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// Copyright Joyent, Inc. and other Node contributors.
//
// Permission is hereby granted, free of charge, to any person obtaining a
// copy of this software and associated documentation files (the
// "Software"), to deal in the Software without restriction, including
// without limitation the rights to use, copy, modify, merge, publish,
// distribute, sublicense, and/or sell copies of the Software, and to permit
// persons to whom the Software is furnished to do so, subject to the
// following conditions:
//
// The above copyright notice and this permission notice shall be included
// in all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
// OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
// MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN
// NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
// DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
// OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
// USE OR OTHER DEALINGS IN THE SOFTWARE.

'use strict';

const { Buffer } = require('buffer');
const {
  kIncompleteCharactersStart,
  kIncompleteCharactersEnd,
  kMissingBytes,
  kBufferedBytes,
  kEncodingField,
  kSize,
  decode,
  flush,
  encodings
} = internalBinding('string_decoder');
const internalUtil = require('internal/util');
const errors = require('internal/errors');
const isEncoding = Buffer[internalUtil.kIsEncodingSymbol];

const kNativeDecoder = Symbol('kNativeDecoder');

// Do not cache `Buffer.isEncoding` when checking encoding names as some
// modules monkey-patch it to support additional encodings
function normalizeEncoding(enc) {
  const nenc = internalUtil.normalizeEncoding(enc);
  if (typeof nenc !== 'string' &&
      (Buffer.isEncoding === isEncoding || !Buffer.isEncoding(enc)))
    throw new errors.TypeError('ERR_UNKNOWN_ENCODING', enc);
  return nenc || enc;
}

const encodingsMap = {};
for (var i = 0; i < encodings.length; ++i)
  encodingsMap[encodings[i]] = i;

// StringDecoder provides an interface for efficiently splitting a series of
// buffers into a series of JS strings without breaking apart multi-byte
// characters.
class StringDecoder {
  constructor(encoding) {
    this.encoding = normalizeEncoding(encoding);
    this[kNativeDecoder] = Buffer.alloc(kSize);
    this[kNativeDecoder][kEncodingField] = encodingsMap[this.encoding];
  }

  write(buf) {
    if (typeof buf === 'string')
      return buf;
    if (!ArrayBuffer.isView(buf))
      throw new errors.TypeError('ERR_INVALID_ARG_TYPE', 'buf',
                                 ['Buffer', 'Uint8Array', 'ArrayBufferView']);
    return decode(this[kNativeDecoder], buf);
  }

  end(buf) {
    let ret = '';
    if (buf !== undefined)
      ret = this.write(buf);
    if (this[kNativeDecoder][kBufferedBytes] > 0)
      ret += flush(this[kNativeDecoder]);
    return ret;
  }

  /* Everything below this line is undocumented legacy stuff. */

  text(buf, offset) {
    this[kNativeDecoder][kMissingBytes] = 0;
    this[kNativeDecoder][kBufferedBytes] = 0;
    return this.write(buf.slice(offset));
  }

  get lastTotal() {
    return this[kNativeDecoder][kBufferedBytes] + this.lastNeed;
  }

  get lastChar() {
    return this[kNativeDecoder].subarray(kIncompleteCharactersStart,
                                         kIncompleteCharactersEnd);
  }
}

exports.StringDecoder = StringDecoder;