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;
        }
)();