Commit be9f858

@@ -12,17 +12,7 @@ public class CreditCard {
   public CreditCard(String num) {
     this.ccNumber = num;
     this.company = this.identifyCompany(num);
-    String reversed = new StringBuilder(num).reverse().toString();
-    for (int i = 0; i < reversed.length(); i++) {
-      if (!Character.isDigit(reversed.charAt(i))) break;
-
-      int digit = Character.getNumericValue(reversed.charAt(i));
-      if ((i + 1) % 2 == 0) {
-        String value = String.valueOf(digit * 2);
-        for (int j = 0; j < value.length(); j++)
-          this.evenSum += Character.getNumericValue(value.charAt(j));
-      } else this.oddSum += digit;
-    }
+    this.calculateSums(num);
   }
 
   public int getEvenSum() {
@@ -46,11 +36,15 @@ public class CreditCard {
   }
 
   public boolean isValid() {
-    return this.validateCompany() && this.validateLength() && this.validateNumber();
+    return this.validateCompany()
+        && this.validateLength()
+        && this.validateNumber()
+        && this.validateSums()
+        && this.isDivisibleBy10();
   }
 
   public boolean isDivisibleBy10() {
-    return false;
+    return ((this.evenSum + this.oddSum) % 10) == 0;
   }
 
   public boolean validateCompany() {
@@ -71,7 +65,7 @@ public class CreditCard {
   }
 
   public boolean validateSums() {
-    return false;
+    return this.evenSum > 0 && this.oddSum > 0;
   }
 
   private String identifyCompany(String number) {
@@ -90,7 +84,33 @@ public class CreditCard {
     return "Unknown";
   }
 
-  private void puts(String format, Object... args) {
-    System.out.println(String.format(format, args));
+  private void calculateSums(String number) {
+    if (!validateNumber()) return;
+
+    String reversed = this.reverseString(number);
+    for (int i = 0; i < reversed.length(); i++) {
+      int digit = this.digitFrom(reversed, i);
+      if (this.isOdd(i + 1)) this.oddSum += digit;
+      else {
+        String value = String.valueOf(digit * 2);
+        for (int j = 0; j < value.length(); j++) this.evenSum += this.digitFrom(value, j);
+      }
+    }
+  }
+
+  private String reverseString(String value) {
+    return new StringBuilder(value).reverse().toString();
+  }
+
+  private boolean isEven(int number) {
+    return number % 2 == 0;
+  }
+
+  private boolean isOdd(int number) {
+    return !this.isEven(number);
+  }
+
+  private int digitFrom(String input, int index) {
+    return Character.getNumericValue(input.charAt(index));
   }
 }