UUID.ts

/*
    Reference:
        https://www.ietf.org/rfc/rfc4122.txt
        https://stackoverflow.com/questions/105034/create-guid-uuid-in-javascript
 */

export class Guid {
    private static bth: string[] = (new Array<number>(256)).fill(0).map((_, i) => i.toString(16).padStart(2, "0"));

    private readonly m_value: Uint32Array;

    public get value() {
        return this.m_value;
    }

    constructor() {
        const result = new Uint32Array(4);

        crypto.getRandomValues(result);

        result[1] = ((result[1] & 0xFFFF0FFF) | 0x00004000);
        result[2] = ((result[2] & 0xFFFFFF3F) | 0x00000080);

        this.m_value = result;
    }

    public toString(): string {
        const tempValue = this.m_value;
        const dataView = new DataView(tempValue.buffer, 0);
        const w = dataView.getUint32(0);
        const x = dataView.getUint32(4);
        const y = dataView.getUint32(8);
        const z = dataView.getUint32(12);

        return (
              Guid.bth[((w >> 24) & 0xFF)]
            + Guid.bth[((w >> 16) & 0xFF)]
            + Guid.bth[((w >> 8) & 0xFF)]
            + Guid.bth[(w & 0xFF)]
            + "-"
            + Guid.bth[((x >> 24) & 0xFF)]
            + Guid.bth[((x >> 16) & 0xFF)]
            + "-"
            + Guid.bth[((x >> 8) & 0xFF)]
            + Guid.bth[(x & 0xFF)]
            + "-"
            + Guid.bth[((y >> 24) & 0xFF)]
            + Guid.bth[((y >> 16) & 0xFF)]
            + "-"
            + Guid.bth[((y >> 8) & 0xFF)]
            + Guid.bth[(y & 0xFF)]
            + Guid.bth[((z >> 24) & 0xFF)]
            + Guid.bth[((z >> 16) & 0xFF)]
            + Guid.bth[((z >> 8) & 0xFF)]
            + Guid.bth[(z & 0xFF)]
        );
    }
}