From 940b56ba5fd9246366ff953082c085ae83decaa9 Mon Sep 17 00:00:00 2001
From: n1073645 <n1073645@gmail.com>
Date: Wed, 26 Feb 2020 10:55:15 +0000
Subject: [PATCH] Luhn Checksum Operation Added

---
 src/core/config/Categories.json         |  1 +
 src/core/operations/LuhnChecksum.mjs    | 62 +++++++++++++++++++++++++
 tests/operations/index.mjs              |  1 +
 tests/operations/tests/LuhnChecksum.mjs | 44 ++++++++++++++++++
 4 files changed, 108 insertions(+)
 create mode 100644 src/core/operations/LuhnChecksum.mjs
 create mode 100644 tests/operations/tests/LuhnChecksum.mjs

diff --git a/src/core/config/Categories.json b/src/core/config/Categories.json
index 0d68efe8..459b3071 100755
--- a/src/core/config/Categories.json
+++ b/src/core/config/Categories.json
@@ -332,6 +332,7 @@
             "Fletcher-32 Checksum",
             "Fletcher-64 Checksum",
             "Adler-32 Checksum",
+            "Luhn Checksum",
             "CRC-8 Checksum",
             "CRC-16 Checksum",
             "CRC-32 Checksum",
diff --git a/src/core/operations/LuhnChecksum.mjs b/src/core/operations/LuhnChecksum.mjs
new file mode 100644
index 00000000..24549072
--- /dev/null
+++ b/src/core/operations/LuhnChecksum.mjs
@@ -0,0 +1,62 @@
+/**
+ * @author n1073645 [n1073645@gmail.com]
+ * @copyright Crown Copyright 2020
+ * @license Apache-2.0
+ */
+
+import Operation from "../Operation.mjs";
+import OperationError from "../errors/OperationError.mjs";
+
+/**
+ * Luhn Checksum operation
+ */
+class LuhnChecksum extends Operation {
+
+    /**
+     * LuhnChecksum constructor
+     */
+    constructor() {
+        super();
+
+        this.name = "Luhn Checksum";
+        this.module = "Crypto";
+        this.description = "The Luhn algorithm, also known as the modulus 10 or mod 10 algorithm, is a simple checksum formula used to validate a variety of identification numbers, such as credit card numbers, IMEI numbers, Canadian Social Insurance Numbers.";
+        this.infoURL = "https://wikipedia.org/wiki/Luhn_algorithm";
+        this.inputType = "string";
+        this.outputType = "number";
+        this.args = [];
+    }
+
+    /**
+     * @param {string} input
+     * @param {Object[]} args
+     * @returns {number}
+     */
+    run(input, args) {
+        let even = false;
+        return input.split("").reverse().reduce((acc, elem) => {
+
+            // Convert element to integer.
+            let temp = parseInt(elem, 10);
+
+            // If element is not an integer.
+            if (isNaN(temp))
+                throw new OperationError("Character: " + elem + " is not a digit.");
+
+            // If element is in an even position
+            if (even) {
+
+                // Double the element and add the quotient and remainder together.
+                temp = 2 * elem;
+                temp = Math.floor(temp/10) + (temp % 10);
+            }
+
+            even = !even;
+            return acc + temp;
+
+        }, 0)  % 10;
+    }
+
+}
+
+export default LuhnChecksum;
diff --git a/tests/operations/index.mjs b/tests/operations/index.mjs
index 3257905d..44f57b07 100644
--- a/tests/operations/index.mjs
+++ b/tests/operations/index.mjs
@@ -97,6 +97,7 @@ import "./tests/DefangIP.mjs";
 import "./tests/ParseUDP.mjs";
 import "./tests/AvroToJSON.mjs";
 import "./tests/Lorenz.mjs";
+import "./tests/LuhnChecksum.mjs";
 
 
 // Cannot test operations that use the File type yet
diff --git a/tests/operations/tests/LuhnChecksum.mjs b/tests/operations/tests/LuhnChecksum.mjs
new file mode 100644
index 00000000..28b17854
--- /dev/null
+++ b/tests/operations/tests/LuhnChecksum.mjs
@@ -0,0 +1,44 @@
+/**
+ * From Decimal tests
+ *
+ * @author n1073645 [n1073645@gmail.com]
+ * @copyright Crown Copyright 2020
+ * @licence Apache-2.0
+ */
+import TestRegister from "../../lib/TestRegister.mjs";
+
+TestRegister.addTests([
+    {
+        name: "Luhn Checksum on standard data",
+        input: "35641709012469",
+        expectedOutput: "7",
+        recipeConfig: [
+            {
+                op: "Luhn Checksum",
+                args: []
+            },
+        ],
+    },
+    {
+        name: "Luhn Checksum on invalid data",
+        input: "35641709b012469",
+        expectedOutput: "Character: b is not a digit.",
+        recipeConfig: [
+            {
+                op: "Luhn Checksum",
+                args: []
+            },
+        ],
+    },
+    {
+        name: "Luhn Checksum on empty data",
+        input: "",
+        expectedOutput: "0",
+        recipeConfig: [
+            {
+                op: "Luhn Checksum",
+                args: []
+            },
+        ],
+    }
+]);