Class: Monetico::Loan

Inherits:
Object
  • Object
show all
Defined in:
lib/monetico/loan.rb

Constant Summary collapse

CADENCE = 
{
  monthly: 12,
  weekly: 52,
}

Instance Method Summary collapse

Constructor Details

#initialize(amount, interest_rate, no_installments, cadence = :monthly, kind = :desc) ⇒ Loan

Returns a new instance of Loan.



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# File 'lib/monetico/loan.rb', line 8

def initialize(amount, interest_rate, no_installments, cadence=:monthly, kind=:desc)
  @amount = amount.big
  @interest_rate = interest_rate.big / CADENCE[cadence] 
  @no_installments = no_installments
  @kind = kind
end

Instance Method Details

#capital ⇒ Object 



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# File 'lib/monetico/loan.rb', line 15

def capital 
  @amount / @no_installments
end

#interests(idx) ⇒ Object 



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# File 'lib/monetico/loan.rb', line 30

def interests(idx)
  (@amount - (idx - 1) * capital) * @interest_rate
end

#payback(range) ⇒ Object 



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# File 'lib/monetico/loan.rb', line 34

def payback(range) 
  from = range.begin
  to = range.end

  if const?
    par = (1 + @interest_rate) ** @no_installments

    range.map do |n|
      { no: n, interests: interests(n), amount: @amount * @interest_rate * par / (par - 1) }
    end
  else
    range.map do |n|
      { no: n, interests: interests(n), amount: capital + interests(n) }
    end
  end 
end

#total_interests ⇒ Object 



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# File 'lib/monetico/loan.rb', line 19

def total_interests
  if const?
    par = (1 + @interest_rate) ** @no_installments
    payback_amount = @amount * @interest_rate * par / (par - 1) 

    payback_amount * @no_installments - @amount 
  else
    0.5.big * @interest_rate * @no_installments * (@amount + capital)
  end
end