require "json"
# This will check if the ISBN is valid
# https://en.wikipedia.org/wiki/International_Standard_Book_Number#Check_digits


# get data from inventaire.io
url =  "https://inventaire.io/api/entities?action=by-uris&uris=isbn%3A#{isbn}&refresh=false"




a = "978-0-306-40615"
b = "12-31231 23.1aa"
c = "0-306-406v155"

isbn10 = "2234086167"
isbn13 = "978-2234086166"

def remove_hyphen_space(isbn_code)
	isbn_code = isbn_code.gsub(/[- .]/, "")
	return isbn_code
end


def is_valid_isbn(isbn_code)
	isbn_code = remove_hyphen_space(isbn_code)
	array = isbn_code.chars
	pp array

	if isbn_code =~ /^[0-9]*$/ 
		pp "ok number only"
		if isbn_code.size == 10
			pp "isbn10"
			pp "check_digit_isbn10"
			i = check = 0
			t = 10
			while i < 9
				check = array[i].to_i * (t - i) + check
				i = i + 1
			end
			pp	result = ( 11 - (check % 11)) % 11
			if (result - array[9].to_i) == 0
				pp "isbn10 is ok"
			else
				pp "isbn10 check key fail"
			end
		elsif isbn_code.size ==13
			pp "isbn13"
			pp "check_digit_isbn13"
			i = check = 0
			while i < 12
				if i % 2 == 0 
					check = array[i].to_i + check
				else
					check = 3 * array[i].to_i + check
				end
				i = i + 1
			end
			pp	result = 10 - (check % 10)
			if result - array[12].to_i == 0
				pp "isbn13 is ok"
			else
				pp "isbn13 check key fail"
			end
		else
			pp "wrong size"
			return false
		end
	else
		pp "ko not only number"
		return false
	end
end



#array.each do |x|
#	x = x.to_i8?
#	case x
#	when Int8
#		else
#			pp "error"
#		end 
#	end
#end

is_valid_isbn(isbn10)
is_valid_isbn(isbn13)

is_valid_isbn(c)
is_valid_isbn(a)
is_valid_isbn(b)


# from oder source
class ISBN::IsValid
  def self.new(isbn : String)
    # Check to make sure string has valid encoding and raise execption if not
    raise Exceptions::Generic.new("ISBN isn't valid") unless isbn.valid_encoding?

    # Remove `-` characters since we want to properly check value
    if (isbn =~ /-/)
      isbn = isbn.split(/-/).join
    end

    case isbn.size
      when 10
        ISBN::IsValid.valid_isbn_10(isbn)
      when 13
        ISBN::IsValid.valid_isbn_13(isbn)
      else
        false
    end
  end

  # There's probably a more elegant way to do the defs below
  # Return false if numbers aren't correct
  def self.valid_isbn_10(isbn : String)
    return false unless isbn.match(/^[0-9]{9}[0-9X]$/)
    return true
  end
  def self.valid_isbn_13(isbn : String)
    return false unless isbn.match(/^[0-9]{12}[0-9X]$/)
    return true   
  end
  
end