/**
 * JavaScript implementations of various PHP functions.
 */

/**
 * Find position of first occurrence of a string
 * @link http://php.net/manual/en/function.strpos.php
 * @param haystack string
 * @param needle mixed
 * @param offset int[optional]
 * @return int the position as an integer. If needle is
 * not found, strpos will return boolean
 * false.
 */
function strpos (haystack, needle, offset) {
    // http://kevin.vanzonneveld.net
    // +   original by: Kevin van Zonneveld (http://kevin.vanzonneveld.net)
    // +   improved by: Onno Marsman
    // +   bugfixed by: Daniel Esteban
    // +   improved by: Brett Zamir (http://brett-zamir.me)
    // *     example 1: strpos('Kevin van Zonneveld', 'e', 5);
    // *     returns 1: 14

    var i = (haystack+'').indexOf(needle, (offset || 0));
    return i === -1 ? false : i;
}

/**
 * Find position of last occurrence of a char in a string
 * @link http://php.net/manual/en/function.strrpos.php
 * @param haystack string
 * @param needle string
 * @param offset int[optional]
 * @return int
 */
function strrpos (haystack, needle, offset) {
    // http://kevin.vanzonneveld.net
    // +   original by: Kevin van Zonneveld (http://kevin.vanzonneveld.net)
    // +   bugfixed by: Onno Marsman
    // +   input by: saulius
    // +   bugfixed by: Brett Zamir (http://brett-zamir.me)
    // *     example 1: strrpos('Kevin van Zonneveld', 'e');
    // *     returns 1: 16
    // *     example 2: strrpos('somepage.com', '.', false);
    // *     returns 2: 8
    // *     example 3: strrpos('baa', 'a', 3);
    // *     returns 3: false
    // *     example 4: strrpos('baa', 'a', 2);
    // *     returns 4: 2

    var i = -1;
    if (offset) {
        i = (haystack+'').slice(offset).lastIndexOf(needle); // strrpos' offset indicates starting point of range till end,
        // while lastIndexOf's optional 2nd argument indicates ending point of range from the beginning
        if (i !== -1) {
            i += offset;
        }
    }
    else {
        i = (haystack+'').lastIndexOf(needle);
    }
    return i >= 0 ? i : false;
}

/**
 * Return part of a string
 * @link http://php.net/manual/en/function.substr.php
 * @param str string
 * @param start int
 * @param length int[optional]
 * @return string the extracted part of string.
 */
function substr (str, start, len) {
  // Returns part of a string
  //
  // version: 909.322
  // discuss at: http://phpjs.org/functions/substr
  // +     original by: Martijn Wieringa
  // +     bugfixed by: T.Wild
  // +      tweaked by: Onno Marsman
  // +      revised by: Theriault
  // +      improved by: Brett Zamir (http://brett-zamir.me)
  // %    note 1: Handles rare Unicode characters if 'unicode.semantics' ini (PHP6) is set to 'on'
  // *       example 1: substr('abcdef', 0, -1);
  // *       returns 1: 'abcde'
  // *       example 2: substr(2, 0, -6);
  // *       returns 2: false
  // *       example 3: ini_set('unicode.semantics',  'on');
  // *       example 3: substr('a\uD801\uDC00', 0, -1);
  // *       returns 3: 'a'
  // *       example 4: ini_set('unicode.semantics',  'on');
  // *       example 4: substr('a\uD801\uDC00', 0, 2);
  // *       returns 4: 'a\uD801\uDC00'
  // *       example 5: ini_set('unicode.semantics',  'on');
  // *       example 5: substr('a\uD801\uDC00', -1, 1);
  // *       returns 5: '\uD801\uDC00'
  // *       example 6: ini_set('unicode.semantics',  'on');
  // *       example 6: substr('a\uD801\uDC00z\uD801\uDC00', -3, 2);
  // *       returns 6: '\uD801\uDC00z'
  // *       example 7: ini_set('unicode.semantics',  'on');
  // *       example 7: substr('a\uD801\uDC00z\uD801\uDC00', -3, -1)
  // *       returns 7: '\uD801\uDC00z'

//Add: (?) Use unicode.runtime_encoding (e.g., with string wrapped in "binary" or "Binary" class) to
//allow access of binary (see file_get_contents()) by: charCodeAt(x) & 0xFF (see https://developer.mozilla.org/En/Using_XMLHttpRequest ) or require conversion first?

  var i = 0, allBMP = true, es = 0, el = 0, se = 0, ret = '';
  str += '';
  var end = str.length;

  // BEGIN REDUNDANT
  this.php_js = this.php_js || {};
  this.php_js.ini = this.php_js.ini || {};
  // END REDUNDANT
  switch(
      (this.php_js.ini['unicode.semantics'] &&
          this.php_js.ini['unicode.semantics'].local_value.toLowerCase())) {
      case 'on': // Full-blown Unicode including non-Basic-Multilingual-Plane characters
          // strlen()
          for (i=0; i < str.length; i++) {
              if (/[\uD800-\uDBFF]/.test(str.charAt(i)) && /[\uDC00-\uDFFF]/.test(str.charAt(i+1))) {
                  allBMP = false;
                  break;
              }
          }

          if (!allBMP) {
              if (start < 0) {
                  for (i = end - 1, es = (start += end); i >= es; i--) {
                      if (/[\uDC00-\uDFFF]/.test(str.charAt(i)) && /[\uD800-\uDBFF]/.test(str.charAt(i-1))) {
                          start--;
                          es--;
                      }
                  }
              }
              else {
                  var surrogatePairs = /[\uD800-\uDBFF][\uDC00-\uDFFF]/g;
                  while ((surrogatePairs.exec(str)) != null) {
                      var li = surrogatePairs.lastIndex;
                      if (li - 2 < start) {
                          start++;
                      }
                      else {
                          break;
                      }
                  }
              }

              if ((start >= end) || (start < 0)) {
                  return false;
              }
              if (len < 0) {
                  for (i = end - 1, el = (end += len); i >= el; i--) {
                      if (/[\uDC00-\uDFFF]/.test(str.charAt(i)) && /[\uD800-\uDBFF]/.test(str.charAt(i-1))) {
                          end--;
                          el--;
                      }
                  }
                  if (start > end) {
                      return false;
                  }
                  return str.slice(start, end);
              }
              else {
                  se = start + len;
                  for (i = start; i < se; i++) {
                      ret += str.charAt(i);
                      if (/[\uD800-\uDBFF]/.test(str.charAt(i)) && /[\uDC00-\uDFFF]/.test(str.charAt(i+1))) {
                          se++; // Go one further, since one of the "characters" is part of a surrogate pair
                      }
                  }
                  return ret;
              }
              break;
          }
          // Fall-through
      case 'off': // assumes there are no non-BMP characters;
                         //    if there may be such characters, then it is best to turn it on (critical in true XHTML/XML)
      default:
          if (start < 0) {
              start += end;
          }
          end = typeof len === 'undefined' ? end : (len < 0 ? len + end : len + start);
          // PHP returns false if start does not fall within the string.
          // PHP returns false if the calculated end comes before the calculated start.
          // PHP returns an empty string if start and end are the same.
          // Otherwise, PHP returns the portion of the string from start to end.
          return (start >= str.length) || (start < 0) || (start > end) ? !1 : str.slice(start, end);
  }
  return undefined; // Please Netbeans
}