Oyster another approach

gistfile1.txt

require './lib/journey'
require './lib/journey_history'

class Oyster
  MAX_BALANCE = 50
  MIN_FARE = 1.7

  attr_reader :balance, :customer_id, :journey_history

  def initialize(balance: 0, customer_id:)
    @balance = balance
    @customer_id = customer_id
    @journey_history = JourneyHistory.new
  end

  def top_up(amount)
    raise "Max top of #{max_top_up} reached" if max_balance_reached?(amount)
    @balance += amount
  end

  def tap_in(start_zone)
    raise "Please Top up Oyster Card" if balance < MIN_FARE
    deduct_fare(current_journey.fare(start_zone)) if @current_journey
    @current_journey = Journey.new(start_zone: start_zone)
  end

  def tap_out(end_zone)
    current_journey.end(end_zone)
    deduct_fare(current_journey.fare(end_zone))
    journey_history.add(current_journey)

    # Sets the current journey back to nil as this is now completed.
    @current_journey = nil
  end

  def current_journey
    @current_journey || Journey.new
  end

  private

  def max_balance_reached?(amount)
    (amount + balance) > MAX_BALANCE
  end

  def deduct_fare(fare)
    puts "Deducting £#{fare} from your balance of £#{balance}. New balance #{balance - fare}"
    @balance -= fare
  end
end

p o = Oyster.new(balance: 50, customer_id: 1)
# A 5 penalty fare should be charged.
p o.tap_in(1)
p "----------"
# A 2.90 fare should be charged.
p o.tap_in(1)
p o.tap_out(2)
p "----------"
# A 1.70 fare should be charged.
p o.tap_in(3)
p o.tap_out(4)
p "----------"
# A penalty fare should be raised
p o.tap_out(5)
p "----------"


-------

class JourneyHistory
  attr_reader :journeys

  def initialize(journeys=[])
    @journeys = journeys
  end

  def add(journey)
    journeys << journey
  end 
end


-------

class Journey
  attr_reader :start_zone, :end_zone

  ZONE_FARES =  [
                  [2.4, 2.9, 3.3, 3.9, 4.7],
                  [2.9, 1.7, 1.7, 2.4, 2.8],
                  [3.3, 1.7, 1.7, 1.7, 2.4],
                  [3.9, 2.4, 1.7, 1.7, 1.7],
                  [4.7, 2.8, 2.4, 1.7, 1.7]
                ]

  PENALTY_FARE = 5

  def initialize(start_zone: nil)
    @start_zone = start_zone
    @end_zone = nil
    fare = nil
  end

  def end(end_zone)
    @end_zone = end_zone
  end

  def fare(end_zone)
    return PENALTY_FARE if penalty_fare?
    ZONE_FARES[start_zone - 1][end_zone -1]
  end

  private

  def complete?
    start_zone && end_zone && fare
  end

  def penalty_fare?
    !start_zone || !end_zone
  end
end