// 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 {

ERR_INVALID_ARG_TYPE,

ERR_UNKNOWN_ENCODING

} = require('internal/errors').codes;

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 (nenc === undefined) {

if (Buffer.isEncoding === isEncoding || !Buffer.isEncoding(enc))

throw new ERR_UNKNOWN_ENCODING(enc);

return enc;

}

return nenc;

}

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.

function StringDecoder(encoding) {

this.encoding = normalizeEncoding(encoding);

this[kNativeDecoder] = Buffer.alloc(kSize);

this[kNativeDecoder][kEncodingField] = encodingsMap[this.encoding];

}

StringDecoder.prototype.write = function write(buf) {

if (typeof buf === 'string')

return buf;

if (!ArrayBuffer.isView(buf))

throw new ERR_INVALID_ARG_TYPE('buf',

['Buffer', 'TypedArray', 'DataView'],

buf);

return decode(this[kNativeDecoder], buf);

};

StringDecoder.prototype.end = function 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. */

StringDecoder.prototype.text = function text(buf, offset) {

this[kNativeDecoder][kMissingBytes] = 0;

this[kNativeDecoder][kBufferedBytes] = 0;

return this.write(buf.slice(offset));

};

Object.defineProperties(StringDecoder.prototype, {

lastChar: {

configurable: true,

enumerable: true,

get() {

return this[kNativeDecoder].subarray(kIncompleteCharactersStart,

kIncompleteCharactersEnd);

}

},

lastNeed: {

configurable: true,

enumerable: true,

get() {

return this[kNativeDecoder][kMissingBytes];

}

},

lastTotal: {

configurable: true,

enumerable: true,

get() {

return this[kNativeDecoder][kBufferedBytes] +

this[kNativeDecoder][kMissingBytes];

}

}

});

exports.StringDecoder = StringDecoder;