84 lines
2.6 KiB
Ruby
84 lines
2.6 KiB
Ruby
# frozen_string_literal: true
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# License: AGPL-3.0-or-later WITH WTO-AP-3.0-or-later
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# Full license explanation at https://github.com/houdiniproject/houdini/blob/master/LICENSE
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require 'numeric'
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module CalculateSuggestedAmounts
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MIN = 25
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MAX = 100_000_000
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BRACKETS = [{ range: MIN...1000, delta: 100 },
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{ range: 1000...5000, delta: 500 },
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{ range: 5000...MAX, delta: 2500 }].freeze
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# Calculates a set of suggested donation amounts based upon our internal special algorithm
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# This is most useful for suggesting amounts a recurring donor could change to
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# @return [Array<Integer>] suggested amounts for your donation
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# @param [Number] amount the amount in cents to start from
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def self.calculate(amount)
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ParamValidation.new({ amount: amount }, amount: { required: true, is_a: Numeric, min: MIN, max: MAX })
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result = []
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step_down_val = step_down_value(amount)
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result.push(step_down_val) unless step_down_val.nil?
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higher_amounts = []
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while higher_amounts.empty? || (higher_amounts.length < 3 && !higher_amounts.last.nil?)
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if higher_amounts.empty?
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higher_amounts.push(step_up_value(amount))
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else
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higher_amounts.push(step_up_value(higher_amounts.last))
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end
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end
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result.concat(higher_amounts.reject(&:nil?))
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end
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def self.step_down_value(amount)
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initial_bracket = get_bracket_by_amount(amount)
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# check_floor_for_delta
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delta_floor = amount.floor_for_delta(initial_bracket[:delta])
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# not on a delta, just send a floor
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if delta_floor != amount
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return delta_floor < MIN ? nil : delta_floor
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end
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potential_lower_amount = amount - initial_bracket[:delta]
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# is potential_lower_amount < our MIN? if so, return nil
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return nil if potential_lower_amount < MIN
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new_bracket = get_bracket_by_amount(potential_lower_amount)
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# if in same bracket, potential_lower_amount is our step_down_value
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return potential_lower_amount if initial_bracket == new_bracket
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# we're going to step down by our new bracket value then
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amount - new_bracket[:delta]
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end
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def self.step_up_value(amount)
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bracket = get_bracket_by_amount(amount)
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# check_ceil_for_delta
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delta_ceil = amount.ceil_for_delta(bracket[:delta])
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# not on a delta, just send a ceil
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if delta_ceil != amount
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return delta_ceil >= MAX ? nil : delta_ceil
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end
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potential_higher_amount = amount + bracket[:delta]
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# is potential_lower_amount < our MIN? if so, return nil
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return nil if potential_higher_amount >= MAX
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potential_higher_amount
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end
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def self.get_bracket_by_amount(amount)
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BRACKETS.detect { |i| i[:range].cover?(amount) }
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end
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end
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