Besides providing exceptional transportation services, Cabify also runs a physical store which sells (only) 3 products:
Code | Name | Price
-------------------------------------------------
VOUCHER | Cabify Voucher | 5.00€
TSHIRT | Cabify T-Shirt | 20.00€
MUG | Cafify Coffee Mug | 7.50€
Various departments have insisted on the following discounts:
-
The marketing department believes in 2-for-1 promotions (buy two of the same product, get one free), and would like for there to be a 2-for-1 special on
VOUCHERitems. -
The CFO insists that the best way to increase sales is with discounts on bulk purchases (buying x or more of a product, the price of that product is reduced), and demands that if you buy 3 or more
TSHIRTitems, the price per unit should be 19.00€.
Cabify's checkout process allows for items to be scanned in any order, and should return the total amount to be paid.
Examples:
Items: VOUCHER, TSHIRT, MUG
Total: 32.50€
Items: VOUCHER, TSHIRT, VOUCHER
Total: 25.00€
Items: TSHIRT, TSHIRT, TSHIRT, VOUCHER, TSHIRT
Total: 81.00€
Items: VOUCHER, TSHIRT, VOUCHER, VOUCHER, MUG, TSHIRT, TSHIRT
Total: 74.50€
Firstly, you need to initialize a Checkout.
You can do it without any Pricing Rule:
iex(1)> checkout = ExCabify.Checkout.new()
%ExCabify.Checkout{codes: [], pricing_rules: []}or with all of them:
iex(2)> pricing_rules = ExCabify.PricingRules.all()
[
%ExCabify.PricingRules.BulkPurchase{
applicable_code: "TSHIRT",
applicable_count: 3,
reduced_prize: 19.0
},
%ExCabify.PricingRules.XForY{
applicable_code: "VOUCHER",
applicable_count: 2,
reduced_count: 1
}
]
iex(3)> checkout = ExCabify.Checkout.new(pricing_rules)
%ExCabify.Checkout{
codes: [],
pricing_rules: [
%ExCabify.PricingRules.BulkPurchase{
applicable_code: "TSHIRT",
applicable_count: 3,
reduced_prize: 19.0
},
%ExCabify.PricingRules.XForY{
applicable_code: "VOUCHER",
applicable_count: 2,
reduced_count: 1
}
]
}You can define them in priv/pricing_rules/ directory.
Then, you are able to scan any code:
iex(4)> checkout = ExCabify.Checkout.scan(checkout, "TSHIRT")
%ExCabify.Checkout{
codes: ["TSHIRT"],
pricing_rules: [
%ExCabify.PricingRules.BulkPurchase{
applicable_code: "TSHIRT",
applicable_count: 3,
reduced_prize: 19.0
},
%ExCabify.PricingRules.XForY{
applicable_code: "VOUCHER",
applicable_count: 2,
reduced_count: 1
}
]
}
iex(5)> checkout = ExCabify.Checkout.scan(checkout, "TSHIRT")
%ExCabify.Checkout{
codes: ["TSHIRT", "TSHIRT"],
pricing_rules: [
%ExCabify.PricingRules.BulkPurchase{
applicable_code: "TSHIRT",
applicable_count: 3,
reduced_prize: 19.0
},
%ExCabify.PricingRules.XForY{
applicable_code: "VOUCHER",
applicable_count: 2,
reduced_count: 1
}
]
}
iex(6)> checkout = ExCabify.Checkout.scan(checkout, "MUG")
%ExCabify.Checkout{
codes: ["MUG", "TSHIRT", "TSHIRT"],
pricing_rules: [
%ExCabify.PricingRules.BulkPurchase{
applicable_code: "TSHIRT",
applicable_count: 3,
reduced_prize: 19.0
},
%ExCabify.PricingRules.XForY{
applicable_code: "VOUCHER",
applicable_count: 2,
reduced_count: 1
}
]
}Finally, you can calculate the Total Price:
iex(7)> ExCabify.Checkout.total(checkout)
32.5To run the test suite, execute:
➜ ex_cabify git:(master) ✗ mix test
..........................
Finished in 0.1 seconds
26 tests, 0 failures
Randomized with seed 37474
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