learn-co-students / green_grocer-nyc-web-071618

Objectives

Create a checkout method to calculate the total cost of a cart of items and apply discounts and coupons as necessary.

Dr. Steve Bruhle, your green grocer, isn't ready, but you are!

Instructions

Implement a method checkout to calculate total cost of a cart of items and apply discounts and coupons as necessary. The checkout method will rely on the consolidate_cart, apply_coupons, and the apply_clearance methods.

The consolidate_cart method

The cart starts as an array of individual items. Translate it into a hash that includes the counts for each item with the consolidate_cart method.

For instance, if the method is given the array below:

[
  {"AVOCADO" => {:price => 3.0, :clearance => true }},
  {"AVOCADO" => {:price => 3.0, :clearance => true }},
  {"KALE"    => {:price => 3.0, :clearance => false}}
]

then the method should return the hash below:

{
  "AVOCADO" => {:price => 3.0, :clearance => true, :count => 2},
  "KALE"    => {:price => 3.0, :clearance => false, :count => 1}
}

The apply_coupons method

If the method is given a cart that looks like this:

{
  "AVOCADO" => {:price => 3.0, :clearance => true, :count => 3},
  "KALE"    => {:price => 3.0, :clearance => false, :count => 1}
}

and a coupon for avocados that looks like this:

{:item => "AVOCADO", :num => 2, :cost => 5.0}

then apply_coupons should return the following hash:

{
  "AVOCADO" => {:price => 3.0, :clearance => true, :count => 1},
  "KALE"    => {:price => 3.0, :clearance => false, :count => 1},
  "AVOCADO W/COUPON" => {:price => 5.0, :clearance => true, :count => 1},
}

Notice how there were three avocados in the cart, but the coupon only applied to two of them. This left one un-couponed avocado in the cart at $3.00 and one "bundle" of discounted avocados totalling $5.00.

The apply_clearance method

This method should discount the price of every item on clearance by twenty percent.

For instance, if this method was given this cart:

{
  "PEANUTBUTTER" => {:price => 3.00, :clearance => true,  :count => 2},
  "KALE"         => {:price => 3.00, :clearance => false, :count => 3}
  "SOY MILK"     => {:price => 4.50, :clearance => true,  :count => 1}
}

it should return a cart with clearance applied to peanutbutter and soy milk:

{
  "PEANUTBUTTER" => {:price => 2.40, :clearance => true,  :count => 2},
  "KALE"         => {:price => 3.00, :clearance => false, :count => 3}
  "SOY MILK"     => {:price => 3.60, :clearance => true,  :count => 1}
}

The checkout method

Create a checkout method that calculates the total cost of the consolidated cart.

When checking out, follow these steps in order:

• Apply coupon discounts if the proper number of items are present.

• Apply 20% discount if items are on clearance.

• If, after applying the coupon discounts and the clearance discounts, the cart's total is over $100, then apply a 10% discount.

Named Parameters

The method signature for the checkout method is consolidate_cart(cart:[]). This, along with the checkout method uses a ruby 2.0 feature called Named Parameters.

Named parameters give you more expressive code since you are specifying what each parameter is for. Another benefit is the order you pass your parameters doesn't matter! checkout(cart: [], coupons: []) is the same as checkout(coupons: [], cart: [])

Resources

• Named Parameters

Reward

• Dr. Brule

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