wip

backend/util-common.ts

@@ -0,0 +1,118 @@
+import dayjs from "dayjs";
+
+// For loading dayjs plugins, don't remove event though it is not used in this file
+import timezone from "dayjs/plugin/timezone";
+import utc from "dayjs/plugin/utc";
+
+import { randomBytes } from "crypto";
+
+export const isDev = process.env.NODE_ENV === "development";
+
+/**
+ * Generate a decimal integer number from a string
+ * @param str Input
+ * @param length Default is 10 which means 0 - 9
+ */
+export function intHash(str : string, length = 10) : number {
+    // A simple hashing function (you can use more complex hash functions if needed)
+    let hash = 0;
+    for (let i = 0; i < str.length; i++) {
+        hash += str.charCodeAt(i);
+    }
+    // Normalize the hash to the range [0, 10]
+    return (hash % length + length) % length; // Ensure the result is non-negative
+}
+
+/**
+ * Delays for specified number of seconds
+ * @param ms Number of milliseconds to sleep for
+ */
+export function sleep(ms: number) {
+    return new Promise(resolve => setTimeout(resolve, ms));
+}
+
+/**
+ * Generate a random alphanumeric string of fixed length
+ * @param length Length of string to generate
+ * @returns string
+ */
+export function genSecret(length = 64) {
+    let secret = "";
+    const chars = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789";
+    const charsLength = chars.length;
+    for ( let i = 0; i < length; i++ ) {
+        secret += chars.charAt(getCryptoRandomInt(0, charsLength - 1));
+    }
+    return secret;
+}
+
+/**
+ * Get a random integer suitable for use in cryptography between upper
+ * and lower bounds.
+ * @param min Minimum value of integer
+ * @param max Maximum value of integer
+ * @returns Cryptographically suitable random integer
+ */
+export function getCryptoRandomInt(min: number, max: number):number {
+
+    // synchronous version of: https://github.com/joepie91/node-random-number-csprng
+
+    const range = max - min;
+    if (range >= Math.pow(2, 32)) {
+        console.log("Warning! Range is too large.");
+    }
+
+    let tmpRange = range;
+    let bitsNeeded = 0;
+    let bytesNeeded = 0;
+    let mask = 1;
+
+    while (tmpRange > 0) {
+        if (bitsNeeded % 8 === 0) {
+            bytesNeeded += 1;
+        }
+        bitsNeeded += 1;
+        mask = mask << 1 | 1;
+        tmpRange = tmpRange >>> 1;
+    }
+
+    const randomBytes = getRandomBytes(bytesNeeded);
+    let randomValue = 0;
+
+    for (let i = 0; i < bytesNeeded; i++) {
+        randomValue |= randomBytes[i] << 8 * i;
+    }
+
+    randomValue = randomValue & mask;
+
+    if (randomValue <= range) {
+        return min + randomValue;
+    } else {
+        return getCryptoRandomInt(min, max);
+    }
+}
+
+/**
+ * Returns either the NodeJS crypto.randomBytes() function or its
+ * browser equivalent implemented via window.crypto.getRandomValues()
+ */
+const getRandomBytes = (
+    (typeof window !== "undefined" && window.crypto)
+
+        // Browsers
+        ? function () {
+            return (numBytes: number) => {
+                const randomBytes = new Uint8Array(numBytes);
+                for (let i = 0; i < numBytes; i += 65536) {
+                    window.crypto.getRandomValues(randomBytes.subarray(i, i + Math.min(numBytes - i, 65536)));
+                }
+                return randomBytes;
+            };
+        }
+
+        // Node
+        : function () {
+            // eslint-disable-next-line @typescript-eslint/no-var-requires
+            return randomBytes;
+        }
+)();