/**
 *  Copyright 2026 Angus.Fenying <fenying@litert.org>
 *
 *  Licensed under the Apache License, Version 2.0 (the "License");
 *  you may not use this file except in compliance with the License.
 *  You may obtain a copy of the License at
 *
 *    https://www.apache.org/licenses/LICENSE-2.0
 *
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS,
 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License.
 */

import * as NodeCrypto from 'node:crypto';
import { uuidToBuffer, uuidToString } from './Utils.js';

/**
 * The options for the UUIDv5 generator.
 */
export type IUuid5Options = Pick<Uuid5Generator, 'namespace'>;

/**
 * The pre-defined namespaces for UUIDv5.
 */
export enum EUuid5PredefinedNamespaces {
    DNS = '6ba7b810-9dad-11d1-80b4-00c04fd430c8',
    URL = '6ba7b811-9dad-11d1-80b4-00c04fd430c8',
    OID = '6ba7b812-9dad-11d1-80b4-00c04fd430c8',
    X500 = '6ba7b814-9dad-11d1-80b4-00c04fd430c8',
}

/**
 * The class for generating UUID in version 5.
 */
export class Uuid5Generator {

    /**
     * The namespace of the UUID, which must be a UUID string.
     */
    public readonly namespace: string;

    private readonly _nsBin: Buffer;

    /**
     * Create a UUIDv5 generator bound to the specified namespace.
     *
     * @param opts  The options for the UUIDv5 generator.
     */
    public constructor(opts: IUuid5Options) {

        this.namespace = opts.namespace;
        this._nsBin = uuidToBuffer(opts.namespace);
    }

    /**
     * Generate a UUIDv5 based on the namespace and the name.
     *
     * @param name  The name to generate the UUID from.
     *
     * @returns A UUIDv5 string.
     */
    public generate(name: string): string {

        return Uuid5Generator.generate(this.namespace, name);
    }

    /**
     * Generate a UUIDv5 based on the namespace and the name, and return it as a Buffer.
     *
     * @param name  The name to generate the UUID from.
     *
     * @returns A UUIDv5 in Buffer format, which is 16 bytes in total.
     */
    public generateAsBuffer(name: string): Buffer {

        return Uuid5Generator.generateAsBuffer(this._nsBin, name);
    }

    /**
     * Generate a UUIDv5 based on the provided namespace and name.
     *
     * @param namespace     The namespace for the UUID, which must be a UUID string or a Buffer of 16 bytes.
     * @param name          The name to generate the UUID from.
     * @returns A UUIDv5 string.
     */
    public static generate(namespace: string | Buffer, name: string): string {

        return uuidToString(Uuid5Generator.generateAsBuffer(namespace, name));
    }

    /**
     * Generate a UUIDv5 based on the provided namespace and name, and return it as a Buffer.
     *
     * @param namespace     The namespace for the UUID, which must be a UUID string or a Buffer of 16 bytes.
     * @param name          The name to generate the UUID from.
     * @returns A UUIDv5 in Buffer format, which is 16 bytes in total.
     */
    public static generateAsBuffer(namespace: string | Buffer, name: string): Buffer {

        const hash = NodeCrypto
            .createHash('sha1')
            .update(typeof namespace === 'string' ? uuidToBuffer(namespace) : namespace)
            .update(name)
            .digest();

        hash[6] = (hash[6] & 0x0f) | 0x50; // the version, set to v5 (0101)
        hash[8] = (hash[8] & 0x3f) | 0x80; // clock_seq_hi_and_reserved, set to 10

        return hash.subarray(0, 16);
    }
}