1var baseToString = require('./_baseToString'),
2    castSlice = require('./_castSlice'),
3    hasUnicode = require('./_hasUnicode'),
4    isObject = require('./isObject'),
5    isRegExp = require('./isRegExp'),
6    stringSize = require('./_stringSize'),
7    stringToArray = require('./_stringToArray'),
8    toInteger = require('./toInteger'),
9    toString = require('./toString');
10
11/** Used as default options for `_.truncate`. */
12var DEFAULT_TRUNC_LENGTH = 30,
13    DEFAULT_TRUNC_OMISSION = '...';
14
15/** Used to match `RegExp` flags from their coerced string values. */
16var reFlags = /\w*$/;
17
18/**
19 * Truncates `string` if it's longer than the given maximum string length.
20 * The last characters of the truncated string are replaced with the omission
21 * string which defaults to "...".
22 *
23 * @static
24 * @memberOf _
25 * @since 4.0.0
26 * @category String
27 * @param {string} [string=''] The string to truncate.
28 * @param {Object} [options={}] The options object.
29 * @param {number} [options.length=30] The maximum string length.
30 * @param {string} [options.omission='...'] The string to indicate text is omitted.
31 * @param {RegExp|string} [options.separator] The separator pattern to truncate to.
32 * @returns {string} Returns the truncated string.
33 * @example
34 *
35 * _.truncate('hi-diddly-ho there, neighborino');
36 * // => 'hi-diddly-ho there, neighbo...'
37 *
38 * _.truncate('hi-diddly-ho there, neighborino', {
39 *   'length': 24,
40 *   'separator': ' '
41 * });
42 * // => 'hi-diddly-ho there,...'
43 *
44 * _.truncate('hi-diddly-ho there, neighborino', {
45 *   'length': 24,
46 *   'separator': /,? +/
47 * });
48 * // => 'hi-diddly-ho there...'
49 *
50 * _.truncate('hi-diddly-ho there, neighborino', {
51 *   'omission': ' [...]'
52 * });
53 * // => 'hi-diddly-ho there, neig [...]'
54 */
55function truncate(string, options) {
56  var length = DEFAULT_TRUNC_LENGTH,
57      omission = DEFAULT_TRUNC_OMISSION;
58
59  if (isObject(options)) {
60    var separator = 'separator' in options ? options.separator : separator;
61    length = 'length' in options ? toInteger(options.length) : length;
62    omission = 'omission' in options ? baseToString(options.omission) : omission;
63  }
64  string = toString(string);
65
66  var strLength = string.length;
67  if (hasUnicode(string)) {
68    var strSymbols = stringToArray(string);
69    strLength = strSymbols.length;
70  }
71  if (length >= strLength) {
72    return string;
73  }
74  var end = length - stringSize(omission);
75  if (end < 1) {
76    return omission;
77  }
78  var result = strSymbols
79    ? castSlice(strSymbols, 0, end).join('')
80    : string.slice(0, end);
81
82  if (separator === undefined) {
83    return result + omission;
84  }
85  if (strSymbols) {
86    end += (result.length - end);
87  }
88  if (isRegExp(separator)) {
89    if (string.slice(end).search(separator)) {
90      var match,
91          substring = result;
92
93      if (!separator.global) {
94        separator = RegExp(separator.source, toString(reFlags.exec(separator)) + 'g');
95      }
96      separator.lastIndex = 0;
97      while ((match = separator.exec(substring))) {
98        var newEnd = match.index;
99      }
100      result = result.slice(0, newEnd === undefined ? end : newEnd);
101    }
102  } else if (string.indexOf(baseToString(separator), end) != end) {
103    var index = result.lastIndexOf(separator);
104    if (index > -1) {
105      result = result.slice(0, index);
106    }
107  }
108  return result + omission;
109}
110
111module.exports = truncate;
112