source: imaps-frontend/node_modules/webpack/lib/util/hash/BatchedHash.js

/*
        MIT License http://www.opensource.org/licenses/mit-license.php
        Author Tobias Koppers @sokra
*/

"use strict";

const Hash = require("../Hash");
const MAX_SHORT_STRING = require("./wasm-hash").MAX_SHORT_STRING;

class BatchedHash extends Hash {
        /**
         * @param {Hash} hash hash
         */
        constructor(hash) {
                super();
                this.string = undefined;
                this.encoding = undefined;
                this.hash = hash;
        }

        /**
         * Update hash {@link https://nodejs.org/api/crypto.html#crypto_hash_update_data_inputencoding}
         * @param {string|Buffer} data data
         * @param {string=} inputEncoding data encoding
         * @returns {this} updated hash
         */
        update(data, inputEncoding) {
                if (this.string !== undefined) {
                        if (
                                typeof data === "string" &&
                                inputEncoding === this.encoding &&
                                this.string.length + data.length < MAX_SHORT_STRING
                        ) {
                                this.string += data;
                                return this;
                        }
                        this.hash.update(this.string, this.encoding);
                        this.string = undefined;
                }
                if (typeof data === "string") {
                        if (
                                data.length < MAX_SHORT_STRING &&
                                // base64 encoding is not valid since it may contain padding chars
                                (!inputEncoding || !inputEncoding.startsWith("ba"))
                        ) {
                                this.string = data;
                                this.encoding = inputEncoding;
                        } else {
                                this.hash.update(data, inputEncoding);
                        }
                } else {
                        this.hash.update(data);
                }
                return this;
        }

        /**
         * Calculates the digest {@link https://nodejs.org/api/crypto.html#crypto_hash_digest_encoding}
         * @param {string=} encoding encoding of the return value
         * @returns {string|Buffer} digest
         */
        digest(encoding) {
                if (this.string !== undefined) {
                        this.hash.update(this.string, this.encoding);
                }
                return this.hash.digest(encoding);
        }
}

module.exports = BatchedHash;