//@tag foundation,core
//@require ../version/Version.js

/**
 * @class Ext.String
 *
 * A collection of useful static methods to deal with strings.
 * @singleton
 */

Ext.String = (function() {
    var trimRegex     = /^[\x09\x0a\x0b\x0c\x0d\x20\xa0\u1680\u180e\u2000\u2001\u2002\u2003\u2004\u2005\u2006\u2007\u2008\u2009\u200a\u2028\u2029\u202f\u205f\u3000]+|[\x09\x0a\x0b\x0c\x0d\x20\xa0\u1680\u180e\u2000\u2001\u2002\u2003\u2004\u2005\u2006\u2007\u2008\u2009\u200a\u2028\u2029\u202f\u205f\u3000]+$/g,
        escapeRe      = /('|\\)/g,
        formatRe      = /\{(\d+)\}/g,
        escapeRegexRe = /([-.*+?\^${}()|\[\]\/\\])/g,
        basicTrimRe   = /^\s+|\s+$/g,
        whitespaceRe  = /\s+/,
        varReplace    = /(^[^a-z]*|[^\w])/gi,
        charToEntity,
        entityToChar,
        charToEntityRegex,
        entityToCharRegex,
        htmlEncodeReplaceFn = function(match, capture) {
            return charToEntity[capture];
        },
        htmlDecodeReplaceFn = function(match, capture) {
            return (capture in entityToChar) ? entityToChar[capture] : String.fromCharCode(parseInt(capture.substr(2), 10));
        },
        boundsCheck = function(s, other){
            if (s === null || s === undefined || other === null || other === undefined) {
                return false;
            }
            
            return other.length <= s.length; 
        };

    return {
        
        /**
         * Inserts a substring into a string.
         * @param {String} s The original string.
         * @param {String} value The substring to insert.
         * @param {Number} index The index to insert the substring. Negative indexes will insert from the end of
         * the string. Example: 
         *
         *     Ext.String.insert("abcdefg", "h", -1); // abcdefhg
         *
         * @return {String} The value with the inserted substring
         */
        insert: function(s, value, index) {
            if (!s) {
                return value;
            }
            
            if (!value) {
                return s;
            }
            
            var len = s.length;
            
            if (!index && index !== 0) {
                index = len;
            }
            
            if (index < 0) {
                index *= -1;
                if (index >= len) {
                    // negative overflow, insert at start
                    index = 0;
                } else {
                    index = len - index;
                }
            }
            
            if (index === 0) {
                s = value + s;
            } else if (index >= s.length) {
                s += value;
            } else {
                s = s.substr(0, index) + value + s.substr(index);
            }
            return s;
        },
        
        /**
         * Checks if a string starts with a substring
         * @param {String} s The original string
         * @param {String} start The substring to check
         * @param {Boolean} [ignoreCase=false] True to ignore the case in the comparison
         */
        startsWith: function(s, start, ignoreCase){
            var result = boundsCheck(s, start);
            
            if (result) {
                if (ignoreCase) {
                    s = s.toLowerCase();
                    start = start.toLowerCase();
                }
                result = s.lastIndexOf(start, 0) === 0;
            }
            return result;
        },
        
        /**
         * Checks if a string ends with a substring
         * @param {String} s The original string
         * @param {String} start The substring to check
         * @param {Boolean} [ignoreCase=false] True to ignore the case in the comparison
         */
        endsWith: function(s, end, ignoreCase){
            var result = boundsCheck(s, end);
            
            if (result) {
                if (ignoreCase) {
                    s = s.toLowerCase();
                    end = end.toLowerCase();
                }
                result = s.indexOf(end, s.length - end.length) !== -1;
            }
            return result;
        },

        /**
         * Converts a string of characters into a legal, parse-able JavaScript `var` name as long as the passed
         * string contains at least one alphabetic character. Non alphanumeric characters, and *leading* non alphabetic
         * characters will be removed.
         * @param {String} s A string to be converted into a `var` name.
         * @return {String} A legal JavaScript `var` name.
         */
        createVarName: function(s) {
            return s.replace(varReplace, '');
        },

        /**
         * Convert certain characters (&, <, >, ', and ") to their HTML character equivalents for literal display in web pages.
         * @param {String} value The string to encode.
         * @return {String} The encoded text.
         * @method
         */
        htmlEncode: function(value) {
            return (!value) ? value : String(value).replace(charToEntityRegex, htmlEncodeReplaceFn);
        },

        /**
         * Convert certain characters (&, <, >, ', and ") from their HTML character equivalents.
         * @param {String} value The string to decode.
         * @return {String} The decoded text.
         * @method
         */
        htmlDecode: function(value) {
            return (!value) ? value : String(value).replace(entityToCharRegex, htmlDecodeReplaceFn);
        },

        /**
         * Adds a set of character entity definitions to the set used by
         * {@link Ext.String#htmlEncode} and {@link Ext.String#htmlDecode}.
         *
         * This object should be keyed by the entity name sequence,
         * with the value being the textual representation of the entity.
         *
         *      Ext.String.addCharacterEntities({
         *          '&amp;Uuml;':'Ü',
         *          '&amp;ccedil;':'ç',
         *          '&amp;ntilde;':'ñ',
         *          '&amp;egrave;':'è'
         *      });
         *      var s = Ext.String.htmlEncode("A string with entities: èÜçñ");
         *
         * __Note:__ the values of the character entities defined on this object are expected
         * to be single character values.  As such, the actual values represented by the
         * characters are sensitive to the character encoding of the JavaScript source
         * file when defined in string literal form. Script tags referencing server
         * resources with character entities must ensure that the 'charset' attribute
         * of the script node is consistent with the actual character encoding of the
         * server resource.
         *
         * The set of character entities may be reset back to the default state by using
         * the {@link Ext.String#resetCharacterEntities} method
         *
         * @param {Object} entities The set of character entities to add to the current
         * definitions.
         */
        addCharacterEntities: function(newEntities) {
            var charKeys = [],
                entityKeys = [],
                key, echar;
            for (key in newEntities) {
                echar = newEntities[key];
                entityToChar[key] = echar;
                charToEntity[echar] = key;
                charKeys.push(echar);
                entityKeys.push(key);
            }
            charToEntityRegex = new RegExp('(' + charKeys.join('|') + ')', 'g');
            entityToCharRegex = new RegExp('(' + entityKeys.join('|') + '|&#[0-9]{1,5};' + ')', 'g');
        },

        /**
         * Resets the set of character entity definitions used by
         * {@link Ext.String#htmlEncode} and {@link Ext.String#htmlDecode} back to the
         * default state.
         */
        resetCharacterEntities: function() {
            charToEntity = {};
            entityToChar = {};
            // add the default set
            this.addCharacterEntities({
                '&amp;'     :   '&',
                '&gt;'      :   '>',
                '&lt;'      :   '<',
                '&quot;'    :   '"',
                '&#39;'     :   "'"
            });
        },

        /**
         * Appends content to the query string of a URL, handling logic for whether to place
         * a question mark or ampersand.
         * @param {String} url The URL to append to.
         * @param {String} string The content to append to the URL.
         * @return {String} The resulting URL
         */
        urlAppend : function(url, string) {
            if (!Ext.isEmpty(string)) {
                return url + (url.indexOf('?') === -1 ? '?' : '&') + string;
            }

            return url;
        },

        /**
         * Trims whitespace from either end of a string, leaving spaces within the string intact.  Example:
         *
         *     var s = '  foo bar  ';
         *     alert('-' + s + '-');                   //alerts "- foo bar -"
         *     alert('-' + Ext.String.trim(s) + '-');  //alerts "-foo bar-"
         *
         * @param {String} string The string to trim.
         * @return {String} The trimmed string.
         */
        trim: function(string) {
            return string.replace(trimRegex, "");
        },

        /**
         * Capitalize the given string
         * @param {String} string
         * @return {String}
         */
        capitalize: function(string) {
            return string.charAt(0).toUpperCase() + string.substr(1);
        },

        /**
         * Uncapitalize the given string.
         * @param {String} string
         * @return {String}
         */
        uncapitalize: function(string) {
            return string.charAt(0).toLowerCase() + string.substr(1);
        },

        /**
         * Truncate a string and add an ellipsis ('...') to the end if it exceeds the specified length.
         * @param {String} value The string to truncate.
         * @param {Number} length The maximum length to allow before truncating.
         * @param {Boolean} [word=false] `true` to try to find a common word break.
         * @return {String} The converted text.
         */
        ellipsis: function(value, len, word) {
            if (value && value.length > len) {
                if (word) {
                    var vs = value.substr(0, len - 2),
                    index = Math.max(vs.lastIndexOf(' '), vs.lastIndexOf('.'), vs.lastIndexOf('!'), vs.lastIndexOf('?'));
                    if (index !== -1 && index >= (len - 15)) {
                        return vs.substr(0, index) + "...";
                    }
                }
                return value.substr(0, len - 3) + "...";
            }
            return value;
        },

        /**
         * Escapes the passed string for use in a regular expression.
         * @param {String} string
         * @return {String}
         */
        escapeRegex: function(string) {
            return string.replace(escapeRegexRe, "\\$1");
        },

        /**
         * Escapes the passed string for ' and \
         * @param {String} string The string to escape
         * @return {String} The escaped string
         */
        escape: function(string) {
            return string.replace(escapeRe, "\\$1");
        },

        /**
         * Utility function that allows you to easily switch a string between two alternating values.  The passed value
         * is compared to the current string, and if they are equal, the other value that was passed in is returned.  If
         * they are already different, the first value passed in is returned.  Note that this method returns the new value
         * but does not change the current string.
         *
         *     // alternate sort directions
         *     sort = Ext.String.toggle(sort, 'ASC', 'DESC');
         *
         *     // instead of conditional logic:
         *     sort = (sort === 'ASC' ? 'DESC' : 'ASC');
         *
         * @param {String} string The current string.
         * @param {String} value The value to compare to the current string.
         * @param {String} other The new value to use if the string already equals the first value passed in.
         * @return {String} The new value.
         */
        toggle: function(string, value, other) {
            return string === value ? other : value;
        },

        /**
         * Pads the left side of a string with a specified character.  This is especially useful
         * for normalizing number and date strings.  Example usage:
         *
         *     var s = Ext.String.leftPad('123', 5, '0');
         *     // s now contains the string: '00123'
         *
         * @param {String} string The original string.
         * @param {Number} size The total length of the output string.
         * @param {String} [character=' '] (optional) The character with which to pad the original string.
         * @return {String} The padded string.
         */
        leftPad: function(string, size, character) {
            var result = String(string);
            character = character || " ";
            while (result.length < size) {
                result = character + result;
            }
            return result;
        },

        /**
         * Allows you to define a tokenized string and pass an arbitrary number of arguments to replace the tokens.  Each
         * token must be unique, and must increment in the format {0}, {1}, etc.  Example usage:
         *
         *     var cls = 'my-class',
         *         text = 'Some text';
         *     var s = Ext.String.format('<div class="{0}">{1}</div>', cls, text);
         *     // s now contains the string: '<div class="my-class">Some text</div>'
         *
         * @param {String} string The tokenized string to be formatted.
         * @param {Mixed...} values The values to replace tokens `{0}`, `{1}`, etc in order.
         * @return {String} The formatted string.
         */
        format: function(format) {
            var args = Ext.Array.toArray(arguments, 1);
            return format.replace(formatRe, function(m, i) {
                return args[i];
            });
        },

        /**
         * Returns a string with a specified number of repetitions a given string pattern.
         * The pattern be separated by a different string.
         *
         *      var s = Ext.String.repeat('---', 4); // = '------------'
         *      var t = Ext.String.repeat('--', 3, '/'); // = '--/--/--'
         *
         * @param {String} pattern The pattern to repeat.
         * @param {Number} count The number of times to repeat the pattern (may be 0).
         * @param {String} sep An option string to separate each pattern.
         */
        repeat: function(pattern, count, sep) {
            if (count < 1) {
                count = 0;
            }
            for (var buf = [], i = count; i--; ) {
                buf.push(pattern);
            }
            return buf.join(sep || '');
        },

        /**
         * Splits a string of space separated words into an array, trimming as needed. If the
         * words are already an array, it is returned.
         *
         * @param {String/Array} words
         */
        splitWords: function (words) {
            if (words && typeof words == 'string') {
                return words.replace(basicTrimRe, '').split(whitespaceRe);
            }
            return words || [];
        }
    };
}());

// initialize the default encode / decode entities
Ext.String.resetCharacterEntities();

/**
 * Old alias to {@link Ext.String#htmlEncode}
 * @deprecated Use {@link Ext.String#htmlEncode} instead
 * @method
 * @member Ext
 * @inheritdoc Ext.String#htmlEncode
 */
Ext.htmlEncode = Ext.String.htmlEncode;


/**
 * Old alias to {@link Ext.String#htmlDecode}
 * @deprecated Use {@link Ext.String#htmlDecode} instead
 * @method
 * @member Ext
 * @inheritdoc Ext.String#htmlDecode
 */
Ext.htmlDecode = Ext.String.htmlDecode;

/**
 * Old alias to {@link Ext.String#urlAppend}
 * @deprecated Use {@link Ext.String#urlAppend} instead
 * @method
 * @member Ext
 * @inheritdoc Ext.String#urlAppend
 */
Ext.urlAppend = Ext.String.urlAppend;