo.add_patient(p2)
# repo.save_csv

# p patient_repo.find(2)

patients.csv

room.rb

require_relative 'patient'

class HospitalError < StandardError
end

class InsufficientCapacityError < HospitalError
end

class Room
  attr_accessor :id
  attr_reader :capacity, :patients

  def initialize(attributes = {})
    @id = attributes[:id]
    @capacity = attributes[:capacity]

    @patients = []
  end

  def full?
    @patients.length == @capacity
  end

  def add_patient(new_patient)
    raise InsufficientCapacityError if full?
    @patients << new_patient
    new_patient.room = self
  end
end

# p1 = Patient.new(name: 'forrest')
# room = Room.new(capacity: 1)
# room.add_patient(p1)
# # p room

# # p p1.room
# puts p1.room == room

# p2 = Patient.new(name: 'arafat')
# room.add_patient(p2)
# p room

room_repository.rb

require "csv"
require_relative 'room'

class RoomRepository
  def initialize(csv_file)
    @csv_file = csv_file

    @rooms = []

    load_csv
  end

  def find(room_id)
    @rooms.find { |room| room.id == room_id.to_i }
  end

  def add_room(new_room)
    new_room.id = @next_id
    @next_id += 1
    @rooms << new_room
    save_csv
  end

  private

  def save_csv
    csv_options = { col_sep: ',', force_quotes: false }

    CSV.open(@csv_file, 'wb', csv_options) do |csv|
      csv << %w{ id capacity }

      @rooms.each do |room|
        csv << [room.id, room.capacity]
      end
    end
  end

  def load_csv
    csv_options = {
      headers: :first_row,
      header_converters: :symbol
    }

    CSV.foreach(@csv_file, csv_options) do |row|
      row[:id]    = row[:id].to_i
      row[:capacity] = row[:capacity].to_i

      @rooms << Room.new(row)
    end

    @next_id = @rooms.empty? ? 1 : @rooms.last.id + 1
  end
end

repo = RoomRepository.new('rooms.csv')

room = repo.find(3)

# require_relative 'patient_repository'

# patient_repo = PatientRepository.new('patients.csv', repo)

# room.patients = patient_repo.find_all_by_room_id(room.id)

p room

# room1 = Room.new(capacity: 10)
# repo.add_room(room1)
# room2 = Room.new(capacity: 20)
# repo.add_room(room2)
# repo.save_csv

# p repo.find(3)

rooms.csv