'use strict';

var stream = require('stream');

const is_object = function(obj){
  return (typeof obj === 'object' && obj !== null && !Array.isArray(obj));
};

class CsvError extends Error {
  constructor(code, message, options, ...contexts) {
    if(Array.isArray(message)) message = message.join(' ').trim();
    super(message);
    if(Error.captureStackTrace !== undefined){
      Error.captureStackTrace(this, CsvError);
    }
    this.code = code;
    for(const context of contexts){
      for(const key in context){
        const value = context[key];
        this[key] = Buffer.isBuffer(value) ? value.toString(options.encoding) : value == null ? value : JSON.parse(JSON.stringify(value));
      }
    }
  }
}

const normalize_columns_array = function(columns){
  const normalizedColumns = [];
  for(let i = 0, l = columns.length; i < l; i++){
    const column = columns[i];
    if(column === undefined || column === null || column === false){
      normalizedColumns[i] = { disabled: true };
    }else if(typeof column === 'string'){
      normalizedColumns[i] = { name: column };
    }else if(is_object(column)){
      if(typeof column.name !== 'string'){
        throw new CsvError('CSV_OPTION_COLUMNS_MISSING_NAME', [
          'Option columns missing name:',
          `property "name" is required at position ${i}`,
          'when column is an object literal'
        ]);
      }
      normalizedColumns[i] = column;
    }else {
      throw new CsvError('CSV_INVALID_COLUMN_DEFINITION', [
        'Invalid column definition:',
        'expect a string or a literal object,',
        `got ${JSON.stringify(column)} at position ${i}`
      ]);
    }
  }
  return normalizedColumns;
};

class ResizeableBuffer{
  constructor(size=100){
    this.size = size;
    this.length = 0;
    this.buf = Buffer.allocUnsafe(size);
  }
  prepend(val){
    if(Buffer.isBuffer(val)){
      const length = this.length + val.length;
      if(length >= this.size){
        this.resize();
        if(length >= this.size){
          throw Error('INVALID_BUFFER_STATE');
        }
      }
      const buf = this.buf;
      this.buf = Buffer.allocUnsafe(this.size);
      val.copy(this.buf, 0);
      buf.copy(this.buf, val.length);
      this.length += val.length;
    }else {
      const length = this.length++;
      if(length === this.size){
        this.resize();
      }
      const buf = this.clone();
      this.buf[0] = val;
      buf.copy(this.buf,1, 0, length);
    }
  }
  append(val){
    const length = this.length++;
    if(length === this.size){
      this.resize();
    }
    this.buf[length] = val;
  }
  clone(){
    return Buffer.from(this.buf.slice(0, this.length));
  }
  resize(){
    const length = this.length;
    this.size = this.size * 2;
    const buf = Buffer.allocUnsafe(this.size);
    this.buf.copy(buf,0, 0, length);
    this.buf = buf;
  }
  toString(encoding){
    if(encoding){
      return this.buf.slice(0, this.length).toString(encoding);
    }else {
      return Uint8Array.prototype.slice.call(this.buf.slice(0, this.length));
    }
  }
  toJSON(){
    return this.toString('utf8');
  }
  reset(){
    this.length = 0;
  }
}

// white space characters
// https://en.wikipedia.org/wiki/Whitespace_character
// https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/Regular_Expressions/Character_Classes#Types
// \f\n\r\t\v\u00a0\u1680\u2000-\u200a\u2028\u2029\u202f\u205f\u3000\ufeff
const np = 12;
const cr$1 = 13; // `\r`, carriage return, 0x0D in hexadécimal, 13 in decimal
const nl$1 = 10; // `\n`, newline, 0x0A in hexadecimal, 10 in decimal
const space = 32;
const tab = 9;

const init_state = function(options){
  return {
    bomSkipped: false,
    bufBytesStart: 0,
    castField: options.cast_function,
    commenting: false,
    // Current error encountered by a record
    error: undefined,
    enabled: options.from_line === 1,
    escaping: false,
    escapeIsQuote: Buffer.isBuffer(options.escape) && Buffer.isBuffer(options.quote) && Buffer.compare(options.escape, options.quote) === 0,
    // columns can be `false`, `true`, `Array`
    expectedRecordLength: Array.isArray(options.columns) ? options.columns.length : undefined,
    field: new ResizeableBuffer(20),
    firstLineToHeaders: options.cast_first_line_to_header,
    needMoreDataSize: Math.max(
      // Skip if the remaining buffer smaller than comment
      options.comment !== null ? options.comment.length : 0,
      // Skip if the remaining buffer can be delimiter
      ...options.delimiter.map((delimiter) => delimiter.length),
      // Skip if the remaining buffer can be escape sequence
      options.quote !== null ? options.quote.length : 0,
    ),
    previousBuf: undefined,
    quoting: false,
    stop: false,
    rawBuffer: new ResizeableBuffer(100),
    record: [],
    recordHasError: false,
    record_length: 0,
    recordDelimiterMaxLength: options.record_delimiter.length === 0 ? 0 : Math.max(...options.record_delimiter.map((v) => v.length)),
    trimChars: [Buffer.from(' ', options.encoding)[0], Buffer.from('\t', options.encoding)[0]],
    wasQuoting: false,
    wasRowDelimiter: false,
    timchars: [
      Buffer.from(Buffer.from([cr$1], 'utf8').toString(), options.encoding),
      Buffer.from(Buffer.from([nl$1], 'utf8').toString(), options.encoding),
      Buffer.from(Buffer.from([np], 'utf8').toString(), options.encoding),
      Buffer.from(Buffer.from([space], 'utf8').toString(), options.encoding),
      Buffer.from(Buffer.from([tab], 'utf8').toString(), options.encoding),
    ]
  };
};

const underscore = function(str){
  return str.replace(/([A-Z])/g, function(_, match){
    return '_' + match.toLowerCase();
  });
};

const normalize_options = function(opts){
  const options = {};
  // Merge with user options
  for(const opt in opts){
    options[underscore(opt)] = opts[opt];
  }
  // Normalize option `encoding`
  // Note: defined first because other options depends on it
  // to convert chars/strings into buffers.
  if(options.encoding === undefined || options.encoding === true){
    options.encoding = 'utf8';
  }else if(options.encoding === null || options.encoding === false){
    options.encoding = null;
  }else if(typeof options.encoding !== 'string' && options.encoding !== null){
    throw new CsvError('CSV_INVALID_OPTION_ENCODING', [
      'Invalid option encoding:',
      'encoding must be a string or null to return a buffer,',
      `got ${JSON.stringify(options.encoding)}`
    ], options);
  }
  // Normalize option `bom`
  if(options.bom === undefined || options.bom === null || options.bom === false){
    options.bom = false;
  }else if(options.bom !== true){
    throw new CsvError('CSV_INVALID_OPTION_BOM', [
      'Invalid option bom:', 'bom must be true,',
      `got ${JSON.stringify(options.bom)}`
    ], options);
  }
  // Normalize option `cast`
  options.cast_function = null;
  if(options.cast === undefined || options.cast === null || options.cast === false || options.cast === ''){
    options.cast = undefined;
  }else if(typeof options.cast === 'function'){
    options.cast_function = options.cast;
    options.cast = true;
  }else if(options.cast !== true){
    throw new CsvError('CSV_INVALID_OPTION_CAST', [
      'Invalid option cast:', 'cast must be true or a function,',
      `got ${JSON.stringify(options.cast)}`
    ], options);
  }
  // Normalize option `cast_date`
  if(options.cast_date === undefined || options.cast_date === null || options.cast_date === false || options.cast_date === ''){
    options.cast_date = false;
  }else if(options.cast_date === true){
    options.cast_date = function(value){
      const date = Date.parse(value);
      return !isNaN(date) ? new Date(date) : value;
    };
  }else if (typeof options.cast_date !== 'function'){
    throw new CsvError('CSV_INVALID_OPTION_CAST_DATE', [
      'Invalid option cast_date:', 'cast_date must be true or a function,',
      `got ${JSON.stringify(options.cast_date)}`
    ], options);
  }
  // Normalize option `columns`
  options.cast_first_line_to_header = null;
  if(options.columns === true){
    // Fields in the first line are converted as-is to columns
    options.cast_first_line_to_header = undefined;
  }else if(typeof options.columns === 'function'){
    options.cast_first_line_to_header = options.columns;
    options.columns = true;
  }else if(Array.isArray(options.columns)){
    options.columns = normalize_columns_array(options.columns);
  }else if(options.columns === undefined || options.columns === null || options.columns === false){
    options.columns = false;
  }else {
    throw new CsvError('CSV_INVALID_OPTION_COLUMNS', [
      'Invalid option columns:',
      'expect an array, a function or true,',
      `got ${JSON.stringify(options.columns)}`
    ], options);
  }
  // Normalize option `group_columns_by_name`
  if(options.group_columns_by_name === undefined || options.group_columns_by_name === null || options.group_columns_by_name === false){
    options.group_columns_by_name = false;
  }else if(options.group_columns_by_name !== true){
    throw new CsvError('CSV_INVALID_OPTION_GROUP_COLUMNS_BY_NAME', [
      'Invalid option group_columns_by_name:',
      'expect an boolean,',
      `got ${JSON.stringify(options.group_columns_by_name)}`
    ], options);
  }else if(options.columns === false){
    throw new CsvError('CSV_INVALID_OPTION_GROUP_COLUMNS_BY_NAME', [
      'Invalid option group_columns_by_name:',
      'the `columns` mode must be activated.'
    ], options);
  }
  // Normalize option `comment`
  if(options.comment === undefined || options.comment === null || options.comment === false || options.comment === ''){
    options.comment = null;
  }else {
    if(typeof options.comment === 'string'){
      options.comment = Buffer.from(options.comment, options.encoding);
    }
    if(!Buffer.isBuffer(options.comment)){
      throw new CsvError('CSV_INVALID_OPTION_COMMENT', [
        'Invalid option comment:',
        'comment must be a buffer or a string,',
        `got ${JSON.stringify(options.comment)}`
      ], options);
    }
  }
  // Normalize option `comment_no_infix`
  if(options.comment_no_infix === undefined || options.comment_no_infix === null || options.comment_no_infix === false){
    options.comment_no_infix = false;
  }else if(options.comment_no_infix !== true){
    throw new CsvError('CSV_INVALID_OPTION_COMMENT', [
      'Invalid option comment_no_infix:',
      'value must be a boolean,',
      `got ${JSON.stringify(options.comment_no_infix)}`
    ], options);
  }
  // Normalize option `delimiter`
  const delimiter_json = JSON.stringify(options.delimiter);
  if(!Array.isArray(options.delimiter)) options.delimiter = [options.delimiter];
  if(options.delimiter.length === 0){
    throw new CsvError('CSV_INVALID_OPTION_DELIMITER', [
      'Invalid option delimiter:',
      'delimiter must be a non empty string or buffer or array of string|buffer,',
      `got ${delimiter_json}`
    ], options);
  }
  options.delimiter = options.delimiter.map(function(delimiter){
    if(delimiter === undefined || delimiter === null || delimiter === false){
      return Buffer.from(',', options.encoding);
    }
    if(typeof delimiter === 'string'){
      delimiter = Buffer.from(delimiter, options.encoding);
    }
    if(!Buffer.isBuffer(delimiter) || delimiter.length === 0){
      throw new CsvError('CSV_INVALID_OPTION_DELIMITER', [
        'Invalid option delimiter:',
        'delimiter must be a non empty string or buffer or array of string|buffer,',
        `got ${delimiter_json}`
      ], options);
    }
    return delimiter;
  });
  // Normalize option `escape`
  if(options.escape === undefined || options.escape === true){
    options.escape = Buffer.from('"', options.encoding);
  }else if(typeof options.escape === 'string'){
    options.escape = Buffer.from(options.escape, options.encoding);
  }else if (options.escape === null || options.escape === false){
    options.escape = null;
  }
  if(options.escape !== null){
    if(!Buffer.isBuffer(options.escape)){
      throw new Error(`Invalid Option: escape must be a buffer, a string or a boolean, got ${JSON.stringify(options.escape)}`);
    }
  }
  // Normalize option `from`
  if(options.from === undefined || options.from === null){
    options.from = 1;
  }else {
    if(typeof options.from === 'string' && /\d+/.test(options.from)){
      options.from = parseInt(options.from);
    }
    if(Number.isInteger(options.from)){
      if(options.from < 0){
        throw new Error(`Invalid Option: from must be a positive integer, got ${JSON.stringify(opts.from)}`);
      }
    }else {
      throw new Error(`Invalid Option: from must be an integer, got ${JSON.stringify(options.from)}`);
    }
  }
  // Normalize option `from_line`
  if(options.from_line === undefined || options.from_line === null){
    options.from_line = 1;
  }else {
    if(typeof options.from_line === 'string' && /\d+/.test(options.from_line)){
      options.from_line = parseInt(options.from_line);
    }
    if(Number.isInteger(options.from_line)){
      if(options.from_line <= 0){
        throw new Error(`Invalid Option: from_line must be a positive integer greater than 0, got ${JSON.stringify(opts.from_line)}`);
      }
    }else {
      throw new Error(`Invalid Option: from_line must be an integer, got ${JSON.stringify(opts.from_line)}`);
    }
  }
  // Normalize options `ignore_last_delimiters`
  if(options.ignore_last_delimiters === undefined || options.ignore_last_delimiters === null){
    options.ignore_last_delimiters = false;
  }else if(typeof options.ignore_last_delimiters === 'number'){
    options.ignore_last_delimiters = Math.floor(options.ignore_last_delimiters);
    if(options.ignore_last_delimiters === 0){
      options.ignore_last_delimiters = false;
    }
  }else if(typeof options.ignore_last_delimiters !== 'boolean'){
    throw new CsvError('CSV_INVALID_OPTION_IGNORE_LAST_DELIMITERS', [
      'Invalid option `ignore_last_delimiters`:',
      'the value must be a boolean value or an integer,',
      `got ${JSON.stringify(options.ignore_last_delimiters)}`
    ], options);
  }
  if(options.ignore_last_delimiters === true && options.columns === false){
    throw new CsvError('CSV_IGNORE_LAST_DELIMITERS_REQUIRES_COLUMNS', [
      'The option `ignore_last_delimiters`',
      'requires the activation of the `columns` option'
    ], options);
  }
  // Normalize option `info`
  if(options.info === undefined || options.info === null || options.info === false){
    options.info = false;
  }else if(options.info !== true){
    throw new Error(`Invalid Option: info must be true, got ${JSON.stringify(options.info)}`);
  }
  // Normalize option `max_record_size`
  if(options.max_record_size === undefined || options.max_record_size === null || options.max_record_size === false){
    options.max_record_size = 0;
  }else if(Number.isInteger(options.max_record_size) && options.max_record_size >= 0);else if(typeof options.max_record_size === 'string' && /\d+/.test(options.max_record_size)){
    options.max_record_size = parseInt(options.max_record_size);
  }else {
    throw new Error(`Invalid Option: max_record_size must be a positive integer, got ${JSON.stringify(options.max_record_size)}`);
  }
  // Normalize option `objname`
  if(options.objname === undefined || options.objname === null || options.objname === false){
    options.objname = undefined;
  }else if(Buffer.isBuffer(options.objname)){
    if(options.objname.length === 0){
      throw new Error(`Invalid Option: objname must be a non empty buffer`);
    }
    if(options.encoding === null);else {
      options.objname = options.objname.toString(options.encoding);
    }
  }else if(typeof options.objname === 'string'){
    if(options.objname.length === 0){
      throw new Error(`Invalid Option: objname must be a non empty string`);
    }
    // Great, nothing to do
  }else if(typeof options.objname === 'number');else {
    throw new Error(`Invalid Option: objname must be a string or a buffer, got ${options.objname}`);
  }
  if(options.objname !== undefined){
    if(typeof options.objname === 'number'){
      if(options.columns !== false){
        throw Error('Invalid Option: objname index cannot be combined with columns or be defined as a field');
      }
    }else { // A string or a buffer
      if(options.columns === false){
        throw Error('Invalid Option: objname field must be combined with columns or be defined as an index');
      }
    }
  }
  // Normalize option `on_record`
  if(options.on_record === undefined || options.on_record === null){
    options.on_record = undefined;
  }else if(typeof options.on_record !== 'function'){
    throw new CsvError('CSV_INVALID_OPTION_ON_RECORD', [
      'Invalid option `on_record`:',
      'expect a function,',
      `got ${JSON.stringify(options.on_record)}`
    ], options);
  }
  // Normalize option `on_skip`
  // options.on_skip ??= (err, chunk) => {
  //   this.emit('skip', err, chunk);
  // };
  if(options.on_skip !== undefined && options.on_skip !== null && typeof options.on_skip !== 'function'){
    throw new Error(`Invalid Option: on_skip must be a function, got ${JSON.stringify(options.on_skip)}`);
  }
  // Normalize option `quote`
  if(options.quote === null || options.quote === false || options.quote === ''){
    options.quote = null;
  }else {
    if(options.quote === undefined || options.quote === true){
      options.quote = Buffer.from('"', options.encoding);
    }else if(typeof options.quote === 'string'){
      options.quote = Buffer.from(options.quote, options.encoding);
    }
    if(!Buffer.isBuffer(options.quote)){
      throw new Error(`Invalid Option: quote must be a buffer or a string, got ${JSON.stringify(options.quote)}`);
    }
  }
  // Normalize option `raw`
  if(options.raw === undefined || options.raw === null || options.raw === false){
    options.raw = false;
  }else if(options.raw !== true){
    throw new Error(`Invalid Option: raw must be true, got ${JSON.stringify(options.raw)}`);
  }
  // Normalize option `record_delimiter`
  if(options.record_delimiter === undefined){
    options.record_delimiter = [];
  }else if(typeof options.record_delimiter === 'string' || Buffer.isBuffer(options.record_delimiter)){
    if(options.record_delimiter.length === 0){
      throw new CsvError('CSV_INVALID_OPTION_RECORD_DELIMITER', [
        'Invalid option `record_delimiter`:',
        'value must be a non empty string or buffer,',
        `got ${JSON.stringify(options.record_delimiter)}`
      ], options);
    }
    options.record_delimiter = [options.record_delimiter];
  }else if(!Array.isArray(options.record_delimiter)){
    throw new CsvError('CSV_INVALID_OPTION_RECORD_DELIMITER', [
      'Invalid option `record_delimiter`:',
      'value must be a string, a buffer or array of string|buffer,',
      `got ${JSON.stringify(options.record_delimiter)}`
    ], options);
  }
  options.record_delimiter = options.record_delimiter.map(function(rd, i){
    if(typeof rd !== 'string' && ! Buffer.isBuffer(rd)){
      throw new CsvError('CSV_INVALID_OPTION_RECORD_DELIMITER', [
        'Invalid option `record_delimiter`:',
        'value must be a string, a buffer or array of string|buffer',
        `at index ${i},`,
        `got ${JSON.stringify(rd)}`
      ], options);
    }else if(rd.length === 0){
      throw new CsvError('CSV_INVALID_OPTION_RECORD_DELIMITER', [
        'Invalid option `record_delimiter`:',
        'value must be a non empty string or buffer',
        `at index ${i},`,
        `got ${JSON.stringify(rd)}`
      ], options);
    }
    if(typeof rd === 'string'){
      rd = Buffer.from(rd, options.encoding);
    }
    return rd;
  });
  // Normalize option `relax_column_count`
  if(typeof options.relax_column_count === 'boolean');else if(options.relax_column_count === undefined || options.relax_column_count === null){
    options.relax_column_count = false;
  }else {
    throw new Error(`Invalid Option: relax_column_count must be a boolean, got ${JSON.stringify(options.relax_column_count)}`);
  }
  if(typeof options.relax_column_count_less === 'boolean');else if(options.relax_column_count_less === undefined || options.relax_column_count_less === null){
    options.relax_column_count_less = false;
  }else {
    throw new Error(`Invalid Option: relax_column_count_less must be a boolean, got ${JSON.stringify(options.relax_column_count_less)}`);
  }
  if(typeof options.relax_column_count_more === 'boolean');else if(options.relax_column_count_more === undefined || options.relax_column_count_more === null){
    options.relax_column_count_more = false;
  }else {
    throw new Error(`Invalid Option: relax_column_count_more must be a boolean, got ${JSON.stringify(options.relax_column_count_more)}`);
  }
  // Normalize option `relax_quotes`
  if(typeof options.relax_quotes === 'boolean');else if(options.relax_quotes === undefined || options.relax_quotes === null){
    options.relax_quotes = false;
  }else {
    throw new Error(`Invalid Option: relax_quotes must be a boolean, got ${JSON.stringify(options.relax_quotes)}`);
  }
  // Normalize option `skip_empty_lines`
  if(typeof options.skip_empty_lines === 'boolean');else if(options.skip_empty_lines === undefined || options.skip_empty_lines === null){
    options.skip_empty_lines = false;
  }else {
    throw new Error(`Invalid Option: skip_empty_lines must be a boolean, got ${JSON.stringify(options.skip_empty_lines)}`);
  }
  // Normalize option `skip_records_with_empty_values`
  if(typeof options.skip_records_with_empty_values === 'boolean');else if(options.skip_records_with_empty_values === undefined || options.skip_records_with_empty_values === null){
    options.skip_records_with_empty_values = false;
  }else {
    throw new Error(`Invalid Option: skip_records_with_empty_values must be a boolean, got ${JSON.stringify(options.skip_records_with_empty_values)}`);
  }
  // Normalize option `skip_records_with_error`
  if(typeof options.skip_records_with_error === 'boolean');else if(options.skip_records_with_error === undefined || options.skip_records_with_error === null){
    options.skip_records_with_error = false;
  }else {
    throw new Error(`Invalid Option: skip_records_with_error must be a boolean, got ${JSON.stringify(options.skip_records_with_error)}`);
  }
  // Normalize option `rtrim`
  if(options.rtrim === undefined || options.rtrim === null || options.rtrim === false){
    options.rtrim = false;
  }else if(options.rtrim !== true){
    throw new Error(`Invalid Option: rtrim must be a boolean, got ${JSON.stringify(options.rtrim)}`);
  }
  // Normalize option `ltrim`
  if(options.ltrim === undefined || options.ltrim === null || options.ltrim === false){
    options.ltrim = false;
  }else if(options.ltrim !== true){
    throw new Error(`Invalid Option: ltrim must be a boolean, got ${JSON.stringify(options.ltrim)}`);
  }
  // Normalize option `trim`
  if(options.trim === undefined || options.trim === null || options.trim === false){
    options.trim = false;
  }else if(options.trim !== true){
    throw new Error(`Invalid Option: trim must be a boolean, got ${JSON.stringify(options.trim)}`);
  }
  // Normalize options `trim`, `ltrim` and `rtrim`
  if(options.trim === true && opts.ltrim !== false){
    options.ltrim = true;
  }else if(options.ltrim !== true){
    options.ltrim = false;
  }
  if(options.trim === true && opts.rtrim !== false){
    options.rtrim = true;
  }else if(options.rtrim !== true){
    options.rtrim = false;
  }
  // Normalize option `to`
  if(options.to === undefined || options.to === null){
    options.to = -1;
  }else {
    if(typeof options.to === 'string' && /\d+/.test(options.to)){
      options.to = parseInt(options.to);
    }
    if(Number.isInteger(options.to)){
      if(options.to <= 0){
        throw new Error(`Invalid Option: to must be a positive integer greater than 0, got ${JSON.stringify(opts.to)}`);
      }
    }else {
      throw new Error(`Invalid Option: to must be an integer, got ${JSON.stringify(opts.to)}`);
    }
  }
  // Normalize option `to_line`
  if(options.to_line === undefined || options.to_line === null){
    options.to_line = -1;
  }else {
    if(typeof options.to_line === 'string' && /\d+/.test(options.to_line)){
      options.to_line = parseInt(options.to_line);
    }
    if(Number.isInteger(options.to_line)){
      if(options.to_line <= 0){
        throw new Error(`Invalid Option: to_line must be a positive integer greater than 0, got ${JSON.stringify(opts.to_line)}`);
      }
    }else {
      throw new Error(`Invalid Option: to_line must be an integer, got ${JSON.stringify(opts.to_line)}`);
    }
  }
  return options;
};

const isRecordEmpty = function(record){
  return record.every((field) => field == null || field.toString && field.toString().trim() === '');
};

const cr = 13; // `\r`, carriage return, 0x0D in hexadécimal, 13 in decimal
const nl = 10; // `\n`, newline, 0x0A in hexadecimal, 10 in decimal

const boms = {
  // Note, the following are equals:
  // Buffer.from("\ufeff")
  // Buffer.from([239, 187, 191])
  // Buffer.from('EFBBBF', 'hex')
  'utf8': Buffer.from([239, 187, 191]),
  // Note, the following are equals:
  // Buffer.from "\ufeff", 'utf16le
  // Buffer.from([255, 254])
  'utf16le': Buffer.from([255, 254])
};

const transform = function(original_options = {}) {
  const info = {
    bytes: 0,
    comment_lines: 0,
    empty_lines: 0,
    invalid_field_length: 0,
    lines: 1,
    records: 0
  };
  const options = normalize_options(original_options);
  return {
    info: info,
    original_options: original_options,
    options: options,
    state: init_state(options),
    __needMoreData: function(i, bufLen, end){
      if(end) return false;
      const {encoding, escape, quote} = this.options;
      const {quoting, needMoreDataSize, recordDelimiterMaxLength} = this.state;
      const numOfCharLeft = bufLen - i - 1;
      const requiredLength = Math.max(
        needMoreDataSize,
        // Skip if the remaining buffer smaller than record delimiter
        // If "record_delimiter" is yet to be discovered:
        // 1. It is equals to `[]` and "recordDelimiterMaxLength" equals `0`
        // 2. We set the length to windows line ending in the current encoding
        // Note, that encoding is known from user or bom discovery at that point
        // recordDelimiterMaxLength,
        recordDelimiterMaxLength === 0 ? Buffer.from('\r\n', encoding).length : recordDelimiterMaxLength,
        // Skip if remaining buffer can be an escaped quote
        quoting ? ((escape === null ? 0 : escape.length) + quote.length) : 0,
        // Skip if remaining buffer can be record delimiter following the closing quote
        quoting ? (quote.length + recordDelimiterMaxLength) : 0,
      );
      return numOfCharLeft < requiredLength;
    },
    // Central parser implementation
    parse: function(nextBuf, end, push, close){
      const {bom, comment_no_infix, encoding, from_line, ltrim, max_record_size,raw, relax_quotes, rtrim, skip_empty_lines, to, to_line} = this.options;
      let {comment, escape, quote, record_delimiter} = this.options;
      const {bomSkipped, previousBuf, rawBuffer, escapeIsQuote} = this.state;
      let buf;
      if(previousBuf === undefined){
        if(nextBuf === undefined){
          // Handle empty string
          close();
          return;
        }else {
          buf = nextBuf;
        }
      }else if(previousBuf !== undefined && nextBuf === undefined){
        buf = previousBuf;
      }else {
        buf = Buffer.concat([previousBuf, nextBuf]);
      }
      // Handle UTF BOM
      if(bomSkipped === false){
        if(bom === false){
          this.state.bomSkipped = true;
        }else if(buf.length < 3){
          // No enough data
          if(end === false){
            // Wait for more data
            this.state.previousBuf = buf;
            return;
          }
        }else {
          for(const encoding in boms){
            if(boms[encoding].compare(buf, 0, boms[encoding].length) === 0){
              // Skip BOM
              const bomLength = boms[encoding].length;
              this.state.bufBytesStart += bomLength;
              buf = buf.slice(bomLength);
              // Renormalize original options with the new encoding
              this.options = normalize_options({...this.original_options, encoding: encoding});
              // Options will re-evaluate the Buffer with the new encoding
              ({comment, escape, quote } = this.options);
              break;
            }
          }
          this.state.bomSkipped = true;
        }
      }
      const bufLen = buf.length;
      let pos;
      for(pos = 0; pos < bufLen; pos++){
        // Ensure we get enough space to look ahead
        // There should be a way to move this out of the loop
        if(this.__needMoreData(pos, bufLen, end)){
          break;
        }
        if(this.state.wasRowDelimiter === true){
          this.info.lines++;
          this.state.wasRowDelimiter = false;
        }
        if(to_line !== -1 && this.info.lines > to_line){
          this.state.stop = true;
          close();
          return;
        }
        // Auto discovery of record_delimiter, unix, mac and windows supported
        if(this.state.quoting === false && record_delimiter.length === 0){
          const record_delimiterCount = this.__autoDiscoverRecordDelimiter(buf, pos);
          if(record_delimiterCount){
            record_delimiter = this.options.record_delimiter;
          }
        }
        const chr = buf[pos];
        if(raw === true){
          rawBuffer.append(chr);
        }
        if((chr === cr || chr === nl) && this.state.wasRowDelimiter === false){
          this.state.wasRowDelimiter = true;
        }
        // Previous char was a valid escape char
        // treat the current char as a regular char
        if(this.state.escaping === true){
          this.state.escaping = false;
        }else {
          // Escape is only active inside quoted fields
          // We are quoting, the char is an escape chr and there is a chr to escape
          // if(escape !== null && this.state.quoting === true && chr === escape && pos + 1 < bufLen){
          if(escape !== null && this.state.quoting === true && this.__isEscape(buf, pos, chr) && pos + escape.length < bufLen){
            if(escapeIsQuote){
              if(this.__isQuote(buf, pos+escape.length)){
                this.state.escaping = true;
                pos += escape.length - 1;
                continue;
              }
            }else {
              this.state.escaping = true;
              pos += escape.length - 1;
              continue;
            }
          }
          // Not currently escaping and chr is a quote
          // TODO: need to compare bytes instead of single char
          if(this.state.commenting === false && this.__isQuote(buf, pos)){
            if(this.state.quoting === true){
              const nextChr = buf[pos+quote.length];
              const isNextChrTrimable = rtrim && this.__isCharTrimable(buf, pos+quote.length);
              const isNextChrComment = comment !== null && this.__compareBytes(comment, buf, pos+quote.length, nextChr);
              const isNextChrDelimiter = this.__isDelimiter(buf, pos+quote.length, nextChr);
              const isNextChrRecordDelimiter = record_delimiter.length === 0 ? this.__autoDiscoverRecordDelimiter(buf, pos+quote.length) : this.__isRecordDelimiter(nextChr, buf, pos+quote.length);
              // Escape a quote
              // Treat next char as a regular character
              if(escape !== null && this.__isEscape(buf, pos, chr) && this.__isQuote(buf, pos + escape.length)){
                pos += escape.length - 1;
              }else if(!nextChr || isNextChrDelimiter || isNextChrRecordDelimiter || isNextChrComment || isNextChrTrimable){
                this.state.quoting = false;
                this.state.wasQuoting = true;
                pos += quote.length - 1;
                continue;
              }else if(relax_quotes === false){
                const err = this.__error(
                  new CsvError('CSV_INVALID_CLOSING_QUOTE', [
                    'Invalid Closing Quote:',
                    `got "${String.fromCharCode(nextChr)}"`,
                    `at line ${this.info.lines}`,
                    'instead of delimiter, record delimiter, trimable character',
                    '(if activated) or comment',
                  ], this.options, this.__infoField())
                );
                if(err !== undefined) return err;
              }else {
                this.state.quoting = false;
                this.state.wasQuoting = true;
                this.state.field.prepend(quote);
                pos += quote.length - 1;
              }
            }else {
              if(this.state.field.length !== 0){
                // In relax_quotes mode, treat opening quote preceded by chrs as regular
                if(relax_quotes === false){
                  const info = this.__infoField();
                  const bom = Object.keys(boms).map(b => boms[b].equals(this.state.field.toString()) ? b : false).filter(Boolean)[0];
                  const err = this.__error(
                    new CsvError('INVALID_OPENING_QUOTE', [
                      'Invalid Opening Quote:',
                      `a quote is found on field ${JSON.stringify(info.column)} at line ${info.lines}, value is ${JSON.stringify(this.state.field.toString(encoding))}`,
                      bom ? `(${bom} bom)` : undefined
                    ], this.options, info, {
                      field: this.state.field,
                    })
                  );
                  if(err !== undefined) return err;
                }
              }else {
                this.state.quoting = true;
                pos += quote.length - 1;
                continue;
              }
            }
          }
          if(this.state.quoting === false){
            const recordDelimiterLength = this.__isRecordDelimiter(chr, buf, pos);
            if(recordDelimiterLength !== 0){
              // Do not emit comments which take a full line
              const skipCommentLine = this.state.commenting && (this.state.wasQuoting === false && this.state.record.length === 0 && this.state.field.length === 0);
              if(skipCommentLine){
                this.info.comment_lines++;
                // Skip full comment line
              }else {
                // Activate records emition if above from_line
                if(this.state.enabled === false && this.info.lines + (this.state.wasRowDelimiter === true ? 1: 0) >= from_line){
                  this.state.enabled = true;
                  this.__resetField();
                  this.__resetRecord();
                  pos += recordDelimiterLength - 1;
                  continue;
                }
                // Skip if line is empty and skip_empty_lines activated
                if(skip_empty_lines === true && this.state.wasQuoting === false && this.state.record.length === 0 && this.state.field.length === 0){
                  this.info.empty_lines++;
                  pos += recordDelimiterLength - 1;
                  continue;
                }
                this.info.bytes = this.state.bufBytesStart + pos;
                const errField = this.__onField();
                if(errField !== undefined) return errField;
                this.info.bytes = this.state.bufBytesStart + pos + recordDelimiterLength;
                const errRecord = this.__onRecord(push);
                if(errRecord !== undefined) return errRecord;
                if(to !== -1 && this.info.records >= to){
                  this.state.stop = true;
                  close();
                  return;
                }
              }
              this.state.commenting = false;
              pos += recordDelimiterLength - 1;
              continue;
            }
            if(this.state.commenting){
              continue;
            }
            if(comment !== null && (comment_no_infix === false || (this.state.record.length === 0 && this.state.field.length === 0))) {
              const commentCount = this.__compareBytes(comment, buf, pos, chr);
              if(commentCount !== 0){
                this.state.commenting = true;
                continue;
              }
            }
            const delimiterLength = this.__isDelimiter(buf, pos, chr);
            if(delimiterLength !== 0){
              this.info.bytes = this.state.bufBytesStart + pos;
              const errField = this.__onField();
              if(errField !== undefined) return errField;
              pos += delimiterLength - 1;
              continue;
            }
          }
        }
        if(this.state.commenting === false){
          if(max_record_size !== 0 && this.state.record_length + this.state.field.length > max_record_size){
            return this.__error(
              new CsvError('CSV_MAX_RECORD_SIZE', [
                'Max Record Size:',
                'record exceed the maximum number of tolerated bytes',
                `of ${max_record_size}`,
                `at line ${this.info.lines}`,
              ], this.options, this.__infoField())
            );
          }
        }
        const lappend = ltrim === false || this.state.quoting === true || this.state.field.length !== 0 || !this.__isCharTrimable(buf, pos);
        // rtrim in non quoting is handle in __onField
        const rappend = rtrim === false || this.state.wasQuoting === false;
        if(lappend === true && rappend === true){
          this.state.field.append(chr);
        }else if(rtrim === true && !this.__isCharTrimable(buf, pos)){
          return this.__error(
            new CsvError('CSV_NON_TRIMABLE_CHAR_AFTER_CLOSING_QUOTE', [
              'Invalid Closing Quote:',
              'found non trimable byte after quote',
              `at line ${this.info.lines}`,
            ], this.options, this.__infoField())
          );
        }else {
          if(lappend === false){
            pos += this.__isCharTrimable(buf, pos) - 1;
          }
          continue;
        }
      }
      if(end === true){
        // Ensure we are not ending in a quoting state
        if(this.state.quoting === true){
          const err = this.__error(
            new CsvError('CSV_QUOTE_NOT_CLOSED', [
              'Quote Not Closed:',
              `the parsing is finished with an opening quote at line ${this.info.lines}`,
            ], this.options, this.__infoField())
          );
          if(err !== undefined) return err;
        }else {
          // Skip last line if it has no characters
          if(this.state.wasQuoting === true || this.state.record.length !== 0 || this.state.field.length !== 0){
            this.info.bytes = this.state.bufBytesStart + pos;
            const errField = this.__onField();
            if(errField !== undefined) return errField;
            const errRecord = this.__onRecord(push);
            if(errRecord !== undefined) return errRecord;
          }else if(this.state.wasRowDelimiter === true){
            this.info.empty_lines++;
          }else if(this.state.commenting === true){
            this.info.comment_lines++;
          }
        }
      }else {
        this.state.bufBytesStart += pos;
        this.state.previousBuf = buf.slice(pos);
      }
      if(this.state.wasRowDelimiter === true){
        this.info.lines++;
        this.state.wasRowDelimiter = false;
      }
    },
    __onRecord: function(push){
      const {columns, group_columns_by_name, encoding, info, from, relax_column_count, relax_column_count_less, relax_column_count_more, raw, skip_records_with_empty_values} = this.options;
      const {enabled, record} = this.state;
      if(enabled === false){
        return this.__resetRecord();
      }
      // Convert the first line into column names
      const recordLength = record.length;
      if(columns === true){
        if(skip_records_with_empty_values === true && isRecordEmpty(record)){
          this.__resetRecord();
          return;
        }
        return this.__firstLineToColumns(record);
      }
      if(columns === false && this.info.records === 0){
        this.state.expectedRecordLength = recordLength;
      }
      if(recordLength !== this.state.expectedRecordLength){
        const err = columns === false ?
          new CsvError('CSV_RECORD_INCONSISTENT_FIELDS_LENGTH', [
            'Invalid Record Length:',
            `expect ${this.state.expectedRecordLength},`,
            `got ${recordLength} on line ${this.info.lines}`,
          ], this.options, this.__infoField(), {
            record: record,
          })
          :
          new CsvError('CSV_RECORD_INCONSISTENT_COLUMNS', [
            'Invalid Record Length:',
            `columns length is ${columns.length},`, // rename columns
            `got ${recordLength} on line ${this.info.lines}`,
          ], this.options, this.__infoField(), {
            record: record,
          });
        if(relax_column_count === true ||
          (relax_column_count_less === true && recordLength < this.state.expectedRecordLength) ||
          (relax_column_count_more === true && recordLength > this.state.expectedRecordLength)){
          this.info.invalid_field_length++;
          this.state.error = err;
        // Error is undefined with skip_records_with_error
        }else {
          const finalErr = this.__error(err);
          if(finalErr) return finalErr;
        }
      }
      if(skip_records_with_empty_values === true && isRecordEmpty(record)){
        this.__resetRecord();
        return;
      }
      if(this.state.recordHasError === true){
        this.__resetRecord();
        this.state.recordHasError = false;
        return;
      }
      this.info.records++;
      if(from === 1 || this.info.records >= from){
        const {objname} = this.options;
        // With columns, records are object
        if(columns !== false){
          const obj = {};
          // Transform record array to an object
          for(let i = 0, l = record.length; i < l; i++){
            if(columns[i] === undefined || columns[i].disabled) continue;
            // Turn duplicate columns into an array
            if (group_columns_by_name === true && obj[columns[i].name] !== undefined) {
              if (Array.isArray(obj[columns[i].name])) {
                obj[columns[i].name] = obj[columns[i].name].concat(record[i]);
              } else {
                obj[columns[i].name] = [obj[columns[i].name], record[i]];
              }
            } else {
              obj[columns[i].name] = record[i];
            }
          }
          // Without objname (default)
          if(raw === true || info === true){
            const extRecord = Object.assign(
              {record: obj},
              (raw === true ? {raw: this.state.rawBuffer.toString(encoding)}: {}),
              (info === true ? {info: this.__infoRecord()}: {})
            );
            const err = this.__push(
              objname === undefined ? extRecord : [obj[objname], extRecord]
              , push);
            if(err){
              return err;
            }
          }else {
            const err = this.__push(
              objname === undefined ? obj : [obj[objname], obj]
              , push);
            if(err){
              return err;
            }
          }
        // Without columns, records are array
        }else {
          if(raw === true || info === true){
            const extRecord = Object.assign(
              {record: record},
              raw === true ? {raw: this.state.rawBuffer.toString(encoding)}: {},
              info === true ? {info: this.__infoRecord()}: {}
            );
            const err = this.__push(
              objname === undefined ? extRecord : [record[objname], extRecord]
              , push);
            if(err){
              return err;
            }
          }else {
            const err = this.__push(
              objname === undefined ? record : [record[objname], record]
              , push);
            if(err){
              return err;
            }
          }
        }
      }
      this.__resetRecord();
    },
    __firstLineToColumns: function(record){
      const {firstLineToHeaders} = this.state;
      try{
        const headers = firstLineToHeaders === undefined ? record : firstLineToHeaders.call(null, record);
        if(!Array.isArray(headers)){
          return this.__error(
            new CsvError('CSV_INVALID_COLUMN_MAPPING', [
              'Invalid Column Mapping:',
              'expect an array from column function,',
              `got ${JSON.stringify(headers)}`
            ], this.options, this.__infoField(), {
              headers: headers,
            })
          );
        }
        const normalizedHeaders = normalize_columns_array(headers);
        this.state.expectedRecordLength = normalizedHeaders.length;
        this.options.columns = normalizedHeaders;
        this.__resetRecord();
        return;
      }catch(err){
        return err;
      }
    },
    __resetRecord: function(){
      if(this.options.raw === true){
        this.state.rawBuffer.reset();
      }
      this.state.error = undefined;
      this.state.record = [];
      this.state.record_length = 0;
    },
    __onField: function(){
      const {cast, encoding, rtrim, max_record_size} = this.options;
      const {enabled, wasQuoting} = this.state;
      // Short circuit for the from_line options
      if(enabled === false){
        return this.__resetField();
      }
      let field = this.state.field.toString(encoding);
      if(rtrim === true && wasQuoting === false){
        field = field.trimRight();
      }
      if(cast === true){
        const [err, f] = this.__cast(field);
        if(err !== undefined) return err;
        field = f;
      }
      this.state.record.push(field);
      // Increment record length if record size must not exceed a limit
      if(max_record_size !== 0 && typeof field === 'string'){
        this.state.record_length += field.length;
      }
      this.__resetField();
    },
    __resetField: function(){
      this.state.field.reset();
      this.state.wasQuoting = false;
    },
    __push: function(record, push){
      const {on_record} = this.options;
      if(on_record !== undefined){
        const info = this.__infoRecord();
        try{
          record = on_record.call(null, record, info);
        }catch(err){
          return err;
        }
        if(record === undefined || record === null){ return; }
      }
      push(record);
    },
    // Return a tuple with the error and the casted value
    __cast: function(field){
      const {columns, relax_column_count} = this.options;
      const isColumns = Array.isArray(columns);
      // Dont loose time calling cast
      // because the final record is an object
      // and this field can't be associated to a key present in columns
      if(isColumns === true && relax_column_count && this.options.columns.length <= this.state.record.length){
        return [undefined, undefined];
      }
      if(this.state.castField !== null){
        try{
          const info = this.__infoField();
          return [undefined, this.state.castField.call(null, field, info)];
        }catch(err){
          return [err];
        }
      }
      if(this.__isFloat(field)){
        return [undefined, parseFloat(field)];
      }else if(this.options.cast_date !== false){
        const info = this.__infoField();
        return [undefined, this.options.cast_date.call(null, field, info)];
      }
      return [undefined, field];
    },
    // Helper to test if a character is a space or a line delimiter
    __isCharTrimable: function(buf, pos){
      const isTrim = (buf, pos) => {
        const {timchars} = this.state;
        loop1: for(let i = 0; i < timchars.length; i++){
          const timchar = timchars[i];
          for(let j = 0; j < timchar.length; j++){
            if(timchar[j] !== buf[pos+j]) continue loop1;
          }
          return timchar.length;
        }
        return 0;
      };
      return isTrim(buf, pos);
    },
    // Keep it in case we implement the `cast_int` option
    // __isInt(value){
    //   // return Number.isInteger(parseInt(value))
    //   // return !isNaN( parseInt( obj ) );
    //   return /^(\-|\+)?[1-9][0-9]*$/.test(value)
    // }
    __isFloat: function(value){
      return (value - parseFloat(value) + 1) >= 0; // Borrowed from jquery
    },
    __compareBytes: function(sourceBuf, targetBuf, targetPos, firstByte){
      if(sourceBuf[0] !== firstByte) return 0;
      const sourceLength = sourceBuf.length;
      for(let i = 1; i < sourceLength; i++){
        if(sourceBuf[i] !== targetBuf[targetPos+i]) return 0;
      }
      return sourceLength;
    },
    __isDelimiter: function(buf, pos, chr){
      const {delimiter, ignore_last_delimiters} = this.options;
      if(ignore_last_delimiters === true && this.state.record.length === this.options.columns.length - 1){
        return 0;
      }else if(ignore_last_delimiters !== false && typeof ignore_last_delimiters === 'number' && this.state.record.length === ignore_last_delimiters - 1){
        return 0;
      }
      loop1: for(let i = 0; i < delimiter.length; i++){
        const del = delimiter[i];
        if(del[0] === chr){
          for(let j = 1; j < del.length; j++){
            if(del[j] !== buf[pos+j]) continue loop1;
          }
          return del.length;
        }
      }
      return 0;
    },
    __isRecordDelimiter: function(chr, buf, pos){
      const {record_delimiter} = this.options;
      const recordDelimiterLength = record_delimiter.length;
      loop1: for(let i = 0; i < recordDelimiterLength; i++){
        const rd = record_delimiter[i];
        const rdLength = rd.length;
        if(rd[0] !== chr){
          continue;
        }
        for(let j = 1; j < rdLength; j++){
          if(rd[j] !== buf[pos+j]){
            continue loop1;
          }
        }
        return rd.length;
      }
      return 0;
    },
    __isEscape: function(buf, pos, chr){
      const {escape} = this.options;
      if(escape === null) return false;
      const l = escape.length;
      if(escape[0] === chr){
        for(let i = 0; i < l; i++){
          if(escape[i] !== buf[pos+i]){
            return false;
          }
        }
        return true;
      }
      return false;
    },
    __isQuote: function(buf, pos){
      const {quote} = this.options;
      if(quote === null) return false;
      const l = quote.length;
      for(let i = 0; i < l; i++){
        if(quote[i] !== buf[pos+i]){
          return false;
        }
      }
      return true;
    },
    __autoDiscoverRecordDelimiter: function(buf, pos){
      const { encoding } = this.options;
      // Note, we don't need to cache this information in state,
      // It is only called on the first line until we find out a suitable
      // record delimiter.
      const rds = [
        // Important, the windows line ending must be before mac os 9
        Buffer.from('\r\n', encoding),
        Buffer.from('\n', encoding),
        Buffer.from('\r', encoding),
      ];
      loop: for(let i = 0; i < rds.length; i++){
        const l = rds[i].length;
        for(let j = 0; j < l; j++){
          if(rds[i][j] !== buf[pos + j]){
            continue loop;
          }
        }
        this.options.record_delimiter.push(rds[i]);
        this.state.recordDelimiterMaxLength = rds[i].length;
        return rds[i].length;
      }
      return 0;
    },
    __error: function(msg){
      const {encoding, raw, skip_records_with_error} = this.options;
      const err = typeof msg === 'string' ? new Error(msg) : msg;
      if(skip_records_with_error){
        this.state.recordHasError = true;
        if(this.options.on_skip !== undefined){
          this.options.on_skip(err, raw ? this.state.rawBuffer.toString(encoding) : undefined);
        }
        // this.emit('skip', err, raw ? this.state.rawBuffer.toString(encoding) : undefined);
        return undefined;
      }else {
        return err;
      }
    },
    __infoDataSet: function(){
      return {
        ...this.info,
        columns: this.options.columns
      };
    },
    __infoRecord: function(){
      const {columns, raw, encoding} = this.options;
      return {
        ...this.__infoDataSet(),
        error: this.state.error,
        header: columns === true,
        index: this.state.record.length,
        raw: raw ? this.state.rawBuffer.toString(encoding) : undefined
      };
    },
    __infoField: function(){
      const {columns} = this.options;
      const isColumns = Array.isArray(columns);
      return {
        ...this.__infoRecord(),
        column: isColumns === true ?
          (columns.length > this.state.record.length ?
            columns[this.state.record.length].name :
            null
          ) :
          this.state.record.length,
        quoting: this.state.wasQuoting,
      };
    }
  };
};

class Parser extends stream.Transform {
  constructor(opts = {}){
    super({...{readableObjectMode: true}, ...opts, encoding: null});
    this.api = transform({on_skip: (err, chunk) => {
      this.emit('skip', err, chunk);
    }, ...opts});
    // Backward compatibility
    this.state = this.api.state;
    this.options = this.api.options;
    this.info = this.api.info;
  }
  // Implementation of `Transform._transform`
  _transform(buf, _, callback){
    if(this.state.stop === true){
      return;
    }
    const err = this.api.parse(buf, false, (record) => {
      this.push(record);
    }, () => {
      this.push(null);
      this.end();
      // Fix #333 and break #410
      //   ko: api.stream.iterator.coffee
      //   ko with v21.4.0, ok with node v20.5.1: api.stream.finished # aborted (with generate())
      //   ko: api.stream.finished # aborted (with Readable)
      // this.destroy()
      // Fix #410 and partially break #333
      //   ok: api.stream.iterator.coffee
      //   ok: api.stream.finished # aborted (with generate())
      //   broken: api.stream.finished # aborted (with Readable)
      this.on('end', this.destroy);
    });
    if(err !== undefined){
      this.state.stop = true;
    }
    callback(err);
  }
  // Implementation of `Transform._flush`
  _flush(callback){
    if(this.state.stop === true){
      return;
    }
    const err = this.api.parse(undefined, true, (record) => {
      this.push(record);
    }, () => {
      this.push(null);
      this.on('end', this.destroy);
    });
    callback(err);
  }
}

const parse = function(){
  let data, options, callback;
  for(const i in arguments){
    const argument = arguments[i];
    const type = typeof argument;
    if(data === undefined && (typeof argument === 'string' || Buffer.isBuffer(argument))){
      data = argument;
    }else if(options === undefined && is_object(argument)){
      options = argument;
    }else if(callback === undefined && type === 'function'){
      callback = argument;
    }else {
      throw new CsvError('CSV_INVALID_ARGUMENT', [
        'Invalid argument:',
        `got ${JSON.stringify(argument)} at index ${i}`
      ], options || {});
    }
  }
  const parser = new Parser(options);
  if(callback){
    const records = options === undefined || options.objname === undefined ? [] : {};
    parser.on('readable', function(){
      let record;
      while((record = this.read()) !== null){
        if(options === undefined || options.objname === undefined){
          records.push(record);
        }else {
          records[record[0]] = record[1];
        }
      }
    });
    parser.on('error', function(err){
      callback(err, undefined, parser.api.__infoDataSet());
    });
    parser.on('end', function(){
      callback(undefined, records, parser.api.__infoDataSet());
    });
  }
  if(data !== undefined){
    const writer = function(){
      parser.write(data);
      parser.end();
    };
    // Support Deno, Rollup doesnt provide a shim for setImmediate
    if(typeof setImmediate === 'function'){
      setImmediate(writer);
    }else {
      setTimeout(writer, 0);
    }
  }
  return parser;
};

exports.CsvError = CsvError;
exports.Parser = Parser;
exports.parse = parse;