updated util hash function and tests

Author: ChadKluck

application-infrastructure/src/tests/index.mjs

@@ -135,35 +135,79 @@ describe('Test validations from config/validations.js', () => {
  */
 
 describe('Test utils', () => {
-	describe('utils.hash.hashLast8', () => {
+	describe('utils.hash.takeLast', () => {
 		it('should return a string of length 8', () => {
 			const input = 'example';
-			const result = utils.hash.hashLast8(input);
+			const result = utils.hash.takeLast(input);
 			expect(result).to.be.a('string');
 			expect(result).to.have.lengthOf(8);
 		});
 
+		it('should return a string of length 6', () => {
+			const input = 'example';
+			const result = utils.hash.takeLast(input, 6);
+			expect(result).to.be.a('string');
+			expect(result).to.have.lengthOf(6);
+		});
+
 		it('should return a different string for different inputs', () => {
 			const input1 = 'example1';
 			const input2 = 'example2';
-			const result1 = utils.hash.hashLast8(input1);
-			const result2 = utils.hash.hashLast8(input2);
+			const result1 = utils.hash.takeLast(input1);
+			const result2 = utils.hash.takeLast(input2);
 			expect(result1).to.not.equal(result2);
 		});
 
 		it('should return the same string for the same input', () => {
 			const input = 'example';
-			const result1 = utils.hash.hashLast8(input);
-			const result2 = utils.hash.hashLast8(input);
+			const result1 = utils.hash.takeLast(input);
+			const result2 = utils.hash.takeLast(input);
 			expect(result1).to.equal(result2);
 		});
 
 		it('should return a string containing only valid characters', () => {
 			const input = 'example';
-			const result = utils.hash.hashLast8(input);
+			const result = utils.hash.takeLast(input, 20);
 			expect(result).to.match(/^[a-f0-9]+$/);
 		});
 	});
+
+	describe('utils.hash.takeFirst', () => {
+		it('should return a string of length 8', () => {
+			const input = 'example';
+			const result = utils.hash.takeFirst(input);
+			expect(result).to.be.a('string');
+			expect(result).to.have.lengthOf(8);
+		});
+
+		it('should return a string of length 6', () => {
+			const input = 'example';
+			const result = utils.hash.takeFirst(input, 6);
+			expect(result).to.be.a('string');
+			expect(result).to.have.lengthOf(6);
+		});
+
+		it('should return a different string for different inputs', () => {
+			const input1 = 'example1';
+			const input2 = 'example2';
+			const result1 = utils.hash.takeFirst(input1);
+			const result2 = utils.hash.takeFirst(input2);
+			expect(result1).to.not.equal(result2);
+		});
+
+		it('should return the same string for the same input', () => {
+			const input = 'example';
+			const result1 = utils.hash.takeFirst(input);
+			const result2 = utils.hash.takeFirst(input);
+			expect(result1).to.equal(result2);
+		});
+
+		it('should return a string containing only valid characters', () => {
+			const input = 'example';
+			const result = utils.hash.takeFirst(input, 20);
+			expect(result).to.match(/^[a-f0-9]+$/);
+		});
+	})
 });
 
 /* ****************************************************************************

application-infrastructure/src/utils/hash.js

@@ -1,12 +1,58 @@
 const crypto = require('crypto');
 
 /**
- * Hash a string using SHA256 and return the last 8 characters
+ * Validates input for takeFirst and takeLast
+ * @param {string} input 
+ * @param {number} n 
+ * @returns {boolean} - True if input is valid, false otherwise}
+ */
+const isValidSliceInput = (input, n) => {
+    // throw error if input is not a string
+    if (typeof input !== 'string') {
+        throw new Error('input must be a string');
+    }
+    // throw error if n is not a number
+    if (typeof n !== 'number') {
+        throw new Error('n must be a number');
+    }
+    // throw error if n is less than 1
+    if (n < 1) {
+        throw new Error('n must be greater than 0');
+    }
+    // throw error if n is greater than 64
+    if (n > 64) {
+        throw new Error('n must be 64 or less');
+    }
+    return true;
+}
+
+/**
+ * Hash a string using SHA256 and return the last set of characters
  * @param {string} input - The string to hash
- * @returns {string} The last 8 characters of the SHA256 hash
+ * @param {number} n - The number of characters to return (default: 8)
+ * @returns {string} The last set of characters of the SHA256 hash
  */
-const hashLast8 = (input) => {
-    return crypto.createHash('sha256').update(input).digest('hex').slice(-8);
+const takeLast = (input, n=8) => {
+    if (!isValidSliceInput(input, n)) {
+        return "";
+    } else {
+        return crypto.createHash('sha256').update(input).digest('hex').slice(-n);
+    }
 };
 
-module.exports = { hashLast8 };
+/**
+ * Hash a string using SHA256 and return the first set of characters
+ * @param {string} input - The string to hash
+ * @param {number} n - The number of characters to return (default: 8)
+ * @returns {string} The first set of characters of the SHA256 hash
+ */
+const takeFirst = (input, n=8) => {
+    if (!isValidSliceInput(input, n)) {
+        return "";
+    } else {
+        return crypto.createHash('sha256').update(input).digest('hex').slice(0, n);
+    }
+};
+
+
+module.exports = { takeLast, takeFirst };

application-infrastructure/src/views/example.view.js

@@ -33,7 +33,7 @@ const transform = (data) => {
 	// take data and create an 8 character hash
 	// since we only expect a list of <20 games this is okay for an example
 	// using sha256, create a hash and retain the last 8 characters
-	const hashId = utils.hash.hashLast8(data);
+	const hashId = utils.hash.takeLast(data, 8);
 
 	const returnData = {
 		id: `G-${hashId}`,