isbn check looks ok

src/main.cr

@@ -0,0 +1,122 @@
+require "json"
+# This will check if the ISBN is valid
+# https://en.wikipedia.org/wiki/International_Standard_Book_Number#Check_digits
+
+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