/*
	Spacebar: A FOSS re-implementation and extension of the Discord.com backend.
	Copyright (C) 2023 Spacebar and Spacebar Contributors
	
	This program is free software: you can redistribute it and/or modify
	it under the terms of the GNU Affero General Public License as published
	by the Free Software Foundation, either version 3 of the License, or
	(at your option) any later version.
	
	This program is distributed in the hope that it will be useful,
	but WITHOUT ANY WARRANTY; without even the implied warranty of
	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
	GNU Affero General Public License for more details.
	
	You should have received a copy of the GNU Affero General Public License
	along with this program.  If not, see <https://www.gnu.org/licenses/>.
*/

import { Snowflake } from "@spacebar/util";
import crypto from "crypto";

// TODO: 'random'? seriously? who named this?
// And why is this even here? Just use cryto.randomBytes?

export function randomString(length = 6) {
    // Declare all characters
    const chars = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789";

    // Pick characers randomly
    let str = "";
    for (let i = 0; i < length; i++) {
        str += chars.charAt(Math.floor(crypto.randomInt(chars.length)));
    }

    return str;
}

export function snowflakeBasedInvite() {
    // Declare all characters
    const chars = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789";
    const base = BigInt(chars.length);
    let snowflake = Snowflake.generateWorkerProcess();

    // snowflakes hold ~10.75 characters worth of entropy;
    // safe to generate a 8-char invite out of them
    const str = "";
    for (let i = 0; i < 10; i++) {
        str.concat(chars.charAt(Number(snowflake % base)));
        snowflake = snowflake / base;
    }

    return str.substr(3, 8).split("").reverse().join("");
}

export function randomUpperString(length: number = 10) {
    const chars = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";

    let result = "";
    for (let i = 0; i < length; i++) {
        result += chars.charAt(Math.floor(Math.random() * chars.length));
    }

    return result;
}