Add adjustment to the adjustment list.

## Examples

  iex> ex_cart = ExCart.Cart.new
  iex> adj = ExCart.Adjustment.new("shipping","Shipping",
  ...> fn(x) ->
  ...> sb = ExCart.Cart.subtotal(x)
  ...>  case sb do
  ...>    sb when sb > 25 -> 0
  ...>    _-> 10
  ...>   end
  iex> end)
  iex> ex_cart = ExCart.Cart.add_adjustment(ex_cart,adj)
  iex> length ex_cart.adjustments
  1

Add a new item into the %ExCart.Cart{} structure, if the item already exists on the structure, this function will update the quantity.

## Examples

  iex> ex_cart = ExCart.Cart.new
  iex> ex_cart = ExCart.Cart.add_item(ex_cart,%ExCart.Item{ sku: "SU04", qty: 1, price: 3 })
  iex> ex_cart = ExCart.Cart.add_item(ex_cart,%ExCart.Item{ sku: "SU04", qty: 1, price: 3 })
  %ExCart.Cart{adjustments: [],items: [%ExCart.Item{attr: %{}, price: 3, qty: 2, sku: "SU04"}]}
  iex> ExCart.Cart.subtotal(ex_cart)
  6

Clear the Cart.

Clear adjustments from the Cart.

Clear items from the Cart.

Get the Adjustment.

Get the Adjustment Result.

Creates an empty %ExCart.Cart{} structure, this structure has by default and empty list of items and and empty list of adjustments

## Examples

  iex> ExCart.Cart.new
  %ExCart.Cart{adjustments: [], items: []}

Remove adjustment from adjustment list.

## Examples

iex> excart = ExCart.Cart.new iex> adj = ExCart.Adjustment.new("shipping","Shipping", ...> fn(x) -> ...> sb = ExCart.Cart.subtotal(x) ...> case sb do ...> sb when sb > 25 -> 0 ...> -> 10 ...> end iex> end) iex> ex_cart = ExCart.Cart.add_adjustment(ex_cart, adj) iex> length ex_cart.adjustments 1 iex> ex_cart = ExCart.Cart.remove_adjustment(ex_cart, "shipping") iex> length ex_cart.adjustments 0

Calculate the sum of the result of multiply the price of each item and its quantity

## Examples

  iex> ex_cart = ExCart.Cart.new
  iex> ex_cart = ExCart.Cart.add_item(ex_cart,%ExCart.Item{ sku: "SU04", qty: 10, price: 2 })
  iex> ExCart.Cart.subtotal(ex_cart)
  20

Calculates the total of the cart that include: subtotal + adjustments

## Examples

iex> ex_cart = ExCart.Cart.new
iex> ex_cart = ExCart.Cart.add_item(ex_cart,%ExCart.Item{ sku: "SU04", qty: 5, price: 3 })
iex> adj = ExCart.Adjustment.new("shipping","Shipping",
...> fn(x) ->
...> sb = ExCart.Cart.subtotal(x)
...>case sb do
...>  sb when sb > 25 -> 0
...>  _-> 10
...>end
...>end)
iex> ex_cart = ExCart.Cart.add_adjustment(ex_cart, adj)
iex> ExCart.Cart.total(ex_cart)
25