56 lines
1.4 KiB
Elixir
56 lines
1.4 KiB
Elixir
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defmodule LibraryFees do
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def datetime_from_string(string) do
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case NaiveDateTime.from_iso8601(string) do
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{:ok, naive_date_time} -> naive_date_time
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_ -> :error
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end
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end
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def before_noon?(datetime) do
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datetime.hour < 12
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end
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defp days_to_return(checkout_datetime) do
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if(before_noon?(checkout_datetime), do: 28, else: 29)
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end
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def return_date(checkout_datetime) do
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checkout_datetime
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|> NaiveDateTime.add(days_to_return(checkout_datetime), :day)
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|> NaiveDateTime.to_date()
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end
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def days_late(planned_return_date, actual_return_datetime) do
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actual_return_datetime
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|> NaiveDateTime.to_date()
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|> Date.diff(planned_return_date)
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|> case do
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late_in_days when late_in_days > 0 -> late_in_days
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_late_in_days -> 0
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end
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end
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def monday?(datetime) do
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datetime
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|> NaiveDateTime.to_date()
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|> Date.day_of_week(:monday)
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|> case do
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1 -> true
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_ -> false
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end
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end
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def calculate_late_fee(checkout, return, rate) do
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checkout_date_time = datetime_from_string(checkout)
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actual_return_date_time = datetime_from_string(return)
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planed_return_date_time = return_date(checkout_date_time)
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fee = days_late(planed_return_date_time, actual_return_date_time) * rate
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case monday?(actual_return_date_time) do
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true -> floor(fee * 0.5)
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_ -> fee
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end
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end
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end
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