// 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 { internalBinding } = require('internal/bootstrap/loaders');
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', 'Uint8Array', 'ArrayBufferView'],
 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;