Class: Owemegod::DebtDistribution

Inherits:
Object
  • Object
show all
Defined in:
lib/owemegod/debt_distribution.rb

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(people) ⇒ DebtDistribution

Returns a new instance of DebtDistribution.



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# File 'lib/owemegod/debt_distribution.rb', line 5

def initialize(people)
  self.people = people
end

Instance Attribute Details

#debts ⇒ Object

Returns the value of attribute debts.



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# File 'lib/owemegod/debt_distribution.rb', line 3

def debts
  @debts
end

#people ⇒ Object

Returns the value of attribute people.



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# File 'lib/owemegod/debt_distribution.rb', line 3

def people
  @people
end

Instance Method Details

#add_debt(from, to, amount) ⇒ Object 



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# File 'lib/owemegod/debt_distribution.rb', line 20

def add_debt(from, to, amount)
  debts << [from, to, amount]
end

#average_expenses ⇒ Object 



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# File 'lib/owemegod/debt_distribution.rb', line 9

def average_expenses
  total_amount = people.reduce(0.0) do |sum, person|
    sum += person.total_expenses
  end
  total_amount / people.length
end

#balance_for(person) ⇒ Object 



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# File 'lib/owemegod/debt_distribution.rb', line 48

def balance_for(person)
  person = people.find{|p| p == person}
  raise "#{person.name} isn't in this distribution" unless person
  initial_balance = average_expenses - person.total_expenses
  initial_balance += incoming_debts_amount(person)
  initial_balance -= outgoing_debts_amount(person)
end

#calculate ⇒ Object 



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# File 'lib/owemegod/debt_distribution.rb', line 56

def calculate
  while(!even?)
    from = most_positive_balance
    to = most_negative_balance

    if balance_for(from) > -balance_for(to)
      add_debt(from, to, -balance_for(to))
    else
      add_debt(from, to, balance_for(from))
    end
  end
end

#even? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/owemegod/debt_distribution.rb', line 77

def even?
  people.all?{|p| balance_for(p) >= 0}
end

#incoming_debts(person) ⇒ Object 



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# File 'lib/owemegod/debt_distribution.rb', line 36

def incoming_debts(person)
  debts.select do |debt|
    debt[1] == person
  end
end

#incoming_debts_amount(person) ⇒ Object 



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# File 'lib/owemegod/debt_distribution.rb', line 42

def incoming_debts_amount(person)
  incoming_debts(person).inject(0.0) do |sum, debt|
    sum += debt[2]
  end
end

#most_negative_balance ⇒ Object 



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# File 'lib/owemegod/debt_distribution.rb', line 73

def most_negative_balance
  people.shuffle.select{|p| balance_for(p) < 0}.min{|p| balance_for(p)}
end

#most_positive_balance ⇒ Object 



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# File 'lib/owemegod/debt_distribution.rb', line 69

def most_positive_balance
  people.shuffle.select{|p| balance_for(p) > 0}.max{|p| balance_for(p)}
end

#outgoing_debts(person) ⇒ Object 



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# File 'lib/owemegod/debt_distribution.rb', line 24

def outgoing_debts(person)
  debts.select do |debt|
    debt[0] == person
  end
end

#outgoing_debts_amount(person) ⇒ Object 



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# File 'lib/owemegod/debt_distribution.rb', line 30

def outgoing_debts_amount(person)
  outgoing_debts(person).inject(0.0) do |sum, debt|
    sum += debt[2]
  end
end