ISSUE andrewagain#16 bug-fix

src/component/App.js

@@ -9,6 +9,10 @@ export default class App extends React.Component {
     total: null,
     next: null,
     operation: null,
+    higherOrder: {
+      next: null,
+      operation: null,
+    },
   };
 
   handleClick = buttonName => {

src/logic/calculate.js

@@ -18,13 +18,25 @@ export default function calculate(obj, buttonName) {
       total: null,
       next: null,
       operation: null,
+      // clear high order values
+      higherOrder: {},
     };
   }
 
   if (isNumber(buttonName)) {
     if (buttonName === "0" && obj.next === "0") {
       return {};
     }
+    // If there is a higher order operation
+    if (obj.higherOrder && obj.higherOrder.operation) {
+      return {
+        higherOrder: {
+          // set higher order number
+          next: buttonName,
+          operation: obj.higherOrder.operation,
+        },
+      };
+    }
     // If there is an operation, update next
     if (obj.operation) {
       if (obj.next) {
@@ -111,11 +123,75 @@ export default function calculate(obj, buttonName) {
 
   // User pressed an operation button and there is an existing operation
   if (obj.operation) {
-    return {
-      total: operate(obj.total, obj.next, obj.operation),
-      next: null,
-      operation: buttonName,
-    };
+    // ISSUE #16 - Calculator makes the sum of the two previous numbers before multiplying
+    // If there is a higher order value, perform calculation
+    if (obj.higherOrder && obj.higherOrder.next) {
+      // calculate higher operation with next values
+      const higherOrderTotal = operate(
+        obj.next,
+        obj.higherOrder.next,
+        obj.higherOrder.operation,
+      );
+      if (isHigherOrderOperation(buttonName)) {
+        // Next is higher order operation
+        return {
+          // Don't calculate total yet
+          next: higherOrderTotal,
+          higherOrder: {
+            next: null,
+            // set higher order operation
+            operation: buttonName,
+          },
+        };
+      } else {
+        // Next is lower order operation
+        return {
+          // Calculate total
+          total: operate(obj.total, higherOrderTotal, obj.operation),
+          next: null,
+          // set lower order operation
+          operation: buttonName,
+          higherOrder: {
+            next: null,
+            operation: null,
+          },
+        };
+      }
+    }
+    // If operation is a higher order operation, perform calculation
+    if (isHigherOrderOperation(obj.operation)) {
+      return {
+        // perform total calculation
+        total: operate(obj.total, obj.next, obj.operation),
+        next: null,
+        // set operation
+        operation: buttonName,
+      };
+    }
+    // If next operation is a lower order operation
+    if (!isHigherOrderOperation(buttonName)) {
+      return {
+        // perform total calculation
+        total: operate(obj.total, obj.next, obj.operation),
+        next: null,
+        // set operation
+        operation: buttonName,
+        higherOrder: {
+          next: null,
+          operation: null,
+        },
+      };
+    }
+    // If next operation is a higher order operation
+    if (isHigherOrderOperation(buttonName)) {
+      return {
+        higherOrder: {
+          next: null,
+          // set operation
+          operation: buttonName,
+        },
+      };
+    }
   }
 
   // no operation yet, but the user typed one
@@ -132,3 +208,10 @@ export default function calculate(obj, buttonName) {
     operation: buttonName,
   };
 }
+
+// Did user press a higher order operation button
+function isHigherOrderOperation(operation) {
+  if (operation === "x" || operation === "÷") {
+    return true;
+  }
+}

src/logic/calculate.test.js

@@ -87,17 +87,29 @@ describe("calculate", function() {
   test(["+", "2", "+"], {
     total: "2",
     operation: "+",
+    higherOrder: {
+      next: null,
+      operation: null,
+    },
   });
 
   test(["+", "2", "+", "+"], {
     total: "2",
     operation: "+",
+    higherOrder: {
+      next: null,
+      operation: null,
+    },
   });
 
   test(["+", "2", "+", "5"], {
     next: "5",
     total: "2",
     operation: "+",
+    higherOrder: {
+      next: null,
+      operation: null,
+    },
   });
 
   test(["+", "2", "5"], {
@@ -112,6 +124,10 @@ describe("calculate", function() {
 
   test(["+", "6", "+", "5", "="], {
     total: "11",
+    higherOrder: {
+      next: null,
+      operation: null,
+    },
   });
 
   test(["0", ".", "4"], {
@@ -133,8 +149,8 @@ describe("calculate", function() {
   });
 
   // should clear the operator when AC is pressed
-  test(["1", "+", "2", "AC"], {});
-  test(["+", "2", "AC"], {});
+  test(["1", "+", "2", "AC"], { higherOrder: {} });
+  test(["+", "2", "AC"], { higherOrder: {} });
 
   test(["4", "%"], {
     next: "0.04",
@@ -158,16 +174,17 @@ describe("calculate", function() {
   //Test that pressing the multiplication or division sign multiple times should not affect the current computation
   test(["2", "x", "x"], {
     total: "2",
-    operation: "x"
+    operation: "x",
   });
 
   test(["2", "÷", "÷"], {
     total: "2",
-    operation: "÷"
+    operation: "÷",
   });
 
   test(["2", "÷", "x", "+", "-", "x"], {
     total: "2",
-    operation: 'x'
+    operation: "-",
+    higherOrder: { next: null, operation: "x" },
   });
 });