'use strict';

var string_decoder = require('../../../../../_virtual/string_decoder.js');
var index = require('../../safe-buffer/index.js');

var hasRequiredString_decoder;

function requireString_decoder () {
	if (hasRequiredString_decoder) return string_decoder.__exports;
	hasRequiredString_decoder = 1;

	/*<replacement>*/

	var Buffer = index.__require().Buffer;
	/*</replacement>*/

	var isEncoding = Buffer.isEncoding || function (encoding) {
	  encoding = '' + encoding;
	  switch (encoding && encoding.toLowerCase()) {
	    case 'hex':case 'utf8':case 'utf-8':case 'ascii':case 'binary':case 'base64':case 'ucs2':case 'ucs-2':case 'utf16le':case 'utf-16le':case 'raw':
	      return true;
	    default:
	      return false;
	  }
	};

	function _normalizeEncoding(enc) {
	  if (!enc) return 'utf8';
	  var retried;
	  while (true) {
	    switch (enc) {
	      case 'utf8':
	      case 'utf-8':
	        return 'utf8';
	      case 'ucs2':
	      case 'ucs-2':
	      case 'utf16le':
	      case 'utf-16le':
	        return 'utf16le';
	      case 'latin1':
	      case 'binary':
	        return 'latin1';
	      case 'base64':
	      case 'ascii':
	      case 'hex':
	        return enc;
	      default:
	        if (retried) return; // undefined
	        enc = ('' + enc).toLowerCase();
	        retried = true;
	    }
	  }
	}
	// Do not cache `Buffer.isEncoding` when checking encoding names as some
	// modules monkey-patch it to support additional encodings
	function normalizeEncoding(enc) {
	  var nenc = _normalizeEncoding(enc);
	  if (typeof nenc !== 'string' && (Buffer.isEncoding === isEncoding || !isEncoding(enc))) throw new Error('Unknown encoding: ' + enc);
	  return nenc || enc;
	}

	// StringDecoder provides an interface for efficiently splitting a series of
	// buffers into a series of JS strings without breaking apart multi-byte
	// characters.
	string_decoder.__exports.StringDecoder = StringDecoder;
	function StringDecoder(encoding) {
	  this.encoding = normalizeEncoding(encoding);
	  var nb;
	  switch (this.encoding) {
	    case 'utf16le':
	      this.text = utf16Text;
	      this.end = utf16End;
	      nb = 4;
	      break;
	    case 'utf8':
	      this.fillLast = utf8FillLast;
	      nb = 4;
	      break;
	    case 'base64':
	      this.text = base64Text;
	      this.end = base64End;
	      nb = 3;
	      break;
	    default:
	      this.write = simpleWrite;
	      this.end = simpleEnd;
	      return;
	  }
	  this.lastNeed = 0;
	  this.lastTotal = 0;
	  this.lastChar = Buffer.allocUnsafe(nb);
	}

	StringDecoder.prototype.write = function (buf) {
	  if (buf.length === 0) return '';
	  var r;
	  var i;
	  if (this.lastNeed) {
	    r = this.fillLast(buf);
	    if (r === undefined) return '';
	    i = this.lastNeed;
	    this.lastNeed = 0;
	  } else {
	    i = 0;
	  }
	  if (i < buf.length) return r ? r + this.text(buf, i) : this.text(buf, i);
	  return r || '';
	};

	StringDecoder.prototype.end = utf8End;

	// Returns only complete characters in a Buffer
	StringDecoder.prototype.text = utf8Text;

	// Attempts to complete a partial non-UTF-8 character using bytes from a Buffer
	StringDecoder.prototype.fillLast = function (buf) {
	  if (this.lastNeed <= buf.length) {
	    buf.copy(this.lastChar, this.lastTotal - this.lastNeed, 0, this.lastNeed);
	    return this.lastChar.toString(this.encoding, 0, this.lastTotal);
	  }
	  buf.copy(this.lastChar, this.lastTotal - this.lastNeed, 0, buf.length);
	  this.lastNeed -= buf.length;
	};

	// Checks the type of a UTF-8 byte, whether it's ASCII, a leading byte, or a
	// continuation byte. If an invalid byte is detected, -2 is returned.
	function utf8CheckByte(byte) {
	  if (byte <= 0x7F) return 0;else if (byte >> 5 === 0x06) return 2;else if (byte >> 4 === 0x0E) return 3;else if (byte >> 3 === 0x1E) return 4;
	  return byte >> 6 === 0x02 ? -1 : -2;
	}

	// Checks at most 3 bytes at the end of a Buffer in order to detect an
	// incomplete multi-byte UTF-8 character. The total number of bytes (2, 3, or 4)
	// needed to complete the UTF-8 character (if applicable) are returned.
	function utf8CheckIncomplete(self, buf, i) {
	  var j = buf.length - 1;
	  if (j < i) return 0;
	  var nb = utf8CheckByte(buf[j]);
	  if (nb >= 0) {
	    if (nb > 0) self.lastNeed = nb - 1;
	    return nb;
	  }
	  if (--j < i || nb === -2) return 0;
	  nb = utf8CheckByte(buf[j]);
	  if (nb >= 0) {
	    if (nb > 0) self.lastNeed = nb - 2;
	    return nb;
	  }
	  if (--j < i || nb === -2) return 0;
	  nb = utf8CheckByte(buf[j]);
	  if (nb >= 0) {
	    if (nb > 0) {
	      if (nb === 2) nb = 0;else self.lastNeed = nb - 3;
	    }
	    return nb;
	  }
	  return 0;
	}

	// Validates as many continuation bytes for a multi-byte UTF-8 character as
	// needed or are available. If we see a non-continuation byte where we expect
	// one, we "replace" the validated continuation bytes we've seen so far with
	// a single UTF-8 replacement character ('\ufffd'), to match v8's UTF-8 decoding
	// behavior. The continuation byte check is included three times in the case
	// where all of the continuation bytes for a character exist in the same buffer.
	// It is also done this way as a slight performance increase instead of using a
	// loop.
	function utf8CheckExtraBytes(self, buf, p) {
	  if ((buf[0] & 0xC0) !== 0x80) {
	    self.lastNeed = 0;
	    return '\ufffd';
	  }
	  if (self.lastNeed > 1 && buf.length > 1) {
	    if ((buf[1] & 0xC0) !== 0x80) {
	      self.lastNeed = 1;
	      return '\ufffd';
	    }
	    if (self.lastNeed > 2 && buf.length > 2) {
	      if ((buf[2] & 0xC0) !== 0x80) {
	        self.lastNeed = 2;
	        return '\ufffd';
	      }
	    }
	  }
	}

	// Attempts to complete a multi-byte UTF-8 character using bytes from a Buffer.
	function utf8FillLast(buf) {
	  var p = this.lastTotal - this.lastNeed;
	  var r = utf8CheckExtraBytes(this, buf);
	  if (r !== undefined) return r;
	  if (this.lastNeed <= buf.length) {
	    buf.copy(this.lastChar, p, 0, this.lastNeed);
	    return this.lastChar.toString(this.encoding, 0, this.lastTotal);
	  }
	  buf.copy(this.lastChar, p, 0, buf.length);
	  this.lastNeed -= buf.length;
	}

	// Returns all complete UTF-8 characters in a Buffer. If the Buffer ended on a
	// partial character, the character's bytes are buffered until the required
	// number of bytes are available.
	function utf8Text(buf, i) {
	  var total = utf8CheckIncomplete(this, buf, i);
	  if (!this.lastNeed) return buf.toString('utf8', i);
	  this.lastTotal = total;
	  var end = buf.length - (total - this.lastNeed);
	  buf.copy(this.lastChar, 0, end);
	  return buf.toString('utf8', i, end);
	}

	// For UTF-8, a replacement character is added when ending on a partial
	// character.
	function utf8End(buf) {
	  var r = buf && buf.length ? this.write(buf) : '';
	  if (this.lastNeed) return r + '\ufffd';
	  return r;
	}

	// UTF-16LE typically needs two bytes per character, but even if we have an even
	// number of bytes available, we need to check if we end on a leading/high
	// surrogate. In that case, we need to wait for the next two bytes in order to
	// decode the last character properly.
	function utf16Text(buf, i) {
	  if ((buf.length - i) % 2 === 0) {
	    var r = buf.toString('utf16le', i);
	    if (r) {
	      var c = r.charCodeAt(r.length - 1);
	      if (c >= 0xD800 && c <= 0xDBFF) {
	        this.lastNeed = 2;
	        this.lastTotal = 4;
	        this.lastChar[0] = buf[buf.length - 2];
	        this.lastChar[1] = buf[buf.length - 1];
	        return r.slice(0, -1);
	      }
	    }
	    return r;
	  }
	  this.lastNeed = 1;
	  this.lastTotal = 2;
	  this.lastChar[0] = buf[buf.length - 1];
	  return buf.toString('utf16le', i, buf.length - 1);
	}

	// For UTF-16LE we do not explicitly append special replacement characters if we
	// end on a partial character, we simply let v8 handle that.
	function utf16End(buf) {
	  var r = buf && buf.length ? this.write(buf) : '';
	  if (this.lastNeed) {
	    var end = this.lastTotal - this.lastNeed;
	    return r + this.lastChar.toString('utf16le', 0, end);
	  }
	  return r;
	}

	function base64Text(buf, i) {
	  var n = (buf.length - i) % 3;
	  if (n === 0) return buf.toString('base64', i);
	  this.lastNeed = 3 - n;
	  this.lastTotal = 3;
	  if (n === 1) {
	    this.lastChar[0] = buf[buf.length - 1];
	  } else {
	    this.lastChar[0] = buf[buf.length - 2];
	    this.lastChar[1] = buf[buf.length - 1];
	  }
	  return buf.toString('base64', i, buf.length - n);
	}

	function base64End(buf) {
	  var r = buf && buf.length ? this.write(buf) : '';
	  if (this.lastNeed) return r + this.lastChar.toString('base64', 0, 3 - this.lastNeed);
	  return r;
	}

	// Pass bytes on through for single-byte encodings (e.g. ascii, latin1, hex)
	function simpleWrite(buf) {
	  return buf.toString(this.encoding);
	}

	function simpleEnd(buf) {
	  return buf && buf.length ? this.write(buf) : '';
	}
	return string_decoder.__exports;
}

exports.__require = requireString_decoder;
