Merge branch 'calculator-improvements' into 'master'

add support for multiple operatoins per message

See merge request !1

src/main/java/resources/CalculatorResource.java

@@ -37,10 +37,11 @@ public class CalculatorResource {
          * 1+2,
          * 10000+1000
          */
-        if(expressionTrimmed.matches("[0-9]+[+][0-9]+")) result = sum(expressionTrimmed);
-        else if(expressionTrimmed.matches("[0-9]+[-][0-9]+")) result = subtraction(expressionTrimmed);
-        else if (expressionTrimmed.matches("[0-9]+[*][0-9]+")) result = multiplication(expressionTrimmed);
-        else if (expressionTrimmed.matches("[0-9]+[/][0-9]+")) result = division(expressionTrimmed);
+        if(expressionTrimmed.matches("^\\d+(?:\\s*[+]\\s*\\d+)*$")) result = sum(expressionTrimmed);
+        else if(expressionTrimmed.matches("^\\d+(?:\\s*[-]\\s*\\d+)*$")) result = subtraction(expressionTrimmed);
+        else if (expressionTrimmed.matches("^\\d+(?:\\s*[*]\\s*\\d+)*$")) result = multiplication(expressionTrimmed);
+        else if (expressionTrimmed.matches("^\\d+(?:\\s*[/]\\s*\\d+)*$")) result = division(expressionTrimmed);
+        else throw new IllegalArgumentException("Could not parse message");
         
         return result;
     }
@@ -53,10 +54,13 @@ public class CalculatorResource {
     public int sum(String expression){
         String[] split = expression.split("[+]");
 
-        int number1 = Integer.parseInt(split[0]);
-        int number2 = Integer.parseInt(split[1]);
+        int sum = 0;
 
-        return number1 + number2;
+        for (String number : split) {
+            sum += Integer.parseInt(number);
+        }
+
+        return sum;
     }
 
     /**
@@ -67,10 +71,13 @@ public class CalculatorResource {
     public int subtraction(String expression){
         String[] split = expression.split("[-]");
 
-        int number1 = Integer.parseInt(split[0]);
-        int number2 = Integer.parseInt(split[1]);
+        int retval = Integer.parseInt(split[0]);
+
+        for (int i = 1; i < split.length; i++) {
+            retval -= Integer.parseInt(split[i]);
+        }
 
-        return number1 - number2;
+        return retval;
     }
 
     /**
@@ -81,10 +88,13 @@ public class CalculatorResource {
     public int multiplication(String expression){
         String[] split = expression.split("[*]");
 
-        int number1 = Integer.parseInt(split[0]);
-        int number2 = Integer.parseInt(split[1]);
+        int product = 1;
 
-        return number1 * number2;
+        for (String number : split) {
+            product *= Integer.parseInt(number);
+        }
+
+        return product;
     }
 
     /**
@@ -95,9 +105,12 @@ public class CalculatorResource {
     public int division(String expression){
         String[] split = expression.split("[/]");
 
-        int number1 = Integer.parseInt(split[0]);
-        int number2 = Integer.parseInt(split[1]);
+        int numerator = Integer.parseInt(split[0]);
+
+        for (int i = 1; i < split.length; i++) {
+            numerator /= Integer.parseInt(split[i]);
+        }
 
-        return number1 / number2;
+        return numerator;
     }
 }