Snowflake.ts

class Snowflake {
	static readonly BITS = {
		EPOCH:      41,
		MACHINE_ID: 10,
		SEQUENCE:   12,
		UNUSED:     1
	};
	static readonly EPOCH = Date.parse("2022-01-01T00:00:00.000Z");
	static readonly MACHINE_ID = 0;
	static readonly MAX_MACHINE_ID = Math.pow(2, Snowflake.BITS.MACHINE_ID);
	static readonly MAX_SEQUENCE = Math.pow(2, Snowflake.BITS.SEQUENCE);
	static SEQUENCE = 0;

	private static binaryToId(bin: string): string {
		let dec = "";

		while (bin.length > 50) {
			const high = parseInt(bin.slice(0, -32), 2);
			const low = parseInt((high % 10).toString(2) + bin.slice(-32), 2);

			dec = (low % 10).toString() + dec;
			bin =
				Math.floor(high / 10).toString(2) +
				Math.floor(low / 10)
					.toString(2)
					.padStart(32, "0");
		}

		let b = parseInt(bin, 2);
		while (b > 0) {
			dec = (b % 10).toString() + dec;
			b = Math.floor(b / 10);
		}

		return dec;
	}

	private static idToBinary(id: string) {
		let bin = "";
		let high = Number(id.slice(0, -10)) || 0;
		let low = Number(id.slice(-10));
		while (low > 0 || high > 0) {
			bin = String(low & 1) + bin;
			low = Math.floor(low / 2);
			if (high > 0) {
				low += 5e9 * (high % 2);
				high = Math.floor(high / 2);
			}
		}

		return bin;
	}

	static decode(id: string) {
		const bin = this.idToBinary(id).toString().padStart(64, "0").split("");

		return {
			timestamp: parseInt(bin.splice(0, Snowflake.BITS.EPOCH).join(""), 2) + this.EPOCH,
			machineId: parseInt(bin.splice(0, Snowflake.BITS.MACHINE_ID).join(""), 2),
			sequence:  parseInt(bin.splice(0, Snowflake.BITS.SEQUENCE).join(""), 2),
			unused:    parseInt(bin.splice(0, Snowflake.BITS.UNUSED).join(""), 2)
		};
	}

	static generate(timestamp = Date.now()): string {
		const bin = `${(timestamp - this.EPOCH).toString(2).padStart(Snowflake.BITS.EPOCH, "0")}${this.MACHINE_ID.toString(2).padStart(Snowflake.BITS.MACHINE_ID, "0")}${(this.SEQUENCE++).toString(2).padStart(Snowflake.BITS.SEQUENCE, "0")}${"0".repeat(Snowflake.BITS.UNUSED)}`;
		if (this.SEQUENCE >= (this.MAX_SEQUENCE - 1)) this.SEQUENCE = 0;
		return this.binaryToId(bin);
	}

	static getSequence() { return Number(this.SEQUENCE); /* make uneditable */ }
}

export default Snowflake;