Modeling Data

patient.eb

class Patient
  attr_reader :name, :cured
  attr_accessor :id, :room # attr_red + attr_writer

  # STATE:
  # - name (String)
  # - cured (Boolean)

  # STRATEGY 1
  # def initialize(name, cured)
  #   @name = name
  #   @cured = cured
  # end

  # STRATEGY 2
  # alternative/improved strategy
  # works for many instance variables
  def initialize(attributes = {})
    @id = attributes[:id]
    @name = attributes[:name]
    @cured = attributes[:cured] || false # adds a default value
    @blood_type = attributes[:blood_type]
    # ...
  end

  # attr_reader (getter)
  # def name
  #   @name
  # end

  # attr_writer (setter)
  # def name=(name)
  #   @name = name
  # end

  def cure
    @cured = true
  end
end

# STRATEGY 1: order of the params matters
# john = Patient.new("John", false)

# STRATEGY 2: order is not important
john = Patient.new({name: "John", cured: false})
mary = Patient.new({cured: true, name: "Mary", blood_type: "O-"})
paul = Patient.new({name: "Paul"})
# curly braces are optional
# if the last argument is an hash
# (Rails uses this syntax everywhere)
susan = Patient.new(name: "Susan", blood_type: "A", cured: true)


# p john
# p mary
# p paul
# p susan.name

# susan.name=("Jane")
# p susan.name

patient_repository.rb

require 'csv'
require_relative 'patient'

class PatientsRepository
  def initialize(csv_file, room_repository)
    @room_repository = room_repository
    @csv_file = csv_file
    @patients = []
    @next_id = 1 # for auto-increment strategy
    load_csv
  end

  def find(id)
    # TODO: return a room with a specific id
  end

  def add(patient)
    # auto-increment strategy
    patient.id = @next_id
    @patients << patient
    @next_id += 1
  end

  private

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

    # go through each row of the csv file

    @next_id = 0
    CSV.foreach(@csv_file, csv_options) do |row|
      # row is a hash like CSV object
      row[:id]    = row[:id].to_i          # Convert column to Integer
      row[:cured] = row[:cured] == "true"  # Convert column to boolean

      # fetch room from the rooms repo
      # with the id row[:room_id]
      room = @room_repository.find(row[:room_id])
      patient.room = room

      @patients << Patient.new(row)
      @next_id = row[:id]
    end

    @next_id += 1
  end
end

repo = PatientsRepository.new("patients.csv")
# john = Patient.new(name: "John")
# susan = Patient.new(name: "Susan")

# repo.add(john)
# repo.add(susan)
p repo

room.rb

require_relative "patient"

class Room
  class CapacityReachedError < Exception; end

  attr_accessor :id
  # STATE?
  # - capacity (Fixnum)
  # - patients (Array of Patient instances)
  def initialize(attributes = {})
    @capacity = attributes[:capacity]
    @patients = attributes[:patients] || [] # set default
  end

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

  def add_patient(patient)
    if full?
      # TODO: raise a custom error
      fail CapacityReachedError, "The room is full"
    else
      @patients << patient
      # inform patient of the room
      patient.room = self # self = the room instance
    end
  end
end

room_1 = Room.new(capacity: 2)
puts "Is it full?"
p room_1.full?

john = Patient.new(name: "John")
room_1.add_patient(john) # Add the patient to the room
# Ask the patient what room he is in?
# p room_1
p john.room

susan = Patient.new(name: "Susan")
room_1.add_patient(susan)

begin
  mary = Patient.new(name: "Mary")
  room_1.add_patient(mary)
# keeps the program from crashing
rescue Room::CapacityReachedError
  puts "Sorry, this room is already full!"
end