Class: Money::Allocation

Inherits:
Object
  • Object
show all
Defined in:
lib/money/money/allocation.rb

Class Method Summary collapse

Class Method Details

.generate(amount, parts, whole_amounts = true) ⇒ Object

Splits a given amount in parts without losing pennies. The left-over pennies will be distributed round-robin amongst the parts. This means that parts listed first will likely receive more pennies than the ones listed later.

The results should always add up to the original amount.

The parts can be specified as:

Numeric — performs the split between a given number of parties evenely
Array<Numeric> — allocates the amounts proportionally to the given array

Raises:

  • (ArgumentError) 


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# File 'lib/money/money/allocation.rb', line 15

def self.generate(amount, parts, whole_amounts = true)
  parts = if parts.is_a?(Numeric)
    Array.new(parts, 1)
  elsif parts.all?(&:zero?)
    Array.new(parts.count, 1)
  else
    parts.dup
  end

  raise ArgumentError, 'need at least one party' if parts.empty?

  result = []
  remaining_amount = amount

  until parts.empty? do
    parts_sum = parts.inject(0, :+)
    part = parts.pop

    current_split = 0
    if parts_sum > 0
      current_split = remaining_amount * part / parts_sum
      current_split = current_split.truncate if whole_amounts
    end

    result.unshift current_split
    remaining_amount -= current_split
  end

  result
end