HORIZON PROJECT

var baseToString = require('./_baseToString'),

    castSlice = require('./_castSlice'),

    hasUnicode = require('./_hasUnicode'),

    isObject = require('./isObject'),

    isRegExp = require('./isRegExp'),

    stringSize = require('./_stringSize'),

    stringToArray = require('./_stringToArray'),

    toInteger = require('./toInteger'),

    toString = require('./toString');

/** Used as default options for `_.truncate`. */

var DEFAULT_TRUNC_LENGTH = 30,

    DEFAULT_TRUNC_OMISSION = '...';

/** Used to match `RegExp` flags from their coerced string values. */

var reFlags = /\w*$/;

/**

 * Truncates `string` if it's longer than the given maximum string length.

 * The last characters of the truncated string are replaced with the omission

 * string which defaults to "...".

 *

 * @static

 * @memberOf _

 * @since 4.0.0

 * @category String

 * @param {string} [string=''] The string to truncate.

 * @param {Object} [options={}] The options object.

 * @param {number} [options.length=30] The maximum string length.

 * @param {string} [options.omission='...'] The string to indicate text is omitted.

 * @param {RegExp|string} [options.separator] The separator pattern to truncate to.

 * @returns {string} Returns the truncated string.

 * @example

 *

 * _.truncate('hi-diddly-ho there, neighborino');

 * // => 'hi-diddly-ho there, neighbo...'

 *

 * _.truncate('hi-diddly-ho there, neighborino', {

 *   'length': 24,

 *   'separator': ' '

 * });

 * // => 'hi-diddly-ho there,...'

 *

 * _.truncate('hi-diddly-ho there, neighborino', {

 *   'length': 24,

 *   'separator': /,? +/

 * });

 * // => 'hi-diddly-ho there...'

 *

 * _.truncate('hi-diddly-ho there, neighborino', {

 *   'omission': ' [...]'

 * });

 * // => 'hi-diddly-ho there, neig [...]'

 */

function truncate(string, options) {

  var length = DEFAULT_TRUNC_LENGTH,

      omission = DEFAULT_TRUNC_OMISSION;

  if (isObject(options)) {

    var separator = 'separator' in options ? options.separator : separator;

    length = 'length' in options ? toInteger(options.length) : length;

    omission = 'omission' in options ? baseToString(options.omission) : omission;

  }

  string = toString(string);

  var strLength = string.length;

  if (hasUnicode(string)) {

    var strSymbols = stringToArray(string);

    strLength = strSymbols.length;

  }

  if (length >= strLength) {

    return string;

  }

  var end = length - stringSize(omission);

  if (end < 1) {

    return omission;

  }

  var result = strSymbols

    ? castSlice(strSymbols, 0, end).join('')

    : string.slice(0, end);

  if (separator === undefined) {

    return result + omission;

  }

  if (strSymbols) {

    end += (result.length - end);

  }

  if (isRegExp(separator)) {

    if (string.slice(end).search(separator)) {

      var match,

          substring = result;

      if (!separator.global) {

        separator = RegExp(separator.source, toString(reFlags.exec(separator)) + 'g');

      }

      separator.lastIndex = 0;

      while ((match = separator.exec(substring))) {

        var newEnd = match.index;

      }

      result = result.slice(0, newEnd === undefined ? end : newEnd);

    }

  } else if (string.indexOf(baseToString(separator), end) != end) {

    var index = result.lastIndexOf(separator);

    if (index > -1) {

      result = result.slice(0, index);

    }

  }

  return result + omission;

}

module.exports = truncate;