Trying to implement a method to discount products' prices (Ruby)

Question

I have this list of products, and I would like to implement a method to change the price of the items according to how much the user buys. So I create 3 products:

item1 = Item.new("item1", 5.00)
item2 = Item.new("item2", 10.00)
item3 = Item.new("item3", 8.00)

Then I have this logic that says for item2 the user can buy 2 items for the price of 1, then for item 2 if the user buys 3 or more there is 1$ discount per unit.

user_input = nil
item_list = []

until user_input == "stop"
  puts 'Which item would you like to add? (type "stop" to exit purchase)'
  user_input = gets.chomp
  if user_input == "item1"
    if item_list.count("item1") % 2 == 0
      item1.price = 2.5
    else
      discount_item1 = item_list.count("item1") - 1
      item1.price = (discount_item1 * 2.5) + 5.00
    end
    item_list << item1
  end

  if user_input == "item2"
    if item_list.count("item2") >= 3
      tshirt.price = 19.00
    else
      tshirt.price = 20.00
    end
    item_list << item2
  end

  if user_input == "item3"
    item_list << item3
  end
end


print "Items:"
sum = item_list.inject(0) do |sum, item|
  print " #{item.name},"
  sum += item.price
end
puts "Total: #{sum}"

Obviously the logic doesn't work. Anyone has any thoughts on doing it? I was thinking do a class Checkout in which I have a method pricing_rules that define all the rules for prices but don't know how to implement it.

---

Answer 1

Considering the fact that you are trying to implement the logic that

1. Item1 the user can buy 2 items for the price of 1
2. Item2 if the user buys 3 or more there is 1$ discount per unit.
3. Item3 no discount

Here is the required code :

user_input = nil
item_list = []
item1_count = 0
item2_count = 0
item3_count = 0
until user_input == "stop"
  puts 'Which item would you like to add? (type "stop" to exit purchase)'
  user_input = gets.chomp
  if user_input == "item1"
    item1_count += 1
  elsif user_input == 'item2'
    item2_count += 1
  elsif user_input == "item3"
    item3_count += 1
    item_list << Item.new('item3', 8)
  end
end

if item1_count.even?
  item1_count.times {item_list << Item.new('item1', 2.5)}
else
  (item1_count-1).times {item_list << Item.new('item1', 2.5)}
  item_list << Item.new('item1', 5)
end

item2_price = (item2_count >= 3) ? 19 : 20
item2_count.times {item_list << Item.new('item2', item2_price)}


print "Items:"
sum = item_list.inject(0) do |sum, item|
  print " #{item.name},"
  sum += item.price
end
puts "Total: #{sum}"

Hope this helps.