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// Copyright 2018-2021 the Deno authors. All rights reserved. MIT license.
import {  create_hash as createHash,  DenoHash,  digest_hash as digestHash,  update_hash as updateHash,} from "./wasm.js";
import * as hex from "../../encoding/hex.ts";import * as base64 from "../../encoding/base64.ts";import type { Hasher, Message, OutputFormat } from "../hasher.ts";
export class Hash implements Hasher {  #hash: DenoHash;  #digested: boolean;
  constructor(algorithm: string) {    this.#hash = createHash(algorithm);    this.#digested = false;  }
  update(message: Message): this {    let view: Uint8Array;
    if (message instanceof Uint8Array) {      view = message;    } else if (typeof message === "string") {      view = new TextEncoder().encode(message);    } else if (ArrayBuffer.isView(message)) {      view = new Uint8Array(        message.buffer,        message.byteOffset,        message.byteLength,      );    } else if (message instanceof ArrayBuffer) {      view = new Uint8Array(message);    } else {      throw new Error("hash: `data` is invalid type");    }
    // Messages will be split into chunks of this size to avoid unnecessarily    // increasing the size of the WASM heap.
    const chunkSize = 65_536;
    for (      let offset = 0;      offset < view.byteLength;      offset += chunkSize    ) {      updateHash(        this.#hash,        new Uint8Array(          view.buffer,          view.byteOffset + offset,          Math.min(chunkSize, view.byteLength - offset),        ),      );    }
    return this;  }
  /** Returns final hash */  digest(): ArrayBuffer {    if (this.#digested) throw new Error("hash: already digested");
    this.#digested = true;    return digestHash(this.#hash);  }
  /**   * Returns hash as a string of given format   * @param format format of output string (hex or base64). Default is hex   */  toString(format: OutputFormat = "hex"): string {    const finalized = new Uint8Array(this.digest());
    switch (format) {      case "hex":        return new TextDecoder().decode(hex.encode(finalized));      case "base64":        return base64.encode(finalized);      default:        throw new Error("hash: invalid format");    }  }}